Big, Bigger, Biggest

For me, formerly an earthquake engineer at the Institute of Water Management in Odessa, Russia, it is a real wonder to read in a popular magazine such a vivid and unembroidered scenario of the forthcoming disastrous event. The article seems to be very instructive. At the same time, there are some details that could be considered misleading. For example, pitching people through broken windows of high-rises is an exaggeration; large amplitudes of swaying in tall buildings do not mean greater horizontal forces in comparison with low ones. Quite the reverse. Then it is stated that since the waves pass through hard materials with small amplitudes, houses planted on bedrock suffer less damage. This statement is not absolutely correct. In an earthquake originating in a local fault, stiff one- and two-story structures that are supported on rigid ground might be subjected to more severe shaking than either taller structures or even similar ones built on a soft soil--all other factors being the same.

VALENTIN SHUSTOV

Los Angeles

In the opinion of our experts, a large number of windows in high-rise buildings would explode outward during a severe earthquake and, inevitably, a few people near the windows would be propelled through the openings. We were not making the assumption that horizontal accelerations would be greater in high-rise buildings than low-rise. As for shaking intensities transmitted by consolidated soils or bedrock, it is true that some very firm structures would react violently to short-amplitude waves. The destruction of one-story structures described in the article was due instead largely to the liquefaction phenomenon that is predicted for parts of the Westside.

--The Editors