JOHANNESBURG, July 13 (Ridgecrest Online) — A preliminary earthquake reported Monday morning near Johannesburg in eastern Kern County was strong enough to be felt across a wide stretch of Southern California, but not strong enough for early reports of major damage.
What happened?
The U.S. Geological Survey said the quake struck at about 9:40 a.m. PDT near Johannesburg, about 18 kilometers, or 11 miles, west-southwest of the community in the Indian Wells Valley region. The agency listed the depth at 7.0 kilometers, or 4.3 miles.
That is a shallow earthquake. Shallow quakes are often felt more strongly at the surface than deeper ones of the same size.
Why did some reports say 4.1 and others say 4.3?
Because the event was still listed as preliminary.
The USGS commonly updates early earthquake estimates as more seismic data come in. In this case, coverage of the agency’s own postings showed two different numbers: 4.3 on the USGS website and 4.1 in a USGS social media post. That means the final magnitude had not yet settled in the public reports available Monday.
For readers, the important point is that both numbers describe a moderate quake, not a major one. On the magnitude scale, even a small change matters, because each step up represents a larger release of energy.
Where was it felt?
USGS shake reports suggested the quake may have been felt across parts of Kern and San Bernardino counties. Reports cited in local coverage also placed shaking farther away in Los Angeles, Orange, and Riverside counties.
People in places such as Burbank and Hollywood also reported feeling it, according to viewer accounts relayed by local broadcasters.
Was there damage?
In the initial reports available Monday, there were no immediate reports of injuries or damage.
That does not rule out smaller effects such as items falling or brief disruptions, but no widespread damage had been reported in the early coverage.
Did earthquake warning systems respond?
LAist reported that the USGS ShakeAlert early warning system was activated and that some areas received an early warning.
ShakeAlert is designed to send a warning after an earthquake begins but before the strongest shaking reaches more distant locations. It does not predict earthquakes; it gives people a few seconds of notice when conditions allow.
Why does this quake matter?
Even a moderate earthquake near Johannesburg gets attention because the area sits in a seismically active part of California. The Monday quake also came after another recent earthquake in the region. VVNG reported that the USGS had listed a preliminary magnitude 4.2 quake near Frazier Park on Sunday, making Monday’s event the second magnitude-4-or-greater quake in Southern California in about 48 hours.
Recent history in the same corridor has also shown that early earthquake numbers can change. For a separate June 1 Johannesburg-area quake, USGS felt-report data cited in Sacramento Bee reporting showed 46 online reports from people who felt weak shaking.
For now, the key facts are straightforward: the USGS reported a shallow, preliminary earthquake near Johannesburg, many people across Southern California felt it, and no immediate injuries or major damage were reported in the early hours after the quake.
