Volcanoes and Volcanic Activity Styles of volcanic eruptions Some

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Volcanoes and Volcanic Activity
Locations of relatively young volcanoes in North America
Relationship between volcanism and plate tectonics
Types of volcanic eruptions and hazards
Types of volcanoes and related landforms
Volcano monitoring: looking for signs that a volcano may be about to erupt
Current volcanic activity & status: http://volcanoes.usgs.gov/
Locations and Origin of Volcanic Activity
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Most volcanism occurs at divergent plate boundaries (ocean ridges and
continental rifts), convergent boundaries (subduction zones), and hot spots.
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Styles of volcanic eruptions
Effusive - lava flows
Pyroclastic - explosive eruptions that produce airborne fragments of lava
A large pyroclastic eruption of
An effusive eruption of basaltic lava in
Hawaii - NASA
Klyuchevskaya Volcano, Kamchatka
Peninsula, Russia in October 1994
NASA STS068-214-043
This Dynamic Planet - USGS
Volcanism at ocean ridges and oceanic hot spots primarily results in mafic (basaltic)
rocks. Volcanism at continental rift zones and continental hot spots produces a broad
range of igneous rock compositions. Subduction zones primarily result in intermediate
(andesitic) and mafic rocks with lesser amounts of felsic rocks.
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Aa (jagged) and pahoehoe (smooth, wrinkled/ropy) lavas
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Some features produced by effusive eruptions
Pahoehoe and aa lava flows
Lava tubes
Columnar fractures
Pillow lavas
Fi
Fissure
eruptions
ti
Lava domes
Obsidian flows
USGS
Lava flow hazards
Fig 5.3 Understanding Earth
USGS
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Columnar jointing (fractures) in lava flows
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Pillow lava
produced by lava
flows under water
Fig 3.2 Understanding Earth
15 million year old pillow lavas and
lava flow, part of the Columbia
River basalts in Washington
Devil’s Post
Pile N. Mon.,,
California
Ch 4 Understanding
Earth
Columns near White Pass,
Washington - S. Kuehn
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Lava domes: Mt. St. Helens lava dome in 1992 (top) and
Novarupta lava dome, Alaska (bottom)
S. Kuehn
USGS
Lava domes are usually formed
by felsic to intermediate lava
(ryholite and dacite) because
these lavas have a high viscosity
and don’t flow very well.
Photos of the growing lava dome at Mt. St. Helens:
http://vulcan.wr.usgs.gov/Volcanoes/MSH/Eruption04/Monitoring/sugarbowl_remote_camera_10-04_to_09-05.html
http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/MSH04/framework.html
fissure_vent-img0001.jpg
A lava flow entering a populated area in Hawaii
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Basaltic lava can flow long distances because of its low viscosity.
Lava covers
Kalapana, Hawaii
23 April 1990
6 June 1990
See:
http://hvo.wr.usgs.gov/kilauea/history/1990Kalapana/
USGS 2553015_L.jpg
13 June 1990
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Some features and products of pyroclastic eruptions
Lava fountains
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Lava fountain from
Pu’u O’o at Kilauea
volcano, Hawaii
Strombolian explosions
Eruption columns
Pyroclastic flows
Tephra
• fragments of lava produced by explosive eruptions
• includes ash, pumice, volcanic bombs, etc.
• closer to the volcano, layers are thicker and coarser
Hazards of pyroclastic eruptions
Ash and pumice fall (tephra fall) hazards
Pyroclastic flow and blast hazards
Next: lava fountain video clip
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Strombolian eruptions
consist of many
individual explosive
bursts or fountains,
each of which lasts
only a few seconds.
Most cinder cones are
built by this type of
activity.
Photo: Strombolian
explosion from a cinder
cone at Veniaminof
volcano, Alaska in 1983
Next: strombolian video clip
Strombolian eruption at Stromboli Volcano, Italy - The incandescent lava
fragments generally consist of partially molten volcanic bombs that become
rounded as they fly through the air. USGS photoglossary - Photo by B. Chouet in 1969
USGS DDS-40-IMG0052.jpg
Wind
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Eruption cloud
Tephra fall
Plinian
Eruption
Column
(pumice & ash)
Mt. St. Helens airfall
tephra distribution and
path of the May 18, 1980
eruption cloud
Fig. 8.26c Keller,
Environmental Geology
Large
Bombs
Mt St Helens ash cloud
May 18, 1980 - Austin Post
USGS
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Ashfall from Mt. Spur in 1992
USGS OFR93-707
OFR93 707 img15.jpg
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Mt. St. Helens ash cloud approaching Ephrata, WA on May 18, 1980.
