Development of Earthquake Development of Earthquake Early WarningEarly Warning

Yih-Min Wu

Dept. of Geosciences, National Taiwan University

如何降低地震災害？如何降低地震災害？

長期– 土地利用規劃中期– 耐震設計短期– 地震預測地震發生

Earthquake Early WaningEarthquake Early Waning

Before Occurrence Before Occurrence – Earthquake Prediction – Predicts EarthquakeEarthquake Prediction – Predicts Earthquake

Before Strong Ground motionBefore Strong Ground motion– Seismic Early Waning System (EWS)Seismic Early Waning System (EWS)– Predicts Shaking Predicts Shaking

Before Damage is DiscoveredBefore Damage is Discovered– Seismic Rapid Reporting System (RRS)Seismic Rapid Reporting System (RRS)– Predicts DamagePredicts Damage– Focusing seismic rescue effortsFocusing seismic rescue efforts

Philosophy

Currently precise prediction of earthquake process is difficult.However, once seismic waves are excited, the process is governed by known “Elasticity theory” and “Earth structure”, and the behavior is more predictable, and we can respond to ever-changing situation associated with an earthquake and its aftermath.

Environment is Changing

Large cities, high-rise buildings, bridges, tunnels, airport, gas, telephone, electricity, etc.

But, developments in modern engineering (e.g., structural control) will allow effective use of rapid seismic information to mitigate seismic hazards.

地震預警地震預警應用範圍應用範圍學校學童躲入桌子底下尋求保護及心理應變。墨西哥市的學校學童躲入桌子底下尋求保護及心理應變。墨西哥市的預警系統研究成果顯示，接受地震預警訊息的學童，在心預警系統研究成果顯示，接受地震預警訊息的學童，在心理上大幅降低對地震之恐懼。 理上大幅降低對地震之恐懼。 工人能離開危險的工作位置。 工人能離開危險的工作位置。 醫院進行的手術能暫時停止或調整精細及關鍵的操作，例醫院進行的手術能暫時停止或調整精細及關鍵的操作，例如如 :: 眼科手術等。 眼科手術等。 運輸系統能自動停止或減速，例如運輸系統能自動停止或減速，例如 :: 高速鐵路列車減速以高速鐵路列車減速以降低翻車之風險。 降低翻車之風險。 維生管線及通訊網路能自動調整、重組或關閉，例如維生管線及通訊網路能自動調整、重組或關閉，例如 :: 關關閉瓦斯及供水管線，減少地震所引起之火災及其他災害。 閉瓦斯及供水管線，減少地震所引起之火災及其他災害。 工廠能及時進行緊急應變，保護振動敏感之設備，例如工廠能及時進行緊急應變，保護振動敏感之設備，例如 ::晶元製造廠。晶元製造廠。

Earthquake early warning (EEW)Earthquake early warning (EEW)

Before Strong Ground MotionBefore Strong Ground Motion– Earthquake Early Waning SystemEarthquake Early Waning System– Predict Shaking Predict Shaking

Regional Warning & Onsite WarningRegional Warning & Onsite Warning

119 120 121 122Longitude (E)

2 2

2 3

2 4

2 5

La

titu

de

(N)

VSN no warning area

1 0 sec

2 0 sec

3 0 sec

Warning tim e

Early Warning T im e of the Earthquake of Sep. 2 0 , 1 9 9 9 (M w7 .6 )

0 sec

Blind zone of on-site warning

Regional Warning v.s. Onsite Warning

- 3 0 3 6 9 1 2 1 5 1 8 2 1

Tim e after P arrival (second)

-12

-8

-4

0

4

8

Dis

pla

ce

me

nt

(cm

)

-20

-10

0

10

20

Ve

loci

ty (

cm

/se

c)

-200

0

200

400

Ac

ce

lera

tio

n (

ga

l)

Pd

PGA

PGV

PGD

c

M w6.6, focal depth 10 kmKnet Station NIG018Epicentral distance 14 km

0.5 cm

Pd threshold warning

BackgroundBackground

Cooper (1868) proposed EEW conceptCooper (1868) proposed EEW concept““arrange a very simple mechanical contrivance arrange a very simple mechanical contrivance

at various points from 10 to 100 miles from at various points from 10 to 100 miles from San Francisco” & “instantaneously ring an San Francisco” & “instantaneously ring an alarm bell… near the center of the city”alarm bell… near the center of the city”

A hundred years later, Japan Railways A hundred years later, Japan Railways designed an EEW system in 1965 and designed an EEW system in 1965 and started to operate in 1966 (Nakamura, started to operate in 1966 (Nakamura, 1988).1988).

Nakamura and Saita (2006)

A concept of the Regional warning

The first successful case The first successful case

The Mexico City Seismic Alert System The Mexico City Seismic Alert System successfully provided about 70 sec of successfully provided about 70 sec of advanced warning of the 14 September, advanced warning of the 14 September, 19951995, Copala (Guerrero, Mexico) , Copala (Guerrero, Mexico) earthquake to the citizens of Mexico City earthquake to the citizens of Mexico City (Espinosa-Aranda (Espinosa-Aranda et al.et al., 1995). , 1995).

