Geologic fault model based on the high-resolution seismic reflection profile and aftershock distribution associated with the 2004 Mid-Niigata Prefecture earthquake (M6.8), central Japan

• Published in: Earth, planets and space Vol. 57; no. 5; pp. 447 - 452
• Main Authors: KATO, Naoko, ECHIGO, Tomoo, IMAIZUMI, Toshifumi, KATO, Hajime, ABE, Shintaro, SATO, Hiroshi, TATEISHI, Masaaki, OGINO, Sumiko, SAKAI, Shinichi, TODA, Shigeru, KOSHIYA, Shin, ITO, Tanio, TOYOSHIMA, Tsuyoshi
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Tokyo Terra 01.01.2005
• Subjects: Cosmochemistry. Extraterrestrial geology; Earth sciences; Earth, ocean, space; Exact sciences and technology; Far East; Japan; folds; 2004 Mid-Niigata Prefecture earthquake; dip; earthquakes; Modeling; rupture; subsurface structure; seismic reflection; aftershocks; two-dimensional models; balanced cross sections; balanced-cross section; surface rupture; Geologic faults; high resolution; geologic sections; seismic reflection profile; mainshocks; central Japan; fault model; depth; Asia; active faults; hills; geometry; active fault-and-fold
• ISSN: 1343-8832; 1880-5981; 1880-5981
• DOI: 10.1186/BF03351832

The Mid-Niigata Prefecture earthquake in 2004 (MJMA 6.8) generated surface ruptures along the eastern rim of the Uonuma Hills. To elucidate the structural linkage between the surface ruptures and the source fault at depth, the high-resolution seismic reflection profile across the surface ruptures and nearby active faults, and the data of aftershock distribution are examined. The 5.2-km-long, high-resolution, depth-converted seismic section reveals an emergent thrust beneath the surface ruptures. A two-dimensional model of the fault geometry has been constructed based on the aftershock distribution and the shallow reflection profile. The development of the main geologic structure are well explained by forward modeling using a balanced cross-section method. In detail, the fault system generated the main shock dips at a steep angle (60DG) below 5 km depth and more shallowly (30DG) near the surface.