The foreshock proved to be just a preview of the main event Less than 30 seconds later, a moment magnitude 7.9 earthquake struck with an epicenter located just seven miles from the center of San Francisco.
1(a), AEs caused by the fracture of individual asperities exhibit similar characteristics to the sequence for natural earthquakes, including foreshock, mainshock, and aftershock events.
One attention-focusing foreshock of such an upheaval was last year's six-month strike in the commercials industry carried out by SAG-AFTRA, the longest actors' walkout in the history of Hollywood.
This powerful aftershock, one of 1,400 reported by scientists today, shows that yesterdays temblor was just a foreshock. The potential for danger cant be underestimated, and residents of Southern California must be prepared in case there are further, more dangerous quakes.