Why is the earthquake that was reported/recorded by network X, or that I felt, not on the Latest Earthquakes map/list?
The USGS Latest Earthquakes map and lists show events that have been located by the USGS and contributing agencies within the last 30 days. They should NOT be considered complete lists of all events in the U.S. and adjacent areas and especially should NOT be considered complete lists of all magnitude 4.5 and greater events that occur around the globe.
In most cases, we locate and report an earthquake in 30 minutes or less of its occurrence when:
- A worldwide earthquake is of magnitude 5.0 or larger.
- An earthquake within the contiguous U.S. and populated regions of Alaska is of magnitude 4.0 and larger.
Earthquakes of magnitude 2.0 or greater within the U.S. and populated regions of Alaska are usually reported rapidly if they occur within the region of a contributing local seismic network.
Our Latest Earthquakes map might not display earthquakes smaller than 5.0 outside the U.S. unless they have caused significant damage or are widely felt (earthquakes this small rarely cause significant damage). At times, some other agency might report an earthquake with a larger magnitude than what we compute from our data, especially for non-U.S. events near magnitude 5.0.
Earthquakes occurring outside the U.S. that are smaller than about magnitude 4.5 can be difficult for the USGS to locate if there are not enough data. The USGS continues to receive data from observatories throughout the world for several months after the events occur. Using those data, we add new events and revise existing events in our Earthquake Catalog and in later publications.
There are many regional networks around the world that can record smaller earthquakes in their region than the National Earthquake Information Center (NEIC) global network can, and in many cases these regional networks do not share their data with the NEIC. So if you think there is a missing earthquake on our maps and lists, please see the national and regional links for the area of interest:
Related
How quickly is earthquake information posted to the USGS website and sent out via the Earthquake Notification Service (ENS) and other feeds? How quickly is earthquake information posted to the USGS website and sent out via the Earthquake Notification Service (ENS) and other feeds?
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). This is because our seismic network is very...
Where can I see current or past seismograms? Where can I see current or past seismograms?
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 allows users to collect and view seismic data from...
Why do USGS earthquake magnitudes differ from those published by other agencies? Why do USGS earthquake magnitudes differ from those published by other agencies?
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 in magnitude of 0.2 or 0.3 units are common and...
What is UTC, and why do you report earthquakes in UTC? What is UTC, and why do you report earthquakes in UTC?
UTC stands for Coordinated Universal Time, and for this purpose is the same as GMT (Greenwich Mean Time). Since the USGS and other seismic network agencies record earthquakes around the globe in all the various time zones, using a single standard time reference is best for record-keeping and exchange of data. The individual event pages with details about each earthquake use UTC for the reference...
NEIC - the National Earthquake Information Center NEIC - the National Earthquake Information Center
Related
How quickly is earthquake information posted to the USGS website and sent out via the Earthquake Notification Service (ENS) and other feeds? How quickly is earthquake information posted to the USGS website and sent out via the Earthquake Notification Service (ENS) and other feeds?
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). This is because our seismic network is very...
Where can I see current or past seismograms? Where can I see current or past seismograms?
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 allows users to collect and view seismic data from...
Why do USGS earthquake magnitudes differ from those published by other agencies? Why do USGS earthquake magnitudes differ from those published by other agencies?
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 in magnitude of 0.2 or 0.3 units are common and...
What is UTC, and why do you report earthquakes in UTC? What is UTC, and why do you report earthquakes in UTC?
UTC stands for Coordinated Universal Time, and for this purpose is the same as GMT (Greenwich Mean Time). Since the USGS and other seismic network agencies record earthquakes around the globe in all the various time zones, using a single standard time reference is best for record-keeping and exchange of data. The individual event pages with details about each earthquake use UTC for the reference...