section 1: introduction

Transcription

SECTION 5.4.7: RISK ASSESSMENT – EARTHQUAKE
5.4.7 EARTHQUAKE
This section provides a profile and vulnerability assessment for the earthquake hazard.
HAZARD PROFILE
This section provides profile information including description, extent, location, previous occurrences and
losses and the probability of future occurrences.
Description
An earthquake is the sudden movement of the Earth’s surface caused by the release of stress accumulated
within or along the edge of the Earth’s tectonic plates, a volcanic eruption or by a manmade explosion
(FEMA, 2001; Shedlock and Pakiser, 1997). Most earthquakes occur at the boundaries where the Earth’s
tectonic plates meet (faults); however, less than 10 percent of earthquakes occur within plate interiors.
New Jersey is in an area where plate interior-related earthquakes occur. As plates continue to move and
plate boundaries change over geologic time, weakened boundary regions become part of the interiors of
the plates. These zones of weakness within the continents can cause earthquakes in response to stresses
that originate at the edges of the plate or in the deeper crust (Shedlock and Pakiser, 1997).
The location of an earthquake is commonly described by its focal depth and the geographic position of its
epicenter. The focal depth of an earthquake is the depth from the Earth’s surface to the region where an
earthquake’s energy originates (the focus or hypocenter). The epicenter of an earthquake is the point on
the Earth’s surface directly above the hypocenter (Shedlock and Pakiser, 1997). Earthquakes usually
occur without warning and their effects can impact areas of great distance from the epicenter (FEMA,
2001).
According to the U.S. Geological Society (USGS) Earthquake Hazards Program, an earthquake hazard is
anything associated with an earthquake that may affect resident’s normal activities. This includes surface
faulting, ground shaking, landslides, liquefaction, tectonic deformation, tsunamis, and seiches. A
description of each of these is provided below.

Surface faulting: Displacement that reaches the earth's surface during slip along a fault.
Commonly occurs with shallow earthquakes, those with an epicenter less than 20 kilometers.

Ground motion (shaking): The movement of the earth's surface from earthquakes or explosions.
Ground motion or shaking is produced by waves that are generated by sudden slip on a fault or
sudden pressure at the explosive source and travel through the earth and along its surface.

Landslide: A movement of surface material down a slope.

Liquefaction: A process by which water-saturated sediment temporarily loses strength and acts as
a fluid, like when you wiggle your toes in the wet sand near the water at the beach. This effect
can be caused by earthquake shaking.

Tectonic Deformation: A change in the original shape of a material due to stress and strain.

Tsunami: A sea wave of local or distant origin that results from large-scale seafloor
displacements associated with large earthquakes, major submarine slides, or exploding volcanic
islands.

Seiche: The sloshing of a closed body of water from earthquake shaking (USGS, 2012).
DMA 2000 Hazard Mitigation Plan Update – Somerset County, New Jersey
August 2013
5.4.7-1
Extent
Seismic waves are the vibrations from earthquakes that travel through the Earth and are recorded on
instruments called seismographs. The magnitude or extent of an earthquake is a measured value of the
earthquake size, or amplitude of the seismic waves, using a seismograph. The Richter magnitude scale
(Richter Scale) was developed in 1932 as a mathematical device to compare the sizes of earthquakes
(USGS, 1989). The Richter Scale is the most widely-known scale that measures the magnitude of
earthquakes (Shedlock and Pakiser, 1997; USGS, 2004). It has no upper limit and is not used to express
damage. An earthquake in a densely populated area, which results in many deaths and considerable
damage, may have the same magnitude and shock in a remote area that did not cause any damage (USGS,
1989). Table 5.4.7-1 presents the Richter Scale magnitudes and corresponding earthquake effects.
Table 5.4.7-1. Richter Scale
Richter
Magnitude
2.5 or less
Earthquake Effects
Usually not felt, but can be recorded by seismograph
2.5 to 5.4
Often felt, but only causes minor damage
5.5 to 6.0
Slight damage to buildings and other structures
6.1 to 6.9
May cause a lot of damage in very populated areas
7.0 to 7.9
Major earthquake; serious damage
8.0 or greater
Great earthquake; can totally destroy communities near the epicenter
Source: USGS, 2006
The intensity of an earthquake is based on the observed effects of ground shaking on people, buildings,
and natural features, and varies with location. Intensity is expressed by the Modified Mercalli Scale; a
subjective measure that describes how strong a shock was felt at a particular location (Shedlock and
Pakiser, 1997; USGS, 2004). The Modified Mercalli Scale expresses the intensity of an earthquake’s
effects in a given locality in values ranging from I to XII. Table 5.4.7-2 summarizes earthquake intensity
as expressed by the Modified Mercalli Scale. Table 5.4.7-3 displays the Modified Mercalli Scale and
peak ground acceleration equivalent.
Table 5.4.7-2. Modified Mercalli Intensity Scale
Mercalli
Intensity
Description
I
Felt by very few people; barely noticeable.
II
Felt by few people, especially on upper floors.
III
Noticeable indoors, especially on upper floors, but may not be recognized as an earthquake.
IV
Felt by many indoors, few outdoors. May feel like passing truck.
V
VI
VII
VIII
IX
Felt by almost everyone, some people awakened. Small objects moves, trees and poles may
shake.
Felt by everyone; people have trouble standing. Heavy furniture can move, plaster can fall off walls.
Chimneys may be slightly damaged.
People have difficulty standing. Drivers feel their cars shaking. Some furniture breaks. Loose bricks
fall from buildings. Damage is slight to moderate in well-built buildings; considerable in poorly built
buildings.
Well-built buildings suffer slight damage. Poorly built structures suffer severe damage. Some walls
collapse.
Considerable damage to specially built structures; buildings shift off their foundations. The ground
cracks. Landslides may occur.
August 2013
5.4.7-2
Mercalli
Intensity
X
XI
XII
Source(s):
Description
Most buildings and their foundations are destroyed. Some bridges are destroyed. Dams are
seriously damaged. Large landslides occur. Water is thrown on the banks of canals, rivers, lakes.
The ground cracks in large areas.
Most buildings collapse. Some bridges are destroyed. Large cracks appear in the ground.
Underground pipelines are destroyed.
Almost everything is destroyed. Objects are thrown into the air. The ground moves in waves or
ripples. Large amounts of rock may move.
Michigan Tech University, 2007; Nevada Seismological Laboratory, 1996
Table 5.4.7-3. Modified Mercalli Intensity (MMI) and PGA Equivalents
MMI
Acceleration (%g)
(PGA)
Perceived Shaking
Potential Damage
I
< .17
Not Felt
None
II
.17 – 1.4
Weak
None
None
III
.17 – 1.4
Weak
IV
1.4 – 3.9
Light
None
V
3.9 – 9.2
Moderate
Very Light
VI
9.2 – 18
Strong
Light
VII
18 – 34
Very Strong
Moderate
Severe
Moderate to Heavy
VIII
34 – 65
Source: NYS HMP, 2011
Modern intensity scales use terms that can be physically measured with seismometers, such as the
acceleration, velocity, or displacements (movement) of the ground. The most common physical measure
is Peak Ground Acceleration (PGA). PGA expresses the severity of an earthquake and is a measure of
how hard the earth shakes, or accelerates, in a given geographic area. PGA is expressed as a percent
acceleration force of gravity (%g). For example, 1.0 g PGA in an earthquake (an extremely strong ground
motion) means that objects accelerate sideways at the same rate as if they had been dropped from the
ceiling. 10% g PGA means that the ground acceleration is 10% that of gravity (NJOEM, 2011). Damage
levels experienced in an earthquake vary with the intensity of ground shaking and with the seismic
capacity of structures as noted in Table 5.4.7-4.
Table 5.4.7-4. Damage Levels Experienced in Earthquakes
Ground Motion
Percentage
1-2% g
Below 10% g
10-20% g
20-50% g
50% + g
Explanation of Damages
Motions are widely felt by people; hanging plants and lamps swing strongly, but damage
levels, if any, are usually very low.
Usually cause only slight damage, except in unusually vulnerable facilities.
May cause minor to moderate damage in well-designed buildings, with higher levels of
damage in poorly designed buildings. At this level of ground shaking, only unusually poor
buildings would be subject to potential collapse.
May cause significant damage in some modern buildings and very high levels of damage
(including collapse) in poorly designed buildings.
May causes higher levels of damage in many buildings, even those designed to resist seismic
forces.
Source: NJOEM, 2011
According to USGS Earthquake Hazards Program, PGA maps (also known as earthquake hazard maps)
are used as planning tools when designing buildings, bridges, highways, and utilities so that they can
withstand shaking associated with earthquake events. These maps are also used as planning tools for the
development of building codes that establish construction requirements appropriate to preserve public
safety.
August 2013
5.4.7-3
The USGS updated the National Seismic Hazard Maps in 2008 which superced the 2002 maps. New
seismic, geologic, and geodetic information on earthquake rates and associated ground shaking were
incorporated into these revised maps. The 2008 map represents the best available data as determined by
the USGS (USGS, 2008).
Figure 5.4.7-1. 2008 Seismic Hazard Map, PGA with 10% Probability of Exceedance in 50 Years
Source: USGS, 2008
Note:
The red circle indicates the approximate location of Somerset County. The figure
indicates that the County has PGA of 3-4%g
August 2013
5.4.7-4
Figure 5.4.7-2. 2002 Seismic Hazard Map, PGA with 10% Probability of Exceedance in 50 Years
Source: USGS, 2002
Note:
The red circle indicates the approximate location of Somerset County. The figure
indicates that the County has PGA of 3-4%g
The 2002 Seismic Hazard Map shows that Somerset County has a PGA between 3 and 4%g (Figure 5.4.72). The 2008 Seismic Hazard Map shows that Somerset County has a PGA between 3 and 4%g (Figure
5.4.7-1). These maps are based on peak ground acceleration (%g) with 10% probability of exceedance in
50 years.
In addition to magnitude and intensity, local soil type can substantially affect an earthquake’s risk. The
National Earthquake Hazard Reduction Program (NEHRP) developed five soil classifications that impact
the severity of an earthquake. The soil classification system ranges from A to E, where A represents hard
rock that reduces ground motions from an earthquake and E represents soft soils that amplify and magnify
ground shaking and increase building damage and losses [Tantala et al. (NYCEM), 2003]. As illustrated
in Figure 5.4.7-3, Somerset County is comprised of seismic soil classes B through E. The majority of the
County is soil classs C; however, class D soils are located along riverine reaches.
August 2013
5.4.7-5
Figure 5.4.7-3. Seismic Soils in Somerset County
Source: NJOEM, 2011
Note:
The black circle indicates the location of Somerset County. The County mainly consists of Class C
soils, with narrow bands of Class D and small locations of Class B and Class E.
Table 5.4.7-5. NEHRP Soil Classifications
Soil Classification
Description
Map Color
A
Very hard rock (e.g., granite, gneisses)
Green
B
Sedimentary rock or firm ground
Yellow
C
Stiff clay
Orange
D
Soft to medium clays or sands
E
Source: FEMA, 2007
Soft soil including fill, loose sand, waterfront, lake bed clays
Light Pink
Red
A probabilistic assessment was conducted for the 100-, 500- and 2,500-year mean return periods (MRP)
through a Level 2 analysis in HAZUS-MH 2.1 to analyze the earthquake hazard for Somerset County.
The HAZUS analysis evaluates the statistical likelihood that a specific event will occur and what
consequences will occur. Figure 5.4.7-4 through Figure 5.4.7-6 illustrates the geographic distribution of
PGA (g) across Somerset County or 100-, 500- and 2,500-year MRP events at the Census-tract level.
August 2013
5.4.7-6
Figure 5.4.7-4. Peak Ground Acceleration Modified Mercalli Scale for a 100-Year MRP Earthquake Event
Source: HAZUS 2.1
Note:
The peak ground acceleration for the 100-year MRP is 0.84 to 1.28 %g.
August 2013
5.4.7-7
Figure 5.4.7-5. Peak Ground Acceleration Modified Mercalli Scale for a 500-Year MRP Earthquake Event
Source: HAZUS 2.1
Note:
The peak ground acceleration for the 500-year MRP is between 4.32 and 6.4 %g
August 2013
5.4.7-8
Figure 5.4.7-6. Peak Ground Acceleration Modified Mercalli Scale for a 2,500-Year MRP Earthquake Event
Source: HAZUS 2.1
Note:
The peak ground acceleration for the 2,500-year MRP is between 16.68 and 23.56 %g.
August 2013
5.4.7-9
Location
The U.S., east of the Rocky Mountains, typically has fewer and generally smaller earthquakes than the
western U.S. At least two factors increase the earthquake risk in New Jersey and the eastern U.S.:

