Abstract

ROJAS, Jorge; BEAUPERTHUY, Luis; MONTILLA, Américo  and  BONIVE, Francisco. Seismic rupture model for the cariaco earthquake, july 1997. Rev. Fac. Ing. UCV [online]. 2011, vol.26, n.2, pp.103-112. ISSN 0798-4065.

For to estimate the behavior the slip occurred at the source that caused the Cariaco earthquake (Sucre state, Venezuela), July 9, 1997, magnitude 6.9 MW, will developwith radiation frequency spectra for long waves contained in the seismograms Network Earthquake of the Venezuelan Andes (RedSAV) located at an average distance of 800 kilometers from the epicentral area. According to the characteristic of spectra obtained, is possible to estimate the offset between the walls of the seismic source fails or the hypocenter. Using digital seismograms of the displacement field and applying the FFT to the first cycle of P waves that emerge in the seismogram of the seven seasons before being named, we find spectra with an average corner frequency of 0.25 Hz to adapt the theoretical advances seismic rupture with the results obtained it was necessary to analyze the coseismic behavior aftershocks, and despite the displacement between the walls of failure could be different from the circular geometry, we approximate the kinematics of a theoretical model of rupture 15 km diameter circular with this value and assuming that the speed of propagation of the rupture is 90% the speed of shear wave (S), we obtained a travel time of 5 seconds. The dimensions obtained (15 km in diameter fractured area) underestimate the total area of coseismic rupture for the Cariaco earthquake, we interpret this low value as a consequence that the spectrum of the first wave cycle, only provides information from the first slide intrinsic source, around the hipocenter, no harshness or interrupted by small barriers.

Keywords : Cariaco Earthquake; Frequency spectra; Corner frequency; Models source seismic; Slip seismic; Fourier Fast Transform (FFT).