Ten New Geologic Maps Critical to Seismic Modeling Published

ROLLA — Ten new geologic maps that are critical to seismic modeling are available for portions of the region, thanks to the Missouri Department of Natural Resources through the St. Louis Area Earthquake Hazards Mapping Project component of the National Earthquake Hazards Reduction Program.

Areas of map coverage include Alton, Cahokia, Clayton, Elsah, Florissant, Grafton, O’Fallon, Oakville, Webster Groves and Wentzville. 

The department’s Division of Geology and Land Survey authored the maps along with previously published Columbia Bottom and Granite City maps. Project partners include the Missouri Department of Transportation, the Missouri University of Science and Technology and the Illinois Geological Survey.

Surficial material maps are critical for seismic modeling. An understanding of the characteristics of the ground enables the department to model expected shaking intensity for an area.

Portions of the St. Louis area maps provide characteristics of surficial material, which includes soil and several hundred feet of deeper unconsolidated material, depth to bedrock and depth to the water table, all of which influence the behavior of the surface due to earthquake induced shaking.

The maps also include shearwave, which is a seismic wave that moves rocks from side to side as it moves through them, velocities of near-surface materials, sample locations and methods, surficial material thickness contours, topographic relief, bedrock elevation contours on Digital Elevation Models and a scaled cross section based on 2007 and 2009 aerial photography.

The project includes 21 surficial material maps. The remaining nine quads are scheduled to be completed by 2013. These maps complement ongoing mapping projects by the department.

In addition to earthquake and other natural hazard evaluation, geologic maps are used in a variety of applications including agriculture, water availability, industrial and commercial development siting, waste disposal facilities, economic assessment of our natural resources, and various planning needs critical to public safety and infrastructure.

Activities are planned for the bicentennial of the Great New Madrid earthquakes of 1811-12 including a multi-state "ShakeOut" earthquake drill April 28, and a National level earthquake response training exercise May 16-20, focused on a coordinated local, state and federal response to a magnitude 7.7 earthquake.

The ShakeOut is an earthquake preparedness drill that provides everyone a chance to practice the “Drop, Cover and Hold On” protective actions that should be taken in the event of a real earthquake.

The department is inviting Missouri K-12 students to share their knowledge about how to prepare for an earthquake by participating in the Great Central U.S. ShakeOut Video Contest. Deadline for entries is March 31. See this web site for more information.

In the event of a large, damaging quake, the department will activate the Post Earthquake Technical Information Clearinghouse or PETIC. The PETIC will be located in Rolla and will serve as a science information center for geologists and other experts who will be entering the affected area.

It is anticipated that preliminary geologic data can aid officials in anticipating the potential for landslide, flooding and effects of further ground movement; thus saving lives and property.

Geologic maps and other items are available for purchase at the Division of Geology and Land Survey, 111 Fairgrounds Road, Rolla or you may order online at the Missouri Geology Store or by calling 573-368-2125.