Eastern earthquakes affect areas ten times larger than western earthquakes; and

The eastern U.S. and New Jersey are more densely populated than the west, with New Jersey
being the most densely populated state in the country.
Earthquakes typically occur in the northern parts of the State, where significant faults are concentrated.
However, low magnitude events can and do occur in areas throughout the State (NJOEM, 2011). New
Jersey has experienced a few small earthquakes throughout the years. Earthquake damage in New Jersey
has been minor, including items knocked off shelves, cracked plaster and masonry, and fallen chimneys.
These, along with earthquakes originating outside of New Jersey, have produced enough damage to be a
concern of planners and emergency managers (Dombroski, 2005).
According to the New Jersey Geological Survey (NJGS), New Jersey has a similar tectonic setting as
New York City, Boston, and Charleston. All three cities have experienced earthquakes with a magnitude
greater than 5 on the Richter scale. Further explanation of the Richter Scale is located in the Extent
section of this profile. Earthquakes of these magnitudes could occur in New Jersey. The risk of
damaging earthquakes, in combination with New Jersey’s population density and building/structural
value, places New Jersey as the tenth highest among all U.S. states for potential economic loss from
earthquakes [Stanford (NJGS), 2003].
Many faults are located within New Jersey, including the Ramapo Fault which separates the Piedmont
and Highlands Physiographic Provinces (Figure 5.4.7-7). This fault runs 70 miles northeast from Morris
County, New Jersey and the Hudson Highlands to Bear Mountain, New York (Groves, 2001). The fault
is a hairline fracture, 50 miles long, and is located 35 miles from New York City. Seismographic stations,
part of the Advanced National Seismic System, are used to monitor earthquakes and ground motion near
important buildings and critical infrastructure along this fault (Lamont-Doherty, 2004). Numerous minor
earthquakes have been recorded in the Ramapo Fault zone, a 10 to 20 mile wide area lying adjacent to and
west of the actual fault (Dombroski, 2005). Over 25 percent of earthquakes experienced in New Jersey
over the past 200 years had their epicenters within 30 miles of this fault (Groves, 2001). In the 1970s and
1980s, earthquake risk along the Ramapo Fault was studied more in depth due to its close proximity to the
Indian Point, New York Nuclear Power Generating Station.
East of the Rocky Mountains, including New Jersey, earthquake faults do not break the ground surface.
Their focuses are at least a few miles below the Earth’s surface and their locations are determined by
interpreting seismographic records. Geological fault lines seen on the surface today are evidence of
ancient events. The presence or absence of mapped faults does not denote either a seismic hazard or the
lack of one, and earthquakes can occur anywhere in New Jersey (Dombroski, 2005).
The closest plate boundary to the East Coast is the Mid-Atlantic Ridge, which is approximately 2,000
miles to the east of Pennsylvania. Over 200 million years ago, when the continent Pangaea rifted apart
forming the Atlantic Ocean, the Northeast coast of America was a plate boundary. Being at the plate
boundary, many faults were formed in the region. Although these faults are geologically old and are
contained in a passive margin, they act as pre-existing planes of weakness and concentrated strain. When
a strain exceeds the strength of the ancient fault, it ruptures causing an earthquake (Lehigh Earth
Observatory, 2006).
August 2013
5.4.7-10
Figure 5.4.7-7. Physiographic Provinces of New Jersey
Source: NJGS, Date Unknown
Note:
Vast majority of Somerset County is located within the Piedmont Province,
with only the northernmost part in the Highlands.
The Ramapo Fault (Figure 5.4.7-8) is part of a system of northeast striking, southeast-dipping faults,
which runs from southeastern New York State to the Hudson River at Stony Point, through eastern
Pennsylvania and beyond. The fault is a hairline fracture, 50 miles long, and is located 35 miles from
New York City. Seismographic stations, part of the Advanced National Seismic System, are used to
monitor earthquakes and ground motion near important buildings and critical infrastructure along this
fault (Lamont-Doherty, 2004; Pasfield, Unknown). Numerous minor earthquakes have been recorded in
the Ramapo Fault zone, a 10 to 20 mile wide area lying adjacent to and west of the actual fault
(Dombroski, 2005).
August 2013
5.4.7-11
Figure 5.4.7-8. Ramapo Fault Line
Source: Rasmusson, 2003
Figure 5.4.7-9 and Figure 5.4.7-10 show the Ramapo Fault Line and the earthquakes that have occurred in
the surrounding area of the fault.
August 2013
5.4.7-12
Figure 5.4.7-9. Ramapo Fault Line
Source: Groves, 2001
The New York Consortium for Earthquake Mitigation (NYCEM) HAZUS MH study presents the results
of a multi-year study that addresses the risks of an earthquake in the New York City area. The New York
City study area includes parts of northern New Jersey (including Somerset County). The study indicates
a low seismic hazard (infrequent damaging earthquakes), but high seismic risk due to its dense
population, concentration of buildings, vulnerable infrastructure, and substantial economic value [Tantala
et al. (NYCEM), 2003]. A USGS earthquake hazard map (Figure 5.4.7-10) indicates peak ground
acceleration (PGA) with a 10 percent chance of being exceeded over 50 years as highest in northeastern
New Jersey, (dark yellow) (USGS, 2002). Further description of PGA is located in the Extent section of
this profile.
August 2013
5.4.7-13
Figure 5.4.7-10. Earthquakes in New York City and the Surrounding Area, 1627-2003
Source: Lamont-Doherty Earth Observatory, 2004
Note:
The Ramapo Fault System is shown as a red line. Hexagons indicate earthquake events prior to
1970 and circles indicate earthquakes post 1970 (when systematic earthquake monitoring began in
the region). The symbol size is proportional to magnitude.
Previous Occurrences and Losses
Many sources provided historical information regarding previous occurrences and losses associated with
earthquakes throughout the State of New Jersey. Therefore, with so many sources reviewed for the
purpose of this HMP, loss and impact information for many events could vary depending on the sources.
According to the NJGS, there are over 150 records of earthquakes in the State, with most of them
occurring in the northern portion. Most of the earthquake events that have occurred in the State have
been too small to cause damage. Figure 5.4.7-11 shows the locations of these earthquakes and their
corresponding magnitudes.
August 2013
5.4.7-14
Figure 5.4.7-11. Earthquakes Epicentered in New Jersey
Source: NJOEM, 2011
Note:
The figure indicates that Somerset County has experienced six earthquake events.
August 2013
5.4.7-15
Table 5.4.7-16 depicts these earthquakes events. Several of these events were located within the vicinity of Somerset County.
Table 5.4.7-6. Earthquake Occurrences in the New York/New Jersey Area, 1737-2012.
Date(s) of
Event
Magnitude
12/19/1737
5.2
11/30/1783
5.3
1/25/1841
10/26/1845
9/9/1848
3/5/1861
0.0
3.8
4.4
0.0
12/11/1874
