scholarly journals Hybrid rhyolitic eruption at Big Glass Mountain, CA, USA

Volcanica ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 257-277
Author(s):  
Jonathan Castro ◽  
Sebastian Walter
Keyword(s):  
Content Analysis ◽  
Isotopic Composition ◽  
Lava Flow ◽  
Hydrogen Isotope ◽  
Lava Flows ◽  
Field Observations ◽  
Close System ◽  
Fall Deposit ◽  
Eruptive Dynamics ◽  
Volatile Loss

Eruptive dynamics of the 1060 CE rhyolitic eruption of Big Glass Mountain (BGM), USA, are investigated with field observations, hydrogen isotope and H2O content analysis of pyroclastic obsidian chips and lavas. Field relations at BGM reveal evidence for hybrid eruption, defined as synchronous explosive venting and effusive emplacement of vast obsidian lava flows.  This activity is particularly well manifested by extensive breccia zones implanted within the BGM obsidian lavas, which may represent rafted tephra cones, in addition to remnants of airfall tephra on the lava. Rhyolitic obsidians collected from a 2.5-m-thick fall deposit and co-eruptive lava flow were studied by FTIR and TCEA methods to elucidate the eruption’s degassing history.  The data, along with VolcDeGas program simulations, demonstrate a correlation between H2O content and H-isotopic composition (δD) that likely reflects ever-increasing amounts of volatile loss via repetitive close-system steps, best described as batched degassing.

scholarly journals Anatomy of a Paroxysmal Lava Fountain at Etna Volcano: The Case of the 12 March 2021, Episode

2021 ◽  
Vol 13 (15) ◽  
pp. 3052
Author(s):  
Sonia Calvari ◽  
Alessandro Bonaccorso ◽  
Gaetana Ganci
Keyword(s):  
Lava Flow ◽  
Ground Deformation ◽  
Monitoring Network ◽  
Lava Flows ◽  
Etna Volcano ◽  
Lava Fountain ◽  
Eruptive Episode ◽  
Lava Fountains ◽  
Borehole Strainmeter ◽  
Ash Plume

On 13 December 2020, Etna volcano entered a new eruptive phase, giving rise to a number of paroxysmal episodes involving increased Strombolian activity from the summit craters, lava fountains feeding several-km high eruptive columns and ash plumes, as well as lava flows. As of 2 August 2021, 57 such episodes have occurred in 2021, all of them from the New Southeast Crater (NSEC). Each paroxysmal episode lasted a few hours and was sometimes preceded (but more often followed) by lava flow output from the crater rim lasting a few hours. In this paper, we use remote sensing data from the ground and satellite, integrated with ground deformation data recorded by a high precision borehole strainmeter to characterize the 12 March 2021 eruptive episode, which was one of the most powerful (and best recorded) among that occurred since 13 December 2020. We describe the formation and growth of the lava fountains, and the way they feed the eruptive column and the ash plume, using data gathered from the INGV visible and thermal camera monitoring network, compared with satellite images. We show the growth of the lava flow field associated with the explosive phase obtained from a fixed thermal monitoring camera. We estimate the erupted volume of pyroclasts from the heights of the lava fountains measured by the cameras, and the erupted lava flow volume from the satellite-derived radiant heat flux. We compare all erupted volumes (pyroclasts plus lava flows) with the total erupted volume inferred from the volcano deflation recorded by the borehole strainmeter, obtaining a total erupted volume of ~3 × 106 m3 of magma constrained by the strainmeter. This volume comprises ~1.6 × 106 m3 of pyroclasts erupted during the lava fountain and 2.4 × 106 m3 of lava flow, with ~30% of the erupted pyroclasts being remobilized as rootless lava to feed the lava flows. The episode lasted 130 min and resulted in an eruption rate of ~385 m3 s−1 and caused the formation of an ash plume rising from the margins of the lava fountain that rose up to 12.6 km a.s.l. in ~1 h. The maximum elevation of the ash plume was well constrained by an empirical formula that can be used for prompt hazard assessment.

On Composite Lava Flows.

1931 ◽  
Vol 68 (4) ◽  
pp. 166-181 ◽  
Author(s):  
W. Q. Kennedy
Keyword(s):  
Lava Flow ◽  
Lava Flows ◽  
The Other ◽  
Geological Survey ◽  
Main Subject ◽  
Lower Carboniferous ◽  
Fluid State ◽  
Mutual Contact ◽  
The World ◽  
Probable Effect

For many years composite minor intrusions, both sills and dykes, have been known from various parts of the world and most petrologists must have speculated as to the probable effect produced in the event of such composite intrusions having reached the surface in the form of an effusion. For obvious reasons it has not been found possible to trace a composite dyke upwards into a lava flow. However, during the revision of 1 inch Sheet 30 (Renfrewshire) for the Geological Survey, the author encountered, in the neighbourhood of Inverkip, a small village on the Firth of Clyde south of Greenock, certain peculiar lava flows which are believed to represent the effusive equivalents of composite minor intrusions. These “composite lavas”, which form the main subject of the present paper, are of Lower Carboniferous age (Calciferous Sandstone Series) and occur interbedded among the more normal flows towards the base of the volcanic group. Two distinct rock varieties, one highly porphyritic, with large phenocrysts (up to 1·5 cms. long) of basic plagioclase, and the other non-porphyritic, are associated within the same flow. The porphyritic type always forms the upper part of the flow and overlies the non-porphyritic; the junction shows unmistakable evidence that both were in a fluid state along their mutual contact at the time of emplacement.

scholarly journals Sensibility analysis of VORIS lava-flow simulations: application to Nyamulagira volcano, Democratic Republic of Congo

2015 ◽  
Vol 3 (3) ◽  
pp. 1835-1860
Author(s):  
A. M. Syavulisembo ◽  
H.-B. Havenith ◽  
B. Smets ◽  
N. d'Oreye ◽  
J. Marti
Keyword(s):  
Lava Flow ◽  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Lava Flows ◽  
Past Century ◽  
Republic Of Congo ◽  
Political Issues ◽  
Aster Gdem ◽  
Volcano Observatory ◽  
Digital Elevation

Abstract. Assessment and management of volcanic risk are important scientific, economic, and political issues, especially in densely populated areas threatened by volcanoes. The Virunga area in the Democratic Republic of Congo, with over 1 million inhabitants, has to cope permanently with the threat posed by the active Nyamulagira and Nyiragongo volcanoes. During the past century, Nyamulagira erupted at intervals of 1–4 years – mostly in the form of lava flows – at least 30 times. Its summit and flank eruptions lasted for periods of a few days up to more than two years, and produced lava flows sometimes reaching distances of over 20 km from the volcano, thereby affecting very large areas and having a serious impact on the region of Virunga. In order to identify a useful tool for lava flow hazard assessment at the Goma Volcano Observatory (GVO), we tested VORIS 2.0.1 (Felpeto et al., 2007), a freely available software (http://www.gvb-csic.es) based on a probabilistic model that considers topography as the main parameter controlling lava flow propagation. We tested different Digital Elevation Models (DEM) – SRTM1, SRTM3, and ASTER GDEM – to analyze the sensibility of the input parameters of VORIS 2.0.1 in simulation of recent historical lava-flow for which the pre-eruption topography is known. The results obtained show that VORIS 2.0.1 is a quick, easy-to-use tool for simulating lava-flow eruptions and replicates to a high degree of accuracy the eruptions tested. In practice, these results will be used by GVO to calibrate VORIS model for lava flow path forecasting during new eruptions, hence contributing to a better volcanic crisis management.

The geochemical stratigraphy, field relations and temporal variation of the Mull–Morvern Tertiary lava succession, NW Scotland

1995 ◽  
Vol 86 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Andrew Craig Kerr
Keyword(s):  
Sea Level ◽  
Main Part ◽  
Volcanic Ash ◽  
Lava Flows ◽  
Field Observations ◽  
Continuous Section ◽  
Flow Units ◽  
Early Tertiary ◽  
The Uk ◽  
Basaltic Lavas

AbstractThe early Tertiary Mull-Morvern lava succession, NW Scotland, represents the thickest continuous section (1000 m from sea level to the top of Ben More) of Tertiary lavas exposed in the UK. This succession has been sampled and geochemically analysed, on a flow-by-flow basis, throughout the lava succession. Field observations during the course of this sampling suggest that the early lava flows (the Staffa Magma sub-Type) ponded in palaeovalleys along with interlava sediments. In the main part of the Mull lava succession (the Mull Plateau Group) the lava flows are on average ∼ 5 m thick. Most previous Hebridean workers have assumed that the red horizons commonly found between these later lava flows, represent weathered flow tops. However, this study has shown that in some places these red ‘boles’ appear to be a combination of both volcanic ash and weathered basalt.Chemically distinctive units of flows have been found throughout the succession. The two most abundant magma sub-types of the Mull Plateau Group, primitive (>9wt% MgO) basalts with Ba/Nb» 15 and more evolved (<9wt% MgO) basalts-hawaiites with Ba/Nb<15, form packets of flow units which can be up to 200 m thick. These chemically distinctive flow units have been correlated across the lava succession. However, the correlation of individual lava flows has proved difficult. The Mull Plateau Group lavas generally become more evolved and less contaminated with continental crust towards the top of the succession, culminating in the trachytes of the Pale Group on Ben More. Basaltic lavas above the Pale Group have markedly different trace element ratios, and seem to represent shallower, more extensive asthenospheric melting than the Mull Plateau Group.

A 3-D genetic approach to high-resolution geological modelling of the volcanic infill of a paleovalley system. Application to the Volvic catchment (Chaîne des Puys, France)

2012 ◽  
Vol 183 (5) ◽  
pp. 395-407 ◽  
Author(s):  
Simon Rouquet ◽  
Pierre Boivin ◽  
Patrick Lachassagne ◽  
Emmanuel Ledoux
Keyword(s):  
Lava Flow ◽  
Lava Flows ◽  
Genetic Approach ◽  
Hydrogeological Model ◽  
Volcanic System ◽  
Geochemical Composition ◽  
Crystalline Bedrock ◽  
Volcanic Events ◽  
Aa Lava ◽  
Scoria Cones

Abstract The Volvic natural mineral water is catched in a complex volcanic aquifer located in the northern part of the “Chaîne des Puys” volcanic system (Auvergne, France). In the watershed, water transits through scoria cones and basaltic to trachybasaltic lava flows. These aa lava flows, emitted by strombolian cones between 75,000 and 10,000 years ago, are emplaced in deep paleovalleys incised within the variscan crystalline bedrock. The volcanic infill is highly heterogeneous. In order to build a hydrogeological model of the watershed, a simple but robust methodology was developed to reconstruct the bedrock morphology and the volcanic infill in this paleovalley context. This methodology, based on the combination of genetic and geometric approaches, appears to be rather efficient to define both the substratum and the lava flows geometry. A 3D geological model is then proposed. It synthesizes the data from 99 boreholes logs, 2D geoelectric profiles, morphologic clues, datings and petrographic data. A genetic approach, integrating aa lava flow morphology and emplacement behaviour, was used to reconstruct the chronology of the volcanic events and lava flow emplacement from the upper part of the Dômes plateau to the Limagne plain. The precision of the volcanic reconstruction is discussed: the main limitation of the methodology are related to the homogeneity of the petrographic and geochemical composition of the lava flows succession (except for the trachyandesitic Nugere lava), the spatially variable borehole density, the lack of a real petrographical and geological description on most of the available geological logs. Nevertheless, the developed methodology combining spatial and genetic approaches appears to be well adapted to constrain complex lava flow infill geometries in paleovalley context.

Lava flow modelling at El Hierro (Canary Islands): the case of Montaña Aguarijo volcano

2021 ◽  
Author(s):  
Alejandro Rodriguez-Gonzalez ◽  
Claudia Prieto-Torrell ◽  
Meritxell Aulinas ◽  
Francisco José Perez-Torrado ◽  
Jose-Luis Fernandez-Turiel ◽  
...  
Keyword(s):  
Lava Flow ◽  
Canary Islands ◽  
Flow Simulation ◽  
Maximum Length ◽  
Lava Flows ◽  
Rheological Parameters ◽  
The Real ◽  
El Hierro ◽  
Typical Morphology ◽  
Spatial Propagation

&lt;p&gt;Lava flow simulations are valuable tools for forecasting and assessing the areas that may be potentially affected by new eruptions, but also for interpreting past volcanic events and understanding the controls on lava flow behaviour. The plugin Q-LavHA v3.0 (Mossoux et al., 2016), integrated into QGIS, allows simulating the inundation probability of an a&amp;#8217;a lava flow from one or more eruptive vents spatially distributed in a Digital Elevation Model (DEM). Q-LavHA allows running probabilistic and deterministic methods to calculate the spatial propagation and the maximum length of lava flows, considering a number of morphometric and/or thermo-rheological parameters.&lt;/p&gt;&lt;p&gt;El Hierro is the smallest and westernmost island of the Canary Archipelago where basaltic lava flows infer the major volcanic hazard. However, no lava flow emplacement modelling has been carried out yet on the island. Here we present Monta&amp;#241;a Aguarijo's lava flow simulation, a monogenetic volcano located on the NW rift of El Hierro. Detailed geological fieldwork and current topographic-bathymetric data were used to reconstruct the pre-eruption (before the eruption modifies the relief) and post-eruption (at the end of the eruption, prior to erosive processes) DEMs. The obtained morphometric parameters of the lava flow (2,268m long; 5m medium thickness; 422,560m&lt;sup&gt;3&lt;/sup&gt;) were used to run probabilistic (Maximum Length) and deterministic (FLOWGO) models. The latter also considers a set of thermo-rheological properties of the lava flow such as initial viscosity, phenocryst content, or vesicle proportion.&lt;/p&gt;&lt;p&gt;Results obtained show a high degree of overlap between the real and simulated lava flows. Therefore, the thermo-rheological parameters considered in the deterministic approach are close to the real ones that constrained Monta&amp;#241;a Aguarijo lava flow propagation. Moreover, this work evidence the effectiveness of Q-LavHA plugin when simulating complex lava flows such as Monta&amp;#241;a Aguarijo&amp;#8217;s lava which runs through a coastal platform, a typical morphology of oceanic volcanic islands.&amp;#160;&amp;#160; &amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Financial support was provided by Project LAJIAL (ref. PGC2018-101027-B-I00, MCIU/AEI/FEDER, EU). This study was carried out in the framework of the Research Consolidated Groups GEOVOL (Canary Islands Government, ULPGC) and GEOPAM (Generalitat de Catalunya, 2017 SGR 1494).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Mossoux, S., Saey, M., Bartolini, S., Poppe, S., Canters F., Kervyn, M. (2016). Q-LAVHA: A flexible GIS plugin to simulate lava flows. &lt;em&gt;Computers &amp; Geosciences&lt;/em&gt;, 97, 98-109.&lt;/p&gt;

Mount Etna and the 1971 eruption - Lengths of lava flows

1973 ◽  
Vol 274 (1238) ◽  
pp. 107-118 ◽  
Keyword(s):  
Lava Flow ◽  
High Viscosity ◽  
Lava Flows ◽  
Mount Etna ◽  
High Rate ◽  
Low Viscosity ◽  
Depression Measurement ◽  
Lateral Extent ◽  
The One ◽  
Single Flow

The principal factor influencing the length of a lava flow is the rate of effusion. With a high rate the lava flows rapidly from the source and tends to form an extensive and far-reaching flow which is simple in character (i.e. made of a single flow unit). With a low rate the lava tends to pile up layer upon layer to form a local accumulation of limited lateral extent near the source, and this accumulation is strongly compound in character (i.e. divisible into flow units). The initial viscosity affects the length indirectly by controlling the thickness of the extrusion, and this thickness control is capable of accounting for the fact that the median length of low-viscosity basaltic extrusions is 3.2 times that of high-viscosity andesite, trachyte and rhyolite ones. Other factors, such as the local topography, are thought to be relatively unimportant, an exception being when lava is ponded in a topographic depression. Measurement of the rate of effusion may be critical in any attempt to predict the distance that a lava flow will travel, such as the one which threatened Fornazzo and other towns and villages on Etna in 1971.

Petrology and geochronology of Vran Kamak paleovolcano, Central Srednogorie, Bulgaria

2020 ◽  
Author(s):  
Stoyan Georgiev ◽  
Eleonora Balkanska ◽  
Irena Peytcheva ◽  
Dian Vangelov
Keyword(s):  
Lava Flow ◽  
Late Cretaceous ◽  
Basaltic Andesite ◽  
Upper Cretaceous ◽  
Small Degree ◽  
Lava Flows ◽  
Oscillatory Zoning ◽  
Primitive Mantle ◽  
Ministry Of Education ◽  
Igneous Activity

&lt;p&gt;Vran Kamak paleovolcano is formed during the Upper Cretaceous igneous activity along the Panagyurishte strip of Central Srednogorie Zone, Bulgaria, part of the magmatic-metalogenic arc belt Apuseni-Banat-Timok-Srednogorie. It represents a comparatively well-preserved, eroded stratovolcano built of epiclastics, pyroclastics and lava flow (with typical hyaloclastite and peperite formation) succession surrounded by marine environment, as only a part from the volcanic cone was over the sea level. The central (conduit) parts of the paleovolcano are intruded by a volcanic neck in the area of Vran Kamak summit. The volcanic activity was accompanied by sedimentary gravity flows and volcaniclastic debris is dispersed in the Late Cretaceous basin. The present study provides new petrological and geochronological data for Vran Kamak paleovolcano.&lt;/p&gt;&lt;p&gt;The analyzed samples from the lava flows show basaltic andesite to andesite composition with SiO&lt;sub&gt;2&lt;/sub&gt; contents ranging from 51 to 55.5 wt %, while the volcanic neck of the Vran Kamak summit is trachydacite (SiO&lt;sub&gt;2&lt;/sub&gt; of 61.54 wt % ). The rocks are medium- to high-K calc-alkaline. On a primitive-mantle normalized diagram, the rocks show peaks in LILE (U, Th, Pb) and troughs in Nb, Ta, Ti and P. Weak negative Eu anomaly (0.83&amp;#8211;0.94) and La&lt;sub&gt;N&lt;/sub&gt;/Yb&lt;sub&gt;N&lt;/sub&gt; (10 to 13) are observed. Fractionation of mafic minerals (amphibole and pyroxene) and plagioclase is visible on the harker diagrams. The &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr&lt;sub&gt;(i)&lt;/sub&gt; ratio of 0.705141 from the volcanic neck shows small degree of crustal assimilation.&lt;/p&gt;&lt;p&gt;The basaltic andesite to andesite lava flows are built of plagioclase (with normal oscillatory zoning, bytownite-labrador, An&lt;sub&gt;88-56&lt;/sub&gt;), amphibole (tschermakite to magnesiohastingsite) and pyroxenes (mostly augite and rare small enstatite crystals embedded in them). Some of the clinopyroxenes form corona texture around the amphibole, showing processes of dewatering. The trachydacite neck is built of porphyries of plagioclase, sanidine, biotite, amphibole (megnesiohornblende to thermakite), magmatically coroded quartz and accessories of zircon, apatite and magnetite set in a fine-grained groundmass. The calculated depths of crystallization and temperatures of the hornblende from the lava flows are 17&amp;#8211;22 km and 930&amp;#8211;970&lt;sup&gt; o&lt;/sup&gt;C and that from the neck are 5.9&amp;#8211;7 km and 800&amp;#8211;830 &lt;sup&gt;o&lt;/sup&gt;C, that give evidence for a complex volcano-plutonic system.&lt;/p&gt;&lt;p&gt;An attempt for LA-ICPMS U-Pb zircon dating of one the lava flows is made, but it contains only xenocrysts which fall in several age intervals: 306&amp;#8211;314 Ma, 440&amp;#8211;450 Ma, 520&amp;#8211;530 Ma, 560&amp;#8211;614 Ma, 810&amp;#8211;830 Ma which represent inherited and recycled component from the local basement. This lava flow has a peperitic contact with sediments faunistically dated at the Turonian/Coniacian boundary (Cremnoceramus deformis erectus, Vangelov et al., 2019). The zircon population of the trachydacite neck is presented mostly by own magmatic grown crystals giving a Concordia age of 91.12 &amp;#177;0.43 Ma.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;. The study is supported by grant DN 04/9 funded by the National Science Fund, Ministry of Education and Science, Bulgaria.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Vangelov, D., Gerdjikov, I., Dochev, D., Dotseva, Z., Velev, S., Dinev, Y., Trayanova, D., Dancheva, J. 2019. Upper Cretaceous lithostratigraphy of the Panagyurishte strip (Central Bulgaria) &amp;#8211; part of the Late Cretaceous Apuseni-Banat-Timok-Srednogorie magmatic belt. &amp;#8211; Geol Balc., 48, 3, 11&amp;#8211;33.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Hyaloclastite formation during the effusion of the first lava flows of Siberian traps into a shallow freshwater basin

2020 ◽  
Author(s):  
Alexander G. Polozov ◽  
Sverre Planke ◽  
John A. Millett ◽  
Dmitrii A. Zastrozhnov ◽  
Dougal A. Jerram ◽  
...  
Keyword(s):  
Lava Flow ◽  
Early Stage ◽  
Basal Part ◽  
Lava Flows ◽  
Large Igneous Province ◽  
Gas Generation ◽  
Pillow Basalt ◽  
Siberian Traps ◽  
Carbon Dioxide Gas ◽  
Tunguska Basin

&lt;p&gt;Hyaloclastites have long been described within numerous volcaniclastic sequences in the Siberian Traps Large Igneous Province. They are typical for the southern and central parts of the Tunguska basin, and we inspected them in 2004-2010. In recent years, we have focused our attention on the northwestern region of the Tunguska basin (Norilsk area) with a volumetric manifestation of basaltic lava flows. We have completed fieldwork in this region from 2006 to 2019, with a recent focus on the understanding of the emplacement environments for the lowermost lava flow erupted directly on the end-Permian boggy surface. We studied pillow basalt at the basal part of the lowermost lava flow in the Norilsk region (Ivakinskaya Formation). In the upper part of this pillow basalt horizon, hyaloclastite is very common, and at the basal part, several tree trunks occur. The hyaloclastite includes black equant angular clasts and rusty red matrix and easily recognize at any outcrops. We studied hyaloclastite with optical microscopy and SEM-EDS. Black clasts composed of sideromelane cracked and altered to palagonite. Sideromelane fragments include crystals of olivine (Fo70), plagioclase (An63-70), and likely OPx altered to chlorite. Sideromelane glass has a basalt composition with elevated P2O5, CaO, and decreased amount of MgO and minor halogens (F, Cl). Some sideromelane clasts bear round inclusions (blobs) entirely infill with dolomite, siderite, and calcite. Every single carbonate inclusion has a specific structure and minerals infill.&lt;/p&gt;&lt;p&gt;We interpret these hyaloclastite rocks formations with carbonate inclusions as a result of lava flow effusion onto the shallow freshwater basin or boggy surface. Water and organic-rich sediments transferred with an explosion to steam and carbon dioxide gas, and this gas mixture was formed a hyaloclastite horizon at the basal part of a lava flow. We suppose that these sideromelane clasts with carbonate blobs are additional evidence of greenhouse gas generation during the early stage of the Siberian Traps lavas eruption.&lt;/p&gt;

Paleointensity derived from igneous rocks of Kamchatka volcanoes of the Late Pleistocene-Holocene epoch

2020 ◽  
Author(s):  
Iuliia Sleptsova ◽  
Valeriy Maksimochkin
Keyword(s):  
Magnetic Field ◽  
Curie Temperature ◽  
Lava Flow ◽  
Geomagnetic Field ◽  
Single Domain ◽  
Igneous Rocks ◽  
Lava Flows ◽  
Virtual Geomagnetic Pole ◽  
Temperature Oxidation ◽  
Curie Temperature Tc

&lt;p&gt;This work is devoted to paleomagnetic studies of lava samples from three volcanoes of Kamchatka in order to define the age of lava flows and to obtain data of paleosecular variations of the geomagnetic field for the Kamchatka region. We studied 53 samples from 7 sites from lava flows of the Avachinsky, the Gorely and the Tolbachik volcanoes. The study of paleosecular variations recorded in the magnetization of the lava flows of volcanoes makes it possible to create a magnetochronological scale for epochs of the same polarity.&lt;/p&gt;&lt;p&gt;According to the data of electron microprobe and thermomagnetic analyzes, the magnetic properties of samples from the lava flows of the Avachinsky volcano are mainly determined by titanic magnetite with a Curie temperature Tc = (540-580) &amp;#176;&amp;#1057;. The study of magnetic mineral grains using electron and magnetic force microscopy showed the presence of decay structures in grains, indicating the high-temperature oxidation of titanomagnetite. Ferrimagnetic grains of samples from the Gorely and Tolbachik volcanoes are represented by titanomagnetite with a Curie temperature Tc = (200&amp;#8211;300) &amp;#176;C. According to the hysteresis characteristics, the magnetic structure of the grains corresponds to a single-domain and pseudo-single-domain state. Thermal and magnetic cleanings showed the predominance of one component in the NRM. The geomagnetic field intensity was determined by the Thellier method in the Coe modification.&lt;/p&gt;&lt;p&gt;It was found that the paleointensity value H&lt;sub&gt;anc&lt;/sub&gt; = 55&amp;#177;3 &amp;#956;T, determined from the NRM of samples of the 2012 eruption from the Tolbachik volcano, differs from the modern magnetic field in the area of this volcano by the IGRF-12 model by only 4% (&amp;#1053;&lt;sub&gt;IGRF&lt;/sub&gt; = 53 &amp;#956;T). This indicates the reliability of our methodology for determining paleointensity from the most stable part of the NRM of igneous rocks.&lt;/p&gt;&lt;p&gt;A comparison of the coordinates of the paleomagnetic pole (N 66&amp;#186;&amp;#177;4&amp;#186;, E 266&amp;#186;&amp;#177;5&amp;#186;) and the virtual dipole magnetic moment of the Earth (VDM = 8.3&amp;#177;0.9*10&lt;sup&gt;22&lt;/sup&gt; A*m&lt;sup&gt;2&lt;/sup&gt;) with data on variations of the geomagnetic field over the past 10,000 years [Burlatskaya, 2007; McElhinny, 1982] allows us to conclude that the investigated lava flow belongs to the historical eruptions of 1827. The coordinates of the virtual geomagnetic pole (N 83&amp;#186;&amp;#177;3&amp;#186;, E 254&amp;#186;&amp;#177;21&amp;#186;) and the value of VDM = 8.0&amp;#177;0.3*10&lt;sup&gt;22&lt;/sup&gt; A*m&lt;sup&gt;2&lt;/sup&gt; determined from the samples belonging to the second lava flow of the Avachinsky volcano indicate that rocks are formed in the result of the eruption, which occurred 5-5.5 thousand years ago.&lt;/p&gt;&lt;p&gt;It was revealed that the magnitude (H&lt;sub&gt;anc&lt;/sub&gt; =65&amp;#177;5&amp;#956;T) and the direction of paleointensity determined by the NRM of the samples from Gorely volcano significantly differ from the characteristics of the modern magnetic field. The assumption is made that the studied samples belong to the outpouring of lava, which occurred about 2.7 thousand years ago, during the &quot;Sterno-Etrussia&quot; geomagnetic excursion.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;This work was supported by the Russian Foundation for Basic Research, project 20-05-00573.&lt;/p&gt;

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