We present the results of tomographic studies using seismic velocity and attenuation in the area of the Colima Volcanic complex (CVC). Our dataset comprises body waves from local earthquakes recorded by the temporary seismic stations of the CODEX network in the Colima area and a few stations of the regional Mapping the Rivera Subduction Zone (MARS) networks, both deployed in 2006–2008. We obtain three‐dimensional distributions of seismic velocities and attenuation in the crust beneath the CVC area. At shallow depths, we observe a large negative anomaly to the south of CVC, coinciding with the location of the Central Colima Graben. This anomaly may represent debris avalanche deposits, as well as shallow magma reservoirs feeding the eruptions of the presently active Volcán de Colima. In contrast, the volcano edifice of Nevado de Colima, which is built of rigid igneous rocks, is associated with high‐velocity and low‐attenuation anomalies at shallow depths. In the deeper section, a major anomaly with high Vp/Vs, low Vs, and high S wave attenuation corresponds to the location of the regional Tamazula fault. As this represents a mechanically weakened zone of the crust, it may form the pathway that feeds CVC. Both velocity and attenuation models show that the fault‐associated conduit brought magma from the mantle through the lower crust to a depth of 15 km. Then, a light fraction of magma may continue to ascend, forming shallow reservoirs beneath the southern flank of CVC.

––The Klyuchevskoy group of volcanoes (KGV) located in the central part of Kamchatka is a unique complex that demonstrates exceptional variety and intensity of volcanic manifestations. These features of the eruptive activity of the KGV are determined by a complex system of magmatic sources in the crust and mantle. While the structure of deep anomalies is quite reliably determined by tomography techniques based on body waves, the structure of the upper crust can only be determined using ambient noise tomography. We present the results of processing data from the KISS temporary network. This network consisted of more than 100 seismic stations that were installed from 2015 to 2016 over a large area covering the Klyuchevskoy group of volcanoes and its surroundings. To retrieve Rayleigh surface waves, cross-correlation of continuous seismic noise records from pairs of stations was used. We obtained the dispersion curves of the group velocities of these Rayleigh surface waves using frequency–time analysis (FTAN) of the calculated correlograms. These curves served as input data for performing ambient noise tomography. Tomography was performed in two stages: (1) computation of two-dimensional group velocity maps for different frequencies and (2) calculation of a three-dimensional model of the shear wave velocity to a depth of about 8 km based on the inversion of local dispersion curves obtained from these maps. The resulting models revealed the structural features of individual volcanic systems of the KGV. High velocities were observed at shallow depths beneath the large basaltic edifices of the Ushkovsky and Tolbachik volcanoes. At greater depths, while the velocity structure beneath Ushkovsky remained unchanged, we detected low velocities beneath Tolbachik. This fact illustrates the difference between dormant and active magmatic systems. Velocity anomalies of a complex shape are observed beneath the Klyuchevskoy, Kamen, and Bezymianny volcanoes, varying both laterally and with depth. Absolute velocities in vertical sections show that the edifices of these volcanoes are relatively low-velocity bodies located on a horizontal high-velocity basement. A low-velocity anomaly was discovered under the Bezymianny Volcano at a depth of 6 km, which is presumably associated with a shallow magma reservoir. An intense low-velocity anomaly was found beneath the Udina Volcano. It was interpreted as an image of a magma reservoir experiencing strong seismic unrest that began in December 2017 and continues to this day.