The seismicity before 2012–2013 Tolbachik Fissure Eruption was relatively weak.
Precursor earthquakes were located under the south-eastern part of the volcano.
The frequency of events rose sharply on the eve of the eruption.
According to seismic data the eruption began at 05:15 UTC on November 27, 2012.
First conclusions about eruption were made using seismological data only.