A series of minor but noticeable earthquakes has rattled communities on both U.S. coasts this week, serving as a reminder of the planet’s constant geological activity. While tremors in New Jersey and California caused no significant damage, they occurred against a backdrop of major seismic events in the Pacific, including a massive earthquake off Russia that triggered widespread tsunami alerts and was linked to a rare volcanic eruption.
In Northern New Jersey, residents were shaken by two separate tremors in less than four days. According to the United States Geological Survey (USGS), a magnitude 2.7 earthquake struck at 12:11 p.m. ET on Tuesday, August 5, 2025, centered about a mile southwest of Hillsdale in Bergen County. This followed a slightly stronger magnitude 3.0 quake that occurred late Saturday night, August 2, near Hasbrouck Heights. The Saturday event was felt more widely, with over 10,500 people reporting the shaking to the USGS. Experts note these events are not aftershocks of the more significant magnitude 4.8 earthquake that struck the region in April 2024, but are related to the reactivation of ancient fault lines, such as the Ramapo Fault system, that lie beneath the surface.
Meanwhile, Southern California experienced its own seismic activity. A magnitude 3.5 earthquake was reported at 4:54 p.m. PT on Tuesday, August 5, in Rialto, a city in the seismically active Inland Empire. The Los Angeles Times reported that weak shaking was felt across the region. California is one of the most seismically active states, with data from Earthquake Track showing 29 earthquakes of magnitude 1.5 or greater in a recent 24-hour period. According to a three-year data sample, California and Nevada experience an average of 234 earthquakes with magnitudes between 3.0 and 4.0 each year.
These relatively minor domestic events unfolded as the Pacific basin contended with the aftermath of a much larger seismic disturbance. In late July 2025, a massive earthquake with a magnitude reported between 8.7 and 8.8 struck off the coast of Russia’s Kamchatka Peninsula. The powerful quake generated tsunami alerts across the Pacific. A full Tsunami Warning was issued for Hawaii and parts of Alaska, while a less severe Tsunami Advisory was put in effect for the entire U.S. West Coast, from California to Washington. While the threat to the U.S. mainland ultimately subsided without major incident, the event highlighted the interconnectedness of seismic hazards.
Adding to the drama, the massive offshore earthquake was linked to the awakening of a long-dormant volcano. On Sunday, August 4, Russia’s Krasheninnikov volcano erupted for the first time in centuries, sending a plume of ash 3.7 miles into the atmosphere. Scientists believe the intense seismic activity in the region directly triggered the eruption.
Earthquakes are a result of the sudden slip of tectonic plates, the massive puzzle pieces that make up Earth’s outer shell, as explained by the USGS. The energy released travels in the form of seismic waves, causing the ground to shake. While unpredictable, their potential impact can be mitigated through preparation. Officials at Ready.gov advise the public to practice the “Drop, Cover, and Hold On” protocol during an earthquake. This involves dropping to the ground, taking cover under a sturdy object, and holding on until the shaking stops. Having an emergency plan and a supply kit are also crucial steps for anyone living in a seismically active region.
