Strong-Motion Observations of the M 7.8 Gorkha, Nepal, Earthquake Sequence and Development of the N-SHAKE Strong-Motion Network

We present and describe strong-motion data observations from the 2015 M 7.8 Gorkha, Nepal, earthquake sequence collected using existing and new Quake-Catcher Network (QCN) and U.S. Geological Survey NetQuakes sensors located in the Kathmandu Valley. A comparison of QCN data with waveforms recorded by a conventional strong-motion (NetQuakes) instrument validates the QCN data. We present preliminary analysis of spectral accelerations, and peak ground acceleration and velocity for earthquakes up to M 7.3 from the QCN stations, as well as preliminary analysis of the mainshock recording from the NetQuakes station. We show that mainshock peak accelerations were lower than expected and conclude the Kathmandu Valley experienced a pervasively nonlinear response during the mainshock. Phase picks from the QCN and NetQuakes data are also used to improve aftershock locations. This study confirms the utility of QCN instruments to contribute to ground-motion investigations and aftershock response in regions where conventional instrumentation and open-access seismic data are limited. Initial pilot installations of QCN instruments in 2014 are now being expanded to create the Nepal–Shaking Hazard Assessment for Kathmandu and its Environment (N-SHAKE) network. Online Material: Figures of Pg arrivals, earthquake locations, epicenter change vectors, and travel-time misfit vector residuals, and tables of QCN and NetQuake stations and relocated hypocenter timing, location, and magnitude.

[1]  R. Herrmann,et al.  Earthquake hypocenters and focal mechanisms in central Oklahoma reveal a complex system of reactivated subsurface strike‐slip faulting , 2015 .

[2]  Aurore Laurendeau,et al.  Overview of the Large 25 April 2015 Gorkha, Nepal, Earthquake from Accelerometric Perspectives , 2015 .

[3]  Rapid Characterization of the Degradation of Composites Using Plate Waves Dispersion Data , 1998 .

[4]  Sergey V. Samsonov,et al.  Rapid Characterization of the 2015 Mw 7.8 Gorkha, Nepal, Earthquake Sequence and Its Seismotectonic Context , 2015 .

[5]  Ramesh P. Singh,et al.  Attenuation relations for strong seismic ground motion in the Himalayan region , 1996 .

[6]  B. N. Upreti,et al.  Nepal Earthquake 2015 , 2015 .

[7]  E. Cochran,et al.  The Quake-Catcher Network Rapid Aftershock Mobilization Program Following the 2010 M 8.8 Maule, Chile Earthquake , 2011 .

[8]  Susan E. Hough,et al.  Ground Motions from the 2015 Mw 7.8 Gorkha, Nepal, Earthquake Constrained by a Detailed Assessment of Macroseismic Data , 2015 .

[9]  Masanobu Shimada,et al.  Line‐of‐sight displacement from ALOS‐2 interferometry: Mw 7.8 Gorkha Earthquake and Mw 7.3 aftershock , 2015 .

[10]  S. Rajaure,et al.  Seismic structure of the crust and the upper mantle beneath the Himalayas: Evidence for eclogitization of lower crustal rocks in the Indian Plate , 2008 .

[11]  F. Waldhauser,et al.  A Double-Difference Earthquake Location Algorithm: Method and Application to the Northern Hayward Fault, California , 2000 .

[12]  James W. Dewey,et al.  Seismicity and tectonics of western Venezuela , 1972, Bulletin of the Seismological Society of America.

[13]  Yann Klinger,et al.  Estimating the return times of great Himalayan earthquakes in eastern Nepal: Evidence from the Patu and Bardibas strands of the Main Frontal Thrust , 2014 .

[14]  Elizabeth S. Cochran,et al.  The Quake-Catcher Network: Citizen Science Expanding Seismic Horizons , 2009 .

[15]  Thomas H. Jordan,et al.  Teleseismic location techniques and their application to earthquake clusters in the South-Central Pacific , 1981 .

[16]  Battalgazi Yildirim,et al.  Improved Rapid Magnitude Estimation for a Community‐Based, Low‐Cost MEMS Accelerometer Network , 2015 .

[17]  Jack W. Baker,et al.  Rapid Earthquake Characterization Using MEMS Accelerometers and Volunteer Hosts Following the M 7.2 Darfield, New Zealand, Earthquake , 2014 .

[18]  N. Bhandary,et al.  Use of a Sparse Geo-Info Database and Ambient Ground Vibration Survey in Earthquake Disaster Risk Study − A Case of Kathmandu Valley − , 2014 .

[19]  John Kubiatowicz,et al.  The worldwide computer. , 2002, Scientific American.

[20]  E. Field,et al.  Nonlinear ground-motion amplification by sediments during the 1994 Northridge earthquake , 1997, Nature.

[21]  Peter Molnar,et al.  Himalayan Seismic Hazard , 2001, Science.

[22]  L. Bollinger,et al.  Primary surface ruptures of the great Himalayan earthquakes in 1934 and 1255 , 2012, Nature Geoscience.

[23]  Jean-Paul Ampuero,et al.  Lower edge of locked Main Himalayan Thrust unzipped by the 2015 Gorkha earthquake , 2015 .