Continued post-collapse volcanic activity can cause the rise of a new edifice. However, details of such edifice rebirth have not been documented yet. Here, we present 7-decade-long photogrammetric ...data for Bezymianny volcano, Kamchatka, showing its evolution after the 1956 sector collapse. Edifice rebirth started with two lava domes originating at distinct vents ~400 m apart. After 2 decades, activity became more effusive with vents migrating within ~200 m distance. After 5 decades, the activity focused on a single vent to develop a stratocone with a summit crater. We determine a long-term average growth rate of 26,400 m
3
/day, allowing us to estimate the regain of the pre-collapse size within the next 15 years. Numerical modeling explains the gradual vents focusing to be associated with loading changes, affecting magma pathways at depth. This work thus sheds light on the complex regrowth process following a sector collapse, with implications for regrowing volcanoes elsewhere.
Regrowth of the Bezymianny volcano, Kamchatka developed from dispersed domes to a focussed stratocone due to loading changes beneath the edifice over the course of seven decades, according to photogrammetric observations throughout the period.
Geyser geothermal fields are scenic volcanic landforms that often contain tens to hundreds of thermal spot vents that erupt boiling water or contain bubbling mud pools. The fields are potentially ...hazardous sites due to boiling water temperatures and changes in vent locations and eruption dynamics, which are poorly understood. Here we report on the rapid and profound changes that can affect such a geyser field and ultimately lead to a dangerous, unanticipated eruption. We studied the Geyser Valley, Kamchatka Peninsula, which is a field of geysers and other thermal features and boiling pools. Using high-resolution tri-stereo satellite data and unmanned aerial systems (UAS) with optical and thermal infrared cameras in 2018 and 2019, we were able to identify a newly emerging explosion site. Structure-from-motion analysis of data acquired before and after the explosion reveals morphological and thermal details of the new vent. The explosion site produced an aureole zone of more than 150 m3 of explosively redeposited gravel and clay, a slightly elliptical crater with a diameter of 7.5 m and a crater rim 0.30 m high. However, comparison with archives of photogrammetric data suggests that this site was thermally active years earlier and contained a crater that was obscured and covered by landslides and river sediments. The results allow us to develop a conceptual model and highlight the hazard potential of thermal features buried by landslides and clastic deposits. Sudden explosions may occur at similar sites elsewhere, highlighting the need for careful assessment and monitoring of geomorphological and hydrological changes at geyser sites in other regions.
The well-documented 1883 eruption of Krakatau volcano (Indonesia) offers an opportunity to couple the eruption’s history with the tsunami record. The aim of this paper is not to re-analyse the ...scenario for the 1883 eruption but to demonstrate that the study of tsunami deposits provides information for reconstructing past eruptions. Indeed, though the characteristics of volcanogenic tsunami deposits are similar to those of other tsunami deposits, they may include juvenile material (e.g. fresh pumice) or be interbedded with distal pyroclastic deposits (ash fall, surges), due to their simultaneity with the eruption. Five kinds of sedimentary and volcanic facies related to the 1883 events were identified along the coasts of Java and Sumatra: (1) bioclastic tsunami sands and (2) pumiceous tsunami sands, deposited respectively before and during the Plinian phase (26–27 August); (3) rounded pumice lapilli reworked by tsunami; (4) pumiceous ash fall deposits and (5) pyroclastic surge deposits (only in Sumatra). The stratigraphic record on the coasts of Java and Sumatra, which agrees particularly well with observations of the 1883 events, is tentatively linked to the proximal stratigraphy of the eruption.
Taipei City, with a population of around 8
million, as well as two nuclear power plants is located in close proximity to the Quaternary, dominantly andesitic Tatun Volcanic Group (TVG) of Northern ...Taiwan. We have investigated the stratigraphy of the youngest volcaniclastic deposits, as well as the morphology of lava flows and domes of the TVG in order to reconstruct the character and timing of the most recent eruptions and related hazardous events in the area.
Our data indicate that recent eruptions of the group were dominated by long-term, voluminous extrusions of crystal-rich, very viscous lavas. These eruptions formed closely spaced monogenetic domes and lava flows. Based on morphological parameters of the lava flows (thicknesses 80–150
m, lengths up to 5.6
km, and volumes up to 0.6
km
3), average rates of magma effusion ranged from 1 to 10
m
3/s, eruption durations from 500 to 1800
days, and lava front speeds from 0.5 to 6
m/h.
Explosive activity of TVG was diverse, ranging from weak phreatic to highly explosive (VEI 4) Plinian eruptions; vulcanian activity with deposition of lithic ashes was most common. Interaction of rising magma with ground water frequently occurred during the eruptions.
This study presents the first radiocarbon dates of various volcaniclastic deposits of the TVG, which indicate that Cising, Siaoguanyin, and possibly Huangzuei volcanoes had magmatic eruptions in the period 13,000–23,000
years ago. In addition, Mt. Cising had a phreatic eruption 6000
years ago, and possibly an effusive eruption just before that. Gravitational collapses of volcanic edifices with volumes 0.01–0.1
km
3 and
H/
L 0.16–0.25 were also common. They occurred on intersections with tectonic faults and may have been triggered by seismic activity. The youngest collapses occurred at Mt. Siaoguanyin (23,000 BP) and Mt. Cising (6000 BP).
It is concluded that the TVG should be considered volcanically active. The results of this study provide a basis for volcanic hazard assessment and mitigation in the area.
The 2012–2013 flank eruption of Tolbachik volcano (Kamchatka) lasted 9 months and produced 0.54 km
3
of basaltic trachyandesite lava, thus becoming one of the most voluminous historical lava ...effusions of basic composition in subduction-related environments globally. From March to July 2013, the volcano monotonously erupted lava of constant composition (SiO
2
= 52 wt%) with a nearly stable effusion rate of 18 m
3
/s. Despite the uniform eruptive and emplacement conditions, the dominant style of lava propagation throughout that time gradually changed from ‘a’a to pahoehoe. We report results of instrumental field measurements of the ‘a’a and pahoehoe flow dynamics (documented with time-lapse cameras) as well as the lava viscosity determined by flow rate and shear stress (using penetrometer) methods. Maximal propagation velocities of the ‘a’a fronts ranged from 2 to 25 mm/s, and those of the pahoehoe from 0.5 to 6 mm/s. The flow front velocities of both lava types experienced short-period fluctuations that were caused by complex flow mechanics of the advancing flow lobes. Minimal viscosities of lava of the ‘a’a lobes ranged from 1.3 × 10
5
to 3.3 × 10
7
Pa s (flow rate method), and those of the pahoehoe from to 5 × 10
3
to 5 × 10
4
Pa s (shear stress method). Our data include the first ever measured profiles of viscosity through the entire thickness of actively advancing pahoehoe lava lobes. We have found that both the ‘a’a and pahoehoe flows were fed by identical parental lava, which then developed contrasting rheological properties, owing to differences in the process of lava transport over the ground surface. The observed transition from the dominant ‘a’a to the dominant pahoehoe propagation styles occurred due to gradual elongation and branching of the lava tube system throughout the course of the eruption. Such evolution became possible because the growing lava field, composed of semisolidified flows, provided an environment for shallow subsurface intrusions and internal migrations of lava that, with time, developed into branches of the lava tube system. Based on our data, we propose phenomenological models of the ‘a’a and pahoehoe flow mechanics.
Abstract
The increase in number and intensity of earthquakes during a pre-eruptive crisis is the main basis of seismic volcano monitoring. However, a strong understanding of how these seismic signals ...relate to magmatic processes in the magma plumbing systems prior to volcanic eruptions is crucial for these efforts. Here we compare the characteristics of a seismo-volcanic crisis prior to the 2010–2013 explosive-extrusive eruption of Kizimen volcano, Kamchatka with the timescales of processes in the magma plumbing system. These timescales are inferred from the numerical modelling of iron-magnesium intracrystalline interdiffusion in 88 zoned orthopyroxene crystals from dacites and silica-rich andesites collected after the eruption. We find that the eruptible magmas were assembled rapidly during a magma mixing process beginning around 1.5 years before the eruption, which is well correlated with the onset of the seismic crisis. We conclude that the observed seismic re-activation marked the onset of magma mixing and led to destabilization of the reservoir, followed by the eruption.
Abstract
Most volcanic eruptions occur through magma pathways that resemble tube-like conduits fed from magma sources at depth. Here we combine remote sensing observations with both analog and ...numerical experiments to describe the extrusion of a spine at the Shiveluch lava dome, Kamchatka (Russian Far East) in April-October 2020. We show that spine growth is preceded by bulging of the dome surface, followed by extrusion in an asymmetric manner. The spine then elongates along a previously identified fracture line and bends toward the north. By repeated morphology analysis and feature tracking, we constrain a spine diameter of ~300 m, extruding at a velocity of 1.7 m/day and discharge rate of 0.3–0.7 m³/s. Particle modeling of an extruding conduit plug highlights that the spine may have inclined to the north due to the topography and hidden architecture of the subsurface. We suggest that such complexities are rather common, where mechanical heterogeneities in the conduit material, mechanical erosion of the hidden spine buried by the co-evolving dome, as well as topographic (un-)buttressing controls directionality of spine growth and spine instability. The results presented here are relevant for understanding the growth and collapse hazards of spines and provide unique insights into the hidden magma-conduit architecture.
For the years 2001 to 2013 of the ongoing eruption of Shiveluch volcano, a combination of different satellite remote sensing data are used to investigate the dome-collapse events and the resulting ...pyroclastic deposits. Shiveluch volcano in Kamchatka, Russia, is one of the world's most active dome-building volcanoes, which has produced some of the largest known historical block-and-ash flows (BAFs). Globally, quantitative data for deposits resulting from such large and long-lived dome-forming eruptions, especially like those at Shiveluch, are scarce. We use Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared (TIR), shortwave infrared (SWIR), and visible-near infrared (VNIR) data to analyze the dome-collapse scars and BAF deposits that were formed during eruptions and collapse events in 2001, 2004, 2005, 2007, 2009, 2010, and two events in 2013. These events produced flows with runout distances of as far as 19km from the dome, and with aerial extents of as much as 22.3km2. Over the 12years of this period of investigation, there is no trend in deposit area or runout distances of the flows through time. However, two potentially predictive features are apparent in our data set: 1) the largest dome-collapse events occurred when the dome exceeded a relative height (from dome base to top) of 500m; 2) collapses were preceded by thermal anomalies in six of the cases in which ASTER data were available, although the areal extent of these precursory thermal areas did not generally match the size of the collapse events as indicated by scar area (volumes are available for three collapse events). Linking the deposit distribution to the area, location, and temperature profiles of the dome-collapse scars provides a basis for determining similar future hazards at Shiveluch and at other dome-forming volcanoes. Because of these factors, we suggest that volcanic hazard analysis and mitigation at volcanoes with similar BAF emplacement behavior may be improved with detailed, synoptic studies, especially when it is possible to access and interpret appropriate remote sensing data in near-real time.
•Distributions of eight large dome-collapse events and resulting block-and-ask flow deposits•Channelization of block-and-ask flows strongly enhances runout distance.•Areas of elevated thermal output on the dome surface can be detected prior to collapse events.
Mount Iriga is a small, dormant stratovolcano of basalt to basaltic andesite composition located in Luzon Island, Philippines. The volcanic edifice includes a well-preserved horseshoe-shaped ...avalanche scar 2 km across with an adjacent fan of hummocky debris avalanche deposit (DAD) formed by large-scale (1.5 km
3
) gravitational edifice collapse. To constrain the age of the collapse and determine the character of volcanic activity that followed, we investigated and dated (using the
14
C accelerator mass spectrometry method) paleosoils and organic lake sediments as well as charcoal-containing pyroclastic deposits that closely pre- and post-dated emplacement of the DAD. We found that the collapse of Iriga occurred soon after its 1830 ± 40 BP explosive magmatic eruption (of St. Vincent type) that produced pyroclastic flows of scoriaceous basaltic andesite. In the avalanche-dammed Lake Buhi, the organic bottom sediments started to accumulate at 1780 ± 30 BP, marking the upper age limit of the DAD emplacement. The edifice collapse itself was not contemporaneous with any geologically detectable explosive eruption. After the collapse, a stubby block lava flow with volume of about 0.02 km
3
was extruded inside the horseshoe-shaped avalanche scar. The next eruption of Iriga, which was its only post-collapse explosive eruption, occurred at 1110 ± 30 BP. This phreatomagmatic eruption left a small steep-walled maar-like crater inside the broad avalanche scar in the vent area of the block lava flow. The extrusion of the block lava and the subsequent phreatomagmatic event were the only eruptions of Iriga that occurred after the edifice collapse. Together with the pre-collapse explosive eruption, they comprise the entire eruptive activity of Iriga during the Late Holocene and all occurred during the last 2000 years.
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