The El Tocuyo, Venezuela, earthquake of 3 August, 1950: Focal parameters and tectonic implications

Abstract

The El Tocuyo earthquake of 1950 event was associated with the Boconó fault system. The Ms magnitude was 6.3; the focal depth was (from pP - P and sP - P) 18 ± 1 Km. The focal mechanism was strike-slip with the nodal planes as follows: Plane Strike Dip Slip A 206 72 -166 B 112 77 -19 Nodal plane A was the fault plane, which corresponds to right-hand strike-slip faulting. No surface rupture has been reported. The epicenter is located in an area limited by the Boconó and Carache faults, and that includes the town of Carora. All published mechanisms for events with mb > 5.0 in this area correspond to strike-slip faulting. However, southeast of this area, the Boconó fault borders on a reverse faulting regime associated with the southern Andean foothills. The partitioning of faulting differs from other areas of the Mérida Andes. Most seismic activity in the region is confined to the upper 18 km of the crust. Strike-slip events with mb > 5.0 tend to nucleate at depths of 16 - 20 km. The depth of the seismogenic zone for strike- slip faults may reach to 18 km or more.