Pizarro, Colombia Earthquake

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Posting Date: November 15, 2004, 12:00:00 PM

On Monday, November 15, 2004 at 04:06 a.m. local time (09:06 UTC), a major earthquake struck the western coast of Colombia near the town of Puerto Pizarro. The U.S. Geological Survey (USGS) has estimated the magnitude of today’s quake at 7.2 and the focal depth at about 10 km. The epicenter was located about 95 km north-northwest of Buenaventura, Colombia and 385 km west of Bogota. The quake was felt throughout western Colombia, and as far away as the capital, Bogota. The earthquake occurred on the convergence boundary of the Nazca plate and the South America plate. The Nazca plate subducts beneath the South America plate at a rate of about 50-55mm/year. According to the USGS Preliminary Determination of Epicenter (PDE) catalog, four earthquakes of magnitude 6.0 or greater have occurred within a 100 km radius of today’s earthquake since 1973. Among these, an earthquake of magnitude 7.2 occurred on November 19, 1991 about 14km from the epicenter of this latest earthquake. Both the 1991 earthquake and today’s event have a typical subduction zone focal mechanism. The earthquake is reported to have injured 6 people and destroyed a dozen homes near the epicenter and the surrounding Choco province. Further away, in Cali, Colombia’s second largest city, two hospitals were evacuated when the tremors caused structural damage, though no injuries were reported there. Using the available information about the seismological parameters of this event, the AIR earthquake team has run the South America earthquake model. Although this was a relatively shallow event and one of significant magnitude, it occurred in an area of relatively sparse population and insured losses are therefore expected to be minimal.

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Posting Date: November 15, 2004, 12:00:00 PM