Lithospheric characteristics and seismic sources in the SCOTIA ARC through waveform inversion.

Plasencia Linares, Milton Percy

Lithospheric characteristics and seismic sources in the SCOTIA ARC through waveform inversion.

Plasencia Linares, Milton Percy

2008-04-18

http://hdl.handle.net/10077/2687

Doctoral Thesis

Abstract

The Scotia Sea region is found between the south American and Antarctic plates and constitutes a complex area tectonics, characterized from numerous active processes and changes in the movement and in the configuration of the plates. The main tectonics characteristics of the Scotia Sea were object of different studies, nevertheless some details of the interactions tectonics, of the margin of plates and of their relative movement remain still uncertain. In this sense, the determination of the features of the lithosphere and the study of the focal mechanisms develop an important role to understand the geodynamic evolution of the area. This study proposes to use the present technologies for the inversion of wave- forms to the end of to obtain the source mechanisms for a series of earthquakes recorded in the proximity of the Antarctic Base Argentina Orcadas. The appli- cation of the method is possible thanks to the digital seismograms recorded from a regional network installed to leave from 1992 and that includes the Antarctic Seismographic Argentinean Italian Network (ASAIN) and other three seismo- graphic stations of the Global Seismographic Network (GSN) operating in the antarctic Peninsula, Tierra del Fuego and in the islands of the Scotia arc. Were analyzed and reproduced seven events that followed the earthquake of magnitude 7,6 Mw 4 August 2003 known in literature like Centenary Earthquake. The main unit of the study (Chapter 3) is preceded of two chapters dedicated respectively to a detailed description of the situation tectonics and the seismicity of the Scotia Sea region (Chapter 1) and the Italian-Argentinean seismographic network ASAIN with special attention for the response in frequency of the seismograph and the characterization of the seismic noise levels (Chapter 2). Like complement to the analysis of the focal mechanisms, applying the Omori’s law, it has determined the curve of temporal decay of the seismic se- quence recorded from the Orcadas station in sixty days following to the Cente- nary Earthquake.