Volcanic Hazards

LAVA

Lava often poses the least risk in an eruption Lava often poses the least risk in an eruption It is partly the thickness of the lava that determines how explosive an eruption is. It is partly the thickness of the lava that determines how explosive an eruption is.

ASH

Ash can cause roofs to collapse and cover the landscape Ash can cause roofs to collapse and cover the landscape Other objects ejected from the volcano can crash back down and kill people. Other objects ejected from the volcano can crash back down and kill people. Can affect the climate. Can affect the climate.

MUDSLIDES (LAHAR)

Lahars are one of the biggest killers during an eruption. Lahars are one of the biggest killers during an eruption. Mixture of solid debris and water that sweeps down the mountain Mixture of solid debris and water that sweeps down the mountain Looks like a mass of wet concrete. Looks like a mass of wet concrete.

This lahar carried away this bridge 55 miles away from Mt. St. Helens. This lahar carried away this bridge 55 miles away from Mt. St. Helens. Lahars killed 23,000 people in a Colombia eruption Lahars killed 23,000 people in a Colombia eruption

This house was impacted by a lahar in Japan in 1995.

PYROCLASTIC FLOW

Another major killer Another major killer Hot, turbulent clouds of ash and gas Hot, turbulent clouds of ash and gas Can travel over 100 mph, can be over 1000 degrees Can travel over 100 mph, can be over 1000 degrees A pyroclastic flow killed 30,000 people here. A pyroclastic flow killed 30,000 people here.

Mount St. Helens had 17 separate flows on May 18 th eruption Mount St. Helens had 17 separate flows on May 18 th eruption

GAS