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Coseismic deformations of the 2015 MW 7.8 Gorkha earthquake and interseismic strain accumulation in the Himalayan tectonic belt and Tibetan plateau

Shuang Zhu, Jingyang Zhao, Jiliang Du, Changyun Chen, Liu Chang, Zaisen Jiang, Hongbao Liang, & Yanqiang Wu

Published February 2016, SCEC Contribution #6748

The principal strain rate, derived from GPS velocities fromthe Tibetan Plateau and the India Plate, shows that the Himalayan tectonic belt exhibits compression deformation in a NE–NS–NE direction from the west to the east. The GPS velocity profiles reflect that the distribution of strain accumulation is uneven: there is a 17.1 mm/yr. compressive deformation distributed over 400 km along 85° E longitude, a 20.9–22.2mm/yr. compressive deformation dispersed across 400–500 km along 79° E longitude, and a 15.3–16.9 mm/yr. compressive deformation spread across 500–600 km along 91° E longitude. The MW 7.8 Gorkha earthquake occurred at the edge of an intense compression deformation zone of about 6.0 × 10−8/yr. in a north–south direction, and an about 90% compressive
strain is absorbed in the 300 km region near the Main Frontal Thrust (MFT). Coseismic displacements,
larger than three standard deviations (3SD), are mainly concentrated within 360 km from the epicenter. The
nodal plane of themain shock divides the areaswhere tensile strain release in an exponential attenuation pattern
is dominant to the north, and where compressive strain with upward movement is dominant to the south. The
results inversed by the SDMprogramreveal that themaximal slip of theGorkha earthquake is 5.33m, and itsmoment magnitude isMW7.85, and the largest stress drop is 4.21Mpa. Slips larger than 0.5mare mainly distributed
in a region approximately 135 km × 105 km, which show that the rupture of the Gorkha earthquake does not
reach the surface. Finally, we estimate that the recurrence period of this earthquake is about 166 ± 20 years according to the strain accumulation before the earthquake and the coseismic release feature.

Citation
Zhu, S., Zhao, J., Du, J., Chen, C., Chang, L., Jiang, Z., Liang, H., & Wu, Y. (2016). Coseismic deformations of the 2015 MW 7.8 Gorkha earthquake and interseismic strain accumulation in the Himalayan tectonic belt and Tibetan plateau. Tectonophysics, 670, 144-154. doi: 10.1016/j.tecto.2015.12.028.