Jefferson County - East-West Gateway Coordinating Council

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Jefferson County – Section 2
probability of a magnitude 6.0 or greater earthquake is 25-40% through the year 2053.
The January estimates show a 7-10% chance of magnitudes between 7.5 and 8.0 in a 50year
period through 2053.
Probable Risk of Modified Mercalli Levels
I-V Highly Likely
VI Highly Likely
VII Highly Likely
VIII-XIII Likely
Landslides have been categorized by the USGS based on incidence and susceptibility.
These categories are found below. The probable risk of future occurrence in the St. Louis
metropolitan area would be ranked as low, less than 1.5% of the area involved, with a
moderate susceptibility and low incidence.
Landslide Incidence
Low- less than 1.5% of area involved
Moderate- 1.5% to 15% of area involved
High- Greater than 15% of area involved
Landslide Susceptibility/Incidence
Moderate susceptibility/low incidence
High susceptibility/low incidence
High susceptibility/moderate incidence
In the USGS Map, Figure J25, susceptibility is not indicated with the same or lower
incidence. Susceptibility to landsliding was defined as the probable degree of response or
the rocks and soils to natural or artificial cutting or loading of slopes, or to anomalously
high precipitation. High, moderate, and low susceptibility are delimited by the same
percentages used in classifying the incidence of landsliding. Some generalization was
necessary at the map scale and several small areas of high incidence and susceptibility were
slightly exaggerated.
Statement of Next Disaster’s Likely Adverse Impact on Community
The next disaster’s likely adverse impact on Jefferson County could be critical in terms of
amount of damage to infrastructure (utilities, communications) buildings, deaths and other
cascading disasters including fire and explosions from natural gas and oil pipeline ruptures.
At the time of the New Madrid earthquake in 1811-1812, St. Louis and other major cities
in the central U.S. were sparsely settled and there were few man-made structures. Today,
this region is home to millions of people, including the populations of large cities, such as