Haiti’s 7.2 earthquake rippled across the US, but it took about 3 minutes to get here
The 7.2-magnitude earthquake that struck Haiti on Saturday and killed nearly 1,500 people was strong enough to be recorded by seismic stations across North America.
Among the first to report detecting the ripples was the Geological Survey of Alabama.
“The seismic waves took a little over 3 minutes to reach Alabama,” the survey posted on Facebook.
That’s a distance of about 1,300 miles.
The slight vibrations lasted nearly 50 minutes and were recorded as far west as Alaska, according to a vibration map shared by the Incorporated Research Institutions for Seismology (IRIS).
The trembling was not perceptible to humans, but the data underscore the impact large earthquakes have far from their epicenter.
“Waves generated by an earthquake travel around and through the earth, but they get smaller (attenuate) as they move away from the earthquake location, just like ripples in a pond,” IRIS said in an Aug. 14 Facebook post.
“Once the earthquake waves are far enough away from the location where the earthquake occurred they can no longer be felt by people, BUT they can still be detected by sensitive seismic instruments.”
That 8.2-magnitude earthquake reported off Alaska last month was also powerful enough to be recorded across the country, according to seismologists.
Subtle “waves” from that quake rolled “across seismic stations in North America” for more than 30 minutes, IRIS said.
The Alaska quake also had an impact on groundwater levels thousands of miles away away — in Anderson County, South Carolina, the U.S. Geological Survey reported.
Changes in groundwater levels after strong quakes are typically “several feet or less,” and can result in wells overflowing or going completely dry, the USGS reports.
“Recovery to the pre-earthquake water level can be nearly instantaneous, or it may take as long as days or months, or may not recover at all,” the USGS says.
This story was originally published August 17, 2021 at 8:13 AM with the headline "Haiti’s 7.2 earthquake rippled across the US, but it took about 3 minutes to get here."