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10 April 2015

Science for Taming Volcanoes

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The 10th and 11th of April of 1815 were two catastrophic days. The summit of Mount Tambora -a 4,300 meter high volcano in the Indonesian island of Sumbawa– erupted violently. The magma devastated nearby villages, killing 60,000 people –according to a conservative estimate. And the side effects affected the whole planet. The year after the disaster, 1816, would be remembered as “the year with no summer” because the cloud of gases emitted by the volcano in the months following the eruption covered the atmosphere, causing global cooling and ruining crops. In Europe, far away from the volcano, the consequences of this mini-climate change were famine, violence and looting, carried out to raid the farmers’ silos. A huge crater -6.5 miles across and one mile deep- evidences the disaster today, on the 200th anniversary of the eruption of Mount Tambora, considered the most powerful eruption ever recorded.

Caldera of Mount Tambora, formed during the 1815 eruption / Credits: Jialiang Gao

“Maybe today we would have prevented those deaths”, says -speaking to OpenMind- Stephen Self, the Berekeley University volcanologist who opened the symposium on the second centenary of the Tambora eruption, held in Bern (Switzerland). “The volcano would be monitored and that would give us weeks or months to evacuate the population”. Two centuries later, the science and technology for predicting when volcanic disasters will occur has evolved dramatically. The report drawn up by Global Volcano Model, the International Association of observatories that monitor the status of volcanoes, indicates that these advances have saved at least 50,000 lives.

The key to this improvement is given by both the study of basic science and technological innovation. Theoretically, the modeling of the complex physical processes that occur in a volcano has allowed producing ever-evolving statistical prediction models. In technological terms, the sum of numerous means of telemetry has refined prediction, which experts compare to the medical diagnosis of a disease: “As in the case of health, a single symptom is not enough”, Self explains. “We need to compile and correlate data on the variation of ground deformation, seismic activity and chemical emissions”.

InSAR image showing the deformation of the volcano Longonot (Kenya) between 2004 and 2006 /Credits: Envisat

Satellites have reinvented the way how this data is obtained. One of the main symptoms of a volcano being at risk of erupting is the ground deformation caused by increased volcanic activity. The InSAR system has enabled great progress by operating in conjunction with classic GPS. A satellite takes two consecutive photographs -separated by a few days- of the same area. Then, by means of interferometry, both photographs are overlapped in order to create a third image showing millimetric ground deviations: “We must complement this with GPS, because a period of several days is not operationally adequate for the constant monitoring of a volcano”, explains Carmen López Moreno, manager of the Central Geophysical Observatory of the National Geographic Institute of Spain. “With a GPS network, ground displacement can be measured in one or more specific points. The two techniques are complementary, because InSAR provides data of large areas that can be correlated with those points”.

This ground deformation must be added to other symptoms for sounding the alarm. One of them is the seismic activity and in order to detect it a network of high precision seismographs must be employed to notice earthquake swarms, small earthquakes (undetectable by traditional measurement devices) that are caused by the internal movement of fluids in the volcano. Another key factor is the emission of gases, mainly SO2 and CO2 in abnormal amounts. Satellites play a key role yet again. NASA’s MODIS and OCO-2 are responsible for detecting abnormalities in this parameter, which may indicate possible eruptions. And in the future, cosmic radiation is expected to be usedand specifically, the elementary particle muon– to obtain unprecedented resolution images of the inner part of volcanoes, which will allow assessing changes in their density.

Despite all this boom in research and technology, there is much room for improvement in terms of the effectiveness of predictions. The phase of volcanic unrest (volcanic restlessness) that precedes most eruptions, culminates in an eruption one out of every two times (47%) and spans over an average period of 500 days, the symptoms rising abruptly hours before the eruption. More seriously, according to the Global Volcano Model study, only 35% of permanent observatories have an adequate technical and scientific capability to monitor volcanoes. The report also predicts that the likelihood of a violent eruption like that of Mount Tambora occuring throughout the 21st century is 33%.

For volcanologist Stephen Self, the remedy is clear: “Money. Money is still the main constraint for countries with high volcanic risk not to fund an observatory. And this also restricts research, because we need to monitor more eruptions to know what the determining factor is in order to define our predictions”. The detailed study of the forthcoming eruptions will enable the improvement of prediction technology and the statistical models theorizing volcanic activity. It will be another step on the scientific path to “tame” volcanoes. Eruptions will continue to be wild and inevitable natural phenomena, but understanding and predicting the behavior of volcanoes allow us to be prepared for the next Tambora and continue saving lives.

By Ángel Luis Sucasas for Ventana al Conocimiento (Knowledge Window)

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