Keynote Speaker
Dr. Chris H. Cramer
Dr. Cramer worked for 23 years for the California Division of Mines and Geology (now California Geological Survey) and 7 years for the U.S. Geological Survey prior to coming to work for CERI at the University of Memphis. During that period he worked in several areas of seismology including probabilistic earthquake hazard and risk, strong ground motion and the effects of site geology, earthquakes and volcanoes, and field seismological studies of geothermal areas, aftershock sequences, reservoir induced seismicity, and the earthquake activity potential of faults. He also has extensive experience with programming and using computer systems to process, model, and interpret geophysical data. As an undergraduate and during his first two years as a graduate student, Chris worked on geophysical problems and did field work in the areas of gravity, magnetism, and geodesy.
The keynote address is entitled:
EARTHQUAKES HAZARDS IN THE CENTRAL U.S.
Major earthquakes have occurred in the central US (CUS), the most famous being the 1811-1812 New Madrid sequence of magnitude 7-8 earthquakes. Magnitude greater than 6 New Madrid earthquakes also occurred in 1843 and 1895. These earthquakes were felt over a wide area of the eastern US. More recently in 2008 a magnitude 5.2 earthquake struck near Mt. Carmel, Illinois in the Wabash Valley seismic zone. The geologic records of earthquake-induced liquefaction indicate large damaging earthquakes have occurred in the recent geologic past in both of these seismic zones. So the potential for damaging earthquakes is significant in the CUS. National, regional, and local seismic hazard maps help us understand what the earthquake hazard is in a region. My presentation will introduce you to the basics of earthquake hazard, including the two kinds of seismic hazard maps, scenario and probabilistic. Seismic hazard depends on the expected magnitude and in some cases the rate of earthquakes in the surrounding region. I will review the geologic and geodetic evidence for large earthquakes in the New Madrid seismic zone and surrounding region. While there appears to be contradictions between geologic and geodetic observations, these contradictions are less in conflict than they seem. However, the reason for earthquakes occurring in the CUS is still poorly understood and lots of mechanisms for their occurrence have been suggested. Nonetheless, the geologic record suggests that earthquake hazard is fairly high. So preparing for the future occurrence of damaging earthquakes is important. A major effort to better understand why earthquakes occur in the CUS is associated with the Earthscope transportable array of seismographs that starts passing through the CUS in 2010.