Phone calls from earthquake-jittery residents flooded police switchboards after a sharp jolt rattled the Los Angeles Basin at about 9:30 Friday morning, but experts at Caltech's seismological laboratory in Pasadena said what people felt was probably a sonic boom.
The calls to law enforcement agencies and news media indicated that Friday's palpable jolt was felt across a broad band of the metropolitan area, stretching from Malibu on the west to La Verne on the east. There were no reports of damage.