Ephrata is about 145 miles from Mt. St. Helens. The ash cloud arrived in less
than 3 hours. USGS Fact Sheet 027-00 Photo by Douglas Miller
Next: Mt St. Helens eruption
cloud and ash fall video clip
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Small, basaltic volcanic bombs
- Note the aerodynamic shapes
USGS bombs-30410914-028_large.JPG
Major air-routes in the north Pacific
A very large, felsic bread
crust bomb
USGS Fact Sheet 030_97
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Aftermath of a pyroclastic flow (1998)
Soufriere Hills volcano, Montserrat
Ch 5 Understanding Earth
Pyroclastic flow at Mt St Helens
One of at least 17 flows which rushed down the side
of the volcano on May 18, 1980.
USGS
Pyroclastic flow at Augustine
Volcano, Alaska in 1986 USGS
Reinforced concrete broken
by a pyroclastic flow - USGS
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Mt. St. Helens before and
after May 18, 1980
Closer view of the hummocks at Mt. St. Helens
– Similar but larger features are present along Interstate 5 west of Mt. Shasta
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July, 2003 - S. Kuehn
USGS MSH vol1 IMG0003.jpg
Next: landslide and
blast video clip
USGS MSH vol1 IMG0045.jpg
Large tree ripped apart by the force of the lateral blast at Mt. St. Helens27
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Damage from lateral blast
Mt. St. Helens, 1980
USGS MSH Vol1 IMG001.jpg
USGS CVO CD2 IMG0006.jpg
Lahars (volcanic mudflows) from Mt St. Helens damaged many homes,29
shut down Interstate-5, and blocked shipping on the Columbia River
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Devastation of a small
town caused by a lahar
from Mt Pinatubo in the
Philippines
USGS 30410135_029_large.jpg
Mt St. Helens lahar damage
USGS MSH vol1 IMG0087.jpg
More about lahars:
http://volcanoes.usgs.gov/Products/Pglossary/lahar.html
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Volcanic hazards
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Some types of volcanoes and related landforms
Summary:
Shield volcanoes
• Lava flow hazards
• Ash and pumice fall
(tephra fall) hazards
Composite volcanoes (also known as stratovolcanoes)
Cinder cones
• Pyroclastic
y
flow
hazards
Calderas
• Landslide/volcano
collapse hazards
Flood basalts
• Volcanic blasts
Oceanic crust
• Volcanic gases
Explosion craters and maars
• Lahar/flood hazards
USGS
http://volcanoes.usgs.gov/hazards/
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Olympus Mons shield volcano, Mars – Olympus Mons is the largest known
volcano in the solar system. It is about 550 km (350 mi) across and about 25 km
(16 mi) high with a 65 km (40 mi) wide caldera at the summit. It is more than 4
times wider than Mauna Loa, the largest volcano on Earth.
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Two shield volcanoes
Top: Mauna Loa volcano, Hawaii – USGS
Bottom: Newberry volcano, Oregon – S. Kuehn
A composite or stratovolcano:
S. Kuehn
Mt. Rainier, Washington
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Top photo: Lava 36
Butte, Oregon - a
cinder cone related
to Newberry
volcano
Rainier.jpg
Note the lava flow
that erupted from
the side of Lava
Butte.
Bottom photo: This cone is one of
two cinder cones called the Red
Cones, located about 5 km south
of Mammoth Mountain volcano
and Long Valley Caldera in
California. These basaltic cones
and associated lava flows were
erupted about 5,000 years ago.
USGS - Photograph by C.D. Miller in
1982
Next: strombolian explosions video clip
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Columbia River basalts, the
Earth’s youngest major
flood basalt province
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Calderas
Crater Lake, Oregon, fills a caldera that was formed when Mount Mazama
erupted catastrophically about 7,600 years ago. Wizard island was built by a
lava flow and cinder cone after long after formation of the caldera.
