# 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:

## Related Content

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### Why don’t you report earthquakes in the local time where the earthquake occurred?

Since we 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. Also, we tried converting UTC to the local time zones for epicenters and reporting them that way for a while on our website, and it confused our web...

### Why do so many earthquakes occur at a depth of 10km?

10 km is a "fixed depth". Sometimes data are too poor to compute a reliable depth for an earthquake. In such a case, the depth is assigned to be 10 km. 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 expect to see a peak around 10...

### How fast does the earthquake information get posted to the web site, get sent out via the Earthquake Notification Service (ENS), ATOM feeds, etc?

First of all, 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 where the earthquake is and how large it is. An Earthquake in California will get processed and posted to the system in 2-1...

### Where can I see current or past seismograms?

The Earthquake Hazards Program has helicorders (seismogram displays) available for several areas in the United States and the World.

### Why do USGS earthquake magnitudes differ from those published by other agencies?

Summary 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,...

### When are tsunami information and links put on the event page?

1. If we get information (alerts) from any of NOAA's Tsunami Warning Centers or 2. For any earthquake, magnitude 5.0 or greater, that occurred in a. the Pacific Ocean, or b. Indonesia, or c. Papua New Guinea, or d. the Caribbean Sea, or e. Hawaii (criteria from David Applegate, 07/20/2005) For More Information, See NOAA's Tsunami Warning Centers:...

### Why/When does the USGS update the magnitude of an earthquake?

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 a part of the standard procedure of assembling a final earthquake catalog. There are physical and...

### Why do some earthquakes disappear from the map/list?

The USGS and networks contributing to the Advance National Seismic System (ANSS) take great effort to provide accurate and timely earthquake information. Occasionally our systems produce erroneous information that is released to the public via our web pages or Earthquake Notification System . These mistakes are generally promptly identified by...

### 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...

### Did I feel an earthquake? Can I report feeling an earthquake?

Report an earthquake experience or related observation through the Did You Feel It? citizen science webpage. The best way to do this is to click on the earthquake that you think you felt on one of the lists on the Earthquakes webpage, and then select the "Tell Us!" link. If you don't see the earthquake you think you felt, use the green "Report an...

### Where can I find current earthquake lists and maps for the world or for a specific area?

The Earthquake Hazards Program Latest Earthquakes Map displays earthquakes in near-realtime and up to the past 30 days of earthquakes. The interface includes three panels: a list of earthquakes, a map, and a settings/options panel. You can pan and zoom the map to view specific areas. Click on an event on the list or map for additional information...
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Date published: May 25, 2017

### 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.”

Date published: January 23, 2012

### 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.

Date published: May 3, 2010

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). Date published: September 24, 2009 ### 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.

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February 27, 2017

April 18, 2016

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### Potential earthquake map shaking

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.

October 17, 1989

### Seismographs at the U.S. Geological Survey

Seismographs at the U.S. Geological Survey record (1) north-south horizontal, (2) east-west horizontal, and (3) vertical components of the earthquake.

### Global Seismographic Network

Global Seismographic Network