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Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake
This item is licensed under:Creative Commons Attribution 4.0 International
Title: | Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake |
Authors: | Takai, Nobuo Browse this author →KAKEN DB | Shigefuji, Michiko Browse this author | Rajaure, Sudhir Browse this author | Bijukchhen, Subeg Browse this author | Ichiyanagi, Masayoshi Browse this author | Dhital, Megh Raj Browse this author | Sasatani, Tsutomu Browse this author →KAKEN DB |
Keywords: | 2015 Gorkha Nepal earthquake | Kathmandu Valley | Strong ground motion | Velocity pulse motion | Valley response |
Issue Date: | 26-Jan-2016 |
Publisher: | Springer |
Journal Title: | Earth, Planets and Space |
Volume: | 68 |
Issue: | 1 |
Start Page: | 1 |
End Page: | 8 |
Publisher DOI: | 10.1186/s40623-016-0383-7 |
Abstract: | On 25 April 2015, a large earthquake of Mw 7.8 occurred along the Main Himalayan Thrust fault in central Nepal. It was caused by a collision of the Indian Plate beneath the Eurasian Plate. The epicenter was near the Gorkha region, 80 km northwest of Kathmandu, and the rupture propagated toward east from the epicentral region passing through the sediment-filled Kathmandu Valley. This event resulted in over 8000 fatalities, mostly in Kathmandu and the adjacent districts. We succeeded in observing strong ground motions at our four observation sites (one rock site and three sedimentary sites) in the Kathmandu Valley during this devastating earthquake. While the observed peak ground acceleration values were smaller than the predicted ones that were derived from the use of a ground motion prediction equation, the observed peak ground velocity values were slightly larger than the predicted ones. The ground velocities observed at the rock site (KTP) showed a simple velocity pulse, resulting in monotonic-step displacements associated with the permanent tectonic offset. The vertical ground velocities observed at the sedimentary sites had the same pulse motions that were observed at the rock site. In contrast, the horizontal ground velocities as well as accelerations observed at three sedimentary sites showed long duration with conspicuous long-period oscillations, due to the valley response. The horizontal valley response was characterized by large amplification (about 10) and prolonged oscillations. However, the predominant period and envelope shape of their oscillations differed from site to site, indicating a complicated basin structure. Finally, on the basis of the velocity response spectra, we show that the horizontal long-period oscillations on the sedimentary sites had enough destructive power to damage high-rise buildings with natural periods of 3 to 5 s. |
Rights: | http://creativecommons.org/licenses/by/4.0 |
Type: | article |
URI: | http://hdl.handle.net/2115/60622 |
Appears in Collections: | 工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 高井 伸雄
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