Abstract

RIVERO, Pedro; BENDITO, América  and  LOBO QUINTERO, William. Quantitative mapping of precursory seismic quiescence in the western region of venezuela. IMME [online]. 2005, vol.43, n.1, pp.1-14. ISSN 0376-723X.

We have analyzed the catalog of recent seismicity (1960-2004) in the western region of Venezuela, to detect decreases that can precede to the occurrence of strong earthquakes in the region. The properties of this quiescence were mapped as a function of time and space by a gridding technique using the ZMAP computer code, evaluating the statistical significance in the variations of the mean rate of earthquake in a volume, compared to the background rate in this same volume. The results show a possible precursory quiescence of 14 months before the 08.17.91 earthquake (5.5mb) in Lara state. Another possible seismic quiescence was detected in Trujillo state, this one lasted 57 months and culminated in an earthquake of 5.2mb in 1993. Some cases in which a decrease in seismicity was not followed by main shock were detected.

Keywords : Seismicity; precursory activity; seismic quiescence; Oca-Ancón fault.