Earthquake Preparedness Guide: How To Stay Safe and Survive
One hundred thousand earthquakes happen on average around the world every month. Not all cause damage, but it only takes one strong earthquake to kill or injure thousands of people and cause millions of dollars of damage. There is usually at least one strong quake per year somewhere around the globe. For the unprepared, the consequences can be devastating.
Are you ready for an earthquake? Are you prepared for the disruption in common services including fresh water, electricity, and healthcare? Do you have a plan and supplies to survive on your own until help arrives or services are restored?
You can protect your family and reduce damage to your property by taking action now. This guide explains how to prepare for a earthquake, answers frequently asked questions about earthquakes, provides a link to the Earthquake Notification Service, and includes a list of resources related to earthquake preparedness and hazards. Continue reading below to learn the important steps you can take to prepare for an earthquake.
- Basic Earthquake Information
- Earthquake Preparedness
- Frequently Asked Questions
- What is the definition of an earthquake?
- What causes most earthquakes?
- Where are earthquakes most likely to occur?
- How many earthquakes happen each year?
- Ho many earthquakes happen every month? Day? Minute?
- How deep do earthquakes occur in the world?
- Where do most earthquakes occur in the world?
- Where do most earthquakes occur in the United States?
- Where did the largest known earthquake occur?
- What was the largest earthquake in the United States?
- Where was the largest earthquake in the continental United States?
- It seems that large earthquakes in the U.S. are responsible for relatively few deaths. Is this true around the world?
- What was the greatest number of people killed in one earthquake?
- How are earthquakes measured?
- What does the Richter scale look like?
- When was the first intrument for detecting earthquakes invented?
- What is the difference between and earthquake prediction and a forecast?
- Does animal behavior change before an earthquake?
- Does the ground really open up and swallow people?
- Do earthquakes cause volcanoes?
- Are earthquakes weather related?
- What are earthquake scientists called?
- How much energy is released in an earthquake?
- Do all large magnitude earthquakes result in great amounts of death and destruction?
- Can earthquakes be prevented?
- Earthquake Notification Service
- Links and Resources for Earthquake Hazards and Preparedness
Earthquakes are the shaking, rolling or sudden shock of the earth’s surface. Earthquakes are caused by the breaking and shifting of rock beneath the earth’s surface along "fault lines" in the earth’s crust. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted -- although scientists are working on it!
Most of the time, you will notice an earthquake by the gentle shaking of the ground. You may notice hanging plants swaying or objects wobbling on shelves. Sometimes you may hear a low rumbling noise or feel a sharp jolt. A survivor of the 1906 earthquake in San Francisco said the sensation was like riding a bicycle down a long flight of stairs.
One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible after effects. Earthquakes can cause buildings and bridges to collapse, telephone and power lines to fall, and result in fires, explosions and landslides. Earthquakes can also cause huge ocean waves, called tsunamis, which travel long distances over water until they crash into coastal areas.
Earthquakes strike suddenly, violently, and without warning at any time of the day or night. If an earthquake occurs in a populated area, it may cause many deaths and injuries and extensive property damage.
The intensity of an earthquake can be measured. One measurement is called the Richter scale. Earthquakes below 4.0 on the Richter scale usually do not cause damage, and earthquakes below 2.0 usually can’t be felt. Earthquakes over 5.0 on the scale can cause damage. A magnitude 6.0 earthquake is considered strong and a magnitude 7.0 is a major earthquake. The Northridge Earthquake, which hit Southern California in 1994, was magnitude 6.7.
Although there are no guarantees of safety during an earthquake, identifying potential hazards ahead of time and advance planning can save lives and significantly reduce injuries and property damage. The following information includes general guidelines for earthquake preparedness and safety. Because injury prevention techniques may vary from state to state, it is recommended that you contact your local emergency management office, health department, or American Red Cross chapter.
WHAT TO DO BEFORE AN EARTHQUAKE
1.Know the terms associated with earthquakes.
