Geologists have invented a tool to gauge the intensity of ancient earthquakes in regions like Japan where seismic activity affects the ocean, providing crucial information currently unavailable to engineers constructing nuclear or hydroelectric plants.
A team of geologists at Tel Aviv University in Israel have developed a technique that allows them to measure the impact of earthquakes for before 100 years, by investigating wave patterns of heavy sediment that penetrates into the light sediments lying over them. “This helps us understand the intensity of earthquakes in bygone eras – it is a yardstick for measuring the impact factor of earthquakes from the past,” said Professor Shmuel Marco, the lead author of the research published today in the journal Geology.
The tool is particularly useful in regions where seismological records are not old enough to predict the likelihood of earthquakes, their timing or location.
Marco started his work after observing unexpected wave phenomenon in disturbed sediment in the Dead Sea region. Along with colleague Eyal Hefetz and doctoral student Nadav Wetzer, Marco studied layers of mud at the Dead Sea, concluding that while layers were originally stratified in a stable manner, heavier sediment now appears to have seeped up in to the lighter sediment.
The researchers have suggested that the hysics governing the sediment patterns is similar to that found in clouds and sea waves. The only difference, according to the researchers, is that in the case of rocks it is earthquake shaking instead of wind that triggers wave formation.
Using the principles of friction, the researchers considered the geometry of the shapes they found in the Dead Sea sediment and combined it with a number of other parameters found in physical science to calculate how earthquakes from the past were distributed in scale, time and place.