2008年岩手・宮城内陸地震震源域北部における稠密余震観測

概要

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On June 14, 2008, the 2008 Iwate-Miyagi Nairiku Earthquake (M JMA 7.2) occurred in the centralpart of northern Honshu, Japan. The northern part of the focal area is near the Dedana fault, whichis south of the western marginal faults of the Kitakami lowlands. Seismic reflection/refractionexperiments were conducted across the Dedana fault in 2006 and 2007 . Deeper extensions of thewest-dipping listric faults were well demonstrated on the seismic reflection section. Revealing therelationship between an active fault system and aftershock distribution is important to constrainthe process of earthquake occurrence. We conducted high-density seismic array observationsacross the northern focal area to investigate the relationships between aftershock distribution andcrustal structure. We obtained high signal-to-noise ratio data. Prominent late arrivals, probablyreflected waves from the deeper part of the crust, can be recognized on the record sections. Theaftershock observations are summarized in this paper, and a detailed analysis showing the preciseaftershock distribution and seismic velocity structure in and around the northern focal area of the 2008 Iwate Miyagi Nairiku earthquake will be published in a separate paper.
2012-03-26