FAQs by Category

Earthquake Myths

• Can you predict earthquakes?
• Can animals predict earthquakes?
• Why are we having so many earthquakes? Has naturally occurring earthquake activity been increasing? Does this mean a big one is going to hit? OR We haven't had any earthquakes in a long time; does this mean that the pressure is building up for a big one?
• Can "MegaQuakes" really happen? Like a magnitude 10 or larger?
• Can some people sense that an earthquake is about to happen (earthquake sensitives)?
• Can the ground open up during an earthquake?
• Will California eventually fall into the ocean?
• Is there earthquake weather?
• Can large amounts of rain in California cause an increase in earthquakes?
• Do solar flares or magnetic storms (space weather) cause earthquakes?
• Are earthquakes associated with variations in the geomagnetic field?
• What is the "Triangle of Life" and is it legitimate?

Earthquakes and Plate Tectonics

• What is an earthquake and what causes them to happen?
• Can we cause earthquakes? Is there any way to prevent earthquakes?
• Foreshocks, aftershocks - what's the difference?
• What is the difference between aftershocks and swarms?
• Why do earthquakes occur in the middle of the continent far from plate boundaries?
• Can the position of the moon or the planets affect seismicity? Are there more earthquakes in the morning/in the evening/at a certain time of the month?
• What is surface faulting or surface rupture in an earthquake?
• At what depth do earthquakes occur? What is the significance of the depth?
• Why are there so many earthquakes in the Geysers area in Northern California?
• Do earthquakes occur in Antarctica?
• What is a hotspot and how do you know it's there?
• Where can I find earthquake educational materials?

Latest Earthquakes

• Where can I find current earthquake lists and maps for the world or for a specific area?
• Did I feel an earthquake? Can I report feeling an earthquake?
• Why is the earthquake that was reported/recorded by network X, or that I felt, not on the map/list?
• Why do some earthquakes disappear from the map/list?
• What is UTC, and why do you report earthquakes in UTC?
• Why isn't the fault the earthquake occurred on or the distance to the nearest fault provided?
• Can I get on a list to receive an email message when there is an earthquake? How do I sign up for earthquake notifications? Are there any Feeds I can subscribe to?
• Why/When does the USGS update the magnitude of an earthquake?
• Why do so many earthquakes occur at a depth of 10km?
• How quickly does the earthquake information get posted to the web site, get sent out via the Earthquake Notification Service (ENS), ATOM feeds, etc?
• Where can I see current or past seismograms?
• Why do USGS earthquakes magnitudes differ from those published by other agencies?
• How do you determine the place name for an earthquake?
• Does the Latest Earthquakes map show non-earthquake seismic events?
• How do I sign up for the ShakeAlert® Earthquake Early Warning System?

Measuring Earthquakes ...magnitudes, locations, seismometers, seismic waves

• How are earthquakes recorded? How are earthquakes measured? How is the magnitude of an earthquake determined?
• Moment magnitude, Richter scale - what are the different magnitude scales, and why are there so many?
• What is the difference between earthquake magnitude and earthquake intensity? What is the Modified Mercalli Intensity Scale?
• How do you determine the magnitude for an earthquake that occurred prior to the creation of the magnitude scale?
• How do seismologists locate an earthquake?
• What was the duration of the earthquake? Why don't you report the duration of each earthquake? How does the duration affect the magnitude?
• How can an earthquake have a negative magnitude?
• What does it mean that the earthquake occurred at a depth of 0 km? How can an earthquake have a negative depth; that would mean it’s in the air. What is the geoid, and what does it have to do with earthquake depth?
• Seismometers, seismographs, seismograms - what's the difference? How do they work?
• How can I make my own seismometer?
• When was the first instrument that actually recorded an earthquake?
• What reference datum is used for earthquake depths?
• What is a Geoid? Why do they use the geoid, and where does its shape come from?

