[S-SS14] 活断層と古地震

[SSS14-11] Mud volcanism and diapirism along the Japan Trench axis: implications for earthquake hydrology

*Myra Keep¹、Troy Rasbury²、Cecilia McHugh³、Michael Strasser⁴、Ken Ikehara⁵、Charlotte Pizer⁴、Yasuyuki Nakamura⁶ (1.University of Western Australia、2.Stony Brook University, USA、3.Queens College, City University of New York, USA、4.University of Innsbruck, Austria、5.National Institute of Advanced Industrial Science and Technology, Japan、6.JAMSTEC)

キーワード：hydroacoustic data, mud volcanoes, Japan Trench, mud diapirism

Mud volcanoes occur commonly as part of subduction zones, usually within the accretionary prism or forearc basin. Although mud volcanism occurs along the Ryuku Trench in southern Japan, no mobile mud activity has been documented along the Japan Trench. Seismic and sub-bottom profile data from IODP Expedition 386 show features consistent with mud diapirism and mud volcanism along an ~600 km transect of the Japan Trench. These features occur in basins along the trench axis itself, and not primarily as part of the forearc basin or accretionary complex (although there is also evidence for them here too). We present evidence for three styles of diapirism, and for active mud volcanoes in the central and northern part of the Japan Trench. Diapiric and volcanic activity shows close spatial relationships to flexural faults on the down-going plate, which may provide the plumbing system for mobile muds to reach the surface.