Text Box: GE5185 Volcanology - Fall 2011
Text Box: Big Ideas in Volcanology
Text Box: Controlling Specific Hazards

Can humans stop or prevent specific volcanic phenomena?  It is not uncommon for lava flows, lahars, volcanic gasses, pyroclastic flows, ash fallout, landslides or edifice collapse threaten human settlements, safety and infrastructure.  Therefore, it is no surprise that multiple efforts have been made to engineer solutions to these hazards.  While engineering controls of some of these specific hazards have had variable results the Big Idea to consider is that attempts have already been made to engineer controls to specific volcanic phenomena. 

Concrete blocks dropped near and through a skylight in a lava tube in an attempt to divert and redirect the flow. Etna, 1992.  Photo by Claude Grandpey. Obtained from Big Think

Successful lava diversion using earthen barriers at Etna, 1983.  Photo by Jack Lockwood, USGS. Obtained from Oregon State University

Text Box: Because lava flows are often slow moving, low energy, move downhill and are constrained by topography there is has been a good success rate in controlling the direction  or rate of the flow.  Engineering techniques might include diversion barriers, flow redirection and lava cooling with water or endothermic reactions.

In 1973 the eruption of Heimeay produced a lava flow that threatened to destroy the port town of Vestmannaeyjar.  By spraying sea water the residents successfully cooled and stopped the advancing lava. Photo courtesy of Sigureir Jonasson. Obtained from USGS 

Bombing lava flows has been an  idea for many years and has been attempted at Mauna Loa at least three times:1935, 1942 and again in the mid-1970’s.  It was also attempted on a lava flow at Etna in 1992 in an attempt to open a skylight and allow for concrete blocks (above left) to be dropped into the flow.  Photo from Lockwood and Torgerson (1980).

Chemical engineering has been suggested as a means to stop or slow a lava flow (Schuiling, 2008).  While this has not yet been tried, the idea is to introduce carbonate rocks such as dolomite or limestone to the lava.  The ensuing endothermic reaction would rapidly cool the lava, increase its viscosity and slow or stop the flow.  Photo obtained from Indiana University.

Text Box: Lahars have killed more people than other volcanic hazard.  The most effective means for controlling a lahar is suppression and diversion.  As Lahars follow the laws of fluvial dynamics  it is assumed that protective steps used for flood and erosion control will also be effective for controlling lahars.  However, these structural engineering technics are only realistic from small to medium sized flows.

Sabo dams  are built at right angles to flow direction and are designed to minimize damages from lahars and volcanic mudflows.  This iron grid Sabo dam in Takayama, Japan works by trapping large rocks and debris  and prevents them from traveling further downstream. Photo obtained from Disaster Prevention Research Institute.

Training dikes are constructed parallel to the drainage and work to dissipate the energy and guide the flow to safe zones where material is allowed to accumulate.  Photo obtained from Sabo International.

Sabo dams only offer a temporary solution as they will eventually fill with sediments. Image obtained from  Wakayama Prefecture.

Text Box: A limnic eruption, or lake overturn, is the sudden eruption of CO2 from the depths of a volcanic lake. This can be the result of some perturbation (disturbance of motion) such as an earthquake, landslide or injection of hot gas.  The rapid release of large volumes of toxic gas can be lethal to people and communities adjacent and downslope from the lake.  Recently engineering solutions have been developed to passively release this gas from bottom of volcanic lakes.

This series of sabo dams on the Oshigadani River, Japan is designed to suppress the production and flow of sediment. Photo obtained from Photo Volcanica.

The principal of degassing requires a small pump to raise saturated water to a point where lower pressure allows for the expansion and exsolution, or release, of the gas (in the form of bubbles) from the water which then lifts the water column to the surface.  Once this process has started it will be self-driven.  Image obtained from Wikipedia.

Degassing at Lake Nyos, Cameroon. In 1986 a limnic eruption killed 1,700 people.  Photo obtained from University of Arizona.

Volcanic ash cloud from the 2010 eruption of Eyjafjallajökull. Photo obtained from Wikipedia.

Could we seed a volcanic ash cloud to induce ice nucleation which might encourage particle aggregation and promote fallout? Image modified from Wikipedia.

Text Box: Volcanic ash is a ubiquitous product from most volcanic eruptions.  It poses a great threat to structures, agriculture, water supplies, aviation and human health. Is it possible to engineer technique to induce particle aggregation in volcanic clouds and encourage fallout? Volcanologists and atmospheric scientist are currently investigating and modeling the processes that naturally influence aggregation and fallout.

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If volcanoes are expected to collapse catastrophically they may pose a disastrous threat to people and communities.  What if it were possible to remove that material with all that dangerous potential energy.

Collapse at Montserrat.  Photo obtained from RedOrbit.

We can remove mountaintops to mine coal.  Couldn’t we excavate a volcanic edifice to reduce the collapse hazard?  Photo by Vivian Stockman, obtained from Ohio Valley Environmental Coalition.