The next series of slides concentrates on a major paleoliquefaction study that was recently conducted just north of the New Madrid seismic zone. These studies were in the vicinity of the Wabash Valley of Indiana-Illinois, where the largest historic earthquake was of M~5.5. The paleoliquefaction study showed that much, much stronger earthquakes have struck there repeatedly throughout the Holocene. (Refer back to slide 11 for location of the Wabash Valley region.)

33. The study in the Wabash Valley region made extensive use of a canoe to search for clastic dikes in the banks of eroding streams. This slide shows a typical bank exposure. In an average day, banks along 15 km of river could be searched. Typically exposed would be a kilometer or more of banks revealing deposits at least 5,000 years in age. In addition, at least half a kilometer of deposits of earlier Holocene age (5,000-10,000 yrs) normally would be exposed. Several kilometers of deposits a few thousand years old also would be available for viewing. Thus, there was a good opportunity to find clastic dikes that had formed throughout the Holocene, and especially during and since the mid-Holocene.