11.   The two quakes occurred on faults of different types.

12.   To avoid gridlock, it may make sense to stay in a safe workplace after a quake occurs, Stangl said.

13.   Why did the Assam quake occur?

14.   A half-dozen smaller quakes occurred before and after the one centered near Castaic.

15.   According to the institute, the quake occurred where the Eurasian and African tectonic plates meet near the southernmost tip of the country.

16.   According to the institute, the quake occurred where the Eurasian and African tectonic plates meet, near the southernmost tip of the country.

17.   Because the quake occurred on land, detection centers have not issued a tsunami warning.

18.   Emergency sirens shrieked across the capital when the quake occurred, and traffic suddenly halted on major highways as drivers stopped and jumped from their swaying cars.

19.   Eric Lamoureux, a spokesman for the California Office of Emergency Services, said the quakes occurred on a previously unknown fault.

20.   He said that figure was likely to rise because many people were trapped in their houses when the quake occurred.