3.4
9/10/1877
8/10/1880
0.0
0.0
Greater NYC Area*
North-Central New
Jersey*
West Orange, NJ
Greater NYC Area*
Greater NYC area*
Newark, NJ
Near Nyack and
Tarrytown, NY
Burlington, NJ
Near Morristown, NJ
8/10/1884
5.2
1/4/1885
Location
FEMA
Declaration
Number
N/A
County
Designated?
Source(s)
Lamont-Doherty
NJGS, LamontDoherty
NJGS
Lamont-Doherty
Lamont-Doherty
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Threw down chimneys
2 Foreshocks (11/24 and 11/30) and 1
aftershock (11/30); threw down chimneys
No reference and/or no damage reported.
N/A
N/A
Lamont-Doherty
N/A
N/A
N/A
N/A
NJGS
NJGS
Greater NYC Area
N/A
N/A
3.4
Hudson Valley
N/A
N/A
1 aftershock 9/1/1880.
Threw down chimneys; felt from Virginia to
Maine
9/1/1895
4.1
Near High Bridge, NJ
N/A
N/A
Location determined by fire and aftershock
5/27/1902
8/11/1902
1/20/1905
4/23/1910
11/6/1912
8/5/1919
0.0
0.0
4.5
0.0
0.0
0.0
Bayonne-Wayne, NJ
Bayonne-Wayne, NJ
Greater NYC Area*
Near Atlantic City, NJ
Near Long Beach, NJ
Cinnaminson, NJ
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Probably located offshore
6/1/1927
3.9
Near Asbury Park, NJ
N/A
N/A
High intensity in Asbury Park.
1/25/1933
0.0
N/A
N/A
7/19/1937
3.5
N/A
N/A
One or few earthquakes beneath Long Island
Lamont-Doherty
9/30/1937
5/16/1938
0.0
0.0
Near Trenton, NJ
Western Long Island,
NY
Verona, NJ
Verona, NJ
Lamont-Doherty
NJGS, LamontDoherty
NJGS
NJGS
Lamont-Doherty
NJGS
NJGS
NJGS
NJGS, LamontDoherty
NJGS
N/A
N/A
N/A
N/A
8/23/1938
3.8
NE of New Egypt, NJ
N/A
N/A
8/23/1938
4.0
Freehold, NJ
N/A
N/A
4 aftershocks felt.
NJGS
NJGS
NJGS, LamontDoherty
NJGS
August 2013
N/A
Losses/Impacts
Lamont-Doherty
5.4.7-16
Date(s) of
Event
Magnitude
Location
12/6/1938
9/13/1939
11/15/1939
4/1/1947
10/16/1949
9/3/1951
8/17/1953
3/31/1954
0.0
0.0
3.4
2.7
0.0
3.6
3.2
0.0
3/23/1957
2.9
12/27/1961
2.7
10/13/1962
12/10/1968
4/25/1969
10/6/1969
2/28/1973
7/10/1973
3/11/1976
4/13/1976
12/5/1976
0.0
2.7
0.0
0.0
3.5
2.6
2.8
3.1
0.0
Verona, NJ
Union City, NJ
Salem County, NJ
Pompton Lakes NJ
Hopewell, NJ
Rockland County, NY
Bergen County, NJ
Long Branch, NJ
Schooley's Mountain,
NJ
5 km W of
Flemington, NJ
Pompton Lakes, NJ
SE of Camden, NJ
Near Sussex, NJ
Ogdensburg, NJ
E.OF Wilmington, DE
E.OF Wilmington, DE
Pompton Lakes, NJ
Near Ridgefield, NJ
12/5/1976
1.8
1/21/1977
6/10/1977
7/2/1977
10/27/1977
11/27/1977
2.7
1.1
2.3
1.5
1.8
12/23/1977
2.3
2/15/1978
4/3/1978
5/18/1978
6/16/1978
6/30/1978
1/30/1979
1.6
2.0
1.5
0.0
2.9
3.5
NJ
Lakehurst, NJ
High Bridge, NJ
Hampton, NJ
Sparta, NJ
Oakland, NJ
NJ
Boonton, NJ
Off Sandy Hook
Bloomingdale, NJ
Sparta, NJ
Mahwah-Oakland, NJ
Cheesequake, NJ
FEMA
Declaration
Number
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
County
Designated?
Losses/Impacts
Source(s)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Walls cracked, dishes broke.
NJGS
NJGS
NJGS
NJGS
NJGS
Lamont-Doherty
NJGS
NJGS
NJGS, LamontDoherty
N/A
N/A
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1 aftershock, some damage.
The shock felt widely.
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
N/A
N/A
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
NJGS
NJGS
NJGS
NJGS
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
5 foreshocks 12/4 to12/8 and 5 aftershocks
12/23
1 aftershock on same day.
August 2013
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
5.4.7-17
Date(s) of
Event
2/2/1979
2/23/1979
Magnitude
3/25/1980
4/5/1980
8/2/1980
8/30/1980
3/19/1981
5/18/1981
6/21/1981
4/12/1982
7/29/1982
9/16/1982
2/19/1983
6/1/1983
9/6/1983
9/15/1983
3/12/1984
5/13/1984
6/3/1984
6/6/1984
8/2/1984
8/12/1984
8/12/1984
10/25/1984
12/3/1984
12/13/1984
12/14/1984
12/15/1984
12/17/1984
1.9
2.9
3.1
“Cheesequake
Earthquake”
2.8
2.9
2.8
3.0
2.0
2.1
1.8
2.4
2.4
1.6
2.7
1.5
1.5
1.5
2.0
2.1
1.3
1.7
1.7
2.4
2.1
2.0
1.5
1.7
1.7
1.8
1.6
10/19/1985
4
2/8/1986
2/23/1986
1.7
1.8
3/10/1979
FEMA
Declaration
Number
N/A
N/A
County
Designated?
Losses/Impacts
Source(s)
N/A
N/A
NJGS
NJGS
N/A
N/A
Felt by some people in Manhattan
NJGS, LamontDoherty
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Ardsley, NY
N/A
N/A
Flanders, NJ
Port Murray, NJ
N/A
N/A
N/A
N/A
Many people in the NYC area felt this
earthquake
Location
Chester, NJ
Chester, NJ
Bernardsville, NJ
(epicenter in Morris
County)
Hainesburg, NJ
S. of Seaside, NJ
Keyport, NJ
Medford Lakes, NJ
Boonton, NJ
Ramsey, NJ
Denville, NJ
Mt Holly, NJ
Seaside Heights, NJ
Franklin, NJ
Oldwick, NJ
Dover, NJ
Fort Lee, NJ
Ringwood, NJ
Asbury Park, NJ
Mount Hope, NJ
Kinnelon, NJ
Near Morristown, NJ
Mount Olive, NJ
Byram, NJ
Byram, NJ
Near Mt. Olive, NJ
Byram, NJ
Byram, NJ
N of Milford, NJ
Byram, NJ
Byram, NJ
August 2013
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
Lamont-Doherty
NJGS
NJGS
5.4.7-18
Date(s) of
Event
Magnitude
Location
6/29/1986
7/15/1986
9/15/1986
9/15/1986
11/23/1986
1.5
1.5
2.3
1.9
2.8
4/24/1987
1.9
5/16/1987
8/5/1987
8/6/1987
8/6/1987
12/6/1987
4/13/1988
1.4
1.7
1.1
1.1
2.1
1.4
8/20/1988
1.0
12/22/1988
12/23/1988
1/22/1989
1/27/1989
9/3/1989
9/3/1989
1/26/1990
5/10/1990
8/21/1990
10/23/1990
5/12/1991
7/5/1991
9/29/1991
1/9/1992
3/4/1992
1.0
1.1
2.0
1.1
2.0
2.5
1.0
1.8
0.7
2.9
1.3
1.3
2.2
3.1
1.4
6/7/1992
0.4
10/13/1992
2/26/1993
5/15/1993
5/23/1994
1.0
2.5
2.6
1.6
Kinnelon, NJ
Franklin, NJ
Near New Egypt, NJ
Near Roebling, NJ
Tranquility, NJ
South of Lake
Mohawk, NJ
Near Paterson, NJ
SW of Newton
SW of Newton
SW of Newton, NJ
Burlington, NJ
Dover, NJ
10 KM NW of
Morristown, NJ
Wanaque, NJ
Wanaque, NJ
Englewood, NJ
NY-NJ Border
S of Staten Island
S of Staten Island
Franklin, NJ
Mt. Freedom, NJ
Wanaque, NJ
Hancock's Bridge, NJ
Wanaque, NJ
Pompton Plains, NJ
Somerdale Boro, NJ
New Brunswick, NJ
Kinnelon, NJ
Jefferson Township,
NJ
West Milford, NJ
Cherry Hill, NJ
Perrineville, NJ
Butler, N.J.
FEMA
Declaration
Number
N/A
N/A
N/A
N/A
N/A
County
Designated?
Losses/Impacts
Source(s)
N/A
N/A
N/A
N/A
N/A
Felt in Sussex and Warren.
NJGS
NJGS
NJGS
NJGS
NJGS
N/A
N/A
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
N/A
N/A
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Felt in NJ, DE and PA.
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
N/A
N/A
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
NJGS
NJGS
NJGS
NJGS
August 2013
5.4.7-19
Date(s) of
Event
Magnitude
Location
1/27/1995
4/1/1995
5/26/1995
10/27/1995
10/27/1995
2/18/1996
2/19/1996
2.3
1.5
1.5
1.3
1.4
1.5
1.7
2/19/1996
0.8
2/23/1996
0.8
2/26/1996
0.0
10/24/1996
2.0
11/12/1996
1.3
11/12/1996
0.8
3/11/1997
0.0
5/25/1997
0.5
6/27/1997
1.6
7/15/1997
2.3
10/21/1997
0.5
10/24/1997
0.5
3/25/1998
6/20/1998
6/30/1998
1.9
1.2
1.9
1/12/1999
1.4
1/31/1999
1.5
Rockaway, NJ
Rockaway, NJ
Kinnelon, NJ
NE of Newton, NJ
NE of Newton, NJ
Ringwood
Ringwood, NJ
5 km W Ringwood,
NJ
6.4 km W of
Ringwood, NJ
Near Mt. Arlington,
NJ
9 km S Crestwood
Village, NJ
21 km NE Newton,
NJ
21 km NE Newton,
NJ
3 km W of Rendall
Park, NJ
1 km NE Fort Lee, NJ
4.6 km N of
Rockaway, NJ
12 km NE of
Princeton, NJ
3 km SW Woodcliff
Lake, NJ
3 km SW Secaucus,
NJ
13 km S Salem, NJ
2 km SE Kinnelon, NJ
3 km S Butler, NJ
1 km NW of Clifton,
NJ
2 km W of Emerson,
NJ
FEMA
Declaration
Number
N/A
N/A
N/A
N/A
N/A
N/A
N/A
County
Designated?
Losses/Impacts
Source(s)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1 aftershock 22 minutes later.
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
