Tilt Observations on the Kamchatka Peninsula in 2012–2016

The paper presents the results of tiltmeter observations on the Kamchatka Peninsula in 2012–2016. Of the six tiltmeter stations operating in this period, two were successful, located in the area of the Klyuchevskaya volcano group, where tiltmeters were installed taking into account the technical requirements. During the period under consideration, two significant geodynamic events occurred on the Kamchatka Peninsula: the Sea of Okhotsk earthquake with MW = 8.3 and a source depth of 630 km; the Tolbachik Fissure eruption, named after the 50th anniversary of the Institute of Volcanology (TFE-50). The simultaneous occurrence of an anomaly, which can be regarded as a precursor, in the behavior of the tilts at two points, as well as activation of a remote foreshock in Avacha Bay, indicate a single geodynamic process on a regional scale preceding the Sea of Okhotsk earthquake. At the point closest to the TFE-50 eruption (distance about 40 km), the N–S component shows a well-pronounced anomaly that began 5 months prior to the eruption, with a positive tilt of ~70 µrad. This indicates the complex geodynamic processes occurring before the TFE-50 eruption, caused by magma migration in layers with neutral buoyancy according to the geophysical model of the magma feeder system of the Klyuchevskaya volcano group. The obtained tilt data indicate that they can be a very significant supplement to the modern method of observing movements of the Earth’s surface using GPS technology.