Earthquake Hazards Program

FAQ

Have questions? The answer is probably here!

Where are the faults in the Central and Eastern U.S.?

Faults vs. Fault Lines on a Map In order to answer this question, we first need to explain some basics about faults. Faults are different from fault lines. A fault is a three-dimensional surface within the planet that might extend up to the surface or might be completely buried. In contrast, a fault line is where the fault cuts the Earth's surface...

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...

Why should people in the eastern United States be concerned about earthquakes?

1) Severe earthquakes have occurred in the eastern U.S.: In November of 1755, an earthquake with an estimated magnitude of 6.0 and a maximum intensity of VIII occurred about 50 miles northeast of Boston, Massachusetts. Boston was heavily damaged. Other strong earthquakes recorded in the continental US were centered in southeastern Missouri near...

What are the Great ShakeOut earthquake drills?

ShakeOut GIF ShakeOut GIF showing what to do in an earthquake if you are near a sturdy desk or table. (Public domain.) The Great ShakeOut earthquake drills are based on scenario earthquakes that could effect the area if they were to actually take place. Great ShakeOut Earthquake Drills are an...

Why are there so many earthquakes at Yellowstone?

Almost all earthquakes at Yellowstone are brittle-failure events caused when rocks break due to crustal stresses. Though we've been looking at Yellowstone for years, no one has yet identified "long-period (LP) events" commonly attributed to magma movement. If LP events are observed, that will NOT mean Yellowstone is getting ready to erupt. LP...

When will the next large earthquake occur in Yellowstone?

Earthquakes cannot be predicted yet, but modern surveillance conducted with seismographs (instruments that measure earthquake locations and magnitudes) and Global Positioning System (GPS) instruments that measure slow ground movements help scientists understand the state of stress in the Earth's crust. Those stresses could trigger earthquakes as...

Are there earthquakes associated with Mount Hood?

Felt earthquakes on Mount Hood (Oregon) occur every two years on average. Seismic monitoring , in effect since 1977, indicates a generalized concentration of earthquakes just south of the summit area and 2-7 kilometers below sea level. A seismic swarm in July 1980, during which nearly 60 earthquakes (mostly 5-6 kilometers deep with a maximum...

Can earthquakes trigger volcanic eruptions?

Sometimes, yes. A few large regional earthquakes (greater than magnitude 6) are considered to be related to a subsequent eruption or to some type of unrest at a nearby volcano. However, volcanoes can only be triggered into eruption by nearby tectonic earthquakes if they are already poised to erupt . This requires two conditions to be met: Enough "...

Do earthquakes large enough to collapse buildings and roads accompany volcanic eruptions?

Not usually. Earthquakes associated with eruptions rarely exceed magnitude 5, and these moderate earthquakes are not big enough to destroy buildings and roads. The largest earthquakes at Mount St. Helens in 1980 were magnitude 5, large enough to sway trees and damage buildings, but not destroy them. During the huge eruption of Mount Pinatubo in...

Can nuclear explosions cause earthquakes?

A nuclear explosion can cause an earthquake and even an aftershock sequence. However, earthquakes induced by explosions have been much smaller than the explosion, and the aftershock sequence produces fewer and smaller aftershocks than a similar size earthquake. Not all explosions have caused earthquakes. The range of a possible earthquake...

How can you tell the difference between an explosion and an earthquake on a seismogram?

Explosions and earthquakes both release a large amount of energy very quickly, and both can be recorded by seismic instruments. However, because the forces involved in each are very different, the waveforms that each creates look different. Nuclear tests are very near the surface of the earth; all of the energy is released from a small volume...

Can we use explosives to cause small earthquakes in order to prevent having large ones?

No. Even huge amounts of explosive almost never cause even small earthquakes, and it would take hundreds and thousands of small earthquakes to equal a large one, even if it could be done. In addition, we wouldn't have any control over the size of the earthquake being created if it worked, since small and large earthquakes all start out in exactly...

What is the Comprehensive Test Ban Treaty (CTBT), and what is the role of seismology in monitoring it?

On September 10, 1996, the United Nations General Assembly voted 158-3 to approve a treaty prohibiting all nuclear tests. The Comprehensive Test Ban Treaty has been signed by 130 nations - including the United States. President Clinton signed the agreement on September 24, 1996. Seismology is one of several fields which plays a role in monitoring...