Detailing Rupture Propagation in Historical Earthquakes by Pairing Photogrammetric Topography with Analog Seismology

Austin Elliott, USGS Earthquake Science Center

Wednesday, October 23, 2019 at 10:30 AM

Location:
Building 3, Rambo Auditorium

Earthquake ruptures commonly exceed anticipated lengths and magnitudes, involving more faults or fault segments than expected from inadequate recurrence models. The inadequacy of both physics-based and empirical models of rupture recurrence is due in part to the relatively short record of modern observations. In order to improve both our understanding of rupture propagation and our collection of empirical rupture parameters, we revisit pre-modern earthquakes using techniques we have recently developed to map and measure coseismic displacement and to digitally analyze their analog waveforms.

In this talk, I will describe analyses of three historic earthquakes from the nascent years of [analog] instrumental seismology: the 1889 Chilik, Kazakhstan, M=8.3, 1911 Sarez, Tajikistan, M=7.3, and 1932 Changma, China, M=7.6 earthquakes. Each of these events is well preserved in the semi-arid to arid environments of Central Asia, permitting us to use newly developed tools to measure coseismic deformation and map the ruptures in high resolution. We also employ newly developed methods to analyze digitized waveforms from analog teleseismic records of these events, relating the observed rupture complexity to seismogenic features of the earthquakes.

By pairing seismological and geomorphological analysis of these earthquakes we gain a modern picture of events that were previously only sparsely mapped, overlooked, or not previously evaluated with contemporary questions on seismic behavior in mind.

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