Stromboli eruption 2007: pyroclastic flows

9 March:From about 5 to 5:30pm, a highly unusual phenomenon on Stromboli was observed: Small pyroclastic flows travelled down on the Sciara del Fuoco below the new lava flow that had started from the new fissure vent at 500 m. These flows were probably triggered by collapse of incandescent material of the lava flow front, but perhaps as well by ground movements along the new fracture corresponding to the new vent higher above. In the latter case, they would be just a more energetic expression of the rolling clouds of vapour and dust we observed along the same path earlier.

The lava flow front from the 400 m vent in the foreground, rockfalls in the center and dust and steam escaping from the inferred new fracture on the Sciara in the background.

At around 5pm, the front of the new flow and/or material from the ground on the (inferred) fracture mobilizes into small pyroclastic flows.

Close-up of the origin area of one of the first flows, about 200 m downhill from the lava flow front.

Fully grown pyroclastic flow.

The end of the flow at the coast.

Another, more powerful pyroclastic flow develops minutes later (1)

Flow on its way down (2)

Flow ending on the shore (3)

Ash and dust after the passage of a flow.

Sliding of glowing blocks triggering another flow (1)

A second later, the flow has moved 50 m downhill (2)

Glowing blocks at the base of the same flow (3)

A weaker pyroclastic flow...

...ending meters away from the shore where the glowing blocks within it separate.

Yet another flow...

...ending on the shore.