Jefferson County - East-West Gateway Coordinating Council

46
Jefferson County – Section 2
Metropolitan area are not as intense and widespread as the landslides in the western
portion of the U.S. Earth movements in the St. Louis Metropolitan area are usually
localized.
Lives Lost, Injuries, Property Damage, Economic Losses/Other Losses
Another earthquake as powerful as the great quakes of 1811-12 may not occur for many
years. Because of differences in the geology east and west of the Rocky Mountains, the
effects of a magnitude 7 quake in the mid-continent United States could be far worse than
those of the 1989 magnitude 7 Loma Prieta, California, earthquake. That quake, which
struck the San Francisco Bay region during the World Series, killed 63 people and caused
$6 billion of property damage. Property damage could range from minor cracks in
structures to complete destruction. Infrastructure including roads, bridges, water and gas
lines may rupture, resulting in an abrupt halt to electricity, heat/cooling source,
communication, transportation, rescue and emergency response services. Ruptured gas
lines and power lines could potentially cause explosions and fires. Cascading emergencies
such as these will compound the initial disaster. Lives lost, injuries, property damage and
economic losses could potentially be in the same range as the earthquake that struck San
Francisco.
Landslides constitute a major geologic hazard because they are widespread, occurring in all
50 states, and cause $1-2 billion in damages and more than 25 fatalities on average each
year. Landslides pose serious threats to highways and structures that support fisheries,
tourism, timber harvesting, mining, and energy production as well as general
transportation. Landslides commonly occur with other major disasters such as earthquakes
and floods that exacerbate relief and reconstruction efforts and expanded development
and other land use has increased the incidence of landslide disasters.
Locations/Areas Affected
Refer to Figure J29 below that depicts the Peak Acceleration (%g) with a 10% probability of
exceedance within 50 years within the EWG planning region. As can be seen, Jefferson
County lies in four peak acceleration zones running northeast to southwest ranging from a
low of 7 in the northwestern corner to almost 15 %g of severity in the southeastern corner
of the county.