Earthquake Hazards

FAQ

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...

Which state has the most damaging earthquakes? The most natural (non-manmade) earthquakes?

California has the most damaging earthquakes, and Alaska and California have the most natural (non-manmade) earthquakes. Find information about earthquakes in each state on our Earthquake Information by Region website (scroll down).

Where can I search an earthquake catalog for past events?

You may be able to find what you’re looking for using our collection of Earthquake Lists , so check that first. If that doesn’t work, you can use one of these Earthquake Catalog Search webpages: Search the World-wide Earthquakes Catalog (M4.5+ worldwide, M2.5+ U.S.) Search the Historic ANSS (Advanced National Seismic System) Composite Catalog (M4...

What is a fault and what are the different types?

A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake - or may occur slowly, in the form of creep . Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated...

What is the relationship between faults and earthquakes? What happens to a fault when an earthquake occurs?

Earthquakes occur on faults - strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults , and thrust earthquakes occur on thrust or reverse faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. The fault surface can be vertical, horizontal,...

What is a "Quaternary" fault?

A Quaternary fault is one that has been recognized at the surface and that has moved in the past 1,600,000 years, a portion of the Quaternary epoch.

Where can I find a fault map of the United States? Is one available in GIS format?

An online map of U.S. Quaternary faults (faults that have been active in the last 1.6 million years) is available via the Quaternary Fault and Fold Database . There is an interactive map application to view the faults online and a seperate database search function. KML (Google Earth-type) files and GIS shape files are also available for download...

How do I find the nearest fault to a property or specific location?

If you are looking for faults in California use: How Close to a Fault Do You Live? (Bay Area Earthquake Alliance) For faults in California and the rest of the United States (as well as the latest earthquakes) use the Latest Earthquakes Map : click on the "gear" icon in the upper-right corner scroll down to Map Layers, and turn on U.S. Faults mouse...

How do I find fault or hazard maps for California?

An online map of faults that includes California can be found in the Faults section of the Earthquake Hazards Program website. Choose the Interactive Fault Map, or download KML files and GIS shapefiles from the links on the page. USGS seismic hazard maps, data and tools for California and other parts of the United States can be found in the...

Why are there no faults in the Great Valley of central California?

The Great Valley is a basin, initially forming ~100 million years ago as a low area between the subducting ocean plate on the west (diving down under the North American plate) and the volcanoes to the east (now the Sierra Nevada mountains). Since its formation, the Great Valley has continued to be low in elevation. Starting about 20 million years...

Why are there so many earthquakes and faults in the Western United States?

This region of the United States has been tectonically active since the supercontinent Pangea broke up roughly 200 million years ago, and in large part because it is close to the western boundary of the North American plate. Since the formation of the San Andreas Fault system 25-30 million years ago, the juxtaposition of the Pacific and North...

Where are the fault lines in the Eastern United States (east of the Rocky Mountains)?

Faults are different from fault lines. A fault is a three-dimensional surface within the planet Earth. At the fault, rocks have broken. The rocks on one side of the fault have moved past the rocks on the other side. In contrast, a fault line is a line that stretches along the ground. The fault line is where the three-dimensional fault intersects...

Why are there so many faults in the Quaternary Faults Database with the same name?

Many faults are mapped as individual segments across an area. These fault segments are given a different value for name, number, code, or dip direction and so in the database each segment occurs as its own unique entity. For example, the San Andreas Fault has several fault segments, from letters a to h, and fault segment 1h has segments with age...

What can I do to be prepared for an earthquake?

There are four basic steps you can take to be more prepared for an earthquake: Step 1: Secure your space by identifying hazards and securing moveable items. Step 2: Plan to be safe by creating a disaster plan and deciding how you will communicate in an emergency. Step 3: Organize disaster supplies in convenient locations. Step 4: Minimize...

What emergency supplies do I need for an earthquake?

Fire extinguisher Adequate supplies of medications that you or family members are taking Crescent and pipe wrenches to turn off gas and water supplies First-aid kit and handbook Flashlights with extra bulbs and batteries Portable radio with extra batteries Water for each family member for at least two weeks (allow at least 1 gallon per person per...

What should I do DURING an earthquake?

If you are INDOORS -- STAY THERE! Get under a desk or table and hang on to it ( Drop, Cover, and Hold on! ) or move into a hallway or against an inside wall. STAY CLEAR of windows, fireplaces, and heavy furniture or appliances. GET OUT of the kitchen, which is a dangerous place (things can fall on you). DON'T run downstairs or rush outside while...

What should I NOT do during an earthquake?

DO NOT turn on the gas again if you turned it off; let the gas company do it DO NOT use matches, lighters, camp stoves or barbecues, electrical equipment, appliances UNTIL you are sure there are no gas leaks. They may create a spark that could ignite leaking gas and cause an explosion and fire DO NOT use your telephone, EXCEPT for a medical or...

What do I do AFTER an earthquake?

WEAR STURDY SHOES to avoid injury from broken glass and debris. Expect aftershocks CHECK FOR INJURIES If a person is bleeding, put direct pressure on the wound, use clean gauze or cloth if available If a person is not breathing administer CPR DO NOT attempt to move seriously injured persons unless they are in further danger of injury COVER injured...

What can I expect in my house when an earthquake occurs? How do I identify it? What can be done?

The contents of your home may be damaged and can be dangerous: Shaking can make light fixtures fall, refrigerators and other large items move across the floor, and bookcases and television sets topple over. IDENTIFY: Look around your house for things that could fall or move. Ask yourself if your cupboard doors could fly open (allowing dishes to...