N/A
N/A
N/A
N/A
NJGS
NJGS
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
August 2013
5.4.7-20
FEMA
Declaration
Number
County
Designated?
Losses/Impacts
Source(s)
8 km W of Fort Dix,
NJ
N/A
N/A
NJGS
2.4
Manhattan
N/A
N/A
Felt in the Upper East Side of Manhattan,
Long Island City, and Queens
Lamont-Doherty
7/14/2001
1.9
7.1 km NE of
Boonton, NJ
N/A
N/A
NJGS
10/17/2001
2.6
Manhattan
N/A
N/A
Felt in the Upper East Side of Manhattan,
Long Island City, Astoria, and Queens
Lamont-Doherty
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
Aftershock 55 min later, 1.3 M
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
NJGS
Date(s) of
Event
Magnitude
5/31/1999
2.3
1/17/2001
Location
5.4 km N of
Somerville, NJ
(epicenter in
Bridgewater)
6 km SW of Morris
Plains,
3 km North of Milford,
NJ
2km NE from
Runnemede, NJ
6km ESE from
Pennsville, NJ
1.3 Km East of Lodi,
NJ
16 km W of Franklin
Lakes, NJ
22km NE of Newton,
NJ
20km NE of Newton,
NJ
20.4km NE of
Newton, NJ
9 km S of Fair Lawn,
NJ
8/9/2002
1.5
8/24/2003
1.5
8/26/2003
3.5
3/22/2004
2.1
12/17/2004
2.0
04/23/2005
1.9
12/09/2005
2.1
02/16/2006
2.6
02/17/2006
0.9
02/21/2006
1.3
05/15/2006
2.0
06/28/2007
2.1
7 km E of Fairfield,
NJ
N/A
N/A
02/03/2009
3.0
3.5km SSW of
Rockaway, NJ
N/A
N/A
02/14/2009
2.4
5 km NNE of
N/A
N/A
August 2013
There were reports of people having felt this
earthquake throughout New Jersey, including
reports in Somerset County.
NJGS, USGS
NJGS, USGS
5.4.7-21
Date(s) of
Event
Magnitude
Location
FEMA
Declaration
Number
County
Designated?
Boonton, NJ
3 km SSW of
Kinnelon, NJ
1 km ESE of Oradell,
NJ
2 km SSE of Dover,
NJ
2/18/2009
1.1
2/16/2009
1.4
2/16/2009
2.3
07/01/2009
2.8
12/21/2009
2.3
12/26/2009
2.0
02/05/2010
1.5
02/07/2010
1.2
02/10/2010
2.2
13 km S of
Phillipsburg, NJ
8 km NW of Morris
Plains, NJ
3 km NW of Far Hills,
NJ
3 km NW of far Hills,
NJ
1 km W of Wanaque
02/21/2010
2.6
02/21/2010
2.3
06/06/2010
2.3
12/25/2010
2.1
05/08/2011
1.2
05/10/2011
1.9
Losses/Impacts
Source(s)
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS, USGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
Gladstone, NJ
N/A
N/A
Gladstone, NJ
N/A
N/A
N/A
N/A
N/A
N/A
This earthquake hit just before 9am and
prompted numerous phone calls to police.
No damages were reported. Many people in
New Jersey reported having felt this
earthquake, including reports in Somerset
County. In Bernardsville, approximately 100
people called the police stating they felt/heard
the earthquake.
This event was most likely an aftershock from
the morning’s earthquake. Numerous people
in New Jersey reported having felt this
earthquake, including reports in Somerset
County.
People reported having felt this earthquake,
including reports in Somerset County.
N/A
N/A
NJGS
N/A
N/A
NJGS
2.25km ESE of
Pennsville, NJ
6 km SE of
Sayreville, NJ
1 km W of Clifton, NJ
1 km SW of Clifton,
NJ
2 km N of Mt. Holly,
August 2013
NJGS, USGS,
NJ.com
NJGS, USGS,
NJ.com
NJGS, USGS
NJGS
5.4.7-22
Date(s) of
Event
Magnitude
05/29/2011
1.3
05/29/2011
1.9
06/09/2011
1.6
07/17/2012
1.1
07/18/2012
1.1
08/23/2012
1.2
Location
NJ
3 km S of Fort Lee,
NJ
24 km SSW of
Lakehurst, NJ
2 km SE of S.
Plainfield, NJ
16 km NW of
Morristown, NJ
18 km NW of
Morristown, NJ
1.4 km E of
Ringwood, NJ
FEMA
Declaration
Number
County
Designated?
Losses/Impacts
Source(s)
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
N/A
N/A
NJGS
People reported having felt this earthquake in
various parts of New Jersey, including reports
NJGS, USGS
in Somerset County.
Greater Philadelphia
Numerous reports of people having felt the
11/23/2012
2.2
N/A
N/A
NJGS, USGS
Area/New Jersey
earthquake in southwestern New Jersey.
Source: NJGS, 2013; USGS, 2013; Won-Young Kim, Lamont-Doherty Earth Observatory of Columbia University, 1999
Note:
Yellow shading indicates an event that occurred in Somerset County.
*
Location very poorly determined; may be uncertain by 50 miles.
E
East
NYC
New York City
FEMA
Federal Emergency Management Agency
NYSDPC
New York State Disaster Preparedness Commission
Km
Kilometers
S
South
N
North
USGS
U.S. Geological Survey
N/A
Not Applicable
W
West
NJ
New Jersey
NJGS
New Jersey Geologicaly Survey
11/05/2012
2.0
3 km SW of Mahwah,
NJ
N/A
August 2013
N/A
5.4.7-23
Earthquakes in Somerset County are not common, with documented information on earthquake events
and their location being relatively scarce. According to Planning Area officials, there is no record of
earthquake occurrences within the Planning Area. However, depending on the magnitude, the impacts of
earthquake events can be far-reaching; therefore, reported incidences within the surrounding counties or
states could have created indirect impacts upon the Planning Area.
Probability of Future Events
Earthquake hazard maps illustrate the distribution of earthquake shaking levels that have a certain
probability of occurring over a given time period. According to the USGS, in 2008, Somerset County had
a PGA of 3-4%g for earthquakes with a 10-percent probability of occurring within 50 years.
Earlier in this section, the identified hazards of concern for Somerset County were ranked. The
probability of occurrence, or likelihood of the event, is one parameter used for ranking hazards. Based on
historical records and input from the Planning Committee, the probability of occurrence for earthquakes
in the County is considered “frequent” (is likely to occur within 25 years as presented in Table 5.3-3).
Although no reported incidences have occurred within Somerset County, it is anticipated that the County
will experience indirect impacts from earthquakes that may affect the general building stock, local
economy and may induce secondary hazards such ignite fires and cause utility failure.
Climate Change
The impacts of global climate change on earthquake probability are unknown. Some scientists say that
melting glaciers could induce tectonic activity. As ice melts and water runs off, tremendous amounts of
weight are shifted on the earth’s crust. As newly freed crust returns to its original, pre-glacier shape, it
could cause seismic plates to slip and stimulate volcanic activity according to research into prehistoric
earthquakes and volcanic activity. NASA and USGS scientists found that retreating glaciers in southern
Alaska may be opening the way for future earthquakes (NASA, 2004).
Secondary impacts of earthquakes could be magnified by climate change. Soils saturated by repetitive
storms could experience liquefaction during seismic activity due to the increased saturation. Dams storing
increased volumes of water due to changes in the hydrograph could fail during seismic events. There are
currently no models available to estimate these impacts
August 2013
5.4.7-24
VULNERABILITY ASSESSMENT
To understand risk, a community must evaluate what assets are exposed or vulnerable in the identified
hazard area. For the earthquake hazard, the entire County has been identified as the exposed hazard area.
Therefore, all assets in Somerset County (population, structures, critical facilities and lifelines), as
described in the County Profile (Section 4), are vulnerable. The following section includes an evaluation
and estimation of the potential impact of the earthquake hazard on Somerset County including the
following:






Overview of vulnerability
Data and methodology used for the evaluation
Impact on: (1) life, safety and health of residents, (2) general building stock, (3) critical facilities, (4)
economy and (5) future growth and development
Effect of climate change on vulnerability
Change of vulnerability as compared to that presented in the 2008 Somerset County Hazard
Mitigation Plan
Further data collections that will assist understanding of this hazard over time
Overview of Vulnerability
Earthquakes usually occur without warning and can impact areas a great distance from their point of
origin. The extent of damage depends on the density of population and building and infrastructure
construction in the area shaken by the quake. Some areas may be more vulnerable than others based on
soil type, the age of the buildings and building codes in place. Compounding the potential for damage –
historically, Building Officials Code Administration (BOCA) used in the Northeast were developed to
address local concerns including heavy snow loads and wind; seismic requirements for design criteria are
not as stringent compared to the west coast’s reliance on the more seismically-focused Uniform Building
Code). As such, a smaller earthquake in the Northeast can cause more structural damage than if it
occurred out west.
The level of seismic hazard, the frequency and severity of earthquakes, is substantially lower in New
Jersey than in more seismically active states such as California or Alaska. The level of seismic risk, the
threat to buildings, infrastructure, and people, is significant in the State, especially in northern New
Jersey. The level of seismic risk (potential damages) in the State is higher than might be expected
because the vast majority of the buildings and infrastructure in New Jersey have been built with minimal
or no consideration of earthquakes; therefore, the majority of buildings and infrastructure in the State is
more vulnerable to earthquake damage than the buildings and infrastructure in more seismically active
states where inventory has been built with consideration of earthquakes (NJOEM, 2011).
The entire population and general building stock inventory of the County is at risk of being damaged or
experiencing losses due to impacts of an earthquake. Potential losses associated with the earth shaking
were calculated for Somerset County for three probabilistic earthquake events, the 100-year, 500- and
2,500-year mean return periods (MRP). The impacts on population, existing structures, critical facilities
and the economy within Somerset County are presented below, following a summary of the data and
methodology used.
Data and Methodology
A probabilistic assessment was conducted for Somerset County for the 100-, 500- and 2,500-year MRPs
through a Level 2 analysis in HAZUS-MH 2.1 to analyze the earthquake hazard and provide a range of
loss estimates for Somerset County. The probabilistic method uses information from historic earthquakes
August 2013
5.4.7-25
and inferred faults, locations and magnitudes, and computes the probable ground shaking levels that may
be experienced during a recurrence period by Census tract. According to the New York City Area
Consortium for Earthquake Loss Mitigation (NYCEM), probabilistic estimates are best for urban
planning, land use, zoning and seismic building code regulations (NYCEM, 2003). The default
assumption is a magnitude 7 earthquake for all return periods. In addition, an annualized loss run was
also conducted in HAZUS-MH 2.1 to estimate the annualized general building stock dollar losses for
Somerset County.
Ground shaking is the primary cause of earthquake damage to man-made structures and soft soils amplify
ground shaking. One contributor to the site amplification is the velocity at which the rock or soil
transmits shear waves (S-waves). The NEHRP developed five soil classifications defined by their shearwave velocity that impact the severity of an earthquake. The soil classification system ranges from A to
E, where A represents hard rock that reduces ground motions from an earthquake and E represents soft
soils that amplify and magnify ground shaking and increase building damage and losses.
As illustrated in Figure 5.4.7-3 as depicted by the New Jersey Geologic and Water Survey, Somerset
County is made up of dense soil/soft rock (C), stiff/soft soils (D) with a small area of soft soils (E) in the
northeastern portion of the county. When unchanged, HAZUS-MH default soil types are class “D”. To
more closely reflect the soils of the County as indicated by the New Jersey Geological and Water Survey
(not available in time for this analysis), HAZUS-MH was updated with the approximate locations of
NEHRP soil classes C and D, as illustrated in Figure 5.4.7-12 below, with the class ‘D’ soils closely
following riverine reaches and floodplains.
In addition to the probabilistic scenarios mentioned, an annualized loss run was conducted in HAZUS 2.1
to estimate the annualized general building stock dollar losses for the County. The annualized loss
methodology combines the estimated losses associated with ground shaking for eight return periods: 100,
250, 500, 750, 1000, 1500, 2000, 2500-year, which are based on values from the USGS seismic
probabilistic curves. Annualized losses are useful for mitigation planning because they provide a baseline
upon which to 1) compare the risk of one hazard across multiple jurisdictions and 2) compare the degree
of risk of all hazards for each participating jurisdiction.
As noted in the HAZUS-MH Earthquake User Manual ‘Uncertainties are inherent in any loss estimation
methodology. They arise in part from incomplete scientific knowledge concerning earthquakes and their
effects upon buildings and facilities. They also result from the approximations and simplifications that
are necessary for comprehensive analyses. Incomplete or inaccurate inventories of the built environment,
demographics and economic parameters add to the uncertainty. These factors can result in a range of
uncertainly in loss estimates produced by the HAZUS Earthquake Model, possibly at best a factor of two
or more.’ However, HAZUS’ potential loss estimates are acceptable for the purposes of this HMP.
The occupancy classes available in HAZUS-MH 2.1 were condensed into the following categories
(residential, commercial, industrial, agricultural, religious, government, and educational) to facilitate the
analysis and the presentation of results. Residential loss estimates address both multi-family and single
family dwellings. Impacts to critical facilities and utilities were also evaluated.
Data used to assess this hazard include data available in the HAZUS-MH 2.1 earthquake model, USGS
data, data provided by NJOEM, professional knowledge, and information provided by the County’s
Planning Committee. All exposure and loss estimates discussed in the assessment below are for Somerset
County.
August 2013
5.4.7-26
Figure 5.4.7-12. Estimated NEHRP Soil Classes in Somerset County Used for the Earthquake Analysis
Source: FEMA, 2009
Note: To estimate the location of the NEHRP soils, FEMA floodplains were classified as soil type D with the
remainder of the County soil type C for the purposes of this risk assessment.
Impact on Life, Health and Safety
Overall, the entire population of Somerset County is exposed to the earthquake hazard event. According
to the 2010 U.S. Census, Somerset County had a population of 323,444 people. The impact of
earthquakes on life, health and safety is dependent upon the severity of the event. Risk to public safety
and loss of life from an earthquake in Somerset County is minimal with higher risk occurring in buildings
as a result of damage to the structure, or people walking below building ornamentation and chimneys that
may be shaken loose and fall as a result of the quake.
August 2013
5.4.7-27
Populations considered most vulnerable are located in the built environment, particularly near
unreinforced masonry construction. In addition, the vulnerable population includes the elderly (persons
over the age of 65) and individuals living below the Census poverty threshold. These socially vulnerable
populations are most susceptible, based on a number of factors including their physical and financial
ability to react or respond during a hazard and the location and construction quality of their housing.
Table 5.4.7-7 summarizes the County population over the age of 65 and individuals living below the
Census poverty threshold.
Table 5.4.7-7. Somerset County Population Statistics (2010 U.S. Census)
U.S. Census 2010 U.S. Census 2010
Census LowU.S. Census 2010
Population
Population
Income
Population
Over 65
Under 5
Households *
323,444
40,002
19,237
10,113
Source: U.S. Census, 2010
Note:
*2007-2011 American Community Survey (5-Year Estimates) - Households with an income of less
than $24,999
Residents may be displaced or require temporary to long-term sheltering due to the event. The number of
