Frequently Asked Questions

Natural Hazards

The USGS monitors and conducts research on a wide range of natural hazards to help decision-makers prepare for and respond to hazard events that threaten life and property.

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USGS map displaying potential to experience damage from a natural or human-induced earthquake in 2017
Not really. The USGS Seismic Hazard Maps website and the Unified Hazard Tool (for building custom maps) are designed to display the probability of different events that might occur in a several-year to several-decade period. The model bases all probability estimates on the average rate of earthquakes over long periods of time. As you shorten the...
Map depicting difference in USGS estimates of earthquake hazards from 2002 and 2014
No. Probabilities and forecasts are rather like climate probabilities and weather forecasts, while predictions are more like statements of when, where, and how large, which is not yet possible for earthquakes. Probabilities describe the long-term chances that an earthquake of a certain magnitude will happen during a time window. Most earthquake...
Map depicting more than 100 aftershocks that have occurred since the magnitude 7.8 earthquake in Nepal on April 25, 2015. To dat
Worldwide the probability that an earthquake will be followed within 3 days by a large earthquake nearby is somewhere just over 6%. In California, that probability is about 6%. This means that there is about a 94% chance that any earthquake will NOT be a foreshock. In California, about half of the biggest earthquakes were preceded by foreshocks;...
3D perspective view of the likelihood that each region of California will experience a magnitude 6.7 within 30 years
Los Angeles area: Within the next 30 years the probability is: 60% that an earthquake measuring magnitude 6.7 46% that an earthquake measuring magnitude 7 31% that an earthquake measuring magnitude 7.5 will occur in the Los Angeles region. San Francisco Bay area: Within the next 30 years the probability is: 72% that an earthquake measuring...
USGS map displaying seismic events in 2015 and 2016 in the central and eastern U.S.
The National Seismic Hazards Mapping project provides an online Web tool for determining the probability of a large earthquake within 50 kilometers (~31 miles) of a specific location in the United States over a certain time period.  The calculation is based on the latest available information from seismic hazard data. However, asking if it's safe...
Image: Damaged Building
Ground shaking is the primary cause of earthquake damage to man-made structures. Many factors influence the strength of earthquake shaking at a site including the earthquake's magnitude, the site's proximity to the fault, the local geology, and the soil type.  More than 250 structures throughout the United States have been outfitted with seismic...
Damage to a house from and earthquake
You should consider the following factors when deciding whether or not to get earthquake insurance: proximity to active earthquake faults seismic history of the region (frequency of earthquakes) time since last earthquake building construction (type of building and foundation) architectural layout materials used quality of workmanship extent to...
Damage to buildings in Cushing, Oklahoma from the magnitude 5.0 earthquake on November 6, 2016
Published maps will only provide generalized, uninterpreted information about specific areas. Every property consists of a unique combination of geologic and structural factors that must be considered to determine what might happen to a house during an earthquake. Therefore, an individual site study is necessary. Geologic factors include: type of...
2014 South Napa Earthquake in California
Determining your risk with regard to earthquakes, or more precisely shaking from earthquakes, isn't as simple as finding the nearest fault. The chances of experiencing shaking from an earthquake and/or having property damage is dependent on many different factors. The National Hazard Maps use all available data to estimate the chances of shaking (...
 2014 USGS National Seismic Hazard Map, displaying intensity of potential ground shaking from an earthquake in 50 years (which i
Seismic hazard is the hazard associated with potential earthquakes in a particular area, and a seismic hazard map shows the relative hazards in different areas. The maps are made by considering what we currently know about: Past faults and earthquakes The behavior of seismic waves as they travel through different parts of the U.S. crust The near-...
USGS scientists conduct passive seismic study in the Washita Reach 1 study area.
Although you may hear the terms “seismic zone” and “seismic hazard zone” used interchangeably, they really describe two slightly different things. A seismic zone is used to describe an area where earthquakes tend to focus; for example, the New Madrid Seismic Zone in the Central United States. A seismic hazard zone describes an area with a...
USGS map displaying potential to experience damage from a natural or human-induced earthquake in 2017
Beginning in 2009, Oklahoma experienced a surge in seismicity. This surge was so large that its rate of magnitude 3 and larger earthquakes exceeded California’s from 2014 through 2017. Bar graph showing the number of M3+ Earthquakes in Oklahoma vs California from 1990 to 2019. California earthquake counts are shown as a blue bar and Oklahoma...