Short‐Period Energy of the 25 April 2015 Mw 7.8 Nepal Earthquake Determined from Backprojection Using Four Arrays in Europe, China, Japan, and Australia

We apply a backprojection analysis to determine the locations and timing of the sources of short-period (0.5-5 s) energy generated by the 2015 Nepal earthquake. We use data from four different arrays at varying azimuths in Europe, China, Japan, and Australia, which show generally consistent features for the rupture propagation. The sources of strong short-period energy are generally distributed east of the epicenter at distances of 10-100 km during the time period of 25-55 s after the initiation. The rupture speed was similar to 1.0 km/s for the first 20 s then accelerated to similar to 3.0 km/s for the remaining 30-40 s. The locations of sources of short-period energy are close to the down-dip edge of the fault and are complementary to the areas of large fault slip that occur further up-dip. The Nepal earthquake might be another example in which regions of large fault slip do not coincide with the source areas of short-period energy, which are likely associated with the damaging strong ground motions. Online Material: Animations of backprojections for the 2015 Nepal earthquake using four different arrays.