Characteristics of the surface ruptures associated with the 2016 Kumamoto earthquake sequence, central Kyushu, Japan

• Published in: Earth, planets, and space Vol. 68; no. 1; p. 1
• Main Authors: Shirahama, Yoshiki, Yoshimi, Masayuki, Awata, Yasuo, Maruyama, Tadashi, Azuma, Takashi, Miyashita, Yukari, Mori, Hiroshi, Imanishi, Kazutoshi, Takeda, Naoto, Ochi, Tadafumi, Otsubo, Makoto, Asahina, Daisuke, Miyakawa, Ayumu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 24.11.2016; Springer Nature B.V
• Subjects: 2016 Kumamoto earthquake sequence and its impact on earthquake science and hazard assessment; 4. Seismology; Earth and Environmental Science; Earth Sciences; Geology; Geophysics/Geodesy; Letter; 2016 Kumamoto earthquake surface rupture; Slip distribution; Futagawa fault zone; Urgent field investigation; Hinagu fault zone
• ISSN: 1880-5981; 1880-5981
• DOI: 10.1186/s40623-016-0559-1

The 2016 Kumamoto earthquake sequence started with a M J (Japan Meteorological Agency magnitude) 6.5 event on April 14, and culminated in a M J 7.3 event on April 16. Associated with the sequence, approximately 34-km-long surface ruptures appeared along the eastern part of the Futagawa fault zone and the northernmost part of the Hinagu fault zone. We carried out an urgent field investigation soon after the earthquake to map the extent and displacement of surface ruptures with the following results. (1) The rupture zone generally consisted of a series of left-stepping en echelon arrays of discontinuous fault traces of various lengths. (2) Slip exceeding 100 cm occurred on previously unrecognized fault traces in the alluvial lowland of the Kiyama plain and on the western rim of the Aso volcano caldera. (3) Large slip with maximum dextral slip of 220 cm was measured throughout the central section of the rupture zone along the Futagawa segment, and the slip gradually decreased bilaterally on the adjoining northeastern and southwestern sections. (4) The surface rupture mostly occurred along fault traces mapped in previous active fault investigations. (5) Most of the surface ruptures were produced by the mainshock, and significant postseismic slip occurred after the mainshock. Graphical Abstract .