people requiring shelter is generally less than the number displaced as some displaced persons use hotels
or stay with family or friends following a disaster event. Table 5.4.7-8 summarizes the households
HAZUS-MH 2.1 estimates will be displaced and population that may require short-term sheltering as a
result of the 100-, 500- and 2,500-year MRP earthquake events.
Table 5.4.7-8. Summary of Estimated Sheltering Needs for Somerset County
Displaced
Households
Persons Seeking
Short-Term Shelter
100-Year Earthquake
0
0
500-Year Earthquake
12
7
2,500-Year Earthquake
269
159
Scenario
Source: HAZUS-MH 2.1
Table 5.4.7-9. Estimated Displaced Households and Population Seeking Short-Term Shelter from the 500- and 2,500-year
MRP Events per Municipality
500-Year MRP Event
Municipality
Bedminister (T)
2,500-Year MRP Event
Persons
Persons
Seeking
Displaced
Seeking Short- Displaced
Short-Term
Households Term Sheltering Households Sheltering
0
0
3
1
Bernards (T)
1
0
13
5
Bernardsville (B)
0
0
5
2
Bound Brook (B)
1
1
19
14
Branchburg (T)
0
0
6
3
Bridgewater (T)
1
1
28
15
Far Hills (B)
0
0
1
0
Franklin (T)
2
1
49
27
Green Brook (T)
0
0
3
2
Hillsborough (T)
1
1
24
12
August 2013
5.4.7-28
500-Year MRP Event
2,500-Year MRP Event
Persons
Persons
Seeking
Displaced
Seeking Short- Displaced
Short-Term
Households Term Sheltering Households Sheltering
1
0
19
10
Municipality
Manville (B)
Millstone (B)
0
0
0
0
Montgomery (T)
0
0
7
4
North Plainfield (B)
2
2
46
34
Peapack Gladstone (B)
0
0
1
1
Raritan (B)
0
0
7
4
Rocky Hill (B)
0
0
0
0
Somerville (B)
1
1
23
15
South Bound Brook (B)
0
0
7
5
Warren (T)
0
0
2
1
0
0
5
2
12
7
269
159
Watchung (B)
Somerset County (Total)
Note:
The population displaced and seeking shelter was calculated using the 2000 U.S. Census data (HAZUS-MH
2.1 default demographic data).
According to the 1999-2003 NYCEM Summary Report (Earthquake Risks and Mitigation in the New
York / New Jersey / Connecticut Region), there is a strong correlation between structural building damage
and the number of injuries and casualties from an earthquake event. Further, the time of day also exposes
different sectors of the community to the hazard. For example, HAZUS considers the residential
occupancy at its maximum at 2:00 a.m., where the educational, commercial and industrial sectors are at
their maximum at 2:00 p.m., and peak commute time is at 5:00 p.m. Whether directly impacted or
indirectly impact, the entire population will have to deal with the consequences of earthquakes to some
degree. Business interruption could keep people from working, road closures could isolate populations,
and loss of functions of utilities could impact populations that suffered no direct damage from an event
itself.
There are no injuries or casualties estimated for the 100-year event. An estimated 6 to 7 injuries that
require medical attention (no hospitalization), and one injury which requires hospitalization are estimated
for the 500-year event. There are zero casualties estimated for the 500-year event.
Table 5.4.7-10 summarizes the injuries and casualties estimated for the 2,500-year MRP earthquake
event.
Table 5.4.7-10. Estimated Number of Injuries and Casualties from the 2,500-Year MRP Earthquake Event
Time of Day
2:00 AM
2:00 PM
5:00 PM
Injuries
Level of Severity
95
114
99
Hospitalization
13
19
18
Casualties
2
3
3
August 2013
5.4.7-29
Impact on General Building Stock
After considering the population exposed to the earthquake hazard, the value of general building stock
exposed to and damaged by 100-, 500- and 2,500-year MRP earthquake events was evaluated. In
addition, annualized losses were calculated using HAZUS-MH 2.1. The entire study area’s general
building stock is considered at risk and exposed to this hazard.
As stated earlier, soft soils (NEHRP soil classed D and E) can amplify ground shaking to damaging levels
even in a moderate earthquake (NYCEM, 2003). Therefore, buildings located on NEHRP soil classes D
and E have an increased risk of damages from an earthquake. Table 5.4.7-11 summarizes the number of
buildings in Somerset County on the approximately located NEHRP soils classed D.
Table 5.4.7-11. Buildings Located on NEHRP Soils Classed D in Somerset County
Total
Building
Count
Number of
Buildings on
NEHRP Soil
Class D
Percent Buildings
on NEHRP Soil
Class D
Bedminister (T)
2,531
86
3.4
Bernards (T)
7,576
101
1.3
Bernardsville (B)
3,282
71
2.2
Bound Brook (B)
3,011
874
29.0
Branchburg (T)
5,369
123
2.3
Bridgewater (T)
14,316
380
2.7
Municipality
Far Hills (B)
536
40
7.5
Franklin (T)
15,592
184
1.2
Green Brook (T)
2,465
162
6.6
Hillsborough (T)
10,812
170
1.6
Manville (B)
4,250
909
21.4
Millstone (B)
221
32
14.5
Montgomery (T)
6,899
129
1.9
5,781
801
13.9
1,118
77
6.9
Raritan (B)
2,418
36
1.5
Rocky Hill (B)
352
9
2.6
Somerville (B)
3,799
98
2.6
1,420
85
6.0
Warren (T)
5,999
113
1.9
Watchung (B)
2,206
58
2.6
99,953
4,538
4.5
The HAZUS-MH 2.1 model estimates the value of the exposed building stock and the loss (in terms of
damage to the exposed stock). Refer to Table 4-3 in the County Profile (Section 4) for general building
stock data replacement value statistics (structure and contents).
For this plan update and using HAZUS-MH 2.1, a probabilistic model was run for the purposes of this
Plan to estimate annualized dollar losses for Somerset County, also factoring in approximate location of
NEHRP soil classes C and D. Annualized losses are useful for mitigation planning because they provide
a baseline upon which to 1) compare the risk of one hazard across multiple jurisdictions and 2) compare
the degree of risk of all hazards for each participating jurisdiction. Please note that annualized loss does
August 2013
5.4.7-30
not predict what losses will occur in any particular year. The estimated annualized losses are
approximately $949,314 per year (building and contents) for the County.
According to NYCEM, where earthquake risks and mitigation were evaluated in the New York, New
Jersey and Connecticut region, most damage and loss caused by an earthquake is directly or indirectly the
result of ground shaking (NYCEM, 2003). NYCEM indicates there is a strong correlation between PGA
and the damage a building might experience. The HAZUS-MH model is based on the best available
earthquake science and aligns with these statements. HAZUS-MH 2.1 methodology and model were used
to analyze the earthquake hazard for the general building stock for Somerset County. See Figure 5.4.7-4
through 5.4.7-6 earlier in this profile that illustrates the geographic distribution of PGA (g) across the
County for 100-, 500- and 2,500-year MRP events at the Census-Tract level.
In addition, according to NYCEM, a building’s construction determines how well it can withstand the
force of an earthquake. The NYCEM report indicates that un-reinforced masonry buildings are most at
risk during an earthquake because the walls are prone to collapse outward, whereas steel and wood
buildings absorb more of the earthquake’s energy. Additional attributes that contribute to a building’s
capability to withstand an earthquake’s force include its age, number of stories and quality of
construction. HAZUS-MH considers building construction and the age of buildings as part of the
analysis. Because the default general building stock was used for this HAZUS-MH analysis, the default
building ages and building types already incorporated into the inventory were used.
Potential building damage was evaluated by HAZUS-MH 2.1 across the following damage categories
(none, slight, moderate, extensive and complete). Table 5.4.7-12 provides definitions of these five
categories of damage for a light wood-framed building; definitions for other building types are included
in HAZUS-MH technical manual documentation. General building stock damage for these damage
categories by occupancy class and building type on a County-wide basis is summarized for the 100-, 500and 2,500-year events in 3, 4, and 5.
Table 5.4.7-12. Example of Structural Damage State Definitions for a Light Wood-Framed Building
Damage
Category
Slight
Description
Small plaster or gypsum-board cracks at corners of door and window openings and wall-ceiling
intersections; small cracks in masonry chimneys and masonry veneer.
Moderate
Large plaster or gypsum-board cracks at corners of door and window openings; small diagonal
cracks across shear wall panels exhibited by small cracks in stucco and gypsum wall panels; large
cracks in brick chimneys; toppling of tall masonry chimneys.
Extensive
Large diagonal cracks across shear wall panels or large cracks at plywood joints; permanent
lateral movement of floors and roof; toppling of most brick chimneys; cracks in foundations;
splitting of wood sill plates and/or slippage of structure over foundations; partial collapse of roomover-garage or other soft-story configurations.
Structure may have large permanent lateral displacement, may collapse, or be in imminent danger
of collapse due to cripple wall failure or the failure of the lateral load resisting system; some
