Why is the earthquake that was reported/recorded by network X, or that I felt, not on the map/list?
The maps and lists show events which have been located by the USGS and contributing agencies within the last 30 days. They should not be considered to be complete lists of all events in the US and adjacent areas and especially should not be considered to be complete lists of all events M4.5+ in the world.
In most cases, we locate and report on earthquakes worldwide of magnitude 5.0 and larger in 30 minutes or less. Additionally, we locate and report on earthquakes magnitude 4.0 and larger within the contiguous US and populated regions of Alaska within 30 minutes. Earthquakes of magnitude 2.0 or greater within the US and populated regions of Alaska are often rapidly reported if they occur within the region of a contributing local seismic network.
We may not rapidly locate earthquakes smaller than 5.0 outside the US unless they have caused significant damage or are widely felt. Earthquakes this small rarely cause significant damage. At times, some other agency may report an earthquake with a larger magnitude than what we compute from our data, especially for non-US events near magnitude 5.0. If our magnitude for the event is less than magnitude 5.0, we may not issue a rapid report for it.
Earthquakes occurring outside the US and 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 later publications.
There are many regional networks around the world that can record smaller earthquakes in their region than the 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 on these webpages:
How fast does the earthquake information get posted to the website, get sent out via the Earthquake Notification Service (ENS), ATOM feeds, etc?
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?
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.”
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.
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).
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.
USGS map showing (1) the locations of major populations and (2) the intensity of potential earthquake ground shaking that has a 2% chance of occurring in 50 years.