April 6th, 2010

7.2 Mw Earthquake in Baja California, Mexico

Posted at 10:16 AM ET

baja-quake-smallA magnitude 7.2 earthquake struck the Mexican peninsula of Baja California at 22:40:41 UTC on April 4 (15:40:41 local time). According to the US Geological Survey (USGS), the earthquake was centered approximately 104 miles (167 kilometers) east-southeast of Tijuana and 38 miles (60 kilometers) south-southeast of the city of Mexicali and occurred at a shallow depth of 6.2 miles (10 kilometers). Reports say that the quake is considered to be one of the strongest to have hit the region in years.

According to California Institute of Technology, more than 100 aftershocks have been reported in the last 15 hours following Sunday’s quake, with many being recorded on the California side of the border just above the epicenter near Mexicali in Mexico. In Mexico, civil protection officials confirmed two deaths in the region and over 100 people have been treated at local area hospitals. Badly damaged roads, cracked buildings, and downed power lines were reported in cities near the epicenter.


Hazard data illustrated in the CAT-i map was taken from i-aXs®, Guy Carpenter’s web-based risk management platform. i-aXs users can view impacted areas on any map as well as see how their portfolios were affected. Please contact your broker or Instrat® representative for assistance or go to www.i-axs.info for further information.

The USGS estimates that almost 900,000 people live in areas impacted by a Modified Mercalli Intensity (MMI) of VII or higher (see Table 1 below), equivalent to very strong shaking with the potential for moderate to heavy damage. A majority of this number includes 597,000 people living in the city of Mexicali. About 5,000 people in the city of Progreso experienced an intensity of VIII, equivalent to severe shaking with the potential for heavy damage.

Mexicali, Baja California’s capital (population of 900,000) was located near the epicentre and received the most damage from the earthquake. There were two fatalities in Mexicali and more than 100 people were injured. The regional government declared a state of emergency for Mexicali, while the governor of the Mexican state of Baja California has requested a natural disaster declaration from the federal government. According to Mexican officials in Mexicali, the entire city lost power and telephone services were disrupted in the aftermath of the quake. The civil defense director said that there has been at least one building collapse, with other public and private buildings damaged.

Though the earthquake claimed two lives and injured numerous others, many are surprised that the human toll was not higher. The chief of the Mexican National Seismological Service cited improved building construction codes as a factor that helped mitigate the amount of serious damage.

According to reports, the earthquake was felt across the whole of Southern California, causing high-rise buildings in Los Angeles and San Diego to sway. The earthquake was also felt in Phoenix, Las Vegas and Yuma, Arizona. There were some power outages reported in Southern California including a power outage that affected more than 600 customers in San Diego County.

In Los Angeles, the fire department was carrying out safety checks on transportation infrastructure, large public venues, apartment buildings and power lines from the ground and air. Calexico, a town across the border from Mexicali, sustained enough damage for the city council to declare a state of emergency. Most damage occurred downtown, where older buildings were not retrofitted to withstand a major earthquake.

A seismologist from the USGS estimated that over 20 million people would have felt the earthquake and predicted that aftershocks would be felt over a wide area during the days to come.

Table 1: Estimated Population Exposed to Earthquake Shaking


Estimated MMI

Estimated Population Exposure

Perceived Shaking









Very Strong










Sources: USGS, WSI, Reuters News, Bloomberg, Associated News, CNN News, BBC News, Agence France Presse, Xinhua News Agency.

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Guy Carpenter’s Instrat® department provides CAT-i reports for major natural catastrophes worldwide. These reports cover catastrophes including worldwide tropical cyclones, earthquakes, major UK and European floods and any other natural event that is likely to incur a significant loss to the (re)insurance industry. Please email CAT.i@guycarp.com if you wish to be added to the free email distribution list.

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