Tolbachik Research Articles

A Joint Study of Seismicity and SAR Interferometry Observations for Assessing the Possibility of an Eruption of the Dormant Bolshaya Udina Volcano

Seismicity began to be recorded in October 2017 around the dormant Bolshaya Udina Volcano (B. Udina in what follows) situated 10 km southeast of Plosky Tolbachik Volcano. Seismic tomography showed the existence of a long-lived magma chamber south of B. Udina in the area of the Tolud River. The chamber has its top at a depth of about 15 km, and may probably be connected to the Plosky Tolbachik plumbing system (Koulakov et al., 2017). Saltykov et al. (2018) and Koulakov et al. (2019) related the observed resumption of seismic activity to a hypothetical emplacement of magma beneath the Udina volcanoes, pointing out a high likelihood of the resumption of volcanic activity. The present study examines data from permanent seismic stations showing a systematic displacement of the center of seismic energy southward from B. Udina from October 2017 through August 2019. The center characterizes the location of the volume that generates the bulk of seismicity. We used images of the Sentinel-1A satellite (wavelength 5.6 cm) taken from a descending orbit of track 60 during the period from June 7, 2017 through September 23, 2017 (10 images) and during the period from May 21, 2018 to September 30, 2018 (12 images) to determine time series and average velocities of displacement on the slopes of B. Udina. Persistent scatterers could only be identified at the foot of B. Udina. An analysis of displacement time series for the surface of the volcano showed that the character of displacements in 2017 and 2018 on the southwestern and eastern slopes remained nearly the same, while the average rate of displacement on the northwestern slope decreased in 2018. We used three images of the ALOS-2 PALSAR-2 satellite (wavelength 23.5 cm) taken on October 4, 2016, June 13, 2016, and October 2, 2018 from an ascending orbit to construct paired interferograms, which characterize displacements for the time period between images. The displacements on both interferograms did not exceed a few centimeters, except for narrow zones confined to local relief forms. The deformations thus detected were most likely due to surface processes. The deformed volumes related to pressure changes in the magma chamber at a depth of 5 km must have linear dimensions of 10–15 km, while the displacement areas detected in the satellite images are considerably smaller. These results suggested an alternative model that postulates the resumption of seismic activity to accompany the retreat and sinking of magma melt from B. Udina into the chamber in the Tolud R. area as identified by tomographic techniques.

Relationship of the Vp/Vs Parameter with the State of the Magmatic Substance and Activity of the Northern Group of Volcanoes in Kamchatka

The dynamics of the volcanic activity, magmatic feeding system, accumulation, movement, and composition of magmas, and structure of the roots of the Northern group of volcanoes (NGV) in Kamchatka are considered. The results of monitoring the field of the ratio of seismic P- and S-wave velocities, the VP/VS parameter in the region of the Klyuchevskaya volcanic group based on the data of the volcanic earthquakes registered by a network of telemetric seismic stations are presented. The parameter changes in space and time during the periods of volcanic activity development. Each segment of the volcanic structure and period of activity is characterized by the own behavior of the field of VP/VS values. In the intermediate magmatic chamber, low VP/VS values are observed beneath the Klyuchevskoi volcano at a depth of 8 to 10 km and beneath Plosky Tolbachik at a depth of 3 to 5 km, which is related to the state of the substance and temperature in these areas, and the entry of a new melt portion of magma and the fluid-gas component from the crust and the mantle. The relation of volcanic earthquakes and earthquakes in the focal zone of Kamchatka, i.e., the ratio of the subduction zone (the sinking Pacific Ocean Plate) and the feeding source of volcanoes, is considered. It is shown that the Klyuchevskoi peripheral chamber is not the only area feeding the NGV. According to the values of the VP/VS parameter, the volcanoes have different magma compositions, which is determined by the physicochemical and temperature features of the medium. In our opinion, the feeding area of volcanoes from the Northern group is a neutral layer that we have identified.

