Resumen

CHOY, José E et al. Implications of the intensity centers location of the caracas 1967 and the caracas 1812 subevent. Rev. Fac. Ing. UCV [online]. 2011, vol.26, n.2, pp.77-88. ISSN 0798-4065.

In this work, intensity centers of Caracas 1967 and Caracas 1812 sub-event are relocated using the Bakun & Wentworth method with two modifications. The first one introduces intensity intervals to account for uncertainties of the historical information, and the second one uses a priori information of the fault strike. The relative locations between those events give important information to understand the relationship between both ruptures. The intensity center parameters of the 1967 event are consistent with instrumental information. The specialized literature showed that the rupture had at least four subevents. Later, other workers relocate the epicenter (10.558ºN y 67.31ºW) very close to the San Sebastián fault. The intensity center determined in this work (10.60ºN y 67.20ºW) lies between the first two subevents. This make sense as these two subevents released approximately 72% of the total moment produced by the earthquake and they are the ones closer to the damage areas; the other two subevents are not only smaller, but also farther away from the coast and therefore they had less influence on the intensity distribution. This also explains why the moment magnitude obtained from intensities (MWI = 6.4 ± 0.3) is smaller than the one obtained by other specialists (MW = 6.6). The Intensity center obtained for the Caracas 1812 subevent is: 10.6ºN and 67.1º W with magnitude MWI = 7.1 ± 0.33; very close to the San Sebastián fault and in between the first two subevents of 1967. This shows that the Caracas 1812 subevent ruptured the San Sebastián fault and perhaps, as in the case of the 1967 event, also ruptured other faults. On the other hand is very likely that broke the segment located between the first two subevents of 1967 and other segments to the west of the first subevent.

Palabras clave : Caracas; 1967; 1812; Earthquake; Intensities; Seismicity; Historical; Epicenter.