EARTHQUAKE EARLY WARNING AND POSSIBLE PRECURSOR FROM SEISMICITY

By NTU Palert, CWB & NCDR teams

1994 1995 1996 1997 1998 1999 2000

200

300

400

500

600

700

Even

ts (M

L > 2

.0)

1994 1995 1996 1997 1998 1999 2000

0.7

0.8

0.9

1

1.1

1.2

1.3

b va

lues

Chi-Chi Mw7.6

A

B

Aveage 435 events / 30 dayss.d.v. 78 events

Aveage = 0.97s.d.v. 0.10

1994 1995 1996 1997 1998 1999 2000Year

0

4

8

12

16

Even

ts (M

L>4.

0)

CAveage = 5.5s.d.v. 2.6

Wu and Chiao (2006)

Background 1994 to Chi-ChiM>=2.0Radius 20 kmDepth <= 40 km

Background1994 to 2003/12/09M>=McB value (Aki)Radius 25 kmDepth <= 35 kmRelocated catalogWu et al. (2008)

Chan et al. (2012)

PALERT EEW

- 3 0 3 6 9 1 2 1 5 1 8 2 1Tim e after P arrival (second)

-12

-8

-4

0

4

8

Dis

plac

emen

t (cm

)

-20

-10

0

10

20

Velo

city

(cm

/sec

)

-200

0

200

400A

ccel

erat

ion

(gal

)

Pd

PGA

PGV

PGD

c

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

0.5 cm

Pd threshold warning

4 5 6 7 8M w

0 . 1

1

1 0

c (s

ec)

Taiwan 11 eventsSouthern California 26 eventsJapan 17 events

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

0.001 0.01 0.1 1 10Pd (cm)

0 . 1

1

1 0

1 0 0

PGV

(cm

/sec

)

Taiwan 507 recordsSouthern California 199 recordsJapan 74 records

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

For both onsite & regional early warning purposes

iTouch for backup power (4 hrs), display and sound warning

345 stations

CWB and Palert real-time strong motion stations

CWBSN & Palert Shaking maps

• Use 5 km as grid spacing and use inverse square distance as weighting factor to calculate each point PGA.

• One point represents 25 square km area.

Grid setting

Case 1

8 3822

Case 2

8 20

40

Thanks for your attention