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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 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...
Image: Bakken Oil Well
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 (...
Research has identified 17 areas in the central and eastern United States with increased rates of induced seismicity.
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
cartoon for fluid injection and withdrawal
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
Epicenter of the Oklahoma 5.6 earthquake on Sept 3, 2016
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...
Oil production and wastewater disposal
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...
Image: Wastewater Disposal Facility in Colorado
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...
Oil and Gas Wastewater Disposal Facility in West Virginia
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...
Earthquake Catalog Map Results Example
You might be able to find what you’re looking for using our collection of Earthquake Lists, so check that first. If that doesn’t work, use one of these Earthquake Catalog Search webpages: World-wide Earthquakes Catalog (M4.5+ worldwide, M2.5+ U.S.) Historic ANSS (Advanced National Seismic System) Composite Catalog (M4.5+ world-wide, all magnitudes...
Image: Northridge, CA Earthquake Damage
California has more earthquakes that cause damage than any other state. Alaska and California have the most earthquakes (not human-induced). Learn more: Earthquake Information by Region (scroll down for individual states)