Article,
A method for determining significant structures in a cloud of earthquakes
Journal of Geophysical Research, 102 (B4): 8245--8254 (April 1997)
DOI: 10.1029/96JB03739
Abstract
The interpretation of a cloud of earthquake hypocenters in terms of
causative structures is not a simple task. Locations are subject
to uncertainties, which will not be the same for every earthquake.
The data should therefore not be interpreted simply by inspection,
which is difficult in the case of three-dimensional data anyway.
Instead, we propose using the location uncertainties as a guide in
processing the data. Earthquake locations are moved inside their
uncertainty or confidence ellipsoids until a simplified picture of
the earthquake cloud is obtained, which can then be interpreted in
terms of some simplified structure such as faults. The aim of the
approach is to give the simplest possible structure that is consistent
with all the location and confidence ellipsoid data. The method is
applied to three synthetic sets of data. These illustrate the potential
and limitations of the method. Application to a real earthquake data
set from Rabaul Caldera in Papua New Guinea gives an image of the
caldera ring fault that suggests departures from the simple ring-fault
structure previously assumed. Sensitivity analysis on the Rabaul
data shows that the method is not unduly sensitive to the assumptions
that have to be made in applying it.
