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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Aurora
Phenomena such as sheet lightning, balls of light, streamers, and steady glows, reported in association with earthquakes are called earthquake lights (EQL). Geophysicists differ on the extent to which they think that individual reports of unusual lighting near the time and epicenter of an earthquake actually represent EQL: some doubt that any of...
Image: Natural Entrance at Carlsbad Caverns
There is nothing different about a cave that would make it immune to the shaking from an earthquake. Just as there are safer and less safer places to be on the surface of the earth during an earthquake, there are also various characteristics inside caves that make some cave locations safer or less safe than others. First of all, whether or not you...
Image: Liquefaction in Subsurface Layer of Sand
Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata,...
Devastation of 1906 San Francisco Earthquake
Two sources for photographs that show earthquake damage are: Earthquake Hazards Program - Earthquake Photo Collections U.S. Geological Survey Photographic Library (see 'earthquakes' in the categories left column)
Image: Damage in Residential Area
Groundwater levels in wells may oscillate up and down while seismic waves pass, and in some cases, the water level may remain higher or lower for a period of time after the seismic wavetrain has ended.
Image: Damage from 2008 Great Sichuan Earthquake in China
There is more damage and more deaths from earthquakes in other parts of the world primarily because of buildings which are poorly designed and constructed for earthquake regions, and population density.
Airplane at McChord  AFB
"Booms" have been reported for a long time, and they tend to occur more in the Northeastern US and along the East Coast. Of course, most "booms" that people hear or experience are actually some type of cultural noise, such as some type of explosion, a large vehicle going by, or sometimes a sonic boom, but there have been many reports of "booms"...
2014 South Napa Earthquake in California
The way an earthquake feels depends on where you are, where the earthquake is, and how big the earthquake is: A large earthquake nearby will feel like a sudden large jolt followed quickly by more strong shaking that may last a few seconds or up to a couple of minutes if it's a rare great event. The shaking will feel violent and it will be...
Potential earthquake map shaking
It isn't that simple. There is not one magnitude above which damage will occur. It depends on other variables, such as the distance from the earthquake, what type of soil you are on, etc. That being said, damage does not usually occur until the earthquake magnitude reaches somewhere above 4 or 5. Learn more: Earthquake Magnitude, Energy Release,...
Image: Installing Antenna and Solar Panel for Seismic Station
The U.S. Geological Survey performs the following functions related to earthquake hazard mitigation: Receives, analyzes, maintains, and distributes data on earthquake activity worldwide. Satellites link our National Earthquake Information Center in Golden, Colorado to a network of seismograph stations. These stations, located throughout the world...
Image: Northridge, CA Earthquake Damage
Earthquake engineers are working to make roads and buildings safer in the event of a major earthquakes. This includes both improving the design of new buildings and bridges as well as strengthening older units to incorporate the latest advances in seismic and structural engineering. The Federal Emergency Management Agency plays a central role in...
Image: Mw6.6 Lushan China Earthquake, April 20 2013
We know of no current "zone" designations for sites outside of the United States. For locations outside the United States for which seismic design is required for military facilities, there exists a standard based on probabilistic spectral ordinates in the manner of the International Building Code and are declared to reflect the 2015 version of...