[S-CG40] Active Tectonics and Seismic Hazards in the Himalayan Region

[SCG40-04] Geodetic Observation for Evaluation of Earthquake Generation Potential in Nepal after the 2015 Gorkha Earthquake

*Bishow Raj Silwal¹、Rajendra Prasad Bhandari¹、Janak Bahadur Chand¹、Mako Ohzono²、Takao Tabei³ (1.Department of Mines and Geology, Nepal、2.Earthquake Research Institute, University of Tokyo, Japan、3.Kochi University, Kochi, Japan)

キーワード：GNSS, Earthquake, Geodetic, Nepal

Nepal is prone to devastating earthquake disaster because it is located in the active collision zone between the Eurasian and Indian tectonic plates. Immediately after the 2015 Gorkha earthquake, Integrated Research on Great Earthquakes and Disaster Mitigation in Nepal Himalaya, SATREPS/NERDiM, was initiated under the collaboration of Nepalese and Japanese governments. One of the project teams is working with an objective of evaluating earthquake generation potential in central Nepal by means of geodetic data collected from Global Navigation Satellite System (GNSS) network, which is able to monitor 3-D site displacements caused by the plate interaction at a high precision of a few millimeters per year. Spatial and temporal variation of displacement field and converted strain accumulation pattern will be useful to reveal physical processes ongoing on the plate interface. Our new GNSS network, composed of ten permanent stations deployed in central and mid-western Nepal covering about 100 km north to south and 400 km east to west, have greatly improved detectability of crustal deformation in the plate convergent region. In addition, we have installed an automated GNSS data processing and archiving system in Kathmandu. Preliminary result shows that the north-south contraction in Nepal is as large as 10-15 mm/yr, equivalent to the strain rate of 0.1 ppm/yr. As the next step, we are preparing estimation of plate locking distribution using the latest plate boundary model. Strain build-up monitored by our system, in conjunction with data from other pre-existing GNSS stations in and around Nepal, will provide very fundamental and important information for evaluating earthquake generation potential in the near future.