A magnitude 4.3 earthquake has struck an area near Eureka, in Humboldt County California.
The shallow earthquake hit Weitchpec, to the northeast of Eureka, at 12:01 a.m. on January 20, the U.S. Geological Survey reported.
It wasn't the only earthquake to rumble the area recently. A magnitude 3.6 temblor hit the same area on January 19, while several smaller earthquakes have also swept throughout the rest of the state. A 2.9 magnitude one hit Portola Valley at 11:09 p.m. on January 19, while New Idria saw a 3.1 magnitude quake at 11.15 p.m.
The magnitude 4.3 earthquake was recorded at a depth of 25.2 kilometers (15.7 miles). Shallow earthquakes are closer to the surface, meaning they are often felt more intensely than deeper ones.
There have so far been no damage reports linked to the quake, based on early USGS data. It's likely that it was felt by people in communities around Humboldt County.
Earthquakes are recorded on a scale ranked by magnitude. Temblors measuring between 4 and 4.9 are considered light earthquakes, but they can usually be felt. They usually cause no significant damage.
Earthquakes aren't unusual in Northern California as it is extremely tectonically active, and the most seismically active spot in the lower states.
This is because it's located at the southern end of the Cascadia subduction zone—where the United States sits right over the ocean floor. The fault (a fracture or discontinuity in rock volume) is located at the northern tip of the San Andreas Fault, the border section between two massive tectonic plates under the Earth's surface.
Humboldt County saw larger, more damaging earthquakes occur at the end of December and the beginning of January. A magnitude 6.4 earthquake rattled the area on December 19 and caused widespread power outages, and at least two deaths.
On New Year's Day, a 5.4-magnitude earthquake shook the area. Half of the residents living in the area didn't have power, and some were left without water.
Experts monitoring seismic activity in the region are concerned that California could be long overdue a huge earthquake.
That is because these tectonic plates are relatively static, meaning a lot of pressure has built up over time. And when they do move, they can produce big earthquakes.
It's highly likely that some areas across the fault will experience a magnitude 6.7 earthquake in the next 30 years, the USGS said.
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