Various temperature proxies have been proposed, including the thermomagnetic characteristics of magnetic minerals (Mishima et al. To estimate slip parameters such as shear stress and slip distance, information about frictional heat within the slip zone is of paramount importance. Thus, in this study we focused on the slip parameters of the subduction fault system taking into consideration the regional heterogeneity of the plate-subduction faults. ( 2016) did not consider the heterogeneity of fault-plane material at different plate subducting segments. Although the style of deformation of sediments in the incoming plate could change with subducting regions during the subductionвЂ“accretion process, which was examined by analyzing mineral veins distributed in an ancient plate-subduction fault (Mukoyoshi et al. Their results indicated a large stress drop and slip of about 75В m near the trench during the earthquake, which is consistent with the amount of slip estimated from observations and surveys (50вЂ“80В m slip) (Fujiwara et al. ( 2016) undertook quantitative laboratory analyses of the properties of plate-interface material retrieved during the Japan Trench Fast Drilling Project (JFAST) and ran simulations of fault weakening and rupture propagation. To investigate the mechanism of gigantic seismic slip along the plate interface during the 2011 Tohoku-oki earthquake, Hirono et al. Notably, coseismic displacement of the seafloor exceeded 50В m at the trench axis during the 2011 Tohoku-oki earthquake (Ito et al. 2006) and the 2011 Tohoku-oki earthquake (Yue and Lay 2011 Ito et al. Fault systems such as these can generate very large tsunamis during great earthquakes such as the 1944 Tonankai earthquake (Park et al. 2015) and the Alaskan (Plafker 1972) and Sunda margins (Kopp and Kukowski 2003). Complex plate-boundary megathrusts, dГ©collements, megasplay faults, and other types of thrust are known at many plate margins, including the Nankai Trough (Park et al.

In a worldwide context, most of the seismic energy released by large earthquakes occurs in plate-subduction zones (Scholz 2002). The slip distances we determined probably represent minimum slips for subduction-zone thrusts and thus provide an important contribution to earthquake preparedness plans in coastal areas facing the Nankai and Sagami Troughs. Thus, potential distance of coseismic slip along the subduction-zone fault system could have regional variations even at shallow depth (в‰¤вЂ‰5.5В km). Numerical simulation of the thermal history of CM extracted from rocks near the two slip zones, taking into consideration these temperature constraints, indicated that slip distances in the ultracataclasite and pseudotachylyte layers were more than 3 and 7В m, respectively.

By comparing the area-under-the-peak ratios of graphitic and disordered bands in those Raman spectra with spectra of experimentally heated CM from surrounding rocks, we determined that the ultracataclasite and pseudotachylyte layers had been heated to temperatures of up to 7В вЊ, respectively. We first obtained the Raman spectra of CM in ultracataclasite and pseudotachylyte layers in discrete slip zones at depths below the seafloor of 1вЂ“4В km and 2.5вЂ“5.5В km, respectively. We derived quantitative estimates of slip along ancient subduction fault systems by using the maturity of carbonaceous material (CM) of discrete slip zones as a proxy for temperature. Understanding variations of slip distance along major thrust systems at convergent margins is an important issue for evaluation of near-trench slip and the potential generation of large tsunamis.

Convergent plate boundary