Stability of the regional stress field in central Japan during the late Quaternary inferred from the stress inversion of the active fault data

Abstract

We analyzed 169 geological fault‐slip data from 37 active faults in central Japan to investigate the late Quaternary stress field stability. Modern stress states have been documented with unprecedented accuracy; however, their stability over time scales beyond instrumental observations is inadequately understood. Because the stress field has changed in the geological past, we compared present stress conditions in central Japan, determined from geophysical observations, with conditions determined by inverting the fault‐slip data from active faults that exhibited cumulative displacement for the past ∼105years. The maximum stress axis obtained from fault‐slip data trends ESE–WNW. This state of stress accounts for 97% of the data and supports the fact that oblique faults with reverse and strike‐slip senses are interlaced in the region. The optimal stress is similar to the present stress state, indicating that the stress field in central Japan has been uniform and stable over the past ∼105 years.

Focal mechanisms and stress field in the Nobi fault area, central Japan

“…They found that the direction of the σ 1 -axis tends to be ESE-WNW and that the stress ratio is close to 1.0, indicating σ 2 ≈ σ 3 , which suggests that the stress field in central Japan has been uniform and stable over the past approximately 10 5 years. The direction of the σ 1 -axis and the stress ratio obtained by Tsutsumi et al (2012) are consistent with the results in this study. Hiramatsu and Iidaka (2015) obtained a spatial distribution of S-wave splitting parameters and found that the observed polarization orientation ranges from E-W to NW-SE, which is consistent with the direction of the σ 1 -axis obtained in this study.…”

“…Terakawa and Matsu'ura (2010) found that compressional stress is dominant in central Japan and that its axis is oriented E-W, which is also consistent with our results. Tsutsumi et al (2012) inverted 169 fault-slip data points from 37 active faults in the eastern part of the Southwest Japan arc, including the Nobi fault area. They found that the direction of the σ 1 -axis tends to be ESE-WNW and that the stress ratio is close to 1.0, indicating σ 2 ≈ σ 3 , which suggests that the stress field in central Japan has been uniform and stable over the past approximately 10 5 years.…”

Long‐term changes in the Coulomb failure function on inland active faults in southwest Japan due to east‐west compression and interplate earthquakes

“…The northern Tohoku region and the Kinki region are similar in that the long‐term E‐W compression generates inland earthquakes and interplate earthquakes drag the regions toward the SSE. On the other hand, the two regions differ in that in the Kinki region, about half of inland active faults are strike slip suggesting that the minimum principal stress ranges from horizontal to vertical in the basic stress field [ Tsutsumi et al ., ], and the focal mechanisms of inland earthquakes are more sensitive to the stress change. In contrast, the elastic stress change due to interplate earthquakes is larger in the northern Tohoku region (0.5–1.0 MPa for the 2011 earthquake) than that in the central Kinki region (0.1–0.3 MPa for the interplate earthquakes along the Nankai Trough), which explains why the change in focal mechanism occurred in the Tohoku region.…”

The weakened lower crust beneath the Nobi fault system, Japan: Implications for stress accumulation to the seismogenic zone

“…The stress regime in central Japan is characterized by E-W or ESE-WNW directed maximum horizontal principal stresses (e.g., Seno, 1999;Terakawa and Matsu'ura, 2010;Townend and Zoback, 2006;Tsutsumi et al, 2012). Seno (1999) modeled this stress regime using a simplified framework of the regional plate configuration and driving forces, and showed that the regime can be explained by ridge push, slab pull, and along-arc variations in differential forces caused by the heterogeneity of the crust-plate structure in this area.…”