Earthquake Hazards Program

FAQ

Why do earthquakes in other countries seem to cause more damage and casualties than earthquakes in the U.S.?

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.

How can an earthquake affect groundwater or changes in wells?

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.

Where can I find photographs of earthquake damage?

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)

What is liquefaction?

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,...

Can you feel an earthquake if you're in a cave? Is it safer to be in a cave during an earthquake?

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...

What are earthquake lights?

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...

Do all wastewater disposal wells induce earthquakes?

No. Of more than 150,000 Class II injection wells in the United States, roughly 40,000 are waste fluid disposal wells for oil and gas operations. Only a small fraction of these disposal wells have induced earthquakes that are large enough to be of concern to the public. Learn more: USGS Induced Earthquakes EPA's Underground Injection Control (UIC...

Is it possible to anticipate whether a planned wastewater disposal activity will trigger earthquakes that are large enough to be of concern?

Currently, there are no methods available to do this in a definitive sense. We have developed methods that use injection information to help us determine whether injection activities might cause induced earthquakes and rule out other injection activities that are unlikely to induce earthquakes, but we cannot say either with certainty. There are a...

How does the injection of fluid at depth cause earthquakes?

The fluid that is injected at depth is sometimes hydraulically connected to faults. When this happens, fluid pressures increase within the fault, counteracting the frictional forces on faults. This makes earthquakes more likely to occur on them. An analog to this system is an air hockey table. When an air hockey table is off, the puck does not...

How large are the earthquakes induced by fluid injection?

The largest earthquake induced by fluid injection that has been documented in the scientific literature was a magnitude 5.8 earthquake on September 23, 2016 in central Oklahoma. Four magnitude 5+ earthquakes have occurred in Oklahoma, three of which occurred in 2016. In 2011, a magnitude 5.3 earthquake was induced by fluid injection in the Raton...

Are earthquakes induced by fluid-injection activities always located close to the point of injection?

No. Given enough time, the pressure increase created by injection can migrate substantial horizontal and vertical distances from the injection location. Induced earthquakes can occur 10 or more miles from injection wells. Induced earthquakes can also occur a few miles below injection wells. Learn more: USGS Induced Earthquakes

Is there any possibility that a wastewater injection activity could interact with a nearby fault to trigger a major earthquake that causes extensive damage over a broad region?

So far, there is no documented example linking injection operations to triggering of major earthquakes. However, we cannot eliminate this possibility. Other human activities--for example oil production in Uzbekistan--have induced M7+ earthquakes. Learn more: USGS Induced Earthquakes

Does the production of oil and gas from shales cause earthquakes? If so, how are the earthquakes related to these operations?

To produce oil and gas from shale formations, it is necessary to increase the interconnectedness of the pore space (permeability) of the shale so that the gas can flow through the rock mass and be extracted through production wells. This is usually done by hydraulic fracturing ("fracking"). Fracking intentionally causes small earthquakes (...

Oklahoma has had a surge of earthquakes since 2009. Are they due to fracking?

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 Bar graph showing the...

Where can I find a list of yearly estimated deaths from earthquakes around the world?

Our Earthquake Statistics website has annual totals for worldwide earthquakes and U.S. earthquakes from 1990 to the near-present. Estimated deaths from those earthquakes are listed at the bottom of the charts. The website also has M3+ earthquake counts by state beginning in 2010.

Which states have the smallest number of earthquakes? Is there any place in the world that doesn't have earthquakes?

Florida and North Dakota are the states with the fewest earthquakes. Antarctica has the least earthquakes of any continent, but small earthquakes can occur anywhere in the World. Our Earthquake Statistics has M3+ earthquake counts for each state beginning in 2010. Learn more: Earthquake Information by Region (scroll down for information by State/...

Where do earthquakes occur?

Earthquakes can strike any location at any time, but history shows they occur in the same general patterns year after year, principally in three large zones of the earth: The world's greatest earthquake belt, the circum-Pacific seismic belt , is found along the rim of the Pacific Ocean, where about 81 percent of our planet's largest earthquakes...

Where can I find a list of the largest earthquakes in the United States? In the World?

The USGS Earthquake Lists, Maps, and Statistics website has statistics about earthquakes in the United States and the world, including a list of the world's 20 largest recorded earthquakes.

Where can I find a list of the largest earthquakes near my town?

Use our online earthquake catalog to search for past earthquakes in your region. Define your search area by drawing a rectangle on a map or by inputting data for a rectangle or circle. Go to our Earthquake Information by Region website and scroll down to find information about earthquakes in each state.

Which country has the most earthquakes?

The answer to this question is not as straightforward as it may seem. In order to most accurately answer it, we will rephrase the question four different ways: For which country do we locate the most earthquakes? Japan. The whole country is in a very active seismic area, and they have the densest seismic network in the world, so they are able to...