How does the USGS tell the difference between an earthquake and a sonic boom?

Steps to identification of a sonic boom:

  • The USGS sees either nothing on our seismic records or a fairly short high-frequency signal  that doesn't look like an earthquake.

  • On rare occasions, we see the event on multiple stations, and the time difference between stations matches the speed of sound in air, which is slower than the speed of seismic waves in rock.

  • Felt reports come from a wide area, which is typical of a fairly large earthquake, but no such event is on our records. 

  • Reports of a bang are a clue that it's a sonic boom, but not an ironclad indicator since shallow earthquakes often sound like booms or bangs.

  • All of the above indicates an atmospheric source such as a sonic boom, artillery fire, or a meteorite or bolide explosion. Bolides are often accompanied by bright light, sound, and ground motion.

  • The final step is getting the military to admit responsibility. In most cases, the best we get is a confirmation that there were planes in the area that "might have gone supersonic."


Related Content

Filter Total Items: 9
Filter Total Items: 4
Date published: June 10, 2015

6 Facts about Human-Caused Earthquakes

The central United States has undergone a dramatic increase in seismicity over the past 6 years. From 1973-2008, there was an average of 24 earthquakes of magnitude 3 and larger per year. 

Date published: January 8, 2014

New Sensor Network to Detail Virginia Earthquakes

Scientists from the U.S. Geological Survey and Virginia Tech will install a 20-station seismic network in the central Virginia area beginning Jan. 8. The new sensors – each about the size of a soda can – will provide information to help the researchers study the background seismicity in the area and any continuing aftershocks of the Aug. 23, 2011 earthquake near Louisa and Mineral, Va.

Date published: March 1, 2013

"Living in Earthquake Country: Los Angeles and the Big One" - Dr. Lucy Jones presentation at LA Natural History Museum

"Living in Earthquake Country: Los Angeles and the Big One" - Dr. Lucy Jones presentation at LA Natural History Museum

Date published: August 15, 2003

Eavesdropping on the Earth: USGS Conducts Seismic Study in San Jose Area

Scientists from the U.S. Geological Survey (USGS) will be "eavesdropping" on the echoes of the earth in the West San Jose area from Aug. 19-30 to help researchers better estimate how and when the ground will shake in regional earthquakes.

Filter Total Items: 5
Image: USGS Scientist Installing Seismograph
March 17, 2015

USGS scientist John Hamilton installing a seismograph in the offices of the major-league soccer team San Jose Earthquakes’ new stadium.

Map showing locations of ANSS stations
November 30, 2000

Map of ANSS free-field seismic stations across the U.S. in 2016 (not shown are additional seismic instruments in buildings and other structures).  Map colors show seismic hazard across the United States derived from the National Seismic Hazard Model.  Background colors indicate the levels of shaking that have a 2% chance of being exceed in a 50-year period.  Shaking is expressed in a percentage of g, which is the acceleration of a falling object due to gravity, with red colors indicating highest shaking and thus higher hazard.  Notice the greater density of stations in regions with either higher hazard, higher risk (e.g., southern California), or both.

Image: Seismographs at the U.S. Geological Survey
October 17, 1989

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