Several hundred earthquakes a week occur in this Hawaii town and experts are baffled

One town in Hawaii is being rattled by several hundred earthquakes a week and the U.S. Geological Survey says the cause is mysterious and growing in intensity.

Hawaii — like California — is prone to seismic activity, but what’s going on under the town of Pahala is different, the USGS said in a May 12 report.

“Until 2015, an average of 7 earthquakes occurred deep beneath Pahala each week. By 2015, the number of earthquakes had approximately quadrupled, with nearly 34 events happening per week,” the USGS reports. “By the spring of 2019, the average number of weekly earthquakes ... increased approximately 70-fold.

“This high rate of earthquake activity, with several hundred earthquakes occurring in an average week, has continued to the present.”

The magnitude of the earthquakes has also been growing since August 2020, with eight in the 4.2 to 4.6 range, experts report.

The USGS says the quakes “are felt regularly by local residents, and, occasionally, people across the entire island.”

Pahala, with a population of about 1,400, is in southern Hawaii.

Data shows the origin is 18 to 25 miles below the town, and extends south about 6 miles offshore, the USGS says.

Multiple theories have been considered as causes — including the frightening idea of a growing pocket of pressurized magma. But no direct evidence has been found to support any of the theories, according to the USGS Hawaiian Volcano Observatory.

Scientists suspect the source is somehow linked to the fact that Pahala is the same distance “from the summits of the three most active volcanoes in Hawaii: Kilauea, Mauna Loa, and Kamaehuakanaloa,” the USGS says.

An investigation into the cause is underway, starting with with hikers placing “a dense array” of seismic nodes around the town. The resulting data from the nodes will help researchers create a 31-mile deep image of the ground below Pahala, the USGS says.

Somewhere in the image will be the mysterious cause — they hope.

“The data and images will be used to precisely locate the earthquakes in this region and, hopefully, ... the locations and distributions of shallow and deep fault zones and potential magma pathways,” the USGS says.

“Together, the results will help us to understand what is causing the frequent earthquake activity deep in the region.”

This story was originally published May 16, 2022 at 12:36 PM with the headline "Several hundred earthquakes a week occur in this Hawaii town and experts are baffled."