From the USGS...
To help make the best decisions to protect communities from earthquakes, new USGS maps display how intense ground shaking could be across the nation.
The USGS recently updated their U.S. National Seismic Hazard Maps, which reflect the best and most current understanding of where future earthquakes will occur, how often they will occur, and how hard the ground will likely shake as a result.
42 States at Risk; 16 States at High Risk
While all states have some potential for earthquakes, 42 of the 50 states have a reasonable chance of experiencing damaging ground shaking from an earthquake in 50 years (the typical lifetime of a building). Scientists also conclude that 16 states have a relatively high likelihood of experiencing damaging ground shaking. These states have historically experienced earthquakes with a magnitude 6 or greater.
The hazard is especially high along the west coast, intermountain west, and in several active regions of the central and eastern U.S., such as near New Madrid, MO, and near Charleston, SC. The 16 states at highest risk are Alaska, Arkansas, California, Hawaii, Idaho, Illinois, Kentucky, Missouri, Montana, Nevada, Oregon, South Carolina, Tennessee, Utah, Washington, and Wyoming.
While these overarching conclusions of the national-level hazard are similar to those of the previous maps released in 2008, details and estimates differ for many cities and states. Several areas have been identified as being capable of having the potential for larger and more powerful earthquakes than previously thought due to more data and updated earthquake models. The most prominent changes are discussed below.
Informed Decisions Based on the Maps
With an understanding of potential ground shaking levels, various risk analyses can be calculated by considering factors like population levels, building exposure, and building construction practices. This is used for establishing building codes, and in the analysis of seismic risk for key structures. This can also help in determining insurance rates, emergency preparedness plans, and private property decisions such as re-evaluating one’s home and making it more resilient.
These maps are part of USGS contributions to the National Earthquake Hazards Reduction Program (NEHRP), which is a congressionally-established partnership of four federal agencies with the purpose of reducing risks to life and property in the U.S. that result from earthquakes. The contributing agencies are the USGS, Federal Emergency Management Agency (FEMA), National Institute of Standards and Technology, and National Science Foundation (NSF). As an example of the collaboration, the hazards identified in the USGS maps underlie FEMA-sponsored seismic design provisions that are incorporated into building codes adopted by states and localities. The maps also reflect investments in research by academic and other scientists supported by grants from the USGS and the NSF.
“The standards for seismic safety in building codes are directly based upon USGS assessments of potential ground shaking from earthquakes, and have been for years,” said Jim Harris, a member and former chair of the Provisions Update Committee of the Building Seismic Safety Council. “The committees preparing those standards welcome this updated USGS information as a basis for making decisions and continuing to ensure the most stable and secure construction.”
Key Updates
East Coast
The eastern U.S. has the potential for larger and more damaging earthquakes than considered in previous maps and assessments. As one example, scientists learned a lot following the magnitude 5.8 earthquake that struck Virginia in 2011. It was among the largest earthquakes to occur along the east coast in the last century, and helped determine that even larger events are possible. Estimates of earthquake hazards near Charleston, SC, have also gone up due to the assessment of earthquakes in the state.
In New York City, the maps indicate a slightly lower hazard for tall buildings than previously thought (but still a hazard nonetheless). Scientists estimated a lower likelihood for slow shaking from an earthquake near the city. Slow shaking is likely to cause more damage to tall structures in contrast, compared to fast shaking which is more likely to impact shorter structures.
Central U.S.
The New Madrid Seismic Zone has been identified to have a larger range of potential earthquake magnitudes and locations than previously identified. This is a result of a range of new research, part of which was recently compiled by the Nuclear Regulatory Commission.
To help make the best decisions to protect communities from earthquakes, new USGS maps display how intense ground shaking could be across the nation.
The USGS recently updated their U.S. National Seismic Hazard Maps, which reflect the best and most current understanding of where future earthquakes will occur, how often they will occur, and how hard the ground will likely shake as a result.
42 States at Risk; 16 States at High Risk
While all states have some potential for earthquakes, 42 of the 50 states have a reasonable chance of experiencing damaging ground shaking from an earthquake in 50 years (the typical lifetime of a building). Scientists also conclude that 16 states have a relatively high likelihood of experiencing damaging ground shaking. These states have historically experienced earthquakes with a magnitude 6 or greater.
The hazard is especially high along the west coast, intermountain west, and in several active regions of the central and eastern U.S., such as near New Madrid, MO, and near Charleston, SC. The 16 states at highest risk are Alaska, Arkansas, California, Hawaii, Idaho, Illinois, Kentucky, Missouri, Montana, Nevada, Oregon, South Carolina, Tennessee, Utah, Washington, and Wyoming.
While these overarching conclusions of the national-level hazard are similar to those of the previous maps released in 2008, details and estimates differ for many cities and states. Several areas have been identified as being capable of having the potential for larger and more powerful earthquakes than previously thought due to more data and updated earthquake models. The most prominent changes are discussed below.
Informed Decisions Based on the Maps
With an understanding of potential ground shaking levels, various risk analyses can be calculated by considering factors like population levels, building exposure, and building construction practices. This is used for establishing building codes, and in the analysis of seismic risk for key structures. This can also help in determining insurance rates, emergency preparedness plans, and private property decisions such as re-evaluating one’s home and making it more resilient.
These maps are part of USGS contributions to the National Earthquake Hazards Reduction Program (NEHRP), which is a congressionally-established partnership of four federal agencies with the purpose of reducing risks to life and property in the U.S. that result from earthquakes. The contributing agencies are the USGS, Federal Emergency Management Agency (FEMA), National Institute of Standards and Technology, and National Science Foundation (NSF). As an example of the collaboration, the hazards identified in the USGS maps underlie FEMA-sponsored seismic design provisions that are incorporated into building codes adopted by states and localities. The maps also reflect investments in research by academic and other scientists supported by grants from the USGS and the NSF.
“The standards for seismic safety in building codes are directly based upon USGS assessments of potential ground shaking from earthquakes, and have been for years,” said Jim Harris, a member and former chair of the Provisions Update Committee of the Building Seismic Safety Council. “The committees preparing those standards welcome this updated USGS information as a basis for making decisions and continuing to ensure the most stable and secure construction.”
Key Updates
East Coast
The eastern U.S. has the potential for larger and more damaging earthquakes than considered in previous maps and assessments. As one example, scientists learned a lot following the magnitude 5.8 earthquake that struck Virginia in 2011. It was among the largest earthquakes to occur along the east coast in the last century, and helped determine that even larger events are possible. Estimates of earthquake hazards near Charleston, SC, have also gone up due to the assessment of earthquakes in the state.
In New York City, the maps indicate a slightly lower hazard for tall buildings than previously thought (but still a hazard nonetheless). Scientists estimated a lower likelihood for slow shaking from an earthquake near the city. Slow shaking is likely to cause more damage to tall structures in contrast, compared to fast shaking which is more likely to impact shorter structures.
Central U.S.
The New Madrid Seismic Zone has been identified to have a larger range of potential earthquake magnitudes and locations than previously identified. This is a result of a range of new research, part of which was recently compiled by the Nuclear Regulatory Commission.
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