Jefferson County - East-West Gateway Coordinating Council

A Regional Overview All-Hazard Mitigation Plan 49
other federal and state agencies, as well as universities and private institutions are
conducting research. Earthquake prediction may some day become a reality, but only after
much more is learned about earthquake mechanisms. The speed of onset is immediate.
See Table J34 below.
TABLE J34 FREQUENCY OF OCCURRENCES OF EARTHQUAKES
DESCRIPTOR MAGNITUDE ANNUAL AVERAGE
Great 8 and higher 1 ¹
Major 7 - 7.9 17 ²
Strong 6 - 6.9 134 ²
Moderate 5 - 5.9 1319 ²
Light (estimated) 4 - 4.9 13,000
Minor (estimated) 3 - 3.9 130,000
Very Minor (estimated) 2 - 2.9 1,300,000
¹ Based on observations since 1900.
² Based on observations since 1990.
The USGS estimates that several million earthquakes occur in the world each year.
Many go undetected because they hit remote areas or have very small magnitudes.
The NEIC now locates about 50 earthquakes each day, or about 20,000 a year.
Map of Hazards
Figure J31 below shows earthquakes that have occurred in the proximity of the St. Louis
Metropolitan area. Also please refer to Figure J26 (located in the back of the Technical
Appendix) that depicts areas that are susceptible to earthquakes. Areas outside of the soil
liquefaction zone will most likely be impacted from an earthquake, but probably to a lesser
degree. The figure also shows regions in the St. Louis metropolitan area that would be
predisposed to earth movements including landslides, sinkhole and mine shaft collapse.
FIGURE J31 EARTHQUAKES IN MISSOURI
Source: United States Geological Survey