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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, R. Briggs, A. Borsa and K. Stark Caltech Tectonics Observatory Sumatra Meeting
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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, R. Briggs, A. Borsa and K. Stark Caltech Tectonics Observatory Sumatra Meeting Pasadena, California October 3, 2007
Acknowledgements • Caltech Tectonics Observatory • Prof. Jean-Philippe Avouac, Director • Prof. Kerry Sieh; Sumatra Lead • 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 • Ron Porcella, Arnie Acosta, Chris Stephens, Dave Boore, Roger Borcherdt, Shane Detweiler, Woody Savage, Mehmet Celebi, Adrian Borsa
Engineering seismology Earthquakes <600 km from Jakarta, Singapore, and Kuala Lumpur PADANG - tsunami threat JAKARTA
Pulau Sikuai - PSKI From Chris Stephens, USGS Menlo Park For the Mw 8.4 at 392 km: 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: 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?
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!
PSKI - Event 1 - Mw 8.4 Velocity records for the Mw 8.4 (by Dave Boore)
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
PSKI - Event 2 - Mw 7.9 Velocity records for the Mw 7.9 (by Dave Boore)
PSKI photograph Courtesy of John Galetzka; Caltech Tectonics Observatory Enclosure and solar array act as an inverted pendulum at 3-10 Hz
Silabu (SLBU) station photos Courtesy of John Galetzka; Caltech Tectonics Observatory Much closer than PSKI ! Data received from JEG yesterday (10/2) • Chris Stephens set to work on it immediately • Data from M 8.4 - P-wave seems to be missing • Data from M 7.9 - record also appears truncated • Still evaluating data - initial plots last night (10/2) Enganno data not yet retrieved from field.
SLBU Waveforms for the Mw 8.4 (by Chris Stephens)
SLBU Velocity for Mw 8.4 ~80 cm/sec broad pulse
SLBU Displacement for Mw 8.4 Need to check this with GPS displacement vectors
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
Data processing, archiving & distribution http://www.strongmotioncenter.org/ Chris Stephens, USGS NSMP Data Center & NCESMD partnership http://nsmp.wr.usgs.gov/
PSKI - Event 1 - Mw 8.4 Waveforms for the Mw 8.4 (by Chris Stephens)
PSKI - Event 2 - Mw 7.9 Waveforms for the Mw 7.9 (by Chris Stephens)
PSKI - Event 3 - Mw 7.0 Waveforms for the Mw 7.0 (by Chris Stephens)
PSKI - Event 3 - Mw 7.0 Waveforms for the Mw 7.0 (by Dave Boore)