How much do we know more about Taiwan earthquakes since the

How much do we know more about Taiwan earthquakes since the

Conference in Commemoration of 100th Anniversary of the 1906 Meishan Earthquake, Taiwan
How Much Do We Know More
about Taiwan Earthquakes since
the 1906 Meishan Earthquake ?
Yi-Ben Tsai
Pacific Gas and Electric Company, San Francisco, California, USA
March 16-18, 2006
National Chung-Cheng University
Outlines
•
•
•
•
•
•
•
•
Introduction
1906 Meishan earthquake and 1907 Omori’s paper
Many more disastrous earthquakes since then
Seismicity and plate tectonics of Taiwan
Strong ground motions
3D seismic tomography
Earthquake forecast, prediction, and warning
Concluding remarks
In commemoration of the 1906
Meishan earthquake, we are here:
• To remember past earthquake victims
• To learn from past and present earthquakes
• To prepare for future earthquakes
Preliminary Note on the Formosa
Earthquake of March 17, 1906
By F. Omori
•
•
•
•
•
•
•
•
•
•
Introduction
Damage
Isoseismals
Faults
Relation to the Faults of the Direction of (vibratory)
Motion
Probable Eastward Extension of the Fault
Duration of the Preliminary Tremor
The Two Severe Earthquakes in 1904
Relation of the Earthquake of March 17, 1906, with
those in 1904.
Periodic Repetitions of Strong After-shocks
Fault
Liquefaction
Structural damage
http://www.cwb.gov.tw/V4/index.htm
(3276)
(2535)
(1275)
(355)
(106)
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
（摘自台灣地區十大災害地震圖集）
1935 Tun-tze-chiao fault
Overall ≒ 40%
Area
Total households
Collapsed households
Collapse rate
Fault zone
3,220
1,889
58.665%
South of fault zone
1,094
505
46.161%
North of fault zone
5,814
1,655
28.466%
1935 Tun-tze-chiao fault
Overall ≒ 2.5%
Area
Population
Death toll
22,075
1,292
5.853%
South of fault zone
7,694
140
1.820%
North of fault zone
38,589
402
1.042%
Fault zone
Fatality rate
1935 Shih-tan fault
Overall ≒ 70%
Area
Total households
Collapsed households
Collapse rate
Fault zone
1,743
1,084
62.192%
East of fault zone
1,040
803
77.212%
West of fault zone
1,092
891
81.593%
1935 Shih-tan fault
Overall ≒ 1.4%
Area
Fault zone
Population
Death toll
Fatality rate
10,380
196
1.888%
East of fault zone
6,146
28
0.456%
West of fault zone
8,149
124
1.522%
Epicenter
Epicenter of
of Chi-Chi
Chi-Chi earthquake
earthquake
Chelungpu
Chelungpu fault
fault
Iso-seismic
Iso-seismic intensity
intensity in
in gals
gals
County
County boundaries
boundaries
88
88
33
88 Number
88
Number of
of fatality
fatality
46
46
：2539
2539
Total
Total fatalities
fatalities：
00
25
25
50
50
Kilometers
Kilometers
66
113
113
1,223
1,223
33
33
941
941
PGA(gal)
80
80
66
N21.78°
N21.78°
N25.41°
N25.41°
E119.36°
E119.36°
E122.05°
E122.05°
(Ouchi et al., 2001)
車籠埔斷層逆衝造成的破壞：豐原中正公園附近樓房傾斜
(Modified from Chen et al., 2001)
Collapse rate
Death rate
00000
555555
Miaoli County
County
Miaoli
66
0.03
0.03
10
10
10
10
10
11
0.001
0.001
Kilometers
Kilometers
Kilometers
Kilometers
Kilometers
Kilometers
0.001
0.001
171
171
1.112
158
158 1.112
11
0.002
0.002
384
384
77
0.008
0.008
Taichung City
City
Taichung
11
10
10
96
96
0.001
0.001 11 0.014
0.014
0.004
0.004
55
0.005
0.005
0.331
0.331
Taichung
Taichung County
County
0.464
0.464
89
89
0.054
0.054
162
162
44
125
125
0.046
0.046
37
37
0.656
0.656
0.098
0.098
0.094
0.094
0.002
0.002
88
88
112
112
0.13
0.13
400
400
0.463
0.463
Changhua
Changhua County
County
88
88
24
24
33
0.02
0.02
222
222
0.091
0.091
0.252
0.252
0.019
0.019
93
93
0.089
0.089
35
35
0.082
0.082
80
80
179
179
0.999
0.999
17
17
0.095
0.095
42
42
0.341
0.341
PGA(gal)
PGA(gal)
88
0.035
0.035
23
23
Yunlin
Yunlin County
County
77
0.039
0.039
0.109
0.109
37
37
0.037
0.037
400
400
Nantou County
County
Nantou
112
112
250
250
0.181
0.181
42
42
0.116
0.116
22
44
250
250
Chiayi City
City
Chiayi
0.032
0.032
0.017
0.017
Chiayi County
County
Chiayi
Taitung County
County
Taitung
N23.38°
N23.38°
N24.40°
N24.40°
E120.37°
E120.37°
Epicenter
Epicenter
384
384 Total
Total fatalities
fatalities
Chelungpu fault
fault
Chelungpu
0.656
0.656 Fatility
Fatility rate
