Abstract Database

DETERMINATION OF LOCAL MAGNITUDE SCALE ML FOR VENEZUELA

MEE13609
VASQUEZ STANESCU Raquel Noemi
Supervisor: Tatsuhiko HARA
Country: Venezuera
Abstract

In this study we determined local magnitude scales ML for Venezuela for vertical and horizontal components, respectively. We measured 636 vertical and horizontal peak amplitude data for 50 inland earthquakes which occurred between 2006 and 2012 that were recorded by 35 broadband stations of the National Seismological Network. The focal depths are shallow (up to 25 km) and the magnitude range is from 3.4 to 5.7. We found a good correlation between maximum amplitudes on the vertical component and those on the horizontal component. The average of the ratio of the horizontal component amplitude to the vertical component amplitude is about 1.7. The local magnitude coefficients for geometrical spreading and anelastic attenuation obtained by linear inversion are 1.031 and 0.00116 for the vertical component and 1.306 and 0.00075 for the horizontal component, respectively. The magnitude residuals calculated for the local magnitude formulas obtained in this study do not show significant dependence on the hypocentral distance. We compared local magnitudes for both components and found that the local magnitude for the vertical component was smaller than that for the horizontal component by about 0.2 in the magnitude range from 3.2 to 5.5. The distance corrections for Venezuela at the distance range larger than 100 km are lower than that for Southern California, which is adopted for the IASPEI standard formula. We evaluated local magnitudes for 6 small inland earthquakes recorded in 2012. We found that local magnitude for the vertical component was smaller than horizontal component by 0.2, which is consistent with our result.