Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake 4. Seismology

Nobuo Takai, Michiko Shigefuji, Sudhir Rajaure, Subeg Bijukchhen, Masayoshi Ichiyanagi, Megh Raj Dhital, Tsutomu Sasatani

Research output: Contribution to journalArticle

55 Citations (Scopus)

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.

Original languageEnglish
Article number10
Journalearth, planets and space
Volume68
Issue number1
DOIs
Publication statusPublished - Dec 1 2016

Fingerprint

Nepal
seismology
ground motion
valleys
earthquakes
valley
earthquake
oscillation
oscillations
rocks
rock
Indian plate
Eurasian plate
thrust fault
pulses
earthquake epicenter
rupture
tectonics
amplification
sediments

All Science Journal Classification (ASJC) codes

  • Geology
  • Space and Planetary Science

Cite this

Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake 4. Seismology. / Takai, Nobuo; Shigefuji, Michiko; Rajaure, Sudhir; Bijukchhen, Subeg; Ichiyanagi, Masayoshi; Dhital, Megh Raj; Sasatani, Tsutomu.

In: earth, planets and space, Vol. 68, No. 1, 10, 01.12.2016.

Research output: Contribution to journalArticle

Takai, Nobuo ; Shigefuji, Michiko ; Rajaure, Sudhir ; Bijukchhen, Subeg ; Ichiyanagi, Masayoshi ; Dhital, Megh Raj ; Sasatani, Tsutomu. / Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake 4. Seismology. In: earth, planets and space. 2016 ; Vol. 68, No. 1.
@article{6c17308591a345cc93a4eefbe769476c,
title = "Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake 4. Seismology",
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.",
author = "Nobuo Takai and Michiko Shigefuji and Sudhir Rajaure and Subeg Bijukchhen and Masayoshi Ichiyanagi and Dhital, {Megh Raj} and Tsutomu Sasatani",
year = "2016",
month = "12",
day = "1",
doi = "10.1186/s40623-016-0383-7",
language = "English",
volume = "68",
journal = "Earth, Planets and Space",
issn = "1343-8832",
publisher = "Terra Scientific Publishing Company",
number = "1",

}

TY - JOUR

T1 - Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake 4. Seismology

AU - Takai, Nobuo

AU - Shigefuji, Michiko

AU - Rajaure, Sudhir

AU - Bijukchhen, Subeg

AU - Ichiyanagi, Masayoshi

AU - Dhital, Megh Raj

AU - Sasatani, Tsutomu

PY - 2016/12/1

Y1 - 2016/12/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84956541445&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84956541445&partnerID=8YFLogxK

U2 - 10.1186/s40623-016-0383-7

DO - 10.1186/s40623-016-0383-7

M3 - Article

AN - SCOPUS:84956541445

VL - 68

JO - Earth, Planets and Space

JF - Earth, Planets and Space

SN - 1343-8832

IS - 1

M1 - 10

ER -