China’s tragic magnitude 6.9 earthquake on April 13 and the recent devastating earthquakes in Haiti, Chile, Mexico, and elsewhere have many wondering if this earthquake activity is unusual.
Scientists say no.
According to Dr. Michael Blanpied, U.S. Geological Survey Associate Coordinator for Earthquake Hazards, an average of 16 magnitude 7 or greater earthquakes—the size that seismologists define as major—have occurred worldwide each year since 1900. Some years have had as few as 6, as in 1986 and 1989, while 1943 had 32, with considerable variability from year to year.
An earthquake rocked Port au Prince, Haiti on January 12, 2010. A man exits a restaurant after he looked for his belongings. Photo by Marco Dormino/ The United Nations United Nations Development Programme.
With six major earthquakes striking in the first four months of this year, he considers that 2010 is well within the normal range. He noted that from April 15, 2009, to April 14, 2010, there have been 18 major earthquakes, a number also well within the expected variation.
“While the number of earthquakes is within the normal range, this does not diminish the fact that there has been extreme devastation and loss of life in heavily populated areas,” said Blanpied.
In Michigan, we normally don’t feel threatened by earthquakes, although they have occurred here. The largest was on August 9, 1947, with a magnitude of 4.6. This earthquake damaged chimneys and cracked plaster over a large area of south-central Michigan and affected a total area of about 50,000 square miles, including points north to Muskegon and Saginaw and parts of Illinois, Indiana, and Wisconsin. Reports of damage to chimneys and some instances of cracked or fallen plaster, broken windows, and merchandise thrown from store shelves were common over the epicentral area. It was also felt in Indiana, Illinois, Ohio, Wisconsin, and Ontario, Canada.
The last earthquake in Michigan was reportedly a 3.9 in September 1994. Although, some residents have said they felt tremors from an earthquake near Cairo, Illinois, in the southeastern region of Missouri, that occurred on March 2.
Blanpied said that although the recent earthquakes around the world are not unusual, they are a stark reminder that earthquakes can produce disasters when they strike populated areas, especially areas where the buildings have not been designed to withstand strong shaking. What can you do to prepare? Scientists cannot predict the timing of specific earthquakes. However, families and communities can improve their safety and reduce their losses by taking actions to make their homes, places of work, schools and businesses as earthquake-safe as possible. The USGS provides information on how you can prepare at the Earthquake Hazards Program Web site at http://earthquake.usgs.gov/prepare/.
