105 GSA Special Nepal (Gorkha) Earthquake Session

Monday, 2 November 2015
8:00 AM - 12:00 PM
Room 345/346

3D VISUALIZATION OF GEOLOGIC, GEODETIC, AND SEISMIC DATA FROM THE APRIL - MAY 2015, NEPAL, EARTHQUAKE DOUBLET

Paper number: 105-5
Program: Special Session
Time: 8:50 AM – 9:05 AM

Authors

Abstract

The availability of tools for simultaneous 3-D visualization of different types of data is valuable for quick analysis of the setting of a major earthquake. 3-D visualization allows for rapid identification of inconsistencies in the preliminary data that are realeased after an earthquake, and it can aid in deciding what other data may be needed.

The Mw 7.8 and Mw 7.3 Nepal earthquakes of April - May 2015 form a doublet, as the magnitude difference between them is only 0.5, they are close in both space and time, and each event shows a typical aftershocks sequence. We used the 3-D modeling and visualization software GocadTM in the first few days after the Mw 7.8 event to better understand how the seismologic and geodetic data that became available shortly after the event fit with the known regional tectonic context. In the first couple of days after the Mw 7.8 earthquake, we first built a 3-D model of the fault based on published works, from which it became clear that the earthquake involved the lower thrust ramp rather than the flat. We were also able to build, within a week of the Mw 7.8 event, a reasonable 3-D model of the static Coulomb stress change in the volume surrounding the earthquake, which showed how significant stress built up both on the MFT flat, and on the ramp itself further east, where the Mw 7.3 earthquake occurred.