S. Kuehn
S. Kuehn
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A simple
model of
caldera
formation
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Preparing for volcanic hazards:
• Study past activity to better understand what the future may bring
• Make maps showing areas of greatest risk
• Land-use planning and disaster preparation
• Education of people who may be affected
• Volcano monitoring - watching for signs that signal an eruption
Major indicators that can be monitored include:
• Changes in the shape of a volcano
• Earthquakes
• Composition of volcanic gases
• Temperature
• Electrical and magnetic changes
• Changes in gravity readings
• Small eruptions that may precede major activity
• Warn and evacuate people when monitoring indicates that an
eruption may be near
Fig 5.16 Understanding Earth
Next: Caldera formation animation
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Annual probability for the
deposition of 1 cm or more of
tephra from all sources in the
Cascade Range
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Volcano monitoring
1 in 100
1 in 500
1 in 1,000
1 in 5
5,000
000
1 in 10,000
USGS
USGS
http://volcanoes.usgs.gov/activity/methods/index.php
http://volcanoes.usgs.gov/about/faq/faqmonitoring.php
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Uplift of the Three
Sisters volcanic area in
Oregon based on
InSAR radar imagery –
the uplift averaging 20
mm per year is related
to ongoing intrusion of
magma at a depth of ~8
km (5 mi).
mi)
Fig. 1 in Wicks et al. (2002),
Geophysical Research Letters, Vol. 29, No. 7
Surface tilt resulting
from the intrusion of
new magma at Kilauea
volcano, Hawaii
More about the Three Sisters area and uplift:
http://vulcan.wr.usgs.gov/Volcanoes/Sisters/framework.html
http://vulcan.wr.usgs.gov/Volcanoes/Sisters/WestUplift/framework.html
Fig. 8.30 Keller,
Environmental Geology
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Volcanic earthquakes: The movement of magma underground produces
characteristic earthquakes, an important sign that an eruption might
happen in the near future.
Compare the magma-generated earthquakes (G and H) to a fault-generated
earthquake (A)
Mt St Helens
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Mount St. Helens Volcano Cam - live photos updated every 5 minutes
http://www.fs.fed.us/gpnf/volcanocams/msh/
USGS Cascades Volcano Observatory – Mt. St. Helens 2004+ eruption
page (and photo gallery)
http://vulcan.wr.usgs.gov/Volcanoes/MSH/Eruption04/framework.html
USGS Cascades Volcano Observatory – Cascade Range current update
http://volcano.wr.usgs.gov/cvo/current_updates.php
Pacific Northwest Volcanoes - Current Seismicity
http://www.pnsn.org/INFO_GENERAL/volcanoes.html
USGS Cascades Volcano Observatory – News and Current Events
http://vulcan.wr.usgs.gov/News/ (e.g. EQ swarm at Mt Rainier Sept 2009)
USGS Cascades Volcano Observatory – Mt St Helens general page
http://vulcan.wr.usgs.gov/Volcanoes/MSH/framework.html
Encyclopedia of Volcanoes
McNut Fig 1
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Volcanoes, volcanic processes, and hazards
Types and Effects of Volcano Hazards
http://volcanoes.usgs.gov/hazards/
Eruption Alerts and Real-time Status
http://volcanoes.usgs.gov/activity/status.php
Preparing for Volcanic Emergencies
http://volcanoes.usgs.gov/hazards/planning.php
USGS Cascades Volcano Observatory
http://vulcan.wr.usgs.gov/home.html
USGS Long Valley, CA Volcano Observatory
http://lvo.wr.usgs.gov/
USGS Hawaiian Volcano Observatory
http://wwwhvo.wr.usgs.gov/observatory/
USGS Alaska Volcano Observatory
http://www.avo.alaska.edu/
Volcanoes, volcanic processes, and hazards
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Volcano World http://volcano.oregonstate.edu/
Volcanoes of the World http://www.swisseduc.ch/stromboli/
USGS Photographic glossary of volcanic terms and features
http://volcanoes.usgs.gov/images/pglossary/index.php
Monitoring Volcanoes for Eruption Warning Signs
http://volcanoes.usgs.gov/activity/methods/index.php
Predicting Volcanic Eruptions - case studies with Kilauea and Mt. St. Helens
http://volcanoes.usgs.gov/edu/predict/
H L
How
Lahars
h Are
A F
Formed
d - U.S.
US G
Geological
l i l Survey
S
http://volcanoes.usgs.gov/hazards/lahar/index.php
USGS Volcano-Related Fact Sheets and Other Resources
http://volcanoes.usgs.gov/Products/sproducts.html#fs
Volcano Watch - satellite images of the world's most active volcanoes
http://www.ssec.wisc.edu/data/volcano.html
Smithsonian Institution, Global Volcanism Program http://www.volcano.si.edu/
Weekly report of worldwide volcanic activity
http://www.volcano.si.edu/reports/usgs/
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