Ouillon, Guy and Sornette, Didier (2011) Segmentation of fault networks determined from spatial clustering of earthquakes. Journal of Geophysical Research, 116 (B2). DOI: https://doi.org/10.1029/2010JB007752
Full text not available from this repository.Abstract
We present a new method of data clustering applied to earthquake catalogs, with the goal of reconstructing the seismically active part of fault networks. We first use an original method to separate clustered events from uncorrelated seismicity using the distribution of volumes of tetrahedra defined by closest neighbor events in the original and randomized seismic catalogs. The spatial disorder of the complex geometry of fault networks is then taken into account by defining faults as probabilistic anisotropic kernels. The structure of those kernels is motivated by properties of discontinuous tectonic deformation and by previous empirical observations of the geometry of faults and of earthquake clusters at many spatial and temporal scales. Combining this a priori knowledge with information theoretical arguments, we propose the Gaussian mixture approach implemented in an expectation maximization (EM) procedure. A cross ‐ validation scheme is then used that allows the determination of the number of kernels which provides an optimal data clustering of the catalog. This three ‐ step approach is applied to a high ‐ quality catalog of relocated seismicity following the 1986 Mount Lewis (M l = 5.7) event in California. It reveals that events cluster along planar patches of about 2 km 2, i.e., comparable to the size of the main event. The finite thickness of those clusters (about 290 m) suggests that events do not occur on well ‐ defined and smooth Euclidean fault core surfaces but rather that there exist a deforming area and a damage zone surrounding faults which may be seismically active at depth. Finally, we propose a connection between our methodology and multiscale spatial analysis, based on the derivation of a spatial fractal dimension of about 1.8 for the set of hypocenters in the Mount Lewis area, consistent with recent observations on relocated catalogs.
| Item Type: | Article |
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| Subjects: | Methodology > Method and procesing > Collective properties of seismicity > Clustering and migration |
| Project: | IS-EPOS project |