The occurrence and the style of volcanic eruptions are largely controlled by the ways in which magma is stored and transported from the mantle to the surface through the crust. Nevertheless, our understanding of the deep roots of volcano-magmatic systems remains very limited. Here, we use the sources of seismovolcanic tremor to delineate the active part of the magmatic system beneath the Klyuchevskoy Volcanic Group in Kamchatka, Russia. The tremor sources are distributed in a wide spatial region over the whole range of crustal depths connecting different volcanoes of the group. The tremor activity is characterized by rapid vertical and lateral migrations explained by fast pressure transients and dynamic permeability. Our results support the conceptual model of extended and highly dynamic trans-crustal magmatic systems.

We apply three different methods based on the analysis of the multicomponent seismic data to detect seismovolcanic tremors and other seismovolcanic signals, to propose an approach to classify them, and to locate their sources. We use continuous seismograms recorded during 1 year by 21 stations at the Piton de la Fournaise volcano (La Réunion, France). The first method allows the detection of seismovolcanic signals based on stability in time of the intercomponent cross‐correlation function. Two other methods based on the simultaneous analysis of the whole network can be used to detect seismovolcanic signals and to locate their sources. In the first network‐based method, the seismic wavefield is analyzed by calculating the width of the network covariance matrix eigenvalue distribution.The second network‐based method consists in performing the 3‐D backprojection of the interstation cross correlations in order to calculate the network response function. Simultaneous analysis of the parameters measured by the three different methods can be used to classify different types of seismovolcanic tremors. Our results demonstrate that all three methods efficiently detect seismovolcanic tremors accompanying the 2010 eruptions and the preceding pre‐eruptive seismic swarms. Furthermore, Methods 2 and 3 based on simultaneous analysis of the whole network detect a large number of volcanic earthquakes. Our location results show that each seismovolcanic tremor is located in a distinct regionof the volcano, close to the eruptive site at a shallow depth, and the preceding seismic crisis is located deeper at about the sea level under the summit crater.