rate (%)
(%)
E121.29°
E121.29°
N24.40°
N24.40°
E120.37°
E120.37°
000000
Miaoli County
County
Miaoli
619
619
11.37
11.37
10
10
10
10
10
10
555555
44
Kilometers
Kilometers
Kilometers
Kilometers
Kilometers
0.02
0.02
1,848
1,848
45.72
1,444
1,444 45.72
3.45
3.45
5,139
5,139
31.91
31.91
634
634
14.59
14.59
28
28
0.11
0.11
Taichung City
City
Taichung
696
696
968
968
Taichung County
Taichung
County
1.09
1.09
14.19
14.19
16
16 34
34
0.04
0.04 33 0.16
0.16
0.04
0.04
848
848
2,208
2,208
2,917
2.74
2.74 2,917
4.68
4.68
6.03
6.03
10
10
0.02
0.02
2,857
2,857
16.64
16.64
400
400
1,913
1,913
Changhua County
County
Changhua
28.68
28.68
2,557
2,557
9.95
9.95
324
324
6,099
6,099
24.77
24.77
330
330
8.1
8.1
11
5,007
5,007
17.22
17.22
2,508
2,508
51.94
51.94
2,374
2,374
359
359
80
80
3.4
3.4
46.81
46.81
1,736
1,736
46.89
46.89
600
600
8.83
8.83
PGA(gal)
PGA(gal)
PGA(gal)
PGA(gal)
PGA(gal)
PGA(gal)
436
436
9.35
9.35
Yunlin County
County
Yunlin
1,140
1,140
331
331
1.2
1.2
400
400
20.38
20.38
2,686
2,686
Nantou County
County
Nantou
250
250
16.44
16.44
190
190
1.99
1.99
88
250
250
0.03
0.03
0.01
0.01
Chiayi County
County
Chiayi
Taitung County
County
Taitung
N23.38°
N23.38°
Chiayi City
City
Chiayi
14
14
Epicenter
Epicenter
5,139
5,139 Totally
Totally collapsed
collapsed households
households
Chelungpu
Chelungpu fault
fault
E121.29°
E121.29°
31.91 Percentage
Percentage rate
rate of
of totally
totally collapsed
collapsed households
households
31.91
Overall ≒ 15%
Area
Total households
Collapsed households
Collapse rate
Fault zone
59,971
8,719
14.539%
East of fault zone
28,124
8,271
29.409%
West of fault zone
85,830
8,348
9.726%
Overall ≒ 0.23%
Area
Population
Death toll
Fatality rate
Fault zone
226,227
543
0.240%
East of fault zone
102,203
565
0.553%
West of fault zone
307,120
333
0.108%
Some observations
• Modern building code is effective in reducing
earthquake losses.
• Strike-slip fault ruptures did cause more destruction
in the fault zone than the surrounding areas on both
sides
• Reverse or thrust fault ruptures did not cause more
destruction in the fault zone than the surrounding
areas on the hanging wall side
• Fault zone restriction of buildings is justified for
strike-slip faults, but is complicated for reverse or
thrust faults
1973-2004，地震規模≧3
中央氣象局資料
1900-2004，地震規模≧6
Time variation of Mc (Chen et al. 2005)
1900-1972
Old CWBSN
1973-1990
TTSN
1991-2004
New CWBSN
Seismicity in Taiwan (1991-2004)
（江, 2005）
(修改自Angelier, 1986)
80 mm/yr
convergence
across the active
Taiwan arc-continent
collision zone
（余水倍博士提供）
Dilatation Rate
(1993-1999)
Remarkable
Contraction
Western Taiwan
Longitudinal Valley
Coastal Range
Significant Extension
Ilan Plain
Northeastern Taiwan
Central Range
（余水倍博士提供）
GPS
150 new stations
Installed and operated
by CWB/IES
(2001-2005)
About 50 pre-existing
stations operated by
CWB/IES/MOI
Near-fault GPS survey
by CGS/IES
（余水倍博士提供）
台灣地形及地層下陷區
水利署資料
（中央大學李錫堤教授提供）
( Davidson, 1903)
中央地質調查所資料
New magnetic anomaly map
(Yen et al., 1992)
(Yen, 2004)
九二一地震水平地動加速度值（左圖）及速度值（右圖）衰減情形
CHI-CHI Earthquake Mw7.6
CHI-CHI Earthquake Mw7.6
1000
1
Campbell form (1997)
Multiply by 2.18
Horizontal Peak Ground Velocity (cm/sec)
Horizontal Peak Ground Acceleration (g)
Campbell form (1997)
Multiply by 0.55
0.1
Campbell form for PGA
STD
Site class-B
Site class-C
Site class-D
Site class-E
ILA
TAP
HWA
upper stations
0.01
100
10
Campbell form for PGV
STD
Site class-B
Site class-C
Site class-D
Site class-E
ILA
TAP
HWA
upper stations
1
0.1
0.001
1
10
100
Closest distance to rupture surface (km)
1000
1
10
100
Closest distance to rupture surface (km)
1000
(Liu and Tsai, 2005)
(Liu and Tsai, 2005)
(Liu and Tsai, 2005)
(Liu and Tsai, 2005)
3D Seismic Tomography
• Rau and Wu, 1995
• Ma et al., 1996
• Kim et al., 2005
(Rau and Wu, 1995)
(Rau and Wu, 1995)
(Ma et al., 1996)
(Ma et al., 1996)
(Kim et al, 2005)
(Ma et al., 1996)
(Rau and Wu, 1995)
(Kim et al, 2005)
(Kim et al, 2005)
Types of Earthquake Notification
• Earthquake forecast: probabilistic, tens
to hundreds of years.
