A southeasterly-dipping static fault model of the 2007 Niigata-ken Chuetsu-oki, Japan, earthquake based on crustal movements, tsunamis, aftershock distribution and neotectonics

We propose a static fault model of the 2007 Niigata-ken Chuetsu-oki earthquake (M 6.8) off the Japan Sea coast of central Japan based on comprehensive examination of coseismic crustal movements, tsunami waveforms, main shock and aftershock distribution, and neotectonics. The earthquake was reverse faulting due to NW-SE compression, but whether the fault plane dips northwestward or southeastward has been controversial. Our model consists of two southeasterly-dipping fault planes. The lengths, widths, dip-directions, dip-angles, depths of the upper edges, dislocation amounts, slip angles, and seismic moments of the northeastern-side and southwestern-side fault planes are; 10 km and 13 km, 12 km and 11 km, N119°E and N132°E, 47° and 29°, 6 km and 2.5 km, 0.9 m and 1.3 m, 100° and 90°, and 3.3 × 10 N⋅m and 5.7 × 10 N⋅m, respectively. Mw becomes 6.6. The shallower extensions of the two fault planes reach the submarine active fault on the southeastern margin of Sado Basin, suggesting that this earthquake was a rupture of the deeper part of this active fault. On land, the Madogasaka fault and a fault at the foot of the Oginojo anticline may have been secondarily displaced in the hanging-wall side.