- Earthquake—a sudden slipping or movement of a portion of the earth’s crust, accompanied and followed by a series of vibrations.
- Aftershock—an earthquake of similar or lesser intensity that follows the main earthquake.
- Fault—the earth’s crust slips along a fault—an area of weakness where two sections of crust have separated. The crust may only move a few inches to a few feet in a severe earthquake.
- Epicenter—the area of the earth’s surface directly above the origin of an earthquake.
- Seismic Waves—are vibrations that travel outward from the center of the earthquake at speeds of several miles per second. These vibrations can shake some buildings so rapidly that they collapse.
- Magnitude—indicates how much energy was released. This energy can be measured on a recording device and graphically displayed through lines on a Richter Scale. A magnitude of 7.0 on the Richter Scale would indicate a very strong earthquake. Each whole number on the scale represents an increase of about 30 times the energy released. Therefore, an earthquake measuring 6.0 is about 30 times more powerful than one measuring 5.0.
2. Look for items in your home that could become a hazard in an earthquake:
- Repair defective electrical wiring, leaky gas lines, and inflexible utility connections.
- Bolt down water heaters and gas appliances (have an automatic gas shut-off device installed that is triggered by an earthquake).
- Place large or heavy objects on lower shelves. Fasten shelves to walls. Brace high and top-heavy objects.
- Store bottled foods, glass, china and other breakables on low shelves or in cabinets that can fasten shut.
- Anchor overhead lighting fixtures.
- Check and repair deep plaster cracks in ceilings and foundations. Get expert advice, especially if there are signs of structural defects.
- Be sure the residence is firmly anchored to its foundation.
- Install flexible pipe fittings to avoid gas or water leaks. Flexible fittings are more resistant to breakage.
3. Know where and how to shut off electricity, gas and water at main switches and valves. Check with your local utilities for instructions.
4. Hold earthquake drills with your household:
- Locate safe spots in each room under a sturdy table or against an inside wall. Reinforce this information by physically placing yourself and your household in these locations.
- Identify danger zones in each room—near windows where glass can shatter, bookcases or furniture that can fall over, or under ceiling fixtures that could fall down.
5. Develop a plan for reuniting your household after an earthquake. Establish an out-of-town telephone contact for household members to call to let others know that they are okay.
6. Review your insurance policies. Some damage may be covered even without specific earthquake insurance. Protect important home and business papers.
7. Prepare to survive on your own for at least three days.
- Assemble a disaster supply kit.
- Keep a stock of food and extra drinking water.
- See our disaster preparation overview guide for more details on what to include in your disaster supply kit as well as information about evacuation.
WHAT TO DO DURING AN EARTHQUAKE
1. Drop, Cover and Hold On!
- Minimize your movements during an earthquake to a few steps to a nearby safe place.
- Stay indoors until the shaking has stopped and you are sure exiting is safe.
- If you are indoors, take cover under a sturdy desk, table or bench, or against an inside wall, and hold on.
- Stay away from glass, windows, outside doors or walls and anything that could fall, such as lighting fixtures or furniture.
- If you are in bed, stay there, hold on and protect your head with a pillow, unless you are under a heavy light fixture that could fall.
- If there isn’t a table or desk near you, cover your face and head with your arms and crouch in an inside corner of the building.
- Doorways should only be used for shelter if they are in close proximity to you and if you know that it is a strongly supported load-bearing doorway.
- If you are outdoors, stay there. Move away from buildings, streetlights and utility wires.
2. If you live in an apartment building or other multi-household structure with many levels, consider the following:
- Get under a desk and stay away from windows and outside walls.
- Stay in the building (many injuries occur as people flee a building and are struck by falling debris from above).
- Be aware that the electricity may go out and sprinkler systems may come on.
- DO NOT use the elevators.
3. If you are in a crowded indoor public location:
- Stay where you are. Do not rush for the doorways.