The new mineral novograblenovite, (NH4,K)MgCl3·6H2O from the Tolbachik volcano, Kamchatka, Russia: mineral description and crystal structure

AbstractThe new mineral novograblenovite, (NH4,K)MgCl3·6H2O, was found on basaltic lava from the 2012–2013 Tolbachik fissure eruption at the Plosky Tolbachik volcano, Kamchatka Peninsula, Russia. It occurs as prismatic, needle-like transparent crystals together with gypsum and halite. Novograblenovite was formed due to the exposure of the host rocks to eruptive gas exhalations enriched in HCl and NH3. Basalt was the source of potassium and magnesium for the mineral formation. Novograblenovite crystallises in the monoclinic space groupC2/c, with unit-cell parametersa= 9.2734(3) Å,b= 9.5176(3) Å,c= 13.2439(4) Å, β = 90.187(2)°,V= 1168.91(2) Å3andZ= 4. The five strongest reflections in the powder X-ray diffraction pattern [dobs, Å (I, %) (h k l)] are: 3.330 (100) (2 2 0), 2.976 (45) ($\bar{1}\; 1\; 4$), 2.353 (29) ($\bar {2}\; 2\; 4$), 3.825 (26) (2 0 2), 1.997 (25) ($\overline {4\; 2} $2). The density calculated from the empirical formula and the X-ray data is 1.504 g cm–3. The mineral is biaxial (+) with α = 1.469(2), β = 1.479(2) and γ = 1.496(2) (λ = 589 nm); 2Vmeas.= 80(10)° and 2Vcalc.= 75.7°. The crystal structure (solved and refined using single-crystal X-ray diffraction data,R1= 0.0423) is based on the perovskite-like network of (NH4,K)Cl6-octahedra sharing chlorine vertices, and comprises [Mg(H2O)6]2+groups in framework channels. The positions of all independent H atoms were obtained by difference-Fourier techniques and refined isotropically. All oxygen, nitrogen and chlorine atoms are involved in the system of hydrogen bonding, acting as donors or acceptors. The formula resulting from the structure refinement is [(NH4)0.7K0.3]MgCl3·6H2O. The mineral is named after Prokopiy Trifonovich Novograblenov, one of the researchers of Kamchatka Peninsula, a teacher, naturalist, geographer and geologist.

Magmatic plumbing systems of the monogenetic volcanic fields: A case study of Tolbachinsky Dol, Kamchatka

Clusters of small-volume volcanoes that individually may be defined as monogenetic, but have interlinked and interconnected plumbing systems, are used to be categorized as monogenetic volcanic fields (MVF). We argue that such volcanic clusters should be distinguished as separate type of volcanism, intermediate between monogenetic and polygenetic. The magma plumbing system structure of the MVF (its complexity and polymagmatic character) is the key argument for the potential separation of them in a classification. To avoid confusion caused by genetic meaning of the used words we suggest using a term “areal volcanism” or “areal volcanic fields” (AVF instead of MVF) as defining this special type of volcanic activity. Here we provide a review of the main characteristic features of one of the largest Holocene AVF, which is active now – the Tolbachik field of cinder cones in the southern part of Klyuchevskaya volcano group (Kamchatka), known in the literature as Tolbachinsky Dol. This paper is focused on the research of magma plumbing system. We consider structural, morphological, geological, geochemical and petrological data on the erupted basalts and their genesis. Specially planned seismic experiments made in 2010–2015 (seismic tomography and microseismic sounding) allowed modeling of the principal elements of the magma plumbing system of Tolbachik AVF. Analysis of the investigations made in this area shows that Tolbachik AVF has a complex, dynamic, variable magmatic feeding system, which can be visualized as a superposition of subvertical and sublateral magma conduits. The contrast composition of the erupted rocks is caused by their different, although genetically connected, magma sources and mixing processes. One of the long-lived eruptive centers of Tolbachik AVF is Plosky Tolbachik stratovolcano, which lost its independent activity and was captured by Tolbachik AVF in Holocene. The AVF formed rejuvenated volcanism using the feeding system of the stratovolcano like an “old anthill”. The magma plumbing system characteristics of Tolbachinsky Dol strongly support the idea of separation of AVF from monogenetic volcanism type in the classification.

