Progress on Early Warning Research in Taiwan

1. Yih-Min Wu National Taiwan University Hiroo Kanamori Caltech Nai-Chi Hsiao Central Weather Bureau, Taiwan Progress on Early Warning Research in Taiwan

2. Topics • P waves method for earthquake early warning • Progress on earthquake early warning system in Taiwan

3. Earthquake occurs, you may think about • Large earthquake? • Cause damage? • Is this place safe?

4. τc & Pd Methods • τcaverage period parameter of the initial three seconds P waves • For magnitude determination • Pd 0.075Hz high pass peak displacement amplitude of the initial three seconds P waves • For intensity estimation & damage identification

6. Earthquake size could be determined by τc!

8. Pd large than 0.5 cm following shakings may cause damage

10. PGV could be predicted by Pd and then Shaking Intensity could be predicted!

12. Pd for regional EEW

13. Pd for magnitude determination

15. Near Source effect!

17. τc & Pd for damaging event identification!

18. 2003 Chengkung 1999 Chi-Chi 1999 Chiayi 1998 Reuyli 1994 Nanoa

19. Warning could be given within one second after P arrival!

21. 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.

23. SimuSac.c Historical SAC Records Earthworm Sniffring4eew.c PICK_RING Imports Picks Share Memory WAVE_RING1 Sniffwave4eew.c Scream2ew-BB WAVE_RING2 sniffwave4eew Import_Smart24 WAVE_RING3 WAVE_RING4 sniffwave4eew Import_Wave TcPd.c Scn2scnl Report 200808_evts.txt

25. Progress on earthquake early warning system in Taiwan

26. Real-time strong-motion network • Accelerometer- • 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

27. Real-time strong-motion network • Accelerometer- • 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

28. Virtual sub-network approach

29. Performances for VSN 0.28 5.46  6.41 km ~17 sec 4.66  4.73 km 29

30. Pd discriminator 3 sec P wave 30

31. Magnitude estimation 31

32. yes Pd > 0.1 Compute Pd Estimate M from yes Network triggered M > 6.0 Create shakemap VSN algorithm from coming signals M 7.1 2002/3/31 M 7.0 Offshore Hualien earthquake

33. yes Pd > 0.1 Compute Pd Estimate M from yes Network triggered M > 6.0 Create shakemap VSN algorithm from coming signals M 6.4 2006/4/1 M 6.5 Taitung earthquake

34. New proposed EEW system All seismographs installed by CWB are included for EEW evaluation Use the Earthworm as the platform of different seismic data format integration Both VSN and P waves methods 34

35. CWB seismographic network New established stations 35

36. Preliminary test for new system 0.48  0.34 12.01  13.01 km 20.2  4.9 sec 36

37. Promotion plan in Taiwan 37

38. Thanks for your attention!