- Move away from tall shelves, cabinets and bookcases containing objects that may fall.
- Take cover and grab something to shield your head and face from falling debris and glass.
- Be aware that the electricity may go out or the sprinkler systems or fire alarms may turn on.
- DO NOT use elevators.
4. In a moving vehicle:
- Stop as quickly as safety permits, and stay in the vehicle.
- Avoid stopping near or under buildings, trees, overpasses or utility wires.
- Then, proceed cautiously, watching for road and bridge damage.
5. If you become trapped in debris:
- Do not light a match.
- Do not move about or kick up dust.
- Cover your mouth with a handkerchief or clothing.
- Tap on a pipe or wall so rescuers can locate you. Use a whistle if one is available. Shout only as a last resort—shouting can cause you to inhale dangerous amounts of dust.
6. Stay indoors until the shaking has stopped and you are sure exiting is safe. Most injuries during earthquakes occur when people are hit by falling objects when entering or exiting buildings.
WHAT TO DO AFTER AN EARTHQUAKE
1. Be prepared for aftershocks. These secondary shock waves are usually less violent than the main quake but can be strong enough to do additional damage to weakened structures.
2. Check for injuries.
- Do not attempt to move seriously injured persons unless they are in immediate danger of death or further injury.
- If you must move an unconscious person, first stabilize the neck and back, then call for help immediately.
- If the victim is not breathing, carefully position the victim for artificial respiration, clear the airway and start mouth-to-mouth resuscitation.
- Maintain body temperature with blankets. Be sure the victim does not become overheated.
- Never try to feed liquids to an unconscious person.
3. If the electricity goes out, use flashlights or battery powered lanterns. Do not use candles, matches or open flames indoors after the earthquake because of possible gas leaks. Read our guide for keeping food safe during an emergency.
4. Wear sturdy shoes in areas covered with fallen debris and broken glass.
5. Check your home for structural damage. If you have any doubts about safety, have your home inspected by a professional before entering.
6. Check chimneys for visual damage. Have a professional inspect the chimney for internal damage before lighting a fire.
7. Clean up spilled medicines, bleaches, gasoline and other flammable liquids. Evacuate the building if gasoline fumes are detected and the building is not well ventilated.
8. Visually inspect utility lines and appliances for damage.
- If you smell gas or hear a hissing or blowing sound, open a window and leave.
- Shut off the main gas valve.
- Report the leak to the gas company from the nearest working phone or cell phone available.
- Stay out of the building.
- If you shut off the gas supply at the main valve, you will need a professional to turn it back on.
- Switch off electrical power at the main fuse box or circuit breaker if electrical damage is suspected or known.
- Shut off the water supply at the main valve if water pipes are damaged.
- Do not flush toilets until you know that sewage lines are intact.
9. Open cabinets cautiously. Beware of objects that can fall off shelves.
10. Use the phone only to report life-threatening emergencies.
11. Listen to news reports for the latest emergency information.
12. Stay off the streets. If you must go out, watch for fallen objects, downed electrical wires, weakened walls, bridges, roads and sidewalks.
13. Stay away from damaged areas unless your assistance has been specifically requested by police, fire or relief organizations.
14. If you live in coastal areas, be aware of possible tsunamis, sometimes mistakenly called tidal waves. When local authorities issue a tsunami warning, assume that a series of dangerous waves is on the way. Stay away from the beach.
- Q. What is the definition of an earthquake?
- A. An earthquake is the sudden, sometimes violent movement of the earth's surface from the release of energy in the earth's crust.
- Q. What causes most earthquakes?
- A. The crust of the earth when it is subject to tectonic forces, bends slightly. But, because the crust is rigid, when the stress or pressure exceeds the strength of the rocks, the crust breaks and snaps into a new position. Vibrations called seismic waves are generated and travel both through the earth and along its surface. These seismic waves cause the movement we call earthquakes.
- Q. Where are earthquakes likely to occur?