• Earthquake prediction: deterministic,
days to years.
• Earthquake warning: empirical, seconds
to tens of seconds
Example of earthquake forecast
• Earthquake probabilities of San Francisco
Bay Area
(http://quake.usgs.gov/research/seimology
/wg02/images/percmap-lrg.jpg).
• Probabilistic seismic hazard map of
California
(http://www.consrv.ca.gov/cgs/rghm/psha/i
ndex.htm).
（鄭錦桐，2002）
Earthquake Reporting and Warning Systems
for Taiwan
CWB’s Taiwan Rapid Earthquake Information Release System
(Wu, 1999)
Taiwan Rapid Earthquake Information Release System
(Wu, 1999)
Chi-Chi earthquake report release automatically on the website
Intensity Map of Chi-Chi Earthquake
Early warning system
(Wu, 1999)
Ground motion record of Chi-Chi earthquake in Taipei area
九二一集集大地震台北地區（北投文林國小）之地動歷時
(cm/sec/sec)
地
動
加
速
度
初 達波
震度
100
5
50
4
剪 力 波
主 振 動 波
3
2
0
-50
-100
10
20
30
40
50
60
70
80
地震發生 後 時 間 （秒 ）
(Wu, 1999)
Early Warning Time of the Earthquake
of Sep. 20, 1999 (ML7.3)
Latitude (N)
25
24
0 sec
10 sec
20 sec
23
30 sec
Warning time
22
No warning area
119
120
121
Longitude (E)
122
(Wu, 1999)
Estimated early warning time for November 14, 1986 (ML6.8) Earthquake
(Wu, 1999)
Anti-Earthquake Measures for the Shinkansen (BULLET TRAIN)
(http://www.shinsai.or.jp/hrc-e/publish/lessons_ghe/lghe17.html)
On-site earthquake warning
• QuakeGuard (www.seismicwarning.comArchitectural Block Diagram).
Seismic Warning - QuakeGuard
Seismic Warning - QuakeGuard
iSTEP sub-projects on earthquake precursors
(2002-2006)
• Sub-project 1: Seismological variations
• Sub-project 2: Geomagnetic variations
• Sub-project 3: Crustal deformation by InSAR
• Sub-project 4: Ionospheric variations
• Sub-project 5: Statistical studies
(Bolt, 1999)
0 km
6 km
12 km
18 km
24 km
30 km
Stress changes
with six months
of aftersocks by
hypoDD (Ma et
al., 2004)
Variations of P wave travel-time residuals
in three periods before and after Chi-Chi earhtquake
Electromagnetic
observational
networks in Taiwan
Satellite receiving station
Ionospheric station
Geomagnetic station
km
Examples of geomagnetic records in quiet times
Examples of geomagnetic records in storm times
Old magnetic anomaly map
New magnetic anomaly map
Co-seismic InSAR images of Chi-Chi earthquake
99/01/21_99/09/23
99/05/06_99/09/23
99/05/06 _99/10/28
Pre-seismic InSAR images of Chi-Chi earthquake
Ionospheric precursors in September 1999
1994-999
M≥5.0 189 Eqk’s
1994-1999: 2191 days
M≥5.0 Eqk’s: 189 (170ays)
Ref: 15-day running MED & IQR
Below Lower Bound:1200-1800 LT
Precursor Shape
416 Anomalies
307 Precursors
Lead Time: 0-5 days
(a) log{p/(1-p)} = 1.50M-6.96
(b) log{p/(1-p)} = 29281.84/d2
Relation between the odds of M≧5.0 earthquakes with the foF2 precursor
in 5 days and the related magnitude and distance
Some observations
• Development of earthquake forecast and
warning has made headways recently.
• Earthquake prediction remains a major
scientific challenge.
• Progress in identifying earthquake precursors
is made by iSTEP and elsewhere.
• Some breakthroughs are possible and
hopefully will come soon.
Concluding Remarks
• We know much more about Taiwan
earthquakes now than a century ago.
• We still don’t know enough about Taiwan
earthquakes.
• There is much more to be learned about
Taiwan earthquakes.
• Hopefully, we will learn enough before
next disastrous earthquake.
Thank you very much