To public systemTo public system

(Espinosa-Aranda (Espinosa-Aranda et al.et al., 1995), 1995)

Successful case in Taiwan Successful case in Taiwan

102 sec after the 102 sec after the 19991999 Chi-Chi Chi-Chi earthquake, the CWB of Taiwan reported earthquake, the CWB of Taiwan reported the hypocenter, magnitude (M7.3), and the hypocenter, magnitude (M7.3), and shaking map to public (Wu et al, 2000). shaking map to public (Wu et al, 2000).

In In 20022002, the CWB achieved 22 sec , the CWB achieved 22 sec reporting time after the occurrence of an reporting time after the occurrence of an earthquake (Wu and Teng, 2002). earthquake (Wu and Teng, 2002).

0 10 20 30 40 50 60 70

Tim e (sec)

-1000

-750

-500

-250

0

250

500

750

1000

-100

-75

-50

-25

0

25

50

75

100

AC

C.

(gal

)

-100

-75

-50

-25

0

25

50

75

100

Td Tpr

S arrival

Tw < 0

S arrival

Tw > 0

Sun Moon Lake ( = 9 km )

Reporting time

Taichung( = 35 km)

Taipei( = 145 km )

09/20/1999 17:47 M w 7.6

S arrival

P arrival

P arrival

P arrival

Successful case in Japan Successful case in Japan

Urgent Earthquake Detection and Alarm Urgent Earthquake Detection and Alarm System (UrEDAS), this system worked System (UrEDAS), this system worked during the Niigata Chutsu earthquake in during the Niigata Chutsu earthquake in 20042004. It immediately detected the P-wave . It immediately detected the P-wave arrival and shut off the train’s power in less arrival and shut off the train’s power in less than 3 seconds after P arrival (Nakamura than 3 seconds after P arrival (Nakamura et al., 2006).et al., 2006).

Nakamura (2009)

Big progress in Japan 2007Big progress in Japan 2007

JMA started official distribution of early warning JMA started official distribution of early warning information to a limited number of organizations information to a limited number of organizations in August, 2006, and plans to distribute it to the in August, 2006, and plans to distribute it to the public in the fall of 2007. public in the fall of 2007.

System was successfully activated during the System was successfully activated during the 2007 Noto Hanto and Niigata Chuetsu-Oki 2007 Noto Hanto and Niigata Chuetsu-Oki earthquakes, and provided accurate information earthquakes, and provided accurate information regarding the source location, magnitude and regarding the source location, magnitude and intensity at about 3.8 s after the arrival of P intensity at about 3.8 s after the arrival of P wave at nearby stations. wave at nearby stations.

Odaka et al. (2003) & Kamigaichi (2004)

Doi (2009)

Doi (2009)

Doi (2009)

Motivation in TaiwanMotivation in Taiwan

EWS in TaiwanEWS in TaiwanUsing the telemetered signals from Using the telemetered signals from strong-motion instruments.strong-motion instruments.Since 2000Since 2000Virtual Sub-Network Approach Virtual Sub-Network Approach (VSN)(VSN)

MML10L10

Wu et al., BSSA, 1998; Wu and Teng, BSSA, 2002.

Real-time strong-motion networkAccelerometer - 102 stations (20km averaged

spacing) 16 bits resolution ± 2g Max. amplitude

Telemetry - Real-time data stream (RTD) 4.8K dedicated telephone

line Sampling rate 50 sps 0.2 sec averaged delay

Data processing - Taipei data center

Windows-based workstation

Virtual sub-network approach

28

Performances for VSNPerformances for VSN

0.28

~17 sec

119 120 121 122

Longitude (E)

2 2

2 3

2 4

2 5

Lat

itu

de

(N)

VSN no warning area

1 0 sec

2 0 sec

3 0 sec

Warning tim e

Expected Early W arning Time of the Earthquake of Sep. 20, 1999 (Mw7.6)

0 sec

For onsite case, an earthquake For onsite case, an earthquake occurs, you may think aboutoccurs, you may think about

Large earthquake?Large earthquake?

Cause damage?Cause damage?

Is this place safe?Is this place safe?

ττcc & & PPdd Methods Methods

ττcc average period parameter of the initial three initial three

seconds P wavesseconds P waves – For magnitude determinationFor magnitude determination

PPdd 0.075Hz high pass peak displacement amplitude of the initial three seconds P waves– For intensity estimation & damage identificationFor intensity estimation & damage identification

Wu and Kanamori (2005a,b; 2008a,b)

- 3 0 3 6 9 1 2 1 5 1 8 2 1

Tim e after P arrival (second)

-12

-8

-4

0

4

8

Dis

pla

ce

me

nt

(cm

)

-20

-10

0

10

20

Ve

loci

ty (

cm

/se

c)

-200

0

200

400

Ac

ce

lera

tio

n (

ga

l)

