Seismicity of west-central Argentina using permanent and temporary stations

SPAGNOTTO, S. L

Heredia, Costa Rica

Otro; INTERNATIONAL TRAINING COURSE ON SEISMOLOGY, SEISMIC DATA ANALYSIS, HAZARD ASSESSMENT AND RISK MITIGATION; 2008

Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences

From the end of the year 2008 to the middle 2009 a network of 24 permanent and 11 temporaries stations (Figure 1) will participate in a joint project conducted by Instituto Nacional de Prevención Sísmica (INPRES), Instituto Geofisico-Sismológico (Universidad Nacional de San Juan), and Departamento de Sismología e Información Metereorológica (Universidad Nacional de la Plata). Most of the stations have short period sensors, but the rest are broadband sensors. The temporary stations will make the spatial distribution larger, more uniform, and dense than the one of the permanent stations. This will permit to locate and quantify the seismicity from small to large magnitudes (M>2.5), and with the addition of the obtained focal mechanisms will help to individualize and delimitated active tectonic features. The region, between latitudes 30-35º S and longitudes 64-70º W, corresponds to the Andean backarc where de subduction of the Nazca plate is flat to the north of 33º S and normal to the south. The seismic activity is very high, and several destructive earthquakes have taken place in the last two centuries (M~7.0, 1861; M~7.7, 1984; Mw=7.0, 1944; Mw=6.8, 1952; Mw=7.4, 1977; Mw=5.9, 1985, etc.) causing more than ~20,000 deaths and a huge damage in properties. INPRES, who is the responsible of the National Seismic Network, usually locate seismicity with M>4.0. The project will locate also events with 2.5<M<4.0, which in a first approximation will give the possibility to evaluate if patterns of small earthquakes could be taken into account as one of the components of earthquake hazard mapping. Although the field experiment have no started yet, we believe that the training course will be a very appropriated opportunity to discuss the overall scope of the project, and the methodology to be used for the data analysis, hazard assessment and eventually risk mitigation. Particularly, since an enormous amount of data will be gathered, it will be important to analyze also the more organized and efficient way to create the data archive.