Seqüência Sísmica De Areado/Mg, Iniciada Em Janeiro De 2004: Resultados Preliminares

Preliminary studies results accomplished by the<br>Seismological Observatory (SIS) of The University of<br>Brasilia (UnB), concerning to the recent Areado/MG<br>seismic sequence, are presented. The studies cover the<br>period from January 28 to May 28, 2004, in which a five<br>short period 3 component stations seismograph network,<br>installed by SIS/UnB and FURNAS, detected 372<br>microeartquakes. The network was installed around a<br>branch of Furnas Reservoir (between the cities of Areado<br>and Alterosa) a week after 3,2 mR mainshock has been<br>felt in Areado and Alterosa. To perform the studies a set<br>of 75 seismic events detected by at least four stations<br>was select for analyses. Hipocentral locations show that<br>the Areado/MG sequence of 2004 belongs to the same<br>sismogenic zone delimited in previous studies carried out<br>by SIS/UnB and IAG/USP in 2003 and SIS/UnB in 1991.<br>The seismogenic area of Areado/MG is located at<br>southern of Minas Gerais State, at boundary between the<br>Brasilia belt and Ribeira belt, which is laid on the complex<br>Varginha-Guaxupé (Fernandes e Berrocal, 2003).<br>The objective of this paper is to present preliminary<br>results of the hipocentral location and focal mechanism to<br>the Areado/MG seismic sequence of January 2004.