- A. Within areas of the crust are fractures, known as faults, along which two crustal blocks have slipped or moved against each other. One block may move up while the other moves down, or one may move horizontally in one direction and the other in the opposite direction. Geologists and seismologists (scientists who study earthquakes and the processes that create them) have found that earthquakes occur repeatedly at faults, which are zones of weakness in the earth's crust.
- Q. How many earthquakes happen each year?
- A. There are over a million quakes annually, including those too small to be felt. The following table shows the average frequency of different magnitudes:
|DESCRIPTION||MAGNITUDE||FREQUENCY PER YEAR|
|Minor (damage slight)||4.0-4.0||13,000 (estimated)|
|Generally felt||3.0-3.9||130,000 (estimated)|
|Potentially perceptible||2.0-2.9||1,300,000 (estimated)|
|Imperceptible||less than 2.0||Several Million (estimated)|
- Q. How many earthquakes happen every month? Day? Minute?
- A. Using the previous table for magnitude 2.0 and above:
- Per month - approximately 100,000
- Per day - approximately 3,600
- Per minute - approximately 2.5
- Per second - approximately 1 every 24 seconds
Of the hundreds of thousands of earthquakes that happen each month, only a few are capable of causing damage. Earthquakes are common natural events.
- Q. How deep do earthquakes occur in the world?
- A. Earthquakes occur in the crust or upper mantle which ranges from the surface to about 800 kilometers deep (about 500 miles).
- Q. Where do most earthquakes occur in the world?
- A. The surface of the earth is divided like a jigsaw puzzle into giant pieces called tectonic or crustal plates. These giant pieces move slowly over partially melted rock known as the mantle. As they move, they slide along each other, move into each other, move away from each other, or one slips under another. On these active plate boundaries about 95% of all the world's earthquakes occur. California, Alaska, Japan, South America, and the Philippines are all on plate boundaries. Only 5% are in areas of the plates far away from the boundaries. These are called mid-plate or intra-plate earthquakes and are, as yet, poorly understood.
- Q. Where do the most earthquakes occur in the United States ?
- A. Alaska has more earthquakes per year than the combined total of the rest of the United States. As many as 4,000 are recorded there every year. Alaska is on a plate boundary where one plate is sliding along another, known as a subduction zone.
- Q. Where did the largest known earthquake occur?
- A. A magnitude 9.5 earthquake in Chile in 1960 was the largest known earthquake and resulted in over 6,000 deaths. It triggered a tsunami or seismic wave (incorrectly known as a tidal wave) that killed people as far away as Hawaii and Japan. Chile is also on a subduction zone.
- Q. What was the largest earthquake in the United States?
- A. The great Alaska earthquake of March 27, 1964, is the largest earthquake in the United States. It had a magnitude of 9.2. 115 people died, with most of the deaths due to the tsunami it generated. Shaking was felt for an estimated 7 minutes, and raised or lowered the ground surface as much as 2 meters (6.5 feet) in some areas and 17 meters (approx. 56 feet) in others. The length of the ruptured fault was between 500 and 1,000 kilometers (310.5 and 621 miles). The amount of energy released was equal to 12,000 Hiroshima-type blasts, or 240 million tons of TNT.
- Q. Where was the largest earthquake in the continental United States?
- A. A series of four great earthquakes occurred in the central United States on December 16, 1811, and January 23, and February 7, 1812. All had estimated magnitudes greater than 7.5 on the Richter Scale, the largest happening on February 7, 1812. They are collectively known as the New Madrid earthquakes (after a small town in Missouri) and were felt as far away as Washington D.C., and Boston, Massachusetts. These events were felt over a region far greater than any other in the United States, an estimated 2 million square miles. There were fewer than 100 deaths, because of the small number of people living in the area. The earthquakes raised and lowered land levels several feet, created one large lake and several smaller lakes, and formed waterfalls on the Mississippi River. One small town was destroyed and there was extensive damage to structures and changes to land surfaces throughout the region. These earthquakes were far away from a plate boundary, and are the largest known to have happened in a mid-plate area.
