Fault zone monitoring with passive image interferometry
Geophysical Journal International, 168 (3):
1029--1033 (March 2007)DOI: 10.1111/j.1365-246X.2006.03284.x
Abstract
The technique of passive image interferometry applies interferometric
methods to correlation functions of seismic noise to monitor small
temporal variations of the Earth interior. We computed the autocorrelation
function of seismic noise recorded at a single seismometer located
in the vicinity of the source region of the Mw=6.6 Mid-Niigata earthquake.
Analysing the temporal evolution of the autocorrelation function,
which is interpreted as the source-receiver collocated elastic wave
Green's function, we detect a sudden decrease of relative seismic
velocity in the Earth crust of -0.6 per cent that coincides with
the occurrence of the earthquake. This drop of seismic velocity is
likely to be caused by the change of stress in the source region
of the earthquake.