Member of Reconnaissance Team Says Los Angeles Earthquake Involved Unusual Ground Motions Vertical Motion Greater Than 1g Preceded Horizontal Ground Motion

BUFFALO, N.Y. -- First-hand assessments of damage inflicted by last week's quake reveal that the 6.6 temblor had an unusual signature, according to Andrei Reinhorn, Ph.D., a member of a reconnaissance team sponsored by the National Center for Earthquake Engineering Research (NCEER), headquartered at the University at Buffalo.

Reinhorn, a professor of civil engineering at UB, is back in Buffalo after inspecting the damage on residential and commercial buildings in the areas near the quake's epicenter.

He noted that last week's quake involved unusual ground motions, which were, to some extent, responsible for the damage.

"There was a very strong up and down motion in this earthquake and it began earlier than the horizontal motion," explained Reinhorn.

He said that according to scientific instruments with which some buildings in the area were fitted, the vertical motion registered more than 1 G, or more than one time the force of gravity.

"This would have been a lot for horizontal motion, but it's an outrageous level of force for vertical motion," he said.

The fact that the vertical motion began earlier than the horizontal made for more extensive damage than would otherwise have occurred, he said.

"If an object that was supported by gravity becomes unseated, then it becomes a free body, which makes it much more vulnerable to the horizontal motion," he explained.