The Shmax Orientations and Fault Types for Tsunami Initial Heights in Mediterranean Region

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Ulutaş E.

Special Symposium for the 20th Anniversary of Kocaeli and Düzce Earthquakes, Kocaeli, Turkey, 25 - 27 September 2019, pp.300

  • Publication Type: Conference Paper / Summary Text
  • City: Kocaeli
  • Country: Turkey
  • Page Numbers: pp.300
  • Kocaeli University Affiliated: Yes

Abstract

In this study, horizontal stress axes (Shmax) were determined to place the possible tsunami sources by using the earthquake focal mechanism data. In order to evaluate the tsunami hazard of an area, it is necessary not only to know where potentially active faults are, but also the orientation of the stress field. Because the maximum stress field are one of the main parameters governing the fault mechanism of the earthquakes. The generation of tsunamis is closely related to the type and dimension of dislocation in the source, being associated with parameters of the earthquake focal mechanism such as strike, dip and rake of the fault. The dislocation in the source is used to calculate initial height of the tsunamis. Here, It was used a methodology to utilize rotations of the maximum horizontal stress due to the focal mechanism solutions considering a catalogue which is from Harvard University, commonly referred to as "centroid moment tensor" or CMT method. The method is one of the most common, robust and reliable ways for computing focal mechanisms. The downloaded total earthquake data from CMT Catalogue consists of 641 events. However only 93 of 641 events overlaid in gridded area of Mediterranean Sea and it should also be noted that the earthquakes above the magnitude threshold Harvard CMT catalog (about Mw>5.5) are only 57 events. All the events are classified as normal fault, normal fault with strike slip component, strike-slip fault, thrust fault, thrust fault with strike slip component and undefined fault mechanism due to  the Shmax orientations obtained from the plunges (pl) of P-, B- and T- axes. The worst tsunami initial height scenarios could be done with the results of the study by using the determined Shmax orientations and fault types of the earthquakes for every 5 km gridded area in Mediterranean Region. Nevertheless, the number of the earthquakes from CMT solutions is not enough for All Mediterranean Sea, for that reason RCMT and EMMA Catalogues should be examined further.