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Near-field strong ground-motion data from the September 12-13, 2007 Sumatra sequence

Near-field strong ground-motion data from the September 12-13, 2007 Sumatra sequence. Preliminary report by Hudnut, K., C. Stephens, D. Boore, J. Galetzka, A. Acosta, J. Genrich, K. Sieh, J.-P. Avouac, T. Heaton, R. Briggs, A. Borsa and K. Stark Real-Time Monitoring & Alert Systems

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Near-field strong ground-motion data from the September 12-13, 2007 Sumatra sequence

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  1. Near-field strong ground-motion data from the September 12-13, 2007 Sumatra sequence Preliminary report byHudnut, K., C. Stephens, D. Boore, J. Galetzka, A. Acosta, J. Genrich, K. Sieh, J.-P. Avouac, T. Heaton, R. Briggs, A. Borsa and K. Stark Real-Time Monitoring & Alert Systems Scientific Requirements Workshop Leavenworth, Washington October 4, 2007

  2. Acknowledgments • Caltech Tectonics Observatory • Jean-Philippe Avouac, Director; Kerry Sieh, Sumatra Lead • Tom Heaton (K2’s), Don Helmberger, Hiroo Kanamori, Rob Clayton • Jeff Genrich, John Galetzka, Rich Briggs, Aron Meltzner, Ozgun Konca, Anthony Sladen, Willy Amidon, Keith Stark (consultant) • LIPI • Danny Natawidjaja • UCSD/SOPAC • Linette Prawirodirjo, Peng Fang, Yehuda Bock • U. S. Geological Survey • Walter Mooney, IOTWS Lead for USGS; Bill Ellsworth - advocacy & support • Ron Porcella (K2’s), Arnie Acosta, Chris Stephens, Dave Boore, Roger Borcherdt, Shane Detweiler, Woody Savage, Mehmet Celebi, Adrian Borsa

  3. Sequence Overview

  4. Historic rupture zones - 1797 & 1833 Outlines of rupture peripheries indicated by thin boundary lines

  5. Engineering seismology Earthquakes <600 km from Jakarta, Singapore, and Kuala Lumpur PADANG - tsunami threat JAKARTA

  6. Station locations PSKI SLBU

  7. Pulau Sikuai - PSKI From Chris Stephens, USGS Menlo Park For the Mw 8.4 at 392 km (horizontal components combined): PGA horiz. of 55.97 cm/s2 ; ~6% g (not ‘huge’) PGV 5.9 cm/s horiz. ; -3.5 cm/s vert. For the Mw 7.9 at 165 km (horizontal components combined): : PGA horiz. of 168.4 cm/s2 ; ~17.2% g (still not ‘huge’) PGV 11.3 cm/s horiz. ; -6.8 cm/s vert. Long-Period Energy? Directivity effects?

  8. Preliminary finite-fault source modelsProf. Chen Ji, UCSB - M 8.4 & Yuehua Zeng, USGS - M 7.9 Thanks to Rich Briggs for the KML files!

  9. PSKI - Event 1 - Mw 8.4 Velocity records for the Mw 8.4 (by Dave Boore)

  10. ShakeMap Ground-Motion Prediction PGV: ~10 cm/s at Padang (computed) 6.9 cm/s (observed) Automated - based on Wald et al. (2005) and finite-fault source model by Chen Ji

  11. PSKI - Event 2 - Mw 7.9 Velocity records for the Mw 7.9 (by Dave Boore) note: data are un-filtered

  12. PSKI photograph Courtesy of John Galetzka; Caltech Tectonics Observatory Enclosure and solar array act as an inverted pendulum at 3-5 Hz & ~20 Hz

  13. Silabu (SLBU) station photos Courtesy of John Galetzka; Caltech Tectonics Observatory Much closer than PSKI ! Data received from JEG two days ago (10/2) • Chris Stephens set to work on it immediately • Data from M 8.4 - P-wave is missing • Data from M 7.9 - record had to be spliced • Still evaluating data - initial plots made yesterday Enganno data not yet retrieved from field. Siberut had a power malfunction and did not record data.

  14. SLBU Waveforms for the Mw 8.4 (by Chris Stephens) note: data are un-filtered

  15. SLBU Velocity for Mw 8.4 ~80 cm/sec broad pulse note: data are un-filtered

  16. SLBU Displacement for Mw 8.4 Approx. 10x larger than from GPS from Peng Fang (static) and Jeff Genrich (kinematic) - all results preliminary note: data are un-filtered

  17. SLBU Spliced record for the Mw 7.9 (by Chris Stephens) Three pulses of energy - Burst 1 @ 5-25 sec Burst 2 @ 35-60 sec Burst 3 @ 70-90 sec 1 2 3

  18. Data processing, archiving & distribution http://www.strongmotioncenter.org/ NSMP Data Center & NCESMD partnership MUST HAVE OPEN DATA http://nsmp.wr.usgs.gov/ Take-away message: GPS and accelerometer data are complementary A robust system will likely require both for redundancy

  19. Proposal - zipper array for early warning and immediate finite-fault source for San Andreas and San Jacinto fault ‘Big Ones’ L A IOC - 36 quadrilaterals shown @ 30 km spacing (shown) FOC - 100 quads @ 10 km spacing ($10 M init. + $3 M/yr)

  20. Backup Slides

  21. PSKI - Event 1 - Mw 8.4 Waveforms for the Mw 8.4 (by Chris Stephens)

  22. PSKI - Event 2 - Mw 7.9 Waveforms for the Mw 7.9 (by Chris Stephens)

  23. PSKI - Event 3 - Mw 7.0 Waveforms for the Mw 7.0 (by Chris Stephens)

  24. PSKI - Event 3 - Mw 7.0 Waveforms for the Mw 7.0 (by Dave Boore)

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