Publication Date:
2013-04-11
Description:
In this study, we modify and extend a data analysis technique to determine the stress orientations between data clusters by adding an additional constraint governing the probability algorithm. We apply this technique to produce a map of the maximum horizontal compressive stress ( S Hmax ) orientations in the greater European region (including Europe, Turkey and Mediterranean Africa). Using the World Stress Map data set release 2008, we obtain analytical probability distributions of the directional differences as a function of the angular distance, . We then multiply the probability distributions that are based on pre-averaged data within 〈 3° of the interpolation point and determine the maximum likelihood estimate of the S Hmax orientation. At a given distance, the probability of obtaining a particular discrepancy decreases exponentially with discrepancy. By exploiting this feature observed in the World Stress Map release 2008 data set, we increase the robustness of our S Hmax determinations. For a reliable determination of the most likely S Hmax orientation, we require that 90 per cent confidence limits be less than ±60° and a minimum of three clusters, which is achieved for 57 per cent of the study area, with uncertainties of less than ±30° for 19 per cent of the area. When the data density exceeds 0.8 x 10 –3 data km –2 , our method provides a means of reproducing significant local patterns in the stress field. Several mountain ranges in the Mediterranean display 90° changes in the S Hmax orientation from their crests (which often experience normal faulting) and their foothills (which often experience thrust faulting). This pattern constrains the tectonic stresses to a magnitude similar to that of the topographic stresses.
Print ISSN:
0956-540X
Electronic ISSN:
1365-246X
Topics:
Geosciences
Published by
Oxford University Press
on behalf of
The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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