Improving the detection of seismic velocity changes by seismic interferometry and physical interpretations on the changes

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540449
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Tohoku University
• Principal Investigator: NAKAHARA Hisashi 東北大学, 理学(系)研究科(研究院), 准教授 (20302078)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 地震波速度変化 / 地震波干渉法 / 物理的解釈

Outline of Final Research Achievements

We have applied a method to use cross correlations of noise records at two stations, auto correlations at single station, cross-correlations between different components at single station for stably detecting seismic velocity changes in Japan by seismic interferometry. Seismic velocity changes detected have been decomposed into coseismic changes and the following post-seismic exponential decays associated with the 2008 Iwate-Miyagi Nairiku earthquake and the 2011 off the Pacific Coast of Tohoku earthquake (Tohoku-Oki ) earthquake, and seasonal variations. Coseismic and post-seismic changes are attributed to damages and their recovery at shallow depths due to strong-ground motion. Seasonal variations may have some relation to changes in the ground-water level.

Free Research Field

地震学