Characterization of Active Faults in the New Madrid Seismic Zone

摘要

This is a final report that discusses the results of the Mid America Earthquake Centerstudy SG-4 entitled, Characterization of Active Faults in the New Madrid Seismic Zone. Partone is entitled Late Cretaceous and Cenozoic Geology of the New Madrid seismic zone and Parttwo is entitled Forward Modeling of the Rupture Scenario of the 1811-1812 New MadridEarthquakes. Part one discusses the geology of the New Madrid seismic zone and provides ageologic framework within which seismological, fault, and engineering characteristics areconstrained. Part one also presents a tectonic model for the New Madrid seismic zone whereinthe upper Mississippi Embayment is undergoing regional differential uplift. This differentialuplift appears to be responsible for different faults becoming active and deactivated through timeand thus provides us with a better understanding of fault behavior through time and space. Parttwo of this report illustrates potential rupture scenarios for the 1811-1812 earthquake sequence.Scenarios are based on the numerical modeling of a combination of historical and geologicaldescriptions of ground deformation after the three main earthquakes. The preferred rupturescenarios suggest to us that the currently aseismic Bootheel lineament was the location of thefirst main rupture, and that subsequent ruptures involved the currently seismic portions of theNew Madrid seismic zone. These two studies contribute significantly towards our MAE Centergoal of characterizing active faults in the New Madrid seismic zone.