Open Access

A new model for the fault beneath the sedimentary basin in the 1891 Nobi earthquake

Earth, Planets and Space200759:BF03352017

https://doi.org/10.1186/BF03352017

Received: 17 December 2004

Accepted: 7 August 2006

Published: 15 March 2007

Abstract

We have investigated the geometry and detailed location of the Gifu-Ichinomiya (GI) fault, a buried fault considered to have ruptured during the 1891 Nobi earthquake. Based on an inversion of coseismic vertical displacements obtained by leveling surveys, we obtain an inclined fault plane showing a reverse fault-type mechanism, rather than the vertical fault plane assumed in previous models. The fault dips 60? to the east and its slip during the earthquake is estimated to have been 1.48 m along the fault dip. The fault is located 5 km east of the location assumed in the previous models. Recent earthquakes have been scattered along the new fault location, not the previously estimated one. Focal mechanisms of the earthquakes that have occurred around the fault are dominated by a reverse fault component, which is consistent with the focal mechanism of the GI fault obtained by the inversion of coseismic displacements. The seismic intensity distribution calculated using the new fault geometry and location explains well the distribution of observed damage caused by the 1891 Nobi earthquake.

Key words

Gifu-Ichinomiya faultCoseismic leveling surveyEarthquake distributionFocal mechanismSeismic damage estimation.