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.
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Where can I see current or past seismograms?
Why do USGS earthquake magnitudes differ from those published by other agencies?
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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?
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Where can I find current earthquake lists and maps for the world or for a specific area?
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