structures may slip and fall off the foundations; large foundation cracks.
Source: HAZUS-MH Technical Manual
Complete
HAZUS-MH 2.1 estimates $0 in damage to Somerset County’s general building stock as a result of a
100-year MRP event. Table 5.4.7-13 through Table 5.4.7-15 summarizes the damage estimated for the
100-, 500- and 2,500-year MRP earthquake events. Damage loss estimates include structural and nonstructural damage to the building and loss of contents.
August 2013
5.4.7-31
Table 5.4.7-13. Estimated Buildings Damaged by General Occupancy for 100-year, 500-year and 2,500-year MRP Earthquake Events
Average Damage State
100-Year MRP
Category
500-Year MRP
None
Slight
Residential
88,548
0
0
0
Commercial
5,204
0
0
850
0
5,282
0
Industrial
Education,
Government,
Religious and
Agricultural
Moderate Extensive Complete
2,500-Year MRP
None
Slight
Moderate Extensive Complete None
0
86,916
1,389
224
17
1
72,337
0
0
5,059
111
31
3
0
3,911
0
0
0
827
17
5
0
0
0
0
0
5,134
113
30
2
0
Slight Moderate Extensive Complete
12,375
3,383
408
46
766
438
80
9
637
121
77
14
1
3,950
831
416
79
7
Note: Based on an inventory of 99,884 buildings.
Table 5.4.7-14. Estimated Number of Buildings Damaged by Building Type for 100-year, 500-year and 2,500-year MRP Earthquake Events
Average Damage State
100-Year MRP
Category
None
500-Year MRP
None
Slight
2,500-Year MRP
Moderate Extensive Complete None
Wood
82,933
0
0
0
0
81,688
1,124
118
3
0
68,683 11,423
2,619
196
12
Steel
5,406
0
0
0
0
5,271
104
29
2
0
4,090
735
484
88
8
Concrete
819
0
0
0
0
798
15
5
0
0
571
84
88
16
1
Reinforced Masonry
803
0
0
0
0
782
14
6
1
0
631
81
73
18
0
Un-reinforced Masonry
9,920
0
0
0
0
9,393
375
133
17
2
6,827
1,739
1,048
263
43
Manufactured housing
4
0
0
0
0
4
0
0
0
0
3
1
1
0
0
Note: Based on an inventory of 99,884 buildings.
August 2013
5.4.7-32
Table 5.4.7-15. Estimated Building Value (Building and Contents) Damaged by the 500- and 2,500-Year MRP Earthquake Events
Estimated Total Damages*
Municipality
Percent of
Total Building
and Contents
RV**
Estimated Residential
Damage
Estimated Commercial
Damage
Annualized
Loss
500-Year
2,500-Year
500Year
2,500Year
500-Year
2,500-Year
500-Year
2,500-Year
Bedminister (T)
$56,989
$3,290,664
$54,765,262
0.1
2.0
$1,482,952
$24,568,713
$656,582
$10,466,411
Bernards (T)
$97,546
$5,490,480
$102,639,178
0.1
1.5
$3,830,875
$72,151,946
$930,711
$16,021,885
Bernardsville (B)
$24,303
$1,259,453
$26,838,365
0.1
1.1
$897,057
$19,248,439
$138,186
$2,779,314
Bound Brook (B)
$16,890
$859,307
$18,624,265
0.1
1.2
$540,619
$12,014,404
$198,429
$4,078,078
Branchburg (T)
$95,778
$5,473,097
$94,138,385
0.1
1.7
$2,363,848
$42,757,801
$511,651
$8,370,261
Bridgewater (T)
$21,929,530
$118,657
$5,893,499
$129,690,154
0.1
1.1
$3,471,039
$76,779,511
$1,048,726
Far Hills (B)
$5,296
$260,580
$5,626,142
0.1
1.1
$118,958
$2,551,132
$35,403
$712,525
Franklin (T)
$160,962
$7,780,883
$175,600,928
0.1
1.1
$4,102,040
$92,521,193
$1,340,749
$28,566,376
Green Brook (T)
$19,270
$991,528
$21,487,887
0.1
1.2
$664,825
$14,715,367
$235,833
$4,848,679
Hillsborough (T)
$97,035
$4,748,059
$105,490,681
0.0
1.1
$2,688,104
$59,981,007
$472,545
$9,991,329
Manville (B)
$21,100
$1,169,238
$22,055,365
0.1
1.4
$758,057
$14,410,826
$258,181
$4,763,235
Millstone (B)
$882
$45,153
$1,010,449
0.0
1.0
$39,305
$882,759
$2,711
$57,329
Montgomery (T)
$62,660
$3,133,328
$69,227,690
0.0
1.0
$2,208,202
$49,178,491
$428,667
$9,116,240
North Plainfield
(B)
$35,431
$1,868,156
$38,702,152
0.1
1.4
$1,328,197
$28,066,479
$364,440
$7,362,161
Peapack
Gladstone (B)
$8,968
$451,572
$9,679,269
0.1
1.1
$259,552
$5,566,242
$75,000
$1,509,453
Raritan (B)
$18,189
$861,938
$19,468,703
0.0
1.1
$353,965
$7,895,997
$184,949
$3,921,117
Rocky Hill (B)
$2,137
$105,127
$2,354,074
0.0
1.0
$67,801
$1,521,058
$18,672
$397,013
August 2013
5.4.7-33
Estimated Total Damages*
Municipality
Percent of
Total Building
and Contents
RV**
Estimated Residential
Damage
Estimated Commercial
Damage
Annualized
Loss
500-Year
2,500-Year
500Year
2,500Year
500-Year
2,500-Year
500-Year
2,500-Year
Somerville (B)
$24,608
$1,218,753
$26,585,300
0.1
1.1
$640,387
$14,269,401
$377,667
$7,959,393
South Bound
Brook (B)
$5,575
$284,593
$6,196,581
0.1
1.2
$199,973
$4,443,605
$51,283
$1,053,959
Warren (T)
$54,257
$2,782,554
$60,656,611
0.1
1.1
$1,955,909
$43,426,141
$397,026
$8,160,633
Watchung (B)
$22,783
$1,144,069
$25,427,158
0.1
1.2
$738,338
$16,874,711
$321,214
$6,751,946
Somerset County
(Total)
$949,314
$49,112,032
$1,016,264,597
0.1
1.2
$28,710,001
$603,825,222
$8,048,624
$158,816,866
Source:
HAZUS-MH 2.1
RV:
Replacement Value
*Total is sum of damages for all occupancy classes (residential, commercial, industrial, agricultural, educational, religious and government).
**Total replacement value (building and contents) for the County is greater than $83 billion.
August 2013
5.4.7-34
It is estimated that there would be nearly $49 million in damages to buildings in the County during a 500year earthquake event. This includes structural damage, non-structural damage and loss of contents,
representing less than one-percent of the total replacement value for general building stock in Somerset
County. For a 2,500-year MRP earthquake event, HAZUS-MH estimates 4,957 buildings will be at least
moderately damaged. The estimated total building damage is greater than $603 million, less than onepercent of the total general building stock replacement value (total replacement value is greater than $83
billion for the County). Residential and commercial buildings account for most of the damage for
earthquake events.
Earthquakes can cause secondary hazard events such as fires. No fires are anticipated as a result of the
100-, 500- or 2,500-year MRP events.
Impact on Critical Facilities
After considering the general building stock exposed to, and damaged by, 100-, 500- and 2,500-year MRP
earthquake events, critical facilities were evaluated. All critical facilities (essential facilities,
transportation systems, lifeline utility systems, high-potential loss facilities and user-defined facilities) in
Somerset County are considered exposed and vulnerable to the earthquake hazard. Refer to subsection
“Critical Facilities” in Section 4 (County Profile) of this Plan for a complete inventory of critical facilities
in the County.
HAZUS-MH 2.1 estimates the probability that critical facilities may sustain damage as a result of 100-,
500- and 2,500-year MRP earthquake events. Additionally, HAZUS-MH estimates percent functionality
for each facility days after the event. For the 100-Year MRP event, HAZUS-MH 2.1 estimates it is 99%
probable that emergency facilities (police, fire, EMS and medical facilities), schools and specific facilities
identified by Somerset County as critical (i.e., user-defined facilities such shelters, municipal buildings
and Departments of Public Works) will not experience any structural damage. These facilities are
estimated to be nearly 100% functional on day one of the 100-year MRP earthquake event. Therefore, the
impact to critical facilities is not significant for the 100-year event.
Table 5.4.7-16 and 5.4.7-17 list the percent probability of critical facilities sustaining the damage category
as defined by the column heading and percent functionality after the event for the 500-year and 2,500year MRP earthquake events.
Table 5.4.7-16. Estimated Damage and Loss of Functionality for Critical Facilities and Utilities in Somerset County for
the 500-Year MRP Earthquake Event
Percent Probability of Sustaining Damage
None
Slight
Moderate
Extensive
Complete
93 - 97
3- 5
<1-2
<1
0
Medical
99
<1
<1
0
0
Police
96
2-5
<1-2
<1
0
Fire
93 - 97
2-5
<1-2
<1
0
Schools
93 - 97
3-5
1-2
<1
0
User Defined
93 - 97
3-5
<1-2
<1
0
Name
Percent Functionality
Day Day Day Day
1
7
30
90
Critical Facilities
EOC
August 2013
93 96
>
93 96
93 97
93 95
93
–
99
100
100
999
9
100
100
99
100
100
99
100
100
100
100
100
100
98 99
97 99
Name
None
Slight
Moderate
Extensive
Complete
Day Day Day Day
1
7
30
90
96
Utilities
Potable Water
97 - 99
<1 -2
<1
0
0
Wastewater
97 - 99
<1-2
<1
0
0
Electric Power
97 - 99
<1-2
<1
0
0
Communication
99
<1
<1
0
0
99 100
98 99
98 99
99
100
100
100
100
100
100
100
100
100
100
100
100
Table 5.4.7-7. Estimated Damage and Loss of Functionality for Critical Facilities and Utilities in Somerset County for the
2,500-Year MRP Earthquake Event
None
Slight
Moderate
Extensive
Complete
EOC
60 - 72
16 - 17
9 - 15
2-4
<1
Medical
88
80 - 83
34 - 36
<1
<1
Police
60 - 73
16 - 21
9 - 15
2–4
<1
Fire
60 - 74
16 - 21
8 - 15
2-4
<1
Schools
60 - 74
16 - 21
9 - 15
2-4
<1
User Defined
58 - 74
16 - 22
2 - 15
2-4
<1
Potable Water
70 - 85
10 - 16
5 - 12
0-1
0-<1
Wastewater
70 - 85
10 - 16
5 - 12
0-1
0-<1
Electric Power
70 - 85
10 - 16
5 - 12
0-1
0-<1
Communication
83 - 84
9 - 10
5
<1
<1
Name
Critical Facilities
Day Day Day Day
1
7
30
90
58 74
58 73
58 73
60 73
60 74
60 74
80–
89
80 88
80 88
81 89
81 89
81 89
83 92
77 88
77 88
97
98–
99
97 99
97 99
99
95 98
98
98
95 98
95 98
95 98
97 99
97 99
97 99
98 99
97 99
99
Utilities
100
100
100
100
100
100
100
100
Impact on Economy
