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Focal mechanisms along inclined earthquake zones, in the Indonesia-Philippine region

1970; American Geophysical Union; Volume: 75; Issue: 8 Linguagem: Inglês

10.1029/jb075i008p01431

2156-2202

Thomas J. Fitch, Péter Molnár,

Geological and Geochemical Analysis

Journal of Geophysical Research (1896-1977)Volume 75, Issue 8 p. 1431-1444 Focal mechanisms along inclined earthquake zones, in the Indonesia-Philippine region Thomas J. Fitch, Thomas J. FitchSearch for more papers by this authorPeter Molnar, Peter MolnarSearch for more papers by this author Thomas J. Fitch, Thomas J. FitchSearch for more papers by this authorPeter Molnar, Peter MolnarSearch for more papers by this author First published: 10 March 1970 https://doi.org/10.1029/JB075i008p01431Citations: 100AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Abstract Twenty-eight now focal mechanisms were determined for intermediate and deep-focus earthquakes in the Indonesia-Philippine region. At intermediate depths beneath simple planar sections of the Sunda and Philippine arcs the axes of minimum compressive stress have a preferred orientation down the dip of the seismic zone, suggesting that the descending slab of lithosphere is under extension in this depth range. Deep-focus mechanisms beneath the Sunda arc have nearly vertically dipping axes of maximum compressive stress, implying that the descending slab is under compression at great depth. These data are consistent with models in which gravitational body forces are important factors in the dynamics of the lithosphere. Focal mechanisms from events located near regions where the seismic zones deviate strongly from a planar configuration show a striking reorientation of the stress axes. In the Banda Sea and northern Celebes regions the seismicity indicates possible contortions in the underthrust slabs. The orientations of the stress axes in these regions are consistent with such contortion and give additional support to the idea that the lithosphere is a stress guide. Citing Literature Volume75, Issue810 March 1970Pages 1431-1444 RelatedInformation