- Q. It seems that large earthquakes in the U.S. are responsible for relatively few deaths. Is this true around the world?
- A. No. In other areas of the world smaller earthquakes are responsible for the deaths of many thousands of people. This is primarily because of buildings which are poorly designed and constructed for earthquake regions, and population density. The following table shows some of the major earthquakes around the world in the last twenty years, and the number of deaths associated with them.
|1971||02-09||San Fernando, California||64||6.5|
- Q. What was the greatest number of people killed in one earthquake?
- A. An earthquake in China in 1556 killed approximately 830,000 people.
- Q. How are earthquakes measured?
- A. A seismometer is an instrument that senses the earth's motion; a seismograph combines a seismometer with recording equipment to obtain a permanent record of the motion. From this record scientists can calculate how much energy was released in an earthquake, which is one way to decide its magnitude. Calculations are made from several different seismograms, both close to and far from an earthquake source to determine its magnitude. Calculations from various seismic stations and seismographs should give the same magnitude, with only one magnitude for any given earthquake.
Richter Magnitude is the scale most people are familiar with, but scientists use other more accurate scales. Another nonscientific way of measuring earthquakes is by their intensity or degree of shaking. Intensity is descriptive, and is determined by inspection of damage and other effects, with the greatest intensity being close to the epicenter, and smaller intensities further away. The Modified Mercalli Intensity Scale uses Roman Numerals from I to XII to describe different earthquake effects is commonly used.
- Q. What does the richter scale look like?
- A. The Richter Scale is not an actual instrument. It is a measure of the amplitude of seismic waves and is related to the amount of energy released. This can be estimated from the recordings of an earthquake on a seismograph. The scale is logarithmic, which means that each whole number on the scale increases by 10. A magnitude 6.0 earthquake is 10 times greater than a 5.0, a 7.0 is 100 times greater, and a magnitude 8.0 is 1,000 times greater.
- Q. When was the first instrument for detecting earthquakes invented?
- A. The earliest known earthquake detection instrument was invented in 132 A.D. by Zhang Heng, a Chinese philosopher. The instrument was a large (2 meters or 6.5 feet in diameter) bronze jar, with a central pendulum inside. Decorating the jar on the outside were a series of dragon heads connected to a pendulum, each with a ball in a hinged mouth. Directly beneath each dragon head, on the surface of the stand, was a bronze toad, head up, mouth open to receive a ball from the dragon's mouth.
During an earthquake, the ground motion would move the pendulum and cause one or more balls to fall from a dragon's mouth into a toad's mouth. The direction of the earthquake was indicated by which of the dragon heads had dropped a ball. This instrument was sensitive enough to perceive shaking too small to be felt, as it detected an earthquake over 600 kilometers (372 miles) away, news of which arrived several weeks later. Earthquake detectors are mentioned later in oriental manuscripts, but in the west earthquake detection instruments did not emerge until centuries later.
- Q. What is the difference between an earthquake prediction and a forecast?
- A. An earthquake prediction involves assigning a specific date, location, and magnitude for an earthquake. A forecast assigns a series of probabilities and a range of years and magnitudes to a region. There is no way to accurately predict earthquakes, but forecasts have been calculated for different areas of the United States. The earthquake in northern California on October 17, 1989 was not predicted, but did fall within the magnitude range, time span, and region forecast by U.S. Geological Survey staff.
- Q. Does animal behavior change before earthquakes?
- A. Changes in animal behavior before earthquakes have been observed and documented in different parts of the world, most recently in the northern California earthquake of October 17, 1989. It has been recorded that a fish in a high school biology lab in California would flip on its side before some earthquakes.
Dogs, cats, snakes, and horses has also been known to behave strangely before earthquakes. Since behavior is not earthquake specific, change in animal behavior can therefore result from other events, and it is impossible to determine beforehand what factor has caused the change. Also, the behavior is not consistent. Sometimes earthquakes occur with no previous behavior change.
