Nepal

Nepal Earthquake – Report #1, 27.04.2015

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1 Seismological Information (and Aftershocks)

The earthquake occurred on Saturday April 25, 2015 at 11:56 local time (ca. 6.11 UTC) with moment magnitude 7.7-8.0 (preferred solution Mw7.8). The epicentral location: 28.15 N 84.71 E (roughly between Pokhara and Kathmandu) is densely populated and the earthquake had a hypocentral depth of 10-15km.

The moment tensor solution indicates a shallow dipping fault plane (auxiliary plane solution less probable for tectonic reasons). The rupture plane strikes parallel to the Himalayan Belt WNW to ESE, and dips with 10° to the North. The rupture process lasted for about 80 sec. Due to sedimentary basin effects the duration of shaking in Kathmandu Valley was probably longer and thus also more damaging.

Aftershocks are concentrated in the region of the epicentre as well as the region 150 kilometres to the east (at the end of the rupture). With magnitudes of 6.6 and 6.7 these should be the largest magnitudes in an average statistical sense (although this is not always the case).