3.9 Aftershock Felt Through Much of Valley

The strongest aftershock of the 1994 Northridge quake to strike this year--a magnitude 3.9 temblor--rattled built-up areas of the northwest San Fernando Valley at 11:51 a.m. Wednesday, but there were no reports of injury or substantial damage.

Caltech seismologists said the epicenter of the quake--and that of a magnitude 3.1 foreshock 22 seconds earlier--was two miles north-northeast of Chatsworth at a depth of 3.5 miles.

The quake was felt through much of the Valley and weakly felt in Santa Monica and northward along the coast.

There have been about 14,700 Northridge quake aftershocks, including 63 larger than the strongest one Wednesday, according to Caltech seismologist Kate Hutton. Wednesday’s was the largest since a spasm of jolts reaching magnitude 5.0 hit an area between the Simi and Santa Clarita valleys in April 1997.