Southeast Asia Seismology
To better understand the earthquakes and associated tectonic setting and ground shaking, we propose to study earthquakes in Southeast Asia, the most seismically active region on the earth, with a series of broadband waveform modeling tools. The proposed works include systematic determination of earthquake focal mechanisms and depth, simulation of broadband ground shaking for scenario earthquakes in the Mentawai seismic gap, and determination of fault morphology using high-frequency waveform modelling of aftershocks from great earthquakes.
In 2017 we successfully applied these techniques to Nepal, Mentawai, and Illapel subduction zones as well as Kumamoto region in Japan, which have provided some new insights into tectonics and earthquake mechanisms.
We have developed broadband waveform modelling techniques and tools to improve the resolution of fault geometry imaging. In the last year, we have successfully evidenced the double-ramp geometry of MTH, clarified the 2005/2009 Mentawai "backthrust" events should have occurred on backstop faults, revealed the anti-dipping fault geometry of the Mw6.2 Kumamoto foreshock and the unilateral rupture of the Mw7.1 mainshock, as well as identified an unmapped left-lateral strike-slip fault in Aceh that hosted the deadly 2016 December 6 Mw6.5 Pidie Jaya earthquake with temporal seismic stations. Combining geodetic and seismic data modelling, we have also shown that the 2017 September 3 North Korea underground nuclear test was followed by a collapsing event 8 minutes 32 seconds after the main explosion.
- Earth Observatory of Singapore
Wenbo Wu, Department of Geoscience, Princeton
Muksin Umar, Syiah Kuala University
- Active backstop faults in the Mentawai region of Sumatra, Indonesia, revealed by teleseismic broadband waveform modeling. Earth and Planetary Science Letters. 483, 29-38. (2018).
- The 2015 Gorkha (Nepal) earthquake sequence: I. Source modeling and deterministic 3D ground shaking. Tectonophysics. 722, 447-461. (2018).
- The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test. Science. (2018).
- Double-ramp on the Main Himalayan Thrust revealed by broadband waveform modeling of the 2015 Gorkha earthquake sequence. Earth and Planetary Science Letters. 473, 83-93. (2017).
- Lithospheric radial anisotropy beneath the Gulf of Mexico. Earth and Planetary Science Letters. 466, 43-52. (2017).