1. Monitoring Volcanoes

The USGS Volcanic Monitoring & Hazards Program monitors volcanoes 1. Flows for signs of possible activity. 2. Explosive blasts Indicators of possible volcanic activity include seismic activity, 3. Pyroclastic flows ground deformation, volcanic 4. Volcanic ash gases, and changes in water 5. levels and chemistry. USGS Seismometers can send 6. Volcanic gases information continuously to monitor volcanoes. Geologists look for specific types of that are often associated with volcanic activity such as “harmonic

Eruption of Chaiten during a storm at night tremors” that may indicate the Source: Eyevine movement of magma. USGS

Interferometric synthetic As magma intrudes upward into a USGS aperture radar (InSAR) volcano, deformation of the ground is a form of remote may be observed. sensing (from a space- Ground deformation is monitored with borne platform) using tiltmeters and high resolution GPS radar to detect changes stations. in the shape of the Earth’s surface. Inflation may proceed a volcanic eruption followed by deflation The interferogram shows ground USGS deformation in the Kilauea caldera from January 17-February 19, 2010. Each color cycle is represents ~1.5 cm deformation; it shows >3 cm change related to cycles of deflation and inflation centered within Kilauea caldera. Interferograms such as this can be used to monitor the inflation of a volcano that may proceed an eruption. 2. Volcanic Hazards: Lava Flows Lava flows are probably the least hazardous of all processes in volcanic eruptions. The style of eruption (explosive or more fluid) depends on a number of factors including lava composition and volatile content. Basaltic (mafic) lava flows are generally very fluid (low Prior to the massive 1980 eruption of Mt. Saint Helens, a "bulge" developed on the north side as magma pushed up within the peak. Measurements indicated viscosity) and can travel the bulge was growing at a rate of up to ~1.5 meters per day. Part of the significant distances. volcano's north side had been pushed upwards and outwards over 135 meters. Hawaii News Now

The map shows the lava flow 3. Volcanic Hazards: Explosive Blasts on the island of Explosive blasts from Hawaii. violent volcanic eruptions The zones of the hazard are can be a significant defined by the proximity to an hazard. The hazard may active vent and topography be signficantly increased (lava flows downhill). with a lateral blast such as the 1980 eruption of Mount St. Helens. The images show the change in Mount St. Helens as a result of the prior to the 1980 eruption after the 1980 eruption lateral blast during the 1980 eruption. Note that much of the flank of the Kilauea has been erupting nearly mountain was blown continuously since 1983. away. After the 1980 eruption, the 4. Volcanic Hazards: Pyroclastic Flows blast zone extended up to The eruption of a composite 19 miles from the volcano volcano can result in the Mayon Volcano, Philippines and resulting in trees and production of a very hot cloud of structures being blown gas and ash (up to 700°C) that down. is heavier than air. As it moves out of the volcanic vent, it moves downslope at speeds of up to 80 USGS

km/hour. Mt. St. Helens This is known as an ash flow or . These types of eruptions can move rapidly up to 10’s of km Slowly the forest around from their source and are utterly Mount St. Helens has devastating. slowly recovered. USGS

http://earthobservatory.nasa.gov/Features/WorldOfChange/sthelens.php

5. Volcanic Hazards: Volcanic Ash The photos to the right show debris (pumice, ash, etc.) carried Ash can be a significant by pyroclastic flows hazard for infrastructure and health. The 1980 eruption of Mount St. Helens resulted in 540,000,000 tons of ash falling over an area of more than 22,000 square miles.

Hazards include: NASA •Disruption of infrastructure including electrical grids and water supply. •Navigation hazard for aircraft. Crandelland Nichols, 1987 •Environmental and Map of hazard zones for pyroclastic flows from future agricultural impacts. eruptions at or near the summit of Mount Shasta. •Human and animal health. USGS Volcanic ash from the eruption 6. Volcanic Hazards: Lahars (volcanic mud flows)5. of Eyjafjallajökull disrupted air A large eruption can produce travel in Europe in 2010. a known as a . The ash is hard and abrasive These occur when the and can quickly cause significant to jet engines. volcanic ash and debris become water-saturated. There is an international monitoring network to provide Composite volcanoes may data on ash clouds and contain large amounts of establish no fly zones. water in the form of snow and ScienceKids glaciers that melted nearly

Volcanic Ash Advisory Center instantaneously during a major eruption. The resulting moves down valleys and can be very destructive.

The USGS has installed a network of sensors that detect lahars by measuring ground vibrations. Detection of a lahar would trigger an immediate planned emergency response actions. Dams and other structures have been built to contain or lessen the impact of lahars. USGS In 1985, 20,000 people were killed in Colombia by a lahar when Nevado del Ruiz erupted. OSU Volcano World 7. Volcanic Hazards: Volcanic Gases Gases released by volcanoes include H2O, CO2, sulfur gases, and many other components. It is estimated that ~3% of deaths related to volcanic hazards are due to gases including asphyxiation and acid corrosion. USGS The 1986 emission (lake overturn) of volcanic gasses at Lake Nyos in Cameroon resulted in the deaths of ~1700 people and 2500 livestock within 25 km of the lake.