PALEOSEISMOLOGY AND URBAN AREAS EAST OF THE U.S. ROCKIES

WHEELER, R.L., U.S. Geological Survey, MS 966, Box 25046, Denver, CO 80225, wheeler@usgs.gov.

Published geologic evidence from the Central and Eastern U. S. singles out 71 faults and other features as known or suspected to have formed by, or have the potential for, Quaternary tectonic faulting (QTF: earthquakes causing liquefaction or significant damage) (http://qfaults.cr.usgs.gov). Nine did not form by QTF. The other 62 can be prioritized for paleoseismic study according to closeness to an urban area (Metropolitan Statistical Area: MSA), MSA population, and seismic hazard as computed from seismicity. No feature ranks high on all three variables but the data show five things. (1) Most States have known or suspected QTF. (2) Of 12 features known to be results of QTF, half cluster in and near the midcontinent New Madrid Seismic Zone. Elsewhere, hazard is highest near Charleston, SC, because of large Holocene earthquakes. Charleston hazard is highly uncertain because paleoearthquake locations are poorly constrained. (3) Most of the 62 features are in MSAs. (4) Paleoseismologists have begun to study most features in high-hazard areas. (5) In areas of moderate hazard, features suspected of QTF but not studied for evidence of large prehistoric earthquakes are numerous in and near the largest MSAs. For example, 13 of the 62 features are in or partly in the Boston-Washington urban corridor (2000 population over 47,000,000). Notable are the Dobbs Ferry fault zone and Mosholu fault (New York City), the Lancaster Seismic Zone and the epicenter of the shallow 1994 Cacoosing Valley earthquake (west of Philadelphia), and the Kingston fault (central New Jersey between New York City and Philadelphia). Six of the 13 features are in the New York-northern New Jersey-Long Island MSA (2000 population over 18,000,000).