Persistent segmentation of the seismicity across seismic cycle at the downdip end of the seismogenic zone: the 2015 Gorkha earthquake in Nepal
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Understanding along strike variations of the seismicity at the down-dip end of the seismogenic zone remains a challenge, partly because little is known about the heterogeneities of frictional properties and fault zone geometry there. Here we look specifically at the seismicity variations along the rupture of the 2015 Gorkha earthquake, Nepal.We first relocate the clusters of aftershocks that occurred during the 5 years following the earthquake. We compare them with the background seismicity that happened during the 4 decades that preceded the event. The heterogeneities show similarities and fall at short distances from heterogeneities in the coseismic slip and the location of high frequency seismic bursts generated during the rupture. These persistent spatial variations of the seismic heterogeneities are intriguing, and could be related with variations of the frictional properties or geometry of the Main Himalayan Thrust fault zone at depth. They suggest also that the seismicity occurring during the interseismic period along the Himalayas may reveal the seismo-geological segmentation, which influences both the coseismic rupture and the postseismic relaxation.