BOSTON, Oct. 29, 2011 — According to catastrophe modeling firm AIR Worldwide, a magnitude 6.9 earthquake occurred near the coast of central Peru today at 18:54 UTC (1:54 pm local time). According to the United States Geological Survey, the quake occurred at a depth of approximately 20 miles. Current indications from the USGS Centroid Moment Solution suggest that this was a subduction event in the collision zone between the Nazca oceanic plate and the South American continental plate.
The epicenter was about 180 miles (286 kilometers) south-southeast of the capital Lima. Buildings in the capital shook for about a minute, but no damage has been reported. Isolated power outages and loss of cell phone signals have been reported, which is hindering the dissemination of information about the quake.
Closest to the epicenter were the towns of Ica, Pisco and Chincha Alta. Ica, which is about 30 miles north-northeast of the epicenter is the largest, with a population of about 220,000. No immediate reports of damage are available.
According to AIR, in 2007, a magnitude 8.0 earthquake (also a subduction event) struck 60 miles north of the epicenter of today’s quake. The tremor caused more than 500 fatalities and over 35,000 buildings were destroyed. Most of the damage was sustained in Pisco, where about 80% of the structures-mostly of adobe construction-were destroyed. The destructive power of today’s magnitude 6.9 earthquake is orders of magnitude lower.
Peru has made significant improvements in their building standards over the past several decades, with newer important buildings, such as schools, performing very well even during very large earthquakes, stated AIR. However, in cities and towns throughout Peru-including those affected by today’s earthquake-about 21% of residences are still made of adobe or quincha.
According to AIR, masonry accounts for 71% of Peru’s residential construction and 64% of that is unreinforced masonry, which is among the construction types most vulnerable to damage from ground shaking. Confined masonry buildings, which are more earthquake resistant, are the second most common type of masonry residences in Peru, but they comprise just 21% of all masonry residential buildings. About 55% of commercial structures are masonry and another 21% are of reinforced concrete.
Given the relatively sparse population in the epicentral area and the fact that insurance penetration is generally low (estimated at just 2% for residential construction), AIR does not expect significant insured losses from this event.