Figure 4-18 Earthquake Losses by Type – M6.5 Golden Fault Scenario
People
Section titled “People”Potential fatalities and injuries are described above in the HAZUS results. Ground movement during an earthquake is seldom the direct cause of death or injury. Most earthquake-related injuries result from collapsing walls, flying glass, and falling objects as a result of the ground shaking, or people trying to move more than a few feet during the shaking. HAZUS estimates the number of people that will be injured and killed by the earthquake. The casualties are broken down into four severity levels that describe the extent of the injuries. The levels are described as follows:
Severity Level 1: Injuries will require medical attention, but hospitalization is not needed.
Severity Level 2: Injuries will require hospitalization but are not considered life-threatening.
Severity Level 3: Injuries will require hospitalization and can become life threatening if not promptly treated.
Severity Level 4: Victims are killed by the earthquake.
The casualty estimates are provided for three times of day: 2:00 AM, 2:00 PM and 5:00 PM. These times represent the periods of the day that different sectors of the community are at their peak occupancy loads. The 2:00 AM estimate considers that the residential occupancy load is at its maximum. The 2:00 PM estimate considers that the educational, commercial, and industrial sector loads are at their maximum. The 5:00 PM represents peak commute time. The models show that for both scenarios the 2:00 PM event time would result in the most casualties. In the probabilistic scenario, most of these would be minor injuries (307 Level 1 and 46 Level 2), and 4 hospitalizations (Level 3) and 8 fatalities (Level 4) are estimated. In the M 6.5 Golden Fault event, the casualty numbers are estimated to be significantly higher, with 4,516 Level 1 and 1,297 Level 2 casualties, 213 hospitalizations, and 415 fatalities.
HAZUS estimates the number of households that are expected to be displaced from their homes due to the earthquake and the number of displaced people that will require accommodations in temporary public shelters. The model estimates that approximately 826 households will be displaced due to the earthquake, and 437 people will seek temporary shelter in public shelters. The Golden Fault scenario would result in an estimated 11,616 displaced households and 6,086 individuals seeking temporary shelter.
Critical Facilities and Infrastructure
Section titled “Critical Facilities and Infrastructure”HAZUS breaks critical facilities into two groups: essential facilities and high potential loss (HPL) facilities. Essential facilities include hospitals, medical clinics, schools, fire stations, police stations and emergency operations facilities. High potential loss facilities include dams, levees, military installations, nuclear power plants and hazardous material sites.
The model estimates the region has 6 hospitals with 780 hospital beds total. The probabilistic scenario estimates that on the day of the earthquake only 566 (73%) would be available for use. After one week 88% of the beds will be back in service. The model did not predict there would be any damage to schools, police, fire stations, or EOCs.
Within HAZUS, the lifeline inventory is divided between transportation and utility lifeline systems. There are 7 transportation systems that include highways, railways, light rail, bus, ports, ferry, and airports. The transportation systems inventory includes over 280.24 miles of highways and 447 bridges. The probabilistic scenario estimated approximately $4.6 million in damage to transportation systems, mostly to highways, bridges, and bus facilities.
There are 6 utility systems that include potable water, wastewater, natural gas, crude & refined oil, electric power, and communications. The inventory value of the utility lifeline systems combined is estimated to be $6.1 billion including 13,106 miles of pipes, and related economic losses to these systems in the probabilistic scenario would be around $486.6 million, with the largest losses to wastewater and electrical power systems.
The expected utility system facility damages in terms of Economic losses in millions of dollars are found in
Table 4-32 Utility System Economic Losses in Millions of Dollars
Section titled “Table 4-32 Utility System Economic Losses in Millions of Dollars”The Golden Fault scenario estimates that on the day of the earthquake only 240 hospital beds (31%) would be available for use. After one week 52% of the beds will be back in service. The model predicted that 3 hospitals, 126 schools, 5 EOCs, 14 police stations, and 20 fire stations would be at least moderately damaged but with > 50% functionality from the event. These figures make up 49% of the county’s essential facilities. The model further estimates that 10 essential facilities would be completely damaged.
The model estimates the Golden Fault scenario would result in $50.55 million in economic losses to the transportation lifelines and $1.1 billion in losses to utility lifelines.
Economy
Section titled “Economy”The 2,500 year probabilistic scenario estimates a total economic loss for the earthquake at $2.2 billion, which includes building and lifeline related losses based on the County’s available inventory. $295.4 million is estimated to result from business interruption.
The M 6.5 Golden Fault scenario results in $11.5 billion in total economic losses for the county, including building and lifeline losses.
Historical, Cultural, and Natural Resources
Section titled “Historical, Cultural, and Natural Resources”Earthquake effects on the environment, natural resources, and historic and cultural assets would likely be minor. The biggest impact would likely be on the older historic properties constructed with unreinforced masonry.
Future Development
Section titled “Future Development”Without earthquake-resistant building considerations, future development will exhibit similar exposure and vulnerability to earthquakes as existing structures. As the region continues to expand, the overall estimated costs of a significant earthquake, both fiscally and in terms of casualty rates, may be expected to rise.
Overall Hazard Significance
Section titled “Overall Hazard Significance”Earthquakes in Jefferson County can impact the entire planning area. Within Colorado’s relatively short historic record, earthquakes have been limited mainly and generally low in magnitude and/or intensity. The geographic extent of the hazard is considered significant. The probability of future large magnitude occurrences is considered unlikely (less than 1 percent probability of occurrence), though the magnitude/severity for a worst-case scenario is catastrophic. In addition, the HMPC considers the hazard to have a high overall impact on the County. While this lends itself to an overall ranking of high, the likelihood of an earthquake event that causes damages and significant impacts on the planning area is extremely low. Furthermore, mitigation activities for the planning area are very expensive and, according to stakeholder input, prohibitive in both timeframe for implementation and overall expense. As such the hazard is rated as medium.