August 15, 2007 Peru Earthquake

First Posting | Summary
Posting Date: August 16, 2007, 4:00:00 PM

A major earthquake struck off the coast of central Peru on Wednesday, August 15, at 23:41 UTC. The USGS initially issued a magnitude estimate of 7.5 but subsequently revised it, first to 7.9 and then to 8.0. Focal depth is estimated at 30.2 km (18.8 miles) which makes this a relatively shallow event. The quake's epicenter was 145 km (90 miles) south-southeast of the capital, Lima. In Lima, panicked residents and office workers in the capital ran from swaying buildings into the streets. At least one fire broke out and there are reports of some houses having collapsed in the center of the city. But Lima's distance from the epicenter spared it from the widespread devastation being seen closer to the epicenter. The death toll has risen to at least 450, and this number is expected to rise. Rescue efforts are being hampered by power and telecommunications outages. Access roads into the most severely affected areas have been made impassable by boulders dislodged by ground motion that lasted nearly two minutes. There have been more than a dozen aftershocks, the largest of which were M6.3 and M6.0. More are expected. There are reports of large numbers of collapsed houses in Ica, Chincha and Pisco. A collapsed church in Ica killed 17; another 200 are reported to have been buried beneath the rubble of a church in Pisco, a port city with a population of 130,000. Pisco's mayor has said that 70% of the town was destroyed in the quake. The destruction is similar in Chincha, a town of more than 100,000 and less than 30 miles from the epicenter. Authorities expect to find more devastation in smaller towns in the epicentral region where houses are old and poorly constructed. AIR estimates that 60% of construction in Peru is masonry, with another 15% traditional adobe. Both construction types offer little or no lateral resistance against ground shaking. Away from the capital, Lima, these percentages are likely to be higher, particularly in the smaller towns and villages. Development of the first Peruvian seismic code began in 1964 based on the recommendations established by the Structural Engineers Association of California. The code was implemented in 1970. After the earthquake of Chimbote-Huarez in 1970 and the Lima earthquake of 1974, the code was reviewed and the second nationwide standard was developed and established in 1977. After the earthquakes in Nazca (1996), Mexico (1985), Loma Prieta (1989), Northridge (1994), and Kobe (1995), the seismic code underwent another revision and new seismic provisions were implemented in 1997. These were most recently reviewed in 2003, but no new major revision of the nationwide code was implemented as a result of that review. Unfortunately, while Peru's building code is now quite good, most of the residential structures are unlikely to have been built to code and many commercial structures in the region predate it. AIR estimates that the percentage of residential structures in Peru that are actually insured against the earthquake peril is quite low. Commercial take-up rates, however, are much higher and these will ultimately drive the insured losses from this event. The AIR earthquake team has assembled the available information in the aftermath of this event and has run simulations based on estimates of epicentral location, depth, magnitude and direction of rupture. Scenarios are now posted on the Scenarios page of the ALERT website where clients can view maps of ground motion intensity and total insured losses in US Dollars (USD). Please note that there remains uncertainty with respect to the quake's actual parameters. AIR is continuing to monitor the situation and will provide additional information if warranted.

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Posting Date: August 16, 2007, 4:00:00 PM