MOSCOW, May 17. /TASS/. Russian scientists have proven that a rise in earthquake activity at depths of around 30 km, can precede volcanic eruptions on the Kamchatka Peninsula. The study’s results have been recently published in the scientific journal Nature GeoScience.
"Our research confirms that long-period earthquakes are connected to the transfer of fluids below ground and might be utilized as reliable evidence of the activation of deep parts of the magma system before the beginning of a volcanic eruption," the article stated.
The study was conducted under the guidance of Nikolay Shapiro, Doctor of Geology-Mineralogy Sciences, leading research associate at the Institute of Volcanology and Seismology of the Far East Branch of the Russian Academy of Sciences and of the Laboratory of Seismology of the Paris Institute of Earth Physics and with financial help from the Russian Foundation for Basic Research. Scientists focused on the volcanoes of Klyuchevsky group on Kamchatka, one of the most active in the world. Some researchers assume that the volcanoes of this group have a joint magma center situated at a depth of about 30 km. Through this center by way of a complex channel system, magma rises to the smaller reservoirs located under each volcano.
Researchers analyzed the data taken from seismographs of that region collected in 2011 and 2012 with a special focus being placed on the long-period earthquakes, which are caused by the flow of magma below ground and changes to pressure in the magma source.
The scientists classified the long-period earthquakes on Kamchatka into two groups: those taking place at a depth less than 5 km and those appearing at about 30 km. Given that, the magnitude of both types of earthquakes has not exceeded the value of 2.5 implying that they could not be felt above ground.
Scientists fixed a surge in activity of deep long-period earthquakes at the beginning of 2011, which were accompanied by a rise in pressure of the magma source at a roughly 30-km depth. This pressure originated from the accumulation of light gaseous constituent of magma fluids, which ‘push’ the magma upwards.
By this means, in April 2011, from November 2011 till February 2012, and from April to October 2012, an upsurge in the activity of deep long-period earthquake followed by volcano eruptions had been recorded. In that way, in April 2011 and September 2012, the volcano Bezymianny spit up explosive eruptions, while in August 2012, the eruption of volcano Klyuchevsky started.
The last period of activity of deep long-period earthquakes preceded the eruption of Tolbachik lasting from November 2012 to August 2013.