Sunday, 22 May 2016

On this day in 1960

A sand layer deposited by the 1960 tsunami,
deposited on top of and later covered by peat
Today, 22nd May 2016, marks the 56th anniversary of the 1960 Great Chilean earthquake. With a magnitude estimated at 9.5, this still stands as the largest instrumentally documented earthquake worldwide. 

Palaeoseismologists have sought to characterise the geological evidence for this earthquake and the subsequent tsunami in a range of different settings. The events of 22nd May 1960 provide a modern case study of the imprints of a great earthquake and tsunami on the geological record and can help us to understand sedimentary and geomorphological evidence for older seismic events for which we do not have corresponding instrumental or historical documentation. 

Dr Philipp Kempf recently published a paper looking at the sediments left by the tsunami in two coastal lakes on Isla de ChiloĆ©, a large island in south central Chile. He summarised his findings on this blog back in September. 

Back in 2013, I wrote about the tsunami deposits and evidence for abrupt land-level change associated with both the 1960 and the 2010 Chilean earthquakes. Here's the paper and a discussion on this blog of an approach that we used involving looking at diatoms (unicellular algae) preserved in the sediments. Coauthors and I later used this approach to investigate the sudden changes in land level that accompanied the 1960 earthquake and three previous great earthquakes in south central Chile. 

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