Geologists are actively studying a previously hidden fault in a northern California forest that they believe is active and capable of producing devastating earthquakes. The discovery comes shortly after a powerful 5.6-magnitude earthquake struck nearby Humboldt County.
Researchers have begun excavating the fault, located in the Shively, California, area, to understand its activity. Mark Hemphill-Haley, professor emeritus of geology at Cal Poly Humboldt, stated that their investigations have confirmed it to be a "very well-presented reverse fault."
Evidence of the fault was first identified four years ago by California Geological Survey geologist Jason Patton, who used lidar technology to scan the Earth's surface. Hemphill-Haley and Patton are collaborating on the research, which is supported by funding from the U.S. Geological Survey. They have excavated a trench measuring 30 feet wide and 15 feet deep to gather data.
The team's analysis suggests the fault has been active, with four significant earthquakes occurring in the last 20,000 years. Their current estimates indicate that this fault could potentially generate a magnitude 7 earthquake. For comparison, a magnitude 7 quake is more than 100 times stronger than the recent 5.6-magnitude earthquake that caused some injuries and damage in Mendocino County.
Historically, earthquakes of magnitude 7.0 or higher are rare in California, with only about 18 such events recorded in the past century. Scientists hope that the ongoing data collection from the Shively fault will enhance preparedness for future significant seismic activity. The discovery also raises concerns given California's location along the Pacific Ring of Fire, a region prone to substantial seismic events, as evidenced by recent devastating earthquakes in Venezuela.