Jefferson County - East-West Gateway Coordinating Council

A Regional Overview All-Hazard Mitigation Plan 129
HAZARD ANALYSIS NARRATIVE
Hazard: Earthquake
Description of Hazard (Type of hazard, pathways/areas likely affected, type of damage,
etc.)
The characteristics of earthquakes include the rolling or shaking of the ground surface,
landslides, liquefaction and amplification. The severity depends on several factors including
soil/slope conditions, closeness to the fault, earthquake magnitude and type of earthquake.
Any person or structure that is present in the land closest to the epicenter will be most
severely affected. Persons or structures farther away from the epicenter will be less severely
affected, dependent upon the geology of the area. The amount of damage depends on 1).
The intensity/strength of the earthquake, 2). The proximity of the earthquake, 3). The
strength/construction of the structure, 4). How well a person is sheltered. Damage can
range from very slight to total.
Historical Statistics (Frequency, strength, # of lives lost, # of injuries, economic losses,
etc.)
Since 1811 there have been 16 earthquakes affecting the EWGCC ranging in magnitude
from 2.4 to 8.2 on the Richter scale. The earthquakes have caused multiple deaths,
.injuries, and damaged properties in the past. The Center for Earthquake Studies estimated
that from a 7.6 scale earthquake, there will be over 1400 deaths, and $2.5 million dollars in
property damage and $500K in utility damage. This data excludes St. Charles and Franklin
Counties due to unavailability.
Statement of Future Probable Severity (Catastrophic/Critical/Limited/Negligible)
Catastrophic
Statement of Probable Risk (Likeliness of future occurrence- (Highly
Likely/Likely/Possible/Unlikely)
Possible
Statement of Next Disaster’s Likely Adverse Impact on the Community
(Catastrophic/Critical/Limited/Negligible)-Catastrophic
The Center for Earthquake Studies estimated that from a 7.6 scale earthquake, there will be
over 1400 deaths, and $2.5 million dollars in property damage and $500K in utility
damage. This data excludes St. Charles and Franklin Counties due to unavailability.
Without mitigation measures: Life Property Emotional Financial
Comments:
Catastrophic Catastrophic Catastrophic Catastrophic