海角大神

Three small聽earthquakes聽rattled parts of central Arizona and were felt in the Phoenix area.

The struck at 11:29 p.m. MST Sunday, followed by a 4.0 quake about 20 minutes later. A smaller, magnitude-3.2 quake, hit at 9 p.m.

The USGS says all the quakes ranged from 3-6 miles in depth and were centered near Black Canyon City, about 45 miles north of Phoenix.

The quakes were notable for at least two reasons beyond their simple rarity in the region, :

First, the largest apparent temblor was preceded by a聽3.2-magnitude聽foreshock, first reported at聽about 9 p.m.
鈥淚t鈥檚 not common, but it does happen where you get small foreshock and that triggers a larger event,鈥澛燫eeves聽said.聽鈥淭ypically the first shock is the main one and everything after is at least a magnitude smaller. This is definitely not common.鈥�
Second, the quake hit relatively close to the Earth鈥檚 surface, which may have made its effect more pronounced. Quakes are measured both in their magnitude 鈥� the power of their shaking 鈥撀燼nd their depth. Their destructive power varies with both those factors, as well as local building standards.

Sunday鈥檚 largest jolt came at 6.5 kilometers 鈥� about 4 miles 鈥� beneath the surface. By comparison, the destructive Northridge earthquake in Southern California in 1994 struck at more than 18 kilometers deep.

The USGS website recorded scores of responses from people in such suburban Phoenix cities as Cave Creek, Peoria, Scottsdale and Glendale who reported feeling at least one of the quakes.

The sheriff's offices in Yavapai County and Maricopa counties didn't immediately comment when contacted about the quakes.