Earthquakes also have impacts on the economy, including: loss of business function, damage to
inventory, relocation costs, wage loss and rental loss due to the repair/replacement of buildings. A Level
2 HAZUS-MH analysis estimates the total economic loss associated with each earthquake scenario, which
includes building- and lifeline-related losses (transportation and utility losses) based on the available
inventory (facility [or GIS point] data only). Direct building losses are the estimated costs to repair or
replace the damage caused to the building. This is reported in the “Impact on General Building Stock”
section discussed earlier. Lifeline-related losses include the direct repair cost to transportation and utility
systems and are reported in terms of the probability of reaching or exceeding a specified level of damage
when subjected to a given level of ground motion. Additionally, economic loss includes business
interruption losses associated with the inability to operate a business due to the damage sustained during
the earthquake as well as temporary living expenses for those displaced. These losses are discussed
below.
August 2013
It is significant to note that for the 500-year event, HAZUS-MH 2.1 estimates the County will incur
approximately $7.54 million in income losses (wage, rental, relocation and capital-related losses) in
addition to the 500 –year event structural, non-structural and content building stock losses ($49 million).
For the 2,500-year event, HAZUS-MH 2.1 estimates the County will incur nearly $123 million in income
losses, mainly to the residential and commercial occupancy classes associated with wage, rental,
relocation and capital-related losses.
The HAZUS-MH analysis conducted did not compute any damage estimates for roadway segments and
railroad tracks. However, it is assumed these features may experience damage due to ground failure and
regional transportation and distribution of these materials will be interrupted as a result of an earthquake
event. Losses to the community that result from damages to lifelines can be much greater than the cost of
repair (HAZUS-MH 2.1 Earthquake User Manual, 2012).
Earthquake events can significantly impact road bridges. These are important because they often provide
the only access to certain neighborhoods. Since softer soils can generally follow floodplain boundaries,
bridges that cross watercourses should be considered vulnerable. A key factor in the degree of
vulnerability will be the age of the facility, which will help indicate to which standards the facility was
built.HAZUS-MH estimates the long-term economic impacts to the County for 15-years after the
earthquake event. In terms of the highway transportation infrastructure, HAZUS-MH estimtes $22
Million in direct repair costs to bridges in the County as a result of a 2,500-year event. No loss is
estimated for highway segments
It is estimated that the rail stations and airports in Somerset County will be 70 - 85% functional on day
one of the 2,500-year event and an estimated 11- to 15-percent probability they will experience slight
damage.
HAZUS-MH 2.1 also estimates the volume of debris that may be generated as a result of an earthquake
event to enable the study region to prepare and rapidly and efficiently manage debris removal and
disposal. Debris estimates are divided into two categories: (1) reinforced concrete and steel that require
special equipment to break it up before it can be transported, and (2) brick, wood and other debris that can
be loaded directly onto trucks with bulldozers (HAZUS-MH Earthquake User’s Manual).
For the 100-year MRP event, HAZUS-MH 2.1 estimates 0 tons of debris will be generated. For the 500year MRP event, HAZUS-MH 2.1 estimates more than 20,000 tons of debris will be generated. For the
2,500-year MRP event, HAZUS-MH 2.1 estimates greater than 265,006 tons of debris will be generated.
Table 5.4.7-17. Estimated Debris Generated by the 500- and 2,500-year MRP Earthquake Events
500-Year
Municipality
Bedminister (T)
Bernards (T)
Bernardsville (B)
Bound Brook (B)
2,500-Year
Brick/Wood
(tons)
Concrete/Steel
(tons)
Brick/Wood
(tons)
Concrete/Steel
(tons)
929
375
8,934
7,713
1,686
429
16,684
8,460
435
106
4,477
2,012
298
77
3,100
1,533
Branchburg (T)
1,503
604
15,091
13,599
Bridgewater (T)
2,027
578
21,349
11,938
Far Hills (B)
90
32
926
639
Franklin (T)
2,696
851
28,651
18,093
Green Brook (T)
334
84
3,525
1,692
Hillsborough (T)
1,611
474
17,165
9,748
August 2013
5.4.7-37
500-Year
2,500-Year
Brick/Wood
(tons)
Concrete/Steel
(tons)
Brick/Wood
(tons)
Concrete/Steel
(tons)
Manville (B)
362
97
3,629
2,002
Millstone (B)
16
3
169
53
1,120
267
11,681
5,105
604
153
6,247
3,155
157
47
1,614
931
Raritan (B)
299
108
3,167
2,279
Rocky Hill (B)
37
10
394
191
Somerville (B)
432
126
4,507
2,628
98
24
1,019
474
Warren (T)
939
220
9,894
4,370
Municipality
Montgomery (T)
Watchung (B)
389
99
4,170
2,056
16,065
4,764
166,394
98,672
Future Growth and Development
As discussed in Section 4, areas targeted for future growth and development have been identified across
the County. It is anticipated that the human exposure and vulnerability to earthquake impacts in newly
developed areas will be similar to those that currently exist within the County. Current building codes
require seismic provisions that should render new construction less vulnerable to seismic impacts than
older, existing construction that may have been built to lower construction standards.
New development located in areas with softer NEHRP soil classes may be more vulnerable to the
earthquake hazard. Refer to 3 for potential new development and approximate NEHRP soil class areas in
Somerset County. Some potential new development is located with approximate NEHRP soil class ‘D’.
August 2013
5.4.7-38
Figure 5.4.7-1. Potential New Development in Somerset County and NEHRP Soil Types
Source: FEMA, 2009
Note: To estimate the location of the NEHRP soils, FEMA floodplains were classified as soil type D with the
remainder of the County soil type C for the purposes of this risk assessment.
August 2013
5.4.7-39
Change of Vulnerability
The earthquake hazard was not evaluated as part of the 2008 original HMP. As summarized in Section
5.2 (Hazards of Concern) the NJ State HMP identifies earthquake as a hazard of concern for the state of
New Jersey. According to the USGS online seismic hazard maps, the peak ground acceleration with a
10% probability of exceedance over 50 years for Somerset County is between 2 and 3% g. FEMA
guidance recommends earthquakes are evaluated further if an area has a 3% g peak acceleration or more.
Somerset County decided to evaluate the earthquake hazard as part of their HMP update.
Effect of Climate Change on Vulnerability
The impacts of global climate change on earthquake probability are unknown. Some scientists say that
melting glaciers could induce tectonic activity. As ice melts and water runs off, tremendous amounts of
weight are shifted on the earth’s crust. As newly freed crust returns to its original, pre-glacier shape, it
could cause seismic plates to slip and stimulate volcanic activity according to research into prehistoric
earthquakes and volcanic activity. NASA and USGS scientists found that retreating glaciers in southern
Alaska may be opening the way for future earthquakes (NASA, 2004).
Secondary impacts of earthquakes could be magnified by climate change. Increased saturation of soils by
more frequent and/or intense storms could increase the risk for liquefaction. Dams storing increased
volumes of water due to changes in the hydrograph could fail during seismic events. There are currently
no models available to estimate these impacts.
Additional Data and Next Steps
A Level 2 HAZUS-MH earthquake analysis was conducted for Somerset County using the default model
data, with the exception of the updated building and critical facility inventories which included userdefined data, and estimated modification to the NEHRP soil data. Additional data needed to further refine
the County’s vulnerability assessment include: (1) updated demographic data to update the default data in
HAZUS-MH; (2) soil liquefaction data; and (3) the NEHRP soil data from the New Jersey Geologic and
Water Survey. Additionally, the County can identify un-reinforced masonry critical facilities and
privately-owned buildings (i.e., residences) using local knowledge and/or pictometry/orthophotos. These
buildings may not withstand earthquakes of certain magnitudes and plans to provide emergency
response/recovery efforts for these properties can be set in place. Further mitigation actions include
training of County and municipal personnel to provide post-hazard event rapid visual damage
assessments, increase of County and local debris management and logistic capabilities, and revised
regulations to prevent additional construction of non-reinforced masonry buildings.
August 2013
5.4.7-40

section 1: introduction

Transcription

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