- Q. Does the ground really open up and swallow people?
- A.This is an earthquake myth. Cracks and fissures appearing in the ground are a common effect of earthquakes. Most of these are narrow and shallow. In very large earthquakes changes in the level of the land can result in larger cracks that can cause a lot of damage to buildings, but people and buildings do not get swallowed by the ground.
- 20. Do earthquakes cause volcanoes?
- A. No, there are different earth processes responsible for volcanoes. Earthquakes may occur in an area before, during, and after a volcanic eruption, but they are the result of the active forces connected with the eruption, and not the cause of volcanic activity.
- Q. Are earthquakes weather related?
- A. In the 4th Century B.C., Aristotle proposed that earthquakes were caused by winds trapped in subterranean caves. Small tremors were thought to have been caused by air pushing on the cavern roofs, and large ones by the air breaking the surface. This theory lead to a belief in earthquake weather, that because a large amount of air was trapped underground, the weather would be hot and calm before an earthquake.
A later theory stated that earthquakes occurred in calm, cloudy conditions, and were usually preceded by strong winds, fireballs, and meteors. There is no connection between weather and earthquakes. They are the result of geologic processes within the earth and can happen in any weather and at any time during the year.
- Q. What are earthquake scientists called?
- A. Seismologists: seismos-from the Greek meaning earthquakes, and ologist-meaning a person who studies (something). A seismologist is a person who studies earthquakes and the mechanics of the earth.
- Q. How much energy is released in an earthquake?
- A. Earthquakes release a tremendous amount of energy, which is why they can be so destructive. The table below shows magnitudes with the approximate amount of TNT needed to release the same amount of energy.
|MAGNITUDE||APPROXIMATE TNT ENERGY|
- Q. Do all large magnitude earthquakes result in great amounts of death and destruction?
- A.No.The destructive forces of an earthquake depends on many factors. Large earthquakes commonly occur in remote areas of the world, with no buildings or people, and are not destructive. In addition to magnitude, some of the factors that determine damage and deaths are: population densities, the density and types of building construction, local geologic conditions, distance from the epicenter, earthquake depth, how long the shaking continues, and the degree of earthquake preparedness in the region.
- Q. Can earthquakes be prevented?
- A. There is no known way to prevent earthquakes, but it is possible to lessen the impact. The amount of devastation from an earthquake can be greatly diminished by building structures using earthquake resistant design, making the interiors of buildings safe from falling objects, and educating people about earthquake safety.
(Example of an ENS notification email)
The Earthquake Notification Service (ENS) is a USGS service that sends automated notification emails when earthquakes happen in your area.
New accounts default to receiving notifications about earthquakes with magnitude 6.0 or greater however you can customize ENS to only deliver messages for certain areas, at specified times, and to multiple addresses. ENS can send text notifications to your cell phone. More information about ENS.
Earthquakes are a significant hazard to life and property in many parts of the United States and other parts of the world. We cannot make earthquakes go away, but there is much we can do to reduce the loss of life and property during earthquakes. These references provide earthquake safety information.
- Next Big Earthquake In the Bay Area
- Putting Down Roots in Earthquake Country
- FEMA Earthquake Safety Information
- Red Cross Earthquake Preparedness
- California Office of Emergency Services (OES)
- California Earthquake Preparedness
- California Seismic Safety Commission
- California Geological Survey
- California Seismic Hazard Zoning Program
- USGS Preparedness Links
- USGS Hazards Fact Sheets
- National Seismic Hazards Maps
- Potential for Large Earthquakes in Northern California
- Predictive Intensity Maps
- California Earthquake Resilience Program
- Earthquakes in Alaska
- Seismic Safety of Buildings: Existing Buildings
- Seismic Safety of Buildings: New Buildings
- Seismic Safety of Lifelines
- Comparison of model building codes and NEHRP recommended provisions