Frequently Asked Questions

Natural Hazards

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.

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Scenery: Valley surrounded by forested mountains. Multiple wisps of steam rise from the valley floor at various locations.
Geothermal energy (heat energy from the Earth's interior), is used to generate electricity in a variety of places throughout the world. Although Yellowstone National Park and its surroundings are a significant geothermal resource, the Park itself is off limits to development. Geothermal developments often cause a decrease in the flow of nearby hot...
Big Sur landslide on May 20, 2017 showing material across Highway 1.
An advisory is a general statement about the potential of landslide activity in a given region relative to developing rainfall predictions. An advisory may include general statements about rainfall conditions that can lead to debris-flow activity, and list precautions to be taken in the event of heavy rainfall. A watch means that landslide-...
Image: 2008 Landslide Near Hongyan Resort, China
An average of 25-50 people are killed by landslides each year in the United States. The worldwide death toll per year due to landslides is in the thousands. Most landslide fatalities are from rock falls, debris flows, or volcanic debris flows (called lahars). Twenty-three people were killed, at least 167 injured, and more than 400 homes were...
Image: Landslide
Yes, in some cases human activities can be a contributing factor in causing landslides. Many human-caused landslides can be avoided or mitigated. They are commonly a result of building roads and structures without adequate grading of slopes, poorly planned alteration of drainage patterns, and disturbing old landslides. Detailed on-site...
Image: Landslide Sampling
Landslides are a serious geologic hazard common to almost every State in the United States. As people move into new areas of hilly or mountainous terrain, it is important to understand the nature of their potential exposure to landslide hazards, and how cities, towns, and counties can plan for land-use, engineering of new construction and...
Image: 2005 Landslide in Conchita, CA
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further...
Magnitude 6.9 Earthquake off Japan on November 21, 2016
Magnitude estimates for a given earthquake can vary between reporting agencies due to differences in methodology, data availability, and inherent uncertainties in seismic data. Individual agencies use magnitude estimation procedures designed to meet the agency's specific needs and monitoring capabilities. Even for well-recorded events, differences...
Image: Seismographs at the U.S. Geological Survey
The USGS Earthquake Hazards Program has helicorders (seismogram displays) available for several areas in the United States and the World. Our research partner IRIS (Incorporated Research Institutions for Seismology) has two applications, the Station Monitor and the Global Seismogram Viewer, for viewing seismograms. IRIS also supplies software that...
Image for real-time earthquake data
USGS earthquake information mechanisms are all triggered by the same system, so they all receive the information at the same time. The time it takes for the system to receive the information primarily depends on the size and location of the earthquake: An earthquake in California is processed and posted to the system in 2.5 minutes (on average)....
Crop of OK earthquake
Ten kilometers is a "fixed depth". Sometimes data are too poor to compute a reliable depth for an earthquake. In such cases, the depth is assigned to be 10 km. Why that number? In many areas around the world, reliable depths tend to average 10 km or close to it. For example, if we made a histogram of the reliable depths in such an area, we'd...
Image: Installing Antenna and Solar Panel for Seismic Station
The USGS often updates an earthquake's magnitude in the hours and sometimes days following the event. Updates occur as more data become available for analysis and more time-intensive analysis is performed. Additional updates are possible as part of the standard procedure of assembling a final earthquake catalog. There are physical and operational...
Screenshot of earthquake notification webpage
Yes, please go to the USGS Earthquake Notification Services (ENS) to sign up for free emails or text messages to your phone. Use the default settings or customize ENS to fit your needs. Also check out the many different Earthquake Feeds.