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Science. 2015 Sep 4;349(6252):1091-5. doi: 10.1126/science.aac6383. Epub 2015 Aug 6.

Slip pulse and resonance of the Kathmandu basin during the 2015 Gorkha earthquake, Nepal.

Author information

1
Department of Geology and Planetary Sciences, California Institute of Technology (Caltech), Pasadena, CA 91125, USA.
2
BerkeleySeismological Laboratory, University of California (UC)-Berkeley, Berkeley, CA 94720, USA.
3
Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, UC-San Diego, La Jolla, CA 92037, USA.
4
Jet Propulsion Laboratory (JPL), Caltech, Pasadena, CA 91109, USA.
5
Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK. Department of Geology and Planetary Sciences, California Institute of Technology (Caltech), Pasadena, CA 91125, USA.
6
Department of Mines and Geology, Lainchour, Kathmandu, Nepal.
7
Nepal Academy of Science and Technology, Khumaltar, Lalitpur, Nepal.
8
Department of Geological Sciences, Central Washington University (CWU), Ellensberg, WA 98926, USA.
9
Tri-Chandra Campus, Tribhuvan University, Ghantaghar, Kathmandu, Nepal.
10
U.S. Geological Survey (USGS), Pasadena, CA 91106, USA.
11
Pacific Northwest Geodetic Array and Department of Geological Sciences, CWU, Ellensberg, WA 98926, USA.
12
UNAVCO, Boulder, CO 80301, USA.
13
Département Analyse et Sureveillance de l'Environnement (DASE), Commissariat à l'Energie Atomique (CEA), 91297 Bruyères-le-Châtel, Arpajon, France.

Abstract

Detailed geodetic imaging of earthquake ruptures enhances our understanding of earthquake physics and associated ground shaking. The 25 April 2015 moment magnitude 7.8 earthquake in Gorkha, Nepal was the first large continental megathrust rupture to have occurred beneath a high-rate (5-hertz) Global Positioning System (GPS) network. We used GPS and interferometric synthetic aperture radar data to model the earthquake rupture as a slip pulse ~20 kilometers in width, ~6 seconds in duration, and with a peak sliding velocity of 1.1 meters per second, which propagated toward the Kathmandu basin at ~3.3 kilometers per second over ~140 kilometers. The smooth slip onset, indicating a large (~5-meter) slip-weakening distance, caused moderate ground shaking at high frequencies (>1 hertz; peak ground acceleration, ~16% of Earth's gravity) and minimized damage to vernacular dwellings. Whole-basin resonance at a period of 4 to 5 seconds caused the collapse of tall structures, including cultural artifacts.

PMID:
26249228
DOI:
10.1126/science.aac6383
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