Airborne volcanic ash is one of the most common, far-travelled, direct hazards associated with explosive volcanic eruptions worldwide. Management of volcanic ash cloud hazards often requires coordinated efforts of meteorological, volcanological, and aviation authorities from multiple countries. These international collaborations during eruptions pose particular challenges due to variable crisis response protocols, uneven agency responsibilities and technical capacities, language differences, and the expense of travel to establish and maintain relationships over the long term. This report introduces some of the recent efforts in enhancing international cooperation and collaboration in the Northern Pacific region.

Trace element data for volcanic rocks of the Payalpan volcano-tectonic structure (Sredinny ridge, Kamchatka) allows distinguishing typical island-arc, rift and transitional series of rocks. Island-arc basaltic and differentiated magmas erupted in the Late Miocene and Pliocene. In the Late Pliocene – Early Pleistocene, there was a voluminous event dominated by the basaltic magmas of rift-type series. This event followed by voluminous eruptions of mainly basaltic andesites of transitional series. At the end of the Pleistocene and probably during the Holocene volume of eruptions diminished and composition of magmas shifted towards rift-type basaltic series. Practically in the same area in the Pleistocene and Holocene the Icha volcano produced basaltic andesite to rhyolite magmas of the island-arc and transitional series. Reasons for spatial overlapping and temporal evolution of the island-arc and rift magma types are also discussed.

A key problem of any video volcano surveillance network is an inconsistent quality and information value of the images obtained. To timely analyze the incoming data, they should be pre-filtered. Additionally, due to the continuous network operation and low shooting intervals, an operative visual analysis of the shots stream is quite difficult and requires the application of various computer algorithms. The article considers the parametric algorithms of image analysis developed by the authors for processing the shots of the volcanoes of Kamchatka. They allow automatically filtering the image flow generated by the surveillance network, highlighting those significant shots that will be further analyzed by volcanologists. A retrospective processing of the full image archive with the methods suggested helps to get a data set, labeled with different classes, for future neural network training.

Three-dimensional structural images of the P-wave velocity below the edifice of the great Klyuchevskoy group of volcanoes in central Kamchatka are derived via tomographic inversion. The structures show a distinct low velocity feature extending from around 20 km depth to 35 km depth, indicating evidence of magma ponding near the Moho discontinuity. The extensive low velocity feature represents, at least to some degree, the source of the large volume of magma currently erupting at the surface near the Klyuchevskoy group.

Detailed studies of volcanic tremor envelopes with frequencies ranging from 5.5⋅10-6 to 2.5⋅10-2 Hz (50 hrs - 40 sec), recorded during the Klyuchevskoi volcano eruptions of 1983 and 1984, revealed five major frequencies: 1.1⋅10-2 Hz (T1 = 1 min 34 sec), 2.5⋅10-3 Hz (T2 = 6 min 10 sec), 4.2⋅10-4 Hz (T3 = 40 min), 5.1⋅10-5 Hz (T4 = 5 hrs 30 min), 7.7⋅10-6 Hz (T5 = 36 hrs), as well as superpositions of their harmonics. In the 1993 eruption, fluctuations in the volcanic tremor envelopes have frequencies of TI = 2 hrs 48 min and TII = 6 hrs 12 min, which correspond to periodicities in the dynamics of eruptions identified by visual observations since 1932. The distribution of peak amplitudes has been found to vary in relation to eruption intensity—increasing eruption strength correlates with an increase in the amplitude of low frequency peaks, and vice versa. It is concluded that volcanic tremor allows monitoring of eruption dynamics. Possible reasons for the occurrence of periodicities are discussed, but a comprehensive model for this phenomenon has not yet been developed.

The Holocene eruptive history of Shiveluch volcano, Kamchatka Peninsula, has been reconstructed using geologic mapping, tephrochronology, radiocarbon dating, XRF and microprobe analyses. Eruptions of Shiveluch during the Holocene have occurred with irregular repose times alternating between periods of explosive activity and dome growth. The most intense volcanism, with frequent large and moderate eruptions occurred around 6500–6400 BC, 2250–2000 BC, and 50–650 AD, coincides with the all-Kamchatka peaks of volcanic activity. The current active period started around 900 BC; since then the large and moderate eruptions has been following each other in 50–400 yrs-long intervals. This persistent strong activity can be matched only by the early Holocene one.
Most Shiveluch eruptions during the Holocene produced medium-K, hornblendebearing andesitic material characterized by high MgO (2.3–6.8 wt %), Cr (47–520 ppm), Ni (18–106 ppm) and Sr (471–615 ppm), and low Y (> 18 ppm). Only two mafic tephras erupted about 6500 and 2000 BC, each within the period of most intense activity.
Many past eruptions from Shiveluch were larger and far more hazardous then the historical ones. The largest Holocene eruption occurred ∼1050 AD and yielded >2.5 km3 of tephra. More than 10 debris avalanches took place only in the second half of the Holocene. Extent of Shiveluch tephra falls exceeded 350 km; travel distance of pyroclastic density currents was > 22 km, and that of the debris avalanches ≤20 km.

Late Pleistocene-Holocene volcanism in Kamchatka results from the subduction of the
Pacific Plate under the peninsula and forms three volcanic belts arranged in en echelon manner
from southeast to northwest. The cross-arc extent of recent volcanism exceeds 250 km and
is one of the widest worldwide. All the belts are dominated by mafic rocks. Eruptives with
SiO2>57% constitute ~25% of the most productive Central Kamchatka Depression belt and
~30% of the Eastern volcanic front, but <10% of the least productive Sredinny Range belt.
All the Kamchatka volcanic rocks exhibit typical arc-type signatures and are represented
by basalt-rhyolite series differing in alkalis. Typical Kamchatka arc basalts display a strong
increase in LILE, LREE and HFSE from the front to the back-arc. La/Yb and Nb/Zr increase
from the arc front to the back arc while B/Li and As, Sb, B, Cl and S concentrations decrease.
The initial mantle source below Kamchatka ranges from N-MORB-like in the volcanic front
and Central Kamchatka Depression to more enriched in the back arc. Rocks from the Central
Kamchatka Depression range in 87Sr/86Sr ratios from 0.70334 to 0.70366, but have almost
constant Nd isotopic ratios (143Nd/144Nd 0.51307–0.51312). This correlates with the highest
U/Th ratios in these rocks and suggest the highest fluid-flux in the source region.
Holocene large eruptions and eruptive histories of individual Holocene volcanoes have been
studied with the help of tephrochronology and 14C dating that permits analysis of time-space
patterns of volcanic activity, evolution of the erupted products, and volcanic hazards.