Natural Hazards
How do volcanoes erupt?
Can you predict earthquakes?
Does the USGS conduct studies on wildfire?
What is a landslide and what causes one?
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.
What do I do AFTER an earthquake? 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 persons with blankets to keep warm SEEK medical...
What is the "Triangle of Life" and is it legitimate? What is the "Triangle of Life" and is it legitimate?
The "Triangle of Life" is a misguided idea about the best location a person should try to occupy during an earthquake. Based on observations of an earthquake in Turkey, the idea doesn't apply to buildings constructed within the United States. Drop, cover, and hold under a table or desk is still the best recommendation, according to the American Red Cross. Learn more: American Red Cross -...
What can I do to be prepared for an earthquake? 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 financial hardship by organizing important documents...
What emergency supplies do I need for an earthquake? 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 day) and purification tablets or chlorine bleach to...
What should I do DURING an earthquake? 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 the building is shaking or while there is danger of...
What should I NOT do during an earthquake? 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 fire emergency. You could tie up the lines needed for...
How can I make my own seismometer? How can I make my own seismometer?
It is relatively easy to acquire the necessary materials and build your own seismometer. The links here are to various sources with information on how to build a seismometer. They range from very simple and inexpensive to sophisticated and pricey. Model Seismograph - Classroom Demonstration Build your own Seismograph Station Build Your Own Seismograph Amateur Seismology Homebuilt Seismograph FAQ
Seismometers, seismographs, seismograms - what's the difference? How do they work? Seismometers, seismographs, seismograms - what's the difference? How do they work?
A seismometer is the internal part of the seismograph, which may be a pendulum or a mass mounted on a spring; however, it is often used synonymously with "seismograph". Seismographs are instruments used to record the motion of the ground during an earthquake. They are installed in the ground throughout the world and operated as part of a seismographic network. The earliest "seismoscope" was...
What was the first instrument that actually recorded an earthquake? What was the first instrument that actually recorded an earthquake?
The earliest seismoscope was invented by the Chinese philosopher Chang Heng in A.D. 132. This was a large urn on the outside of which were eight dragon heads facing the eight principal directions of the compass. Below each dragon head was a toad with its mouth opened toward the dragon. When an earthquake occurred, one or more of the eight dragon-mouths would release a ball into the open mouth of...
How can an earthquake have a negative magnitude? How can an earthquake have a negative magnitude?
Magnitude calculations are based on a logarithmic scale, so a ten-fold drop in amplitude decreases the magnitude by 1. If an amplitude of 20 millimetres as measured on a seismic signal corresponds to a magnitude 2 earthquake, then: 10 times less (2 millimetres) corresponds to a magnitude of 1; 100 times less (0.2 millimetres) corresponds to magnitude 0; 1000 times less (0.02 millimetres)...
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? 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?
An earthquake cannot physically occur at a depth of 0 km or -1km (above the surface of the earth). In order for an earthquake to occur, two blocks of crust must slip past one another, and it is impossible for this to happen at or above the surface of the earth. So why do we report that the earthquake occurred at a depth of 0 km or event as a negative depth sometimes? First of all, the depth of an...
What was the duration of the earthquake? Why don't you report the duration of each earthquake? How does the duration affect the magnitude? What was the duration of the earthquake? Why don't you report the duration of each earthquake? How does the duration affect the magnitude?
The duration of an earthquake is related to its magnitude but not in a perfectly strict sense. There are two ways to think about the duration of an earthquake. The first is the length of time it takes for the fault to rupture and the second is the length of time shaking is felt at any given point (e.g. when someone says "I felt it shake for 10 seconds" they are making a statement about the...