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Delineation of probable asperities on the Atotsugawa fault, central Japan, using a dense temporary seismic network
Author(s) -
Kato Aitaro,
Iidaka Takashi,
Kurashimo Eiji,
Nakagawa Shigeki,
Hirata Naoshi,
Iwasaki Takaya
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl029604
Subject(s) - geology , seismology , induced seismicity , asperity (geotechnical engineering) , fault (geology) , section (typography) , explosive material , geotechnical engineering , chemistry , organic chemistry , advertising , business
We elucidate the velocity structure along the Atotsugawa fault by inverting arrival times from local earthquakes and explosive sources using double‐difference tomography. High P‐wave ( V p ) and S‐wave ( V s ) velocity bodies are located in the western and eastern sections with depths greater than 2 km. Most earthquake hypocenters are distributed at the periphery of the high‐velocity bodies. At the western section, high‐ V p body extends for 20 km along fault strike and 10 km perpendicular to strike. We suggest that the high‐velocity body imaged at the western section is an asperity that ruptured in the 1858 Hietsu Earthquake. In contrast, the central section of the Atotsugawa fault is characterized by low‐ V p and low‐ V p / V s values. The extremely low seismicity and the creep‐like movements observed at the central section are attributed to this local crustal heterogeneity associated with crustal fluids.