Petrological and geochemical evolution of the Tolbachik volcanic massif, Kamchatka, Russia

Abstract Data on the geology, petrography, and geochemistry of Middle–Late-Pleistocene rocks from the Tolbachik volcanic massif (Kamchatka, Klyuchevskaya group of volcanoes) are presented and compared with rocks from the neighboring Mount Povorotnaya, Klyuchevskaya group basement, and Holocene–historical Tolbachik monogenetic cones. Two volcanic series of lavas, middle-K and high-K, are found in the Tolbachik massif. The results of our data analysis and computer modeling of crystallization at different P–T–H 2 O–fO 2 conditions allow us to reconstruct the geochemical history of the massif. The Tolbachik volcanic massif started to form earlier than 86 ka based on K–Ar dating. During the formation of the pedestal and the lower parts of the stratovolcanoes, the middle-K melts, depleted relative to NMORB, fractionated in water-rich conditions (about 3% of H 2 O). At the Late Pleistocene–Holocene boundary, a large fissure zone was initiated and the geodynamical regime changed. Upwelling associated with intra-arc rifting generated melting from the same mantle source that produced magmas more enriched in incompatible trace elements and subduction components; these magmas are high-K, not depleted relative to N-MORB melts with island arc signatures and rift-like characteristics. The fissure opening caused degassing during magma ascent, and the high-K melts fractionated at anhydrous conditions. These high-K rocks contributed to the formation of the upper parts of stratovolcanoes. At the beginning of Holocene, the high-K rocks became prevalent and formed cinder cones and associated lava fields along the fissure zone. However, some features, including 1975–1976 Northern Breakthrough, are represented by middle-K high-Mg rocks, suggesting that both middle-K and high-K melts still exist in the Tolbachik system. Our results show that fractional crystallization at different water conditions and a variably depleted upper mantle source are responsible for all observed variations in rocks within the Tolbachik volcanic massif. Sr–Nd isotopes are consistent with 2–4% crustal assimilation during formation of the pedestal and stratovolcanoes, while the young lava fields do not show evidence of crustal assimilation. Major and trace element data coupled with K–Ar dating provide strong evidence that Mount Povorotnaya, located in 8 km northeast of Plosky Tolbachik, is an old block of the Tolbachik massif pedestal and for the moment it is the oldest (306 ka) known object in Klyuchevskaya group of volcanoes.

The Tolbachik volcanic massif: A review of the petrology, volcanology and eruption history prior to the 2012–2013 eruption

The primary goal of this paper is to summarize all of the published data on the Tolbachik volcanic massif in order to provide a clear framework for the geochronologic, petrologic, geochemical and to a lesser extent the geophysical and tectonic characteristics of the Tolbachik system established prior to the 2012–2013 eruption. The Tolbachik massif forms the southwestern part of the voluminous Klyuchevskoy volcanic group in Kamchatka. The massif includes two large stratovolcanoes, Ostry (“Sharp”) Tolbachik and Plosky (“Flat”) Tolbachik, and a 70 km long zone of the basaltic monogenetic cones that form an arcuate rift-like structure running across the Plosky Tolbachik summit. The Tolbachik massif gained international attention after the 1975–1976 Great Tolbachik Fissure Eruption (GTFE), which was one of the largest eruptions of the 20th century and one of the six largest basaltic fissure eruptions in historical time. By the end of the GTFE, 2.2 km3 of volcanic products of variable basaltic compositions with MORB-like isotopic characteristics covered an area of > 1000 km2. During the following three decades more than 700 papers on various aspects of this eruption have been published both in national and international journals. Although the recent 2012–2013 eruption, which is the main topic of this volume, was not as long as the GTFE in duration or as large in area and volume of the erupted deposits, it brought to the surface a unique volcanic material never found before. In order to understand the data from new eruptions and make significant progress towards a better understanding of the Tolbachik magmatic system it is important to be able to put the new results into the historic context of previous research.