Earthquake Hazards ...maps, probabilities, and earthquake engineering

• What is the probability that an earthquake is a foreshock to a larger earthquake?
• What is the difference between earthquake early warning, earthquake forecasts, earthquake probabilities, and earthquake prediction?
• What is a seismic zone, or seismic hazard zone?
• What is seismic hazard? What is a seismic hazard map? How are they made? How are they used? Why are there different maps, and which one should I use?
• What are the earthquake hazards/risks where I live?
• How will my house hold up in an earthquake? Can the USGS send someone out to evaluate my property?
• How do I decide whether or not to get earthquake insurance?
• How do earthquakes affect buildings?
• What is the likelihood of a large earthquake at location X? Is it safe to go to X since they've been having a lot of earthquakes lately?
• What is the probability that an earthquake will occur in the Los Angeles Area? the San Francisco Bay area?
• What is the probability that an earthquake is a foreshock to a larger earthquake?
• Can the National Seismic Hazard Maps be used as an earthquake forecast tool for the near future?
• How do I get earthquake hazard maps for locations outside of the US?
• How are engineers working to make roads and buildings safer?
• What is the USGS doing to mitigate and respond to earthquake hazards?

Earthquake Effects and Experiences

• At what magnitude does damage begin to occur in an earthquake?
• What does an earthquake feel like?
• What are Tsunamis?
• What is it about an earthquake that causes a tsunami?
• What are those booms I sometimes hear before or during an earthquake?
• How does the USGS tell the difference between an earthquake and a sonic boom?
• Why do earthquakes in other countries seem to cause more damage and casualties than earthquakes in the U.S.?
• Can a large earthquake trigger earthquakes in distant locations or on other faults?
• How can an earthquake effect groundwater or changes in wells?
• Where can I find photographs of earthquake damage?
• What is liquefaction?
• Can you feel an earthquake if you're in a cave? Is it safer to be in a cave during an earthquake?
• What are earthquake lights?

Induced Earthquakes

• Does fracking cause earthquakes?
• Do all wastewater disposal wells induce earthquakes?
• Is it possible to anticipate whether a planned wastewater disposal activity will trigger earthquakes that are large enough to be of concern?
• How does the injection of fluid at depth cause earthquakes?
• How large are the earthquakes induced by fluid injection?
• Are earthquakes induced by fluid-injection activities always located close to the point of injection?
• 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?
• Does the production of oil and gas from shales cause earthquakes? If so, how are the earthquakes related to these operations?
• Oklahoma has had a surge of earthquakes since 2009? Are they due to fracking?

Historical Earthquakes and Statistics

• Where can I find a list of yearly estimated deaths from earthquakes around the world?
• Which States have the smallest number of earthquakes? Is there any place in the world that doesn't have earthquakes?
• Where do earthquakes occur?
• Where can I find a list of the largest earthquakes in the United States? in the World?
• Where can I find a list of the largest earthquakes near my town?
• Which Country has the most earthquakes?
• Which State has the most damaging earthquakes? Which State has the most natural earthquakes (not human-induced)?
• Where can I search an earthquake catalog for past events?

Faults

• What is a fault and what are the different types?
• What is the relationship between faults and earthquakes? What happens to a fault when an earthquake occurs?
• What is a "Quaternary" fault?
• Where can I find a fault map of the US? Is one available in GIS format?
• How do I find the nearest fault to a property or specific location?
• How do I find fault or hazard maps for California?
• Why are there no faults in the Great Valley of central California?
• Why are there so many earthquakes and faults in the Western United States?
• Where are the faults in the Central and Eastern U.S.?
• Why are there so many faults in the Quaternary Faults Database with the same name?

Earthquake Preparedness

• What can I do to be prepared for an earthquake?
• What emergency supplies do I need for an earthquake?
• What should I do DURING an earthquake?
• Things NOT to do during an earthquake?
• What do I do AFTER an earthquake?
• What can I expect in my house when an earthquake occurs? How do I identify it? What can be done?
• Why should people in the eastern U.S. be concerned about earthquakes?
• What are the Great ShakeOut earthquake drills?
• What is the "Triangle of Life" and is it legitimate?

Earthquakes and Volcanoes

• Why are there so many earthquakes at Yellowstone?
• When will the next large earthquake occur in Yellowstone?
• Are there earthquakes associated with Mount Hood?
• Can earthquakes trigger volcanic eruptions?
• Do earthquakes large enough to collapse buildings and roads accompany volcanic eruptions?

Nuclear Explosions and Seismology

• Can nuclear explosions cause earthquakes?
• How can you tell the difference between an explosion and an earthquake on a seismogram?
• Can we use a lot of explosives to cause small earthquakes in order to prevent having large ones?
• What is the Comprehensive Test Ban Treaty (CTBT), and what is the role of seismology in monitoring it?