Posted on 31 Mar 2010
Less than two months after a devastating earthquake struck the Caribbean country of Haiti, an even stronger seismic event struck on the southern Pacific coast of South America facing Chile. The Feb. 27 Chile quake has been described by seismologists as the seventh strongest earthquake ever measured. The spate of catastrophes occurring in the first quarter of 2010 was rounded out by European windstorm Xynthia, which began on the same day as the Chile quake and ended the following day.
The earthquakes could influence thinking about catastrophe modeling and planning. While high-intensity, low-frequency events can be identified as such retroactively, we were reminded that their timing cannot be predicted. Further, the Chile quake was a reminder of the potential, in geographies associated with frequent seismic activities, for major quakes, serving as a warning that the possibility exists for a significant quake to strike in regions -- such as the U.S. Pacific Northwest and cities such as San Francisco -- that are less prepared for the consequences and likely to suffer high insurance losses.
Chile is an earthquake-prone nation, owing to its position at the eastern edge of the Nazca tectonic plate. The most powerful earthquake ever recorded was a 9.5-magnitude event centered near Valdivia, Chile, in 1960. By some calculations, the 2010 Chile quake released 500 times the tectonic energy liberated by the Haiti event, which measured 7.0 on the Moment Magnitude Scale.
Nevertheless, the human toll of the Chile earthquake was far less than that in Haiti. Estimates of the Chile quake's death toll were as high as 802, but the Chilean government reported that 342 people died in the disaster. By contrast, more than 200,000 people died in the Haiti quake. Insurance losses, however, were much higher for the Chile quake, ranging from $3 billion to $8 billion as opposed to hundreds of millions of dollars in Haiti, according to Oakland, Calif.-based catastrophe modeling firm EQECAT. But the difference has at least as much to do with the fact that more lives and property are insured in Chile than in Haiti.
According to Claire Souch, VP of Newark, Calif.-based RMS, property damage and related loss of life was likely far less in Chile than it would have been in other countries owing to the South American nation's building codes. One positive outcome of Chile's history of earthquakes is that its building standards are some of the most stringent globally, comments Souch. Close to half of the properties in Chile have been built in the past 40 years, when the building codes have been in force. In sharp contrast to the shanty housing destroyed by the Haiti earthquake, most residential buildings in Chile are made of reinforced concrete.
However rigorous Chile's construction standards, though, the country suffered the collapse of many structures, including buildings and roads. In addition, tsunamis resulting from the quake caused damage to harbors on the Chilean coast and killed at least four people on Robinson Crusoe Island, according to a Reuters report. The total economic loss will likely be severe from damage not only to buildings, but from the widespread impact on infrastructure, including roads, bridges, airports, and utilities and telecommunications networks, comments Jayanta Guin, SVP of research and modeling at AIR Worldwide.
Ignoring the 'Big One'
Economic and insurance losses could be much higher should an earthquake of similar magnitude strike San Francisco. But San Franciscans are reminded of the quake dangers frequently by perceptible shaking. That is not the case in the Pacific Northwest, where seismic activity is seldom perceptible and usually associated with volcanic eruptions rather than earthquakes per se. The Chile quake should be a wake-up call to the U.S. Northwest and Oregon in particular, according to Patrick Corcoran, a hazard education and outreach specialist with Oregon State University.
The release of pressure between two overlapping tectonic plates along the subduction zone regularly generates massive 9.0-magnitude earthquakes, including five over the last 1,400 years, Corcoran recently warned, adding that the last Big One was 309 years ago. "We are in a geologic time when we can expect another Big One, either in our lives or those of our children," he said. "Prudence dictates that we overcome our human tendencies to ignore this inevitability."