The main trends in the dynamics of vegetation on the territory affected by the catastrophic eruption of Bezymyanny Volcano on March 30, 1956 (Kamchatka)

The transformation of the vegetation cover in the impact zone of the 1956 eruption, in territories covered by various deposits, is considered. As a result of a gigantic eruption (VEI 5), vegetation was exposed to a series of different volcanic impacts. Five main categories of events are distinguished: the movement of material of a huge volume of volcano edifice over a large distance as a result of a giant clastic avalanch, the pyroclastic surge of a direct blast, the pyroclastic flows, the formation of a giant eruptive cloud and ashfalls, as well as the lahars. The volume of erupted (initially high-temperature) deposits was, according to various estimates, in the amount of 1.35-1.5 km3, the volume of cold deposits of a clastic avalanche was 0.5-0.8 km3. The volume of lahar was 0.5 km3. The area covered by the pyroclastic wave of the directed explosion was about 500 km2. Within this lesion zone, deposits of pyroclastic flows have occupied 30-40 km2, and clastic avalanche deposits from 35 to 60 km2. Below 900 m above sea level (a.s.l.) these deposits buried cover of subalpine dwarf alder (dominant species is Alnus fruticosa) and mountain meadow vegetation, as well as forest vegetation (dominant species is Betula ermanii) at its upper limit. Forest and partially dwarf alder vegetation was destroyed on a vast territory mainly under the influence of a pyroclastic wave (in the altitude range from 700-800 to 200 m a.s.l.), as well as lahars (in the range of 250-50 m a.s.l.). Primary successions occur in the alpine and partially subalpine zone on avalanche deposits and pyroclastic flows deposits, as well as in the upper part of the zone impacted by pyroclastic surge of the direct blast (40-45 km2). In part of the territories where thick deposits of the lahars were formed, primary successions also probably occurred. In the zone of primary successions, deposits of a clastic avalanche are settled by plants most slowly due to not-favourable edaphic factors. The process is somewhat more efficient on the deposits of pyroclastic flows (the same ratio was noted on the Shiveluch Volcano). The surface overlapped by deposits of the pyroclastic surge is populated relatively quickly. Secondary succession occurs in the zone of damage to the forest and dwarf trees by the influence of a pyroclastic wave, as well as in the zone of passage of the lahars. Restoring of vegetation to its previous state will take from 50 to ~500 years on different deposits and in different parts of an impact zone.

Late Pleistocene–Holocene Volcaniclastic Ejecta Along the Southern Apron of the Esan Volcanic Complex, Japan

The Esan volcanic complex (EVC), northern Japan, is an active volcanic complex. The EVC represents a potential threat owing to its close proximity to inhabited areas, and abundant phreatic deposits occur around its volcanic aprons. Eleven samples of black paleosol and charcoal were collected from trenches dug at two sites (A and B) for the purpose of 14C dating. Sites A and B are located 2.6 km and 2.2 km from the source crater, respectively, and the deposits at these sites represent a proximal facies. At least 11 (at site A) and 12 (at site B) volcaniclastic units are identified. A newly identified Holocene phreatic unit (Es-0) is dated at ca 11 ka and is older than the EsMP unit that is a Holocene lava-dome building episode at ca 9 ka. Holocene phreatic episodes Es-1 and Es-3 can be divided into three and five subunits, respectively, and include a pyroclastic surge deposit that would have posed a threat to current local communities. The sequence of Holocene eruptions includes at least 11 tephra events over 11,000 years. The material ejected during phreatic explosions is characterised by highly heterogeneous grain size. Therefore, grain size analysis of erupted phreatic material might not effectively discriminate the processes of deposition, in contrast to such analysis of magmatic ejecta. The topography of the EVC largely constrains the area of deposition of phreatic ejecta.

Emplacement Temperature of the Overbank and Dilute-Detached Pyroclastