JSCE Disaster reports- Investigation Report on Earthquake near Awajishima on April 13, 2013 [FS2013-E-0002]

Title:
Investigation Report on Earthquake near Awajishima on April 13, 2013

Authour:
Atsushi MIKAMI¹, Takashi KIYOTA², Kazuo KONAGAI³ and Toshihiko KATAGIRI⁴

1 Member of JSCE, Associate Professor, Dept. of Civil and Environmental Eng., The University of Tokushima, Tokushima, Japan, amikami@ce.tokushima-u.ac.jp
2 Member of JSCE, Associate Professor, Inst., Industrial Science, University of Tokyo, Tokyo, Japan
3 Fellow of JSCE, Professor, Yokohama National University, Yokohama, Japan
4 Member of JSCE, Technical Engineer, Inst., Industrial Science, University of Tokyo, Tokyo, Japan

Key Facts
・Hazard Type: Earthquake
・Date of the disaster: April 13, 2013
・Location of the survey (Lat. Lon., name or address): Awajishima-Island, Japan
・Date of the field survey (if any): April 13 – April 23, 2013
・Survey tools (if any): Portable GPS receivers

Key findings:
1)Strong motions on rocks were successfully recorded at both Naruto and Awaji sides of Onaruto-Bridge, a 1629m long suspension bridge across the Naruto Strait. There was about half a second time delay recognized in the record at Naruto side about 2km southwest of Awaji site.
2)Although the observed peak ground acceleration of about 600 gal was reached near the epicenter, overall damage to structures was insignificant.
3)Comparing velocity response spectra of both April 13th earthquake and the Hyogoken-Nanbu earthquake of 1995, it was found that long-period components of the Hyogoken-Nanbu earthquake surpassed those of the April 13th earthquake indicating that the April 13th earthquake was less significant than the overwhelming Hyogoken-Nanbu earthquake.
4)Damaged structures were confined at some locations such as reclaimed lands and estuary regions on alluvial soil deposits developed along rivers.

Key Words:
Earthquake near Awajishima, strong ground motion, damage to houses, soil liquefaction

Paper: PDF 1.04MB