Pd

PGA

PGV

PGD

c

M w6.6, focal depth 10 kmKnet Station NIG018Epicentral distance 14 km

0.5 cm

Pd threshold warning

0 3 6 9 12

Tim e (sec)

- 1

0

1- 4

0

4

Dis

pla

cem

ent

(cm

)

- 1

0

1- 2

0

2- 0 . 5

0

0 . 5

c m easured

c 4.4s, Mw8.3

c 3.8s, Mw7.6

c 3.2s, Mw7.2

c 2.4s, Mw6.7

c 1.3s, Mw6.1

EpicentralDistance

71 km

8 km

70 km

13 km

13 km

Station CodeDepth

HKD11242 km

TCU0798 km

MYG01142 km

TTR00711 km

NIG0209 km

Japan

Japan

Japan

Japan

Taiwan

2 2 2 2

2 20

2 2

0

2

ˆ( ) 4 | ( ) |4

ˆ( ) | ( ) |

1 2

W

W

C

u t dt f u f dfr f

u t dt u f df

rf

Earthquake size could be determined by τc!

4 5 6 7 8

M w

0 . 1

1

1 0

c (

sec)

Taiwan 11 eventsSouthern California 26 eventsJapan 17 events

log (c) = 0.296 M w - 1.716Sdv=0.122, R=0.933

Pd large than 0.5 cm following shakings may cause damage

0.01 0.1 1 10

Pd, Displacem ent (cm )

0.1

1

10

100

Fil

tere

d P

GD

(cm

)

No dam age records (168)No dam age events average (21)Damage records (40)Damage events average (5)

0.5 cm

4 cm

Chi-Chi

PGV could be predicted by Pd and then Shaking Intensity could

be predicted!

0.001 0.01 0.1 1 10Pd (cm)

0 . 1

1

1 0

1 0 0

PGV

(cm

/se

c)

Taiwan 507 recordsSouthern California 199 recordsJapan 74 records

Linear regression over 780 recordslog(PGV)=0.920 log(Pd) + 1.642SDV = 0.326

τc & Pd for damaging event identification!

5 6 7 8

Mw

0.01

0.1

1

10 c

*Pd

(se

c*c

m)

No damage records (168)No damage events average (21)Damage records (40)Damage events average (5)

Damage

No Damage

1999 Chi-Chi

2003Chengkung

1998Reuyli

1999Chiayi

1994Nanoa

Warning could be given within one second after P arrival!

- 2 - 1 0 1 2 3 4Tim e after P arrival (sec)

- 4

- 2

0

2

4

6

- 2

- 1

0

1

2

Dis

pla

cem

ent

(cm

)

2007/03/25 Noto Mw6.7 earthquake

ISK006=7 km

ISK005=19 km

Combination with modern MEMS sensor. Cheaper device may install to every building to give warning within three seconds after P arrival after a large earthquake occurs.

An examination using building array records from a damage building

0.1 1 10

PG V (cm/s)

0

0.5

1

1.5

2

Pd

(cm

)

Ch03: Free-field

Ch11: F1

Ch18: RF

Ch21: RF

Ch22: RF

Taitung EQ

Chengkung EQChi-Chi EQ

Pd=0.5 cm

Applications on the EEW Information

uncontrolled

controlled

Kh

Kanamori (2005)

0.5 g

8 feet

controlled

Kanamori (2005)

Nakamura (2009)

Doi (2009)

Takamatsu (2009)

Takamatsu (2009)

Takamatsu (2009)

Takamatsu (2009)

Takamatsu (2009)

Motosaka (2009)

Motosaka (2009)

Motosaka (2009)

Motosaka (2009)

Sugano (2009)

Sugano (2009)

Sugano (2009)

Sugano (2009)

Sugano (2009)

Human SensorHuman Sensor

Thanks toThanks toProfs. Ta-Liang Teng (USC), Willie H. K. Lee Profs. Ta-Liang Teng (USC), Willie H. K. Lee (USGS), Yi-Ben Tsai (PG&E), Tzay-Chyn Shin (USGS), Yi-Ben Tsai (PG&E), Tzay-Chyn Shin (CWB), Richard Allen (UC Berkeley) (CWB), Richard Allen (UC Berkeley)

Drs. Nai-Chi Hsiao (CWB), Chien-Hsin Chang Drs. Nai-Chi Hsiao (CWB), Chien-Hsin Chang (CWB), Chien-Fu Wu (CWB), Li Zhao (IES), (CWB), Chien-Fu Wu (CWB), Li Zhao (IES), Yamada Masumi (Kyoto Univ.), Barry Hirshorn Yamada Masumi (Kyoto Univ.), Barry Hirshorn (PWTC)(PWTC)

Mrs. Da-Yi Chen (CWB), Jang-Tian Shieh (NTU)Mrs. Da-Yi Chen (CWB), Jang-Tian Shieh (NTU)

Central Weather Bureau, TaiwanCentral Weather Bureau, Taiwan

NIED, JapanNIED, Japan

SCEC, USASCEC, USA