Why isn't the fault on which the earthquake occurred or the distance to the nearest fault provided?
Seismologists evaluate the hypocenter location and the focal mechanism of an earthquake to decide if the earthquake occurs on a named fault. Research shows that many earthquakes occur on small, un-named faults located near well-known faults. For example, most of the aftershocks of the 1989 M6.9 Loma Prieta earthquake occurred on small, subsidiary faults within a few hundred meters of the mainshock rupture plane. On other fault segments like the San Andreas fault near Parkfield, most of the earthquakes occur on the San Andreas fault. It is difficult to automate this decision process, and it would be misleading to imply on the basis of only distance that an earthquake occurs on a named fault.
Related Content
What is UTC, and why do you report earthquakes in UTC?
Why do so many earthquakes occur at a depth of 10km?
How quickly is earthquake information posted to the USGS website and sent out via the Earthquake Notification Service (ENS) and other feeds?
Where can I see current or past seismograms?
Why do USGS earthquake magnitudes differ from those published by other agencies?
Why/When does the USGS update the magnitude of an earthquake?
Why do some earthquakes disappear from the map/list?
Can I get on a list to receive an email message when there is an earthquake? How do I sign up for earthquake notifications? Are there any Feeds I can subscribe to?
Did I feel an earthquake? Can I report feeling an earthquake?
Why is the earthquake that was reported/recorded by network X, or that I felt, not on the Latest Earthquakes map/list?
Where can I find current earthquake lists and maps for the world or for a specific area?
Updated USGS Earthquake Monitoring Strategy Released
The USGS Earthquake Hazards Program recently released a new strategic plan for earthquake monitoring entitled the “Advanced National Seismic System – Current Status, Development Opportunities, Priorities, 2017-2027.”
A 100-year-long History of Earthquakes and Seismic Monitoring in Hawaii
The Hawaiian Volcano Observatory’s 1912–2012 Centennial—100 Years of Tracking Eruptions and Earthquakes
HAWAI‘I ISLAND, Hawaii —The history of earthquakes and seismic monitoring in Hawai‘i during the past century will be the topic of a presentation at the University of Hawai‘i at Hilo on Thursday, January 26, at 7:00 p.m.
Millions Awarded for Earthquake Monitoring in the United States
More than $7 million in cooperative agreements will be awarded for earthquake monitoring by the U.S Geological Survey in 2010. This funding will contribute to the development and operation of the USGS Advanced National Seismic System (ANSS).
Recovery Act Funds Will Upgrade Earthquake Monitoring
USGS will Grant Universities $5 Million to Beef Up Public Safety Grants totaling $5 million under the American Recovery and Reinvestment Act are being awarded to 13 universities nationwide to upgrade critical earthquake monitoring networks and increase public safety.
HayWired scenario earthquake map
HayWIred scenario earthquake map.
Earthquake Catalog Map Results Example
Example of results returned when searching the USGS Earthquake Catalog. The ANSS Comprehensive Earthquake Catalog (ComCat) contains earthquake source parameters (e.g. hypocenters, magnitudes, phase picks and amplitudes) and other products (e.g. moment tensor solutions, macroseismic information, tectonic summaries, maps) produced by contributing seismic
...
Closeup of the San Andreas Fault
Closeup shot of the same area above. The cross-cutting feature is a road cut going through the fault.
Map of known active geologic faults in the San Francisco Bay region
Map of known active geologic faults in the San Francisco Bay region, California, including the Hayward Fault. The 72 percent probability of a magnitude (M) 6.7 or greater earthquake in the region includes well-known major plate-boundary faults, lesser-known faults, and unknown faults. The percentage shown within each colored circle is the probability that a M 6.7 or
...
Interactive Quarternary Fault Database
This database contains information on faults and associated folds in the United States that demonstrate geological evidence of coseismic surface deformation in large earthquakes during the Quaternary (the past 1.6 million years).
Scenario Earthquake Map
Interactive map showing earthquake scenario data
Eastern Earthquakes
This map shows earthquakes above magnitude 4.0 in the eastern United States since 1973, the first year with a complete catalog. There are 184 earthquakes recorded. An earthquake of magnitude 4.0 or greater can cause minor or more significant damage. The circle sizes correspond to earthquake magnitude, ranging from 4.0 to 5.9 (the largest was in the Gulf of Mexico).