New Bayesian formulation to integrate body-wave polarization in non-linear earthquake location
Résumé
Earthquake location is most of the time computed
using arrival times of seismic waves observed on
monitoring networks. However, three-component
seismometers enable measurement of the seismic
wave polarization which is also hypocentre dependent.
Especially for local and sparse seismic networks, as
can be encountered in local reservoir applications such
as geothermal field monitoring, this information can
be used in addition to the travel-times to better
constrain the hypocentre of local earthquakes.
We propose a new Bayesian formulation for the
likelihood function of an earthquake hypocentre
associated with the P-wave polarization information.
The formulation is consistent with directional statistics
contrarily to existing ones. The whole information of
the P-wave covariance matrix is used. The non-
linearity of the location problem is kept with this
approach. Hence, the polarization information can be
treated at the same level as the time information to
build a joint probability density function of the
earthquake location. Earthquake hypocentres are
therefore provided with a realistic uncertainty domain.