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A series of more than 400 aftershocks have been recorded following a significant 5.2-magnitude earthquake near Bakersfield, which impacted much of Southern California earlier in the week.
The earthquake originated from the southern end of the Central Valley, roughly 90 miles north of downtown Los Angeles, striking just after 9 p.m. on Tuesday. The tremor was widely felt across Kern, Los Angeles, and Ventura counties. In the ensuing two days, authorities documented 74 aftershocks with a magnitude of 2.5 or higher, centered within 10 miles of the initial quake’s epicenter.
According to the U.S. Geological Survey, when considering even minor tremors, the total number of aftershocks in the area reaches over 400 within just two days of Tuesday’s event.
Aftershocks are typically smaller seismic events that occur in the vicinity of a larger earthquake, known as the “mainshock,” a term that applies to Tuesday’s 5.2-magnitude quake. Dr. Lucy Jones, a California-based seismologist, explains that aftershocks are a result of adjustments along the fault line that initially slipped during the mainshock.
The sequence also includes foreshocks, which are smaller quakes that precede a larger event. Dr. Jones confirmed that Tuesday’s quake did not act as a foreshock, as no subsequent events of comparable size have occurred.
In the aftermath of the quake, Dr. Jones noted the probability of a quake being a foreshock diminishes over time. She stated that within three days of a quake like the one in Kern County, the likelihood of it being a foreshock is virtually nonexistent.
Dr. Jones described the quake activity following the initial 5.2-magnitude event as “a pretty active sequence,” noting that a quarter of all aftershocks typically occur within the first hour of the mainshock. Specifically, this sequence included at least two aftershocks with magnitudes exceeding 4.0 occurring within an hour of the main earthquake.
This region is historically seismic, with a notable 7.2-magnitude earthquake reported in the same area back in 1952. However, Dr. Jones clarified that the recent quake does not seem to be linked to the fault involved in the 1952 event.