Spatial variation in geometry of seismogenic zone and heterogeneous distribution of slip during 2015 Gorkha Earthquake, Central Nepal
Abstract
The Mw 7.8 Gorkha Earthquake (25th April 2015) is powerful earthquake ripped through Central Nepal that occurs about 77 Km northwest of Kathmandu Valley. The rupture mechanism of the main event is characterized by variation in slip distribution throughout the seismogenic zone. This study is focused on imaging the structure of the seismogenic zone and to estimate spatial variation in geometry responsible for the heterogenous slip distribution during large earthquakes.
Depth of earthquakes with magnitude more than 4.0 were recalculated using teleseismic body wave modeling. Depth section along different SW-NE and NW-SE profiles were prepared. Along each profile the top surface of the seismogenic zone was approximated as the best fit surface that incorporated the hypocenters with minimum error (< 2.5 km). Location (i.e., x,y,z) of the seismogenic zone was computed along each profile to portray the 3D-image of the seismogenic zone. Slip distribution of the 2015 Gorkha Earthquake was estimated using finite source model by modeling teleseismic body waveforms. The analysis reveals that geometry of the seismogenic zone varies spatially not only in S-N direction but also in W-E direction. A 30 km wide NS trending valley is identified at 78 km southeast of the hypocenter of the 2015 Gorkha Earthquake. The maximum slip of the event (~3.0 m) is localized in the western part of the valley where a 8.0 km wide bulge is identified along NS direction. Towards east of the valley seismic slip abruptly diffuses indicating no significant stress accumulation (or asperity). Another small valley within the seismogenic zone acting as high stress accumulation zone (asperity) is identified at 15.0 km SW of the hypocenter where the slip is estimated to 1.5 m.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S21F0587G
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITY;
- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS