Strong ground motions recorded by a near-source seismographic array during the 16 August 2005 Miyagi-Ken-Oki, Japan, earthquake (Mw 7.2)

Hisashi Nakahara, Kaoru Sawazaki, Nobumasa Takagi, Takeshi Nishimura, Haruo Sato, Hiroyuki Fujiwara

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

An earthquake of Mw 7.2 took place on August 16, 2005 at a plate boundary between the Pacific plate and the North American plate off the coast of Miyagi Prefecture, Northeast Japan. During the Miyagi-Ken-Oki event, we succeeded in recording strong ground motions at six stations in a seismograhic array with an epicentral distance of about 70 km, where we have been operating seven strong-motion seismometers in an aperture of about 500 m since April 2004. The predominant period of the ground motion was shorter than 0.3 s. The peak ground acceleration exceeded 1.7 g at a station where non-linear site response may have occurred during the mainshock. The short-period strong ground motions show a large spatial variation, with up to a ten-fold difference in amplitude even within the array. However, there is a similarity between waveforms registered at different stations for periods longer than 0.4 s. Therefore, the difference in the ground motions may be mainly attributed to the difference in the shallow structure just beneath the stations.

Original languageEnglish
Pages (from-to)1555-1559
Number of pages5
Journalearth, planets and space
Volume58
Issue number12
DOIs
Publication statusPublished - 2006 Jan 1

Keywords

  • Array
  • Miyagi-Ken-Oki earthquake
  • Non-linear site response
  • Spatial variation
  • Strong ground motion

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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