Magma migration at the onset of the 2012–13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analysis

Abstract In contrast of the 1975–76 Tolbachik eruption, the 2012–13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma movement prior to this important eruption. A clear seismic migration within the seismic swarm, started 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava flows, was recorded (at ~ 11:00 UTC, 27 November 2012). In order to get a first order approximation of the magma location, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest that the seismicity migrated toward the eruption location. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano followed by a lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16–20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975–76 Tolbachik eruption and can be considered as a possible aborted eruption.

Infrasound from the 2012–2013 Plosky Tolbachik, Kamchatka fissure eruption

Abstract We use both regional and local infrasound data to investigate the dynamics of the 2012–2013 eruption of Tolbachik Volcano, Kamchatka, Russia during select periods of time. Analysis of regional data recorded at the IMS array IS44 in southern Kamchatka, ~ 384 km from the vent focuses on the eruption onset in November 2012, while analysis of local data focuses on activity in February and August 2013. Signals recorded from Tolbachik suggest a change in eruptive intensity possibly occurred from November 27–30, 2012. Local infrasound data recorded at distances of 100–950 m from the vent are characterized primarily by repeated, transient explosion signals indicative of gas slug bursts. Three methods are employed to pick slug burst events in February and August. The nature of slug bursts makes a monopole acoustic source model particularly fitting, permitting volume outflux and slug radius calculations for individual events. Volume outfluxes and slug radii distributions provide three possible explanations for the eruption style of Tolbachik Volcano from mid-February to late August. Cumulative outflux for slug bursts (i.e. mass of emissions from individual bursts) derived by infrasound for both February and August range from

Reprint of "Seismic monitoring of the Plosky Tolbachik eruption in 2012–2013 (Kamchatka Peninsula Russia)"

Abstract The active basaltic volcano Plosky Tolbachik (Pl. Tolbachik) is located in the southern part of the Klyuchevskoy volcano group on the Kamchatka Peninsula. The previous 1975–1976 Great Tolbachik Fissure Eruption (1975–1976 GTFE) occurred in the southern sector of Pl. Tolbachik. It was preceded by powerful earthquakes with local magnitudes between 2.5 and 4.9 and it was successfully predicted with a short-term forecast. The Kamchatka Branch of Geophysical Survey (KBGS) of the Russian Academy of Science (RAS) began to publish the results of daily seismic monitoring of active Kamchatka volcanoes on the Internet in 2000. Unlike the 1975–1976 GTFE precursor, (1) seismicity before the 2012–2013 Tolbachik Fissure Eruption (2012–2013 TFE) was relatively weak and earthquake magnitudes did not exceed 2.5. (2) Precursory earthquake hypocenters at 0–5 km depth were concentrated mainly under the southeastern part of the volcano. (3) The frequency of events gradually increased in September 2012, and rose sharply on the eve of the eruption. (4) According to seismic data, the explosive-effusive 2012–2013 TFE began at ~ 05 h 15 min UTC on November 27, 2012; the outbreak occurred between the summit of the Pl. Tolbachik and the Northern Breakthrough of the 1975–1976 GTFE. (5) Because of bad weather, early interpretations of the onset time and the character of the eruption were made using seismological data only and were confirmed later by other monitoring methods. The eruption finished in early September 2013. This article presents the data obtained through real-time seismic monitoring and the results of retrospective analysis, with additional comments on the future monitoring of volcanic activity.

A multi-sensor satellite assessment of SO 2 emissions from the 2012–13 eruption of Plosky Tolbachik volcano, Kamchatka

Abstract Prolonged basaltic effusive eruptions at high latitudes can have significant atmospheric and environmental impacts, but can be challenging to observe in winter conditions. Here, we use multi-sensor satellite data to assess sulfur dioxide (SO2) emissions from the 2012–2013 eruption of Plosky Tolbachik volcano (Kamchatka), which lasted ~ 9–10 months and erupted ~ 0.55 km3 DRE. Observations from the Ozone Monitoring Instrument (OMI), the Ozone Mapping and Profiler Suite (OMPS), the Atmospheric Infrared Sounder (AIRS), and the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to evaluate volcanic activity, SO2 emissions and heat flux associated with the effusion of lava flows. Gaps in the primary OMI SO2 time-series dataset occurred due to instrument limitations and adverse meteorological conditions. Four methods were tested to assess how efficiently they could fill these data gaps and improve estimates of total SO2 emissions. When available, using data from other SO2 observing instruments was the most comprehensive way to address these data gaps. Satellite measurements yield a total SO2 loading of ~ 200 kt SO2 during the 10-month Plosky Tolbachik eruption, although actual SO2 emissions may have been greater. Based on the satellite SO2 measurements, the Fast Fourier Transform (FFT) multi-taper method (MTM) was used to analyze cyclical behavior in the complete data series and a 55-day cycle potentially attributable to the eruptive behavior of Plosky Tolbachik during the 2012 – 2013 eruption was identified.

Seismic monitoring of the Plosky Tolbachik eruption in 2012–2013 (Kamchatka Peninsula Russia)

Seismic monitoring of the Plosky Tolbachik eruption in 2012–2013 (Kamchatka Peninsula Russia)

Overview of the precursors and dynamics of the 2012–13 basaltic fissure eruption of Tolbachik Volcano, Kamchatka, Russia

Abstract We present a broad overview of the 2012–13 flank fissure eruption of Plosky Tolbachik Volcano in the central Kamchatka Peninsula. The eruption lasted more than nine months and produced approximately 0.55 km3 DRE (volume recalculated to a density of 2.8 g/cm3) of basaltic trachyandesite magma. The 2012–13 eruption of Tolbachik is one of the most voluminous historical eruptions of mafic magma at subduction related volcanoes globally, and it is the second largest at Kamchatka. The eruption was preceded by five months of elevated seismicity and ground inflation, both of which peaked a day before the eruption commenced on 27 November 2012. The batch of high-Al magma ascended from depths of 5–10 km; its apical part contained 54–55 wt.% SiO2, and the main body 52–53 wt.% SiO2. The eruption started by the opening of a 6 km-long radial fissure on the southwestern slope of the volcano that fed multi-vent phreatomagmatic and magmatic explosive activity, as well as intensive effusion of lava with an initial discharge of > 440 m3/s. After 10 days the eruption continued only at the lower part of the fissure, where explosive and effusive activity of Hawaiian–Strombolian type occurred from a lava pond in the crater of the main growing scoria cone. The discharge rate for the nine month long, effusion-dominated eruption gradually declined from 140 to 18 m3/s and formed a compound lava field with a total area of ~ 36 km2; the effusive activity evolved from high-discharge channel-fed 'a'a lavas to dominantly low-discharge tube-fed pahoehoe lavas. On 23 August, the effusion of lava ceased and the intra-crater lava pond drained. Weak Strombolian-type explosions continued for several more days on the crater bottom until the end of the eruption around 5 September 2013. Based on a broad array of new data collected during this eruption, we develop a model for the magma storage and transport system of Plosky Tolbachik that links the storage zones of the two main genetically related magma types of the volcano (high-Al and high-Mg basalts) with the clusters of local seismicity. The model explains why precursory seismicity and dynamics of the 2012–13 eruption was drastically different from those of the previous eruption of the volcano in 1975–76.

Constraints on unrest in the Tolbachik volcanic zone in Kamchatka prior the 2012–13 flank fissure eruption of Plosky Tolbachik volcano from local seismicity and GPS data

Abstract A new fissure eruption began on 27 November 2012 on the southern slope of Plosky Tolbachik volcano, which is located in central Kamchatka, Russia, and is part of the Klyuchevskoy volcano group. We analyzed the displacement of the earth surface and the seismicity during several months before the eruption onset. According to seismic and GPS data the eruption was preceded by about 4–5 months (July–November 2012) of synchronous crustal deformation and seismicity. The seismic anomaly comprises low energy level seismicity (mainly M = 1.2–2.3) under Plosky Tolbachik volcano at a depth of less than 5 km. In the 2–3 weeks immediately preceding the eruption the rate of seismicity and the amount of radiated seismic energy exceeded the long-term average values (2000–2011) by more than 40 times. The deformation anomaly was recorded by displacement of the GPS points at distances from 20 to 60 km to the north of Tolbachik. The principal axis of the compressive strain was approximately directed towards the Tolbachik eruption site. The permanent GPS network detected radial compression and tangential stretching. The compressive strain reached about 10 − 7 prior to eruption onset. The comparable duration of seismic and deformation anomalies (~ 4–5 months before the eruption) is consistent with a common origin, connected to magma rising from depth, and is interpreted as indicating that they were medium-term precursors to the eruption. Data recorded during this unrest episode of the Tolbachik volcanic zone will contribute to understanding of the reawakening of volcanic activity in this region and others worldwide with similar characteristics.

Tectonics and magma chambers of the recent Tolbachik Fissure Eruption (Kamchatka Peninsula)

Structural-geological, petrological, seismotectonic, and seismotomographic data received in regions of areal volcanism of the south-southwest sector of the Plosky Tolbachik volcano area are considered. The fissure eruption occurring here from November 2012 to the middle of September 2013 was called 50 years of IVS after the 50th anniversary of the Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences. A joint analysis of new and retrospective data allows us to suggest a model for the recent eruption and formulate some problems for future studies and eruption forecasting.

Another “Great Tolbachik” Eruption?

AbstractOn 27 November 2012 at 1715 local time, a focused swarm of earthquakes was interpreted as the start of a new ongoing eruption on the south flank (Tolbachinsky Dol) of Plosky Tolbachik volcano in east central Kamchatka, Russia (Figure 1a) [Samoylenko et al., 2012]. Visual observations on 29 November showed ash shooting from two fractures as well as long, rapidly moving lava flows. Although the initial ash clouds reached 6 kilometers in height, subsequent ashfall has been limited to the area around the main vents, and no permanent settlements are in danger from advancing lava flows (the closest settlements are about 40 kilometers from the volcano). Including this eruption, six different volcanoes are presently active in Kamchatka.

The large fissure eruption in the region of Plosky Tolbachik volcano in Kamchatka, 1975–1976

The paper describes the course of the Large Tolbachik fissure eruption taking place in Kamchatka from July 6, 1975 to December 10, 1976. The eruption zone extended for 30 km. The formation of monogenic scoria cones nearly 300 m high, lava tubes and basalt sheets up to 80 m thick and more than 40 km2 in area and subsidence of the Plosky Tolbachik summit caldera to a depth of more than 400 m were observed during the eruption. The volume of eruption products amounted to more than 2 km3. It was the largest basalt eruption which has taken place in the Kurile-Kamchatka volcanic belt in historic time.

Seismic data on magma chambers of the large tolbachik eruption

This paper discusses the methods and techniques of observation that can at present be applied to a seismic refraction study of active volcanoes with a view of determining the magma chamber location. A system of magma chambers has been outlined in the earth’s crust and transition layer between the crust and the mantle under the Tolbachik Volcano group. Magma chambers are dynamically related to each other. The feeding magma chambers of the newly-formed Tolbachik volcanoes and Plosky Tolbachik volcano are assumed to be interrelated through the transition zone between the crust and the mantle.