A preliminary magnitude-3.4 earthquake shook near Redlands on Friday evening, according to the U.S. Geological Survey.
The quake hit roughly 4.3 miles south-southwest of the San Bernardino County city around 6:40 p.m., the agency said.
Light shaking was reported in Redlands, San Bernardino, Rialto, Riverside, Moreno Valley and Jurupa Valley, the USGS’ Did You Feel It tool showed.
Just a little over 12 hours earlier, a magnitude-3.1 earthquake struck about 4 miles southeast of Loma Linda.
Did you feel it?
Whether you feel shaking from an earthquake largely depends on three major factors — magnitude, distance and local soil conditions. Magnitude refers to the strength of the quake. The closer your location to the epicenter, the more likely you’ll feel the effects of seismic waves that become less intense as they move out from the fault. Generally, the looser the soil under your location, the greater the amplification.
Aftershocks
Some earthquakes are followed by a larger earthquake, in which case the first quake would then be called a foreshock. For example, the magnitude-9.1 Japan earthquake and tsunami in 2011 was preceded by a magnitude-7.3 foreshock two days earlier.
Aftershocks decrease over time, but can continue for days, weeks, months and years.