Lorca earthquake caused by human activity

By Mason Jones

THE earthquake that killed nine people in Lorca last year was caused by human activity, scientists have said.

Researchers studying surface maps now believe the May 2011 disaster, which measured 5.1 in magnitude and injured over a hundred, was caused by groundwater extraction.

A team from the University of Western Ontario, Canada, used satellite radar data to trace ground movements close to a large water basin south of the Murcia city.

The aim was to highlight how human activity such as drainage or drilling can end up having a seismic effect.

Their findings suggested the Lorca tremor was related to a drop in the level of groundwater in a local aquifer – which can create pressure at the earth’s surface.

“The evidence we have collected in this study could be necessary to expand research in other future events that occur near dams, aquifers and melting glaciers, where you have tectonic faults close to these sources,” said Pablo Gonzalez, the study’s main author.

Interestingly, the new data suggests the human drainage merely sped up a process that would have eventually happened naturally, because of the high seismic activity in the area.
“It does not take much to trigger an earthquake – even strong rainfall can do the job,” said Jean-Philippe Avouac from the California Institute of Technology.