Geologists have uncovered a link between earthquakes and volcanoes of Kamchatka
MOSCOW, may 15 — RIA Novosti. Observation of Kluchevskaya Sopka and its neighbours have helped Russian scientists to figure out how to use a deep “volcanic” earthquakes for predicting imminent eruptions, according to a paper published in the journal Nature Geoscience.
“To accurately predict exactly when the eruption will occur after the activation of a deep lesion, it is impossible. You can roughly say that if the depth of the observed increase in activity of long-period earthquakes, we can expect that in a few weeks or months, will activate the upper part of the volcanic system, with possible eruptions,” explains Nicholas Shapiro from the Institute of Volcanology and seismology Feb RAS, Petropavlovsk-Kamchatsky, whose word brings the press service of the Russian science Foundation.
Beneath every volcano there is a magma chamber — a reservoir of porous rocks that can absorb large quantities of liquid magma. Before the eruption this camera is full, which leads to its “ballooning” and the rise of elevation in the vicinity of the volcano. Because of how much “swollen” camera, scientists can estimate the amount of the contained magma and to evaluate the strength of the eruption and the likelihood of its occurrence.
The process of filling this chamber, as the scientists explain, usually runs “jerky” and not at a constant speed. As a result, the pressure inside the magma chamber periodically changed dramatically, and these changes give rise to relatively weak and long-period seismic waves, moving in the direction of the surface. People these quakes not felt, but seismologists have fixed their many active volcanoes.
Shapiro and his colleagues found that these shocks can be used for early prediction of volcanic eruptions, watching the seismic activity in the area Klyuchevskaya volcano neighboring volcanoes Bezymianny and Tolbachik Flat in 2011 and 2012.
These observations revealed several interesting patterns. The eruption of each of these three volcanoes are usually preceded by two types of long-period oscillations. First tremors occurred at a depth of 30 kilometers, where it is suspected that a common magmatic chamber, feed Klyuchevskaya Sopka and its two “neighbors”. Then similar but slightly different fluctuations occurred directly beneath the volcanoes themselves, at a relatively shallow depth, in kilometers or even less.
Usually about a month after the onset of oscillations had the eruption, but their presence was not a guarantee of rapid awakening of volcanoes — in some cases, Klyuchevskaya Sopka and its cousins again “fell asleep” and the next disaster was canceled. However, the increase of seismic activity at great depths, as noted by Shapiro of his colleagues, allows to predict possible eruptions and to prepare for them.
On average, as shown by monitoring these fluctuations, magma rises to the surface relatively slow — it moves at a speed of 10 meters per second spends about 2-3 months to overcome the 30 km distance between the deep magma chamber and volcanoes of Kamchatka. In the case of the eruption of Tolbachik volcano in November 2012, this process took 5 months, which leaves a lot of time to prepare for the eruption and to carry out additional measurements.