By the Numbers

# This Week's Events Should Happen Only Once Every 128 Years

In this handout satellite image provided by the National Oceanic and Atmospheric Administration (NOAA), shows Hurricane Irene on August 25, 2011 in the Caribbean Sea.
Source: NOAA

How likely is it that on the East Coast of the U.S., in the same week, an earthquake is felt and a hurricane makes landfall? Statistically speaking, this should occur only once every 128 years.

Based upon information from the United States Geological Survey (USGS), there have been 6 earthquakes since 1973 of magnitude 5.0 or greater that could be felt on the East Coast. According to the USGS, this 38 year span is representative of general seismic activity over the past century in a region where earthquakes are relatively rare.

During any given week, this would mean that the odds that cities on the East Coast would feel an earthquake is roughly 0.304%. In the past 38 years, an earthquake has happened every 329 weeks, or about once every 6.3 years. The last quake that could be felt on the east coast was in April 2008, a 5.2 earthquake with an epicenter in Southern Illinois.

On the other hand, the more common event for the East Coast of the U.S. are hurricanes that make landfall. According to the Colorado State University, which forecasts annual hurricane activity in the U.S., during the peak season for hurricanes between August and September, on any given week, there is about a one in 20 chance that a hurricane will make landfall, a probability of approximately 5%. This calculation is based upon data for 2011, which was predicted to have higher hurricane activity than in a normal year.

Given these rough estimations, based on the best data available, this would mean that the chance of a hurricane and earthquake occurring within a week of each-other is approximately 0.01518%, or once every 6,660 weeks. That means the events of this past week should only happen once every 128 years.

So, how rare is this event? Letâ€™s compare it to how often an individual could expect, on average, to experience some other relatively unlikely events:

Getting audited by the IRS: Once every 110 years
Dying in a car crash: Once every 6,700 years
Attacked by shark (swimming once per day): Once every 31,546 years
Getting struck by lightning: Once every 80,000 years
Winning the Powerball lottery (one play per day): Once every 537,634 years