Lecture 9: Volcanic Hazards Our Hazardous Environment GEOG 1110 Dr. Thieme

Volcanic Hazards gases 2 CO 2 SO 2 H 2 S F 2 lava flows bombs, ash pyroclastic flows landslides mudflows (“lahars”)

Molten Sulfur and Sulfur Gases in an Indonesian volcano

Lake Nyos, Cameroon, West Africa

Carbon Monoxide (CO) is poisonous

Mt Unzen, Japan 1991 eruption pyroclastic flows killed 43 more than 600 homes and one school destroyed claimed the lives of volcanologists Maurice and Katya Kraft

Pyroclastic Flow (nuée ardentes)

Pyroclastic Flows along the Mitzunashi River

A lahar triggered by rainfall on the Nima II River in Guatemala. The lahar developed on the slopes of Santiaguito volcano

Damage caused by a lahar on the Toutle River triggered by the Mount St. Helens eruption in Washington state.

Pompeii - pyroclastic flows killed over 16,000

High Risk in Cascade Mtns High Risk in Yellowstone Moderate Risk in Areas of Southwest Caldera eruption could impact entire U.S.

06.13.a-d How Do We Monitor Volcanoes? Increased seismic activity Increased gas activity Changes in topography Changes in temperature

Volcanoes and climate Explosive eruptions emit huge quantities of gases and fine-grained debris into the atmosphere which filter out and reflect a portion of the incoming solar radiation Examples of volcanism affecting climate Mount Tambora, Indonesia – 1815 Krakatau, Indonesia – 1883 Mount Pinatubo, Philippines