Geophysics have predicted sharp increase in risk of a major earthquake in California  connected with seismic activity in the area near San Andreas Fault, formed between the Pacific and North American plates, Los Angeles Times reported.

Last week, several seismologists recorded weak tremors measuring up to 4.3. Earthquakes lasted about a day.  In total sensors recorded 200 local sites with tremors.

The quakes occurred in one of California’s most seismically complex areas.

A big earthquake happens on average in this area once every 150 or 200 years, so experts think the region is long overdue for a major quake.

According to the U.S. Geological Survey, as of Tuesday, the chances of a magnitude 7 or greater earthquake being triggered on the southern San Andreas Fault over the next seven days were as high as 1 in 100 and as low as 1 in 3,000.