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Frequency of the Occurrences of Giant Earthquakes

Earthquakes are the natural phenomenon that occurs due to sudden release of energy in the form seismic waves. When the tectonic plates in the earth’s crust get dislocated because of seismic wave and when two blocks of the earth slip past one another suddenly, earthquake occurs. An international team of scientists has discovered that giant earthquakes repeat at relatively regular intervals.

When the occurrence of smaller earthquakes was studied, it was found that they do repeat at some intervals; however, they are more irregular than giant quakes. No one can ever deny of the disaster brought about by the major earthquakes. Who can forget the effect of the giant quakes in south-central Chile in 1960 that had a magnitude of 9.5? It is believed that giant earthquakes release a huge amount of energy. Therefore, seismological data or historical documents simply do not go back far enough in time to reveal the patterns of the recurrence of big earthquakes. By analyzing sediments on the bottom of two Chilean lakes, scientists recognized that each strong earthquake produces underwater landslides which get preserved in the sedimentary layers that accumulate on the floor of the lake. By sampling these layers, they retrieved the complete earthquake history over the last 5000 years. An analysis of these layers made them to compare the patterns in which earthquakes of different magnitude take place. Based on this approach, the team found that giant earthquakes reoccur every 292 ±93 years and thus the probability for such giant quakes is very low in the coming 50-100 years.

By: Anuja Arora