What are the mystery rumbling noises coming from Herðubreið, a tuya in north-east Iceland?
Observers and scientists are baffled and perplexed.

There are mystery rumbling noises coming from the mesa-shaped volcano Herðubreið in northeast Iceland.
But nobody is able to pinpoint their source. Is it an avalanche, a landslide, a tsunami, a volcano eruption, or something else entirely?
Herðubreið is a tuya in north-east Iceland. A tuya is a flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are somewhat rare worldwide, being confined to regions which were covered by glaciers and had active volcanism during the same period.
Herðubreið is situated in the midst of the Ódáðahraun desert and close to Askja volcano. The desert is a large lava field originating from eruptions of Trölladyngja. End of July 2014, a landslide triggered a tsunami at the Askja volcano. Could it be the cause of these mystery rumbling noises?
First rangers reported the noises, which lasted about 30 seconds. Then rescued French tourists said there had witnessed an avalanche. Now scientists and meteorologists start working on these mystery noises and rumblings.