Charleston soils help locate earthquake impacts

Published: April 6, 2011

CLEMSON — Even the soil in Charleston has a history to tell. Old soils from the 1886 Charleston earthquake help scientists figure the impact of future earthquakes in the area.

Geophysicists and engineers study soil liquefaction — soils that transform from a solid to a liquid by the strain of earthquake forces. The results can be disastrous: building foundations collapse, dams breach, bridge abutments fail.

Geophysicists will be in Charleston the week of April 11 for the Symposium on the Application of Geophysics to Engineering and Environmental Problems.

“Soils tend to strengthen over time unless they liquefy and their aging clock restarts, while young soils, such as fill materials, are more prone to soil liquefaction,” said Ron Andrus, a civil engineer at Clemson University who uses steel probes and ground vibrators to evaluate soil liquefaction conditions in the area. “In Charleston, there are some areas at greater risk of soil liquefaction than others. Along the peninsula, inland locations are less likely to be affected than coastal sites with younger soils.” 

A soil liquefaction map and historical analysis of Charleston is available online.

For the symposium, the Network for Earthquake Engineering Simulation at the University of Texas Austin is demonstrating a massive soil vibrator, nicknamed T-Rex. The federally funded network focuses on the seismic hazard in the United States. 

Properly called a “Triaxial Vibroseis,” the vehicle looks like a monster truck with a Ph.D. T-Rex carries scientific equipment that generates vibrations over a small area, allowing researchers to determine how soil maintains its strength under strain. The soil behaves as it would if an earthquake occurs.

On April 11 from 10:30 a.m. until 2 p.m. at the Clemson University Coastal REC, T-Rex will demonstrate a soil liquefaction test. Andrus and civil engineer Kenneth Stokoe of Austin will be on hand to explain the test and talk about soil liquefaction.  

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Note: For a non-technical overview of liquefaction go to this website.