Deep and shallow long-period volcanic seismicity linked by fluid-pressure transfer

• Published in: Nature geoscience Vol. 10; no. 6; pp. 442 - 445
• Main Authors: Shapiro, N. M., Droznin, D. V., Droznina, S. Ya, Senyukov, S. L., Gusev, A. A., Gordeev, E. I.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01.06.2017
• Subjects: Earth science; Earthquakes; Sciences of the Universe; Volcanoes; Volcanology; Russia; Russia, Kamchatskaya
• ISSN: 1752-0894; 1752-0908
• DOI: 10.1038/ngeo2952

Volcanic long-period earthquakes are attributed to pressure fluctuations that result from unsteady mass transport in the plumbing system of volcanoes. Whereas most of the long-period seismicity is located close to the surface, the volcanic deep long-period earthquakes that occur in the lower crust and uppermost mantle reflect the activity in the deep parts of magmatic systems. Here, we present observations of long-period earthquakes that occurred in 2011-2012 within the Klyuchevskoy volcano group in Kamchatka, Russia. We show two distinct groups of long-period sources: events that occurred just below the active volcanoes, and deep long-period events at depths of ∼30 km in the vicinity of a deep magmatic reservoir. We report systematic increases of the long-period seismicity levels prior to volcanic eruptions with the initial activation of the deep long-period sources that reflects pressurization of the deep reservoir and consequent transfer of the activity towards the surface. The relatively fast migration of the long-period activity suggests that a hydraulic connection is maintained between deep and shallow magmatic reservoirs. The reported observations provide evidence for the pre-eruptive reload of the shallow magmatic reservoirs from depth, and suggest that the deep long-period earthquakes could be used as a reliable early precursor of eruptions.