Daily SumUp

Global tremors that were felt for nine days last year have been traced to massive tsunami caused by a rockslide in Greenland.

Scientists in September last year recorded a 10.88-millihertz seismic signal that originated from East Greenland, according to the journal Science.

Those signals would be picked up by sensors around the world.

"It kept appearing, every 90 seconds for nine days," Dr Stephen Hicks, who was involved in the study, told the BBC.

A team of scientists used seismic data, satellite imagery and photos of the fjord to investigate the cause.

Their study led them to understand that a rock and ice avalanche in Greenland's Dickson fjord on September 16 had triggered a 200-metre tall tsunami.

The tsunami wave was trapped in the narrow fjord, which is 38km long and about 3km wide, and sloshed back and forth.

The movement created so much energy it caused global tremors.

"We've never seen such a large scale movement of water over such a long period," Hicks said.

Scientists in the journal attributed the avalanche to rising temperatures that have thinned glaciers at the bottom of the mountain.

Just 25 days after the September 16 event, the area saw another landside which further eroded the gully.

"We are witnessing a rise in giant, tsunami-causing landslides, particularly in Greenland," Hicks said.