18,051 Quakes Recorded in Southland Last Year

A total of 4,660 measurable earthquakes occurred in Southern California in the fourth quarter of 1996, of which 50 were at least magnitude 3.0, seismologists from Caltech and the U.S. Geological Survey reported Friday.

For the whole year, there were 18,051 quakes recorded in the Southland, the strongest of which was a magnitude 5.3 in the Coso mountain range north of Ridgecrest on Nov. 27. There were 23,412 quakes in 1995.

Most of the quakes last year were in the weak magnitude 1 and 2 range and were not felt by anyone.

The scientists said that 196 Northridge aftershocks were recorded in the fourth quarter, two of which exceeded magnitude 3.0.

That brought the total of Northridge aftershocks since the 6.7 quake took place in 1994 to 13,523.

There were also 822 new Landers aftershocks, including eight measuring between magnitude 3.0 and 3.9 and two measuring 4.0 or higher.

That brought the total of Landers aftershocks since that 7.3-magnitude quake in 1992 to 65,380. The scientists said there have been 22 Landers aftershocks of at least magnitude 5.0.

There were 1,782 aftershocks in the Coso range between Nov. 27 and Dec. 31, 19 of which were between magnitude 3.0 and 3.9; one was at least magnitude 5.0.

“At the present rate . . . we should expect four Northridge and 22 Landers aftershocks of magnitude 3.0 or larger in the next year,” said the seismologists, Kate Hutton of Caltech and Lucy Jones of the Geological Survey.

Friday, meanwhile, a magnitude 3.2 quake hit an area near the San Jacinto fault zone, nine miles north of Fontana.