Volcanic Hazards p. 138-140, web reading Volcano Facts Volcano Hazards Fall processes Flow processes Other types Predicting Volcanic Eruptions

Giant Caldera Volcano: Yellowstone Old Faithful Ground collapse ~ Area of NYC Material ejected ~1000 km3 Ash Fall

Toba, Indonesia The Biggest Eruption? 75,000 years ago

Toba, Indonesia The Biggest Eruption? Caldera diameter 100x35 km Volume erupted 2,800 km3 10 cm of ash fell in India, 3000 km away Volcanic winter for a decade With global cooling 3-5°C Might have affected human evolution

Volcanic Eruptions over the last 10,000 years 1300 active volcanoes 550 eruptions (< 2000 yrs) <10% potentially destructive volcanoes have been studied in detail ~800 million people worldwide @ risk >50% of world’s volcanoes in nations with per capita GDP <20% US

Volcanic Hazards Fall Processes Flow Processes Web reading

Lava Flows Basaltic lava (low viscosity) Usually slow moving (<10 mph) Rarely life threatening

Nyiragongo volcano, Congo Goma, Jan. 19, 2002 Molten lava flows down a street in the eastern Congolese town of Goma Saturday Jan. 19, 2002. More than half of Goma has been consumed by lava forcing several hundred thousand people to flee the city after a nearby volcano erupted on Thursday Jan. 17. (AP Photo/Sayyid Azim) Congolese residents of Goma watch as part of the main street lies covered in lava, January 19, 2002. The Nyiragongo volcano erupted, killing more than 45 people and sending thousands of others fleeing into neighboring Rwanda. REUTERS/George Mulala Nyiragongo volcano, Congo Goma, Jan. 19, 2002

Nyiragongo volcano, Congo Goma, Jan. 19, 2002

Pyroclastic Flows High density mixture of hot ash, rock, and hot gases Temp. >500C Velocity > 80-100 mph

Pyroclastic Flows

Mt Unzen, Japan Pyroclastic flows Eruption in June, 1991, killed 40 journalists and 3 experienced volcanologists Copy words from Stan’s version

Ash Falls (Tephra Falls) can cover large areas for days to weeks ash will last on the ground for months to years making land and water unusable provide material for future hazards (lahars) Mount Pinatubo, Philippines June 1991

Ash fall in Rabaul, Papua New Guinea, 1994

Volcanic Ash–Danger to Aircraft High-pressure nozzle guide vane assembly removed from Rolls-Royce RB211-524C2-19 after volcanic ash encounter shows heavy deposits of resolidified ash on nozzle guide vane leading edges. This assemblage was removed from the British Airways B-747 that suffered a temporary four-engine flameout after flying through an ash plume from Indonesia's Mt. Galunggung on June 24, 1982. Volcanic ash can be a serious hazard to aviation even thousands of miles from an eruption. Airborne ash can diminish visibility, damage flight control systems, and cause jet engines to fail. USGS Part of a 747 engine

Poisonous Gas Emissions Volcanic Smog-Vog CO2, SO2, HCl, HF H2S Lake Nyos, Cameroon

Poisonous Gas Emissions Lake Nyos, Cameroon (1986) Controlled degassing, 1995 Lake Nyos “River” of CO2 50 m thick layer Bottom of lake Saturated in CO2 CO2 gas from Magma

Volcanic Landslides Mt. St. Helens May 18, 1980 Debris Flow 2.3 km3 of material Largest debris landslide in recorded history

This downstream view of the North Fork Toutle River valley, north and west of St. Helens, shows part of the nearly 2/3 cubic miles (2.3 cubic kilometers) of debris avalanche that slid from the volcano on May 18. This is enough material to cover Washington, D.C. to a depth of 14 feet (4 meters). The avalanche traveled approximately 15 miles (24 kilometers) downstream at a velocity exceeding 150 miles per hour (240 km/hr). It left behind a hummocky deposit with an average thickness of 150 feet (45 m) and a maximum thicknes of 600 feet (180 meters). The avalanche traveled approximately 15 miles downstream at a velocity exceeding 150 mph. It left behind a hummocky deposit with an average thickness of 150 feet and a maximum thickness of 600 feet.

Mt. St. Helens May 18, 1980 Figure 5.10

Mt. St. Helens

Lahars (Mudflows) A mixture of volcanic fragments and water Mudflows are channeled along valleys on the flanks of volcanoes. Mudflows have the consistency of wet concrete and move at high speeds (up to 20-60 mph). Pinatubo

Nevado del Ruiz Nov. 13, 1985 Canyon that channeled the lahar that destroyed Armero and killed 23,000 people

The November 13, 1985 lahar from Nevado del Ruiz Town of Armero The November 13, 1985 lahar from Nevado del Ruiz The November 13, 1985 lahar from Nevado del Ruiz -- The lahar deposit forms the flat plane at the base of the River Lagunillas canyon. The lethal lahar killed over 23,000 people, most of which from from the town of Armero, located about 70 kilometers from the summit of the volcano. Courtesy of R.J. Janda, USGS. The November 13, 1985 lahar from Nevado del Ruiz, Columbia -- After travelling over 70 kilometers from the summit of the Nevado del Ruiz volcano, this destructive lahar buried the village of Armero at the mouth of the River Lagunillas canyon, which was located in the center of this photograph. The lahar killed over 23,000 people, most of which were from Armero. Courtesy of J. Marso, USGS.

Volcano Monitoring and Prediction Goal: Prevent a Volcanic Crisis from turning into a Volcanic Disaster

Volcanoes of the “Lower 48”

Volcano Monitoring and Prediction Long-Term based on Historical Records and Geologic History Age-dating of volcanic deposits  Eruption Frequency Types and amounts of eruption products  Size of Eruption

Volcano Monitoring and Prediction Short Term: systematic observations of volcano’s visible and subsurface activity Seismicity Ground tilt Gas emissions

Rising Magma Ground Deformation Rising magma and increasing pressure exerted by gases often cause volcanoes to deform, or swell, before an eruption

Rising Magma Moving Magma and Volcanic Fluids Trigger Earthquakes High pressure causes rocks to break, triggering earthquakes Rising magma and volcanic gases exert pressure Magma rises into reservoir beneath volcano

Forecasting Volcanic Activity Ideal Forecast includes Location Timing Character of eruption and magnitude

Forecasting Volcanic Activity Ideal Forecast includes Location Timing Character of eruption and magnitude Effective Forecasting involves Scientists Public officials News media Informed Public Friday Video Path of a Killer Volcano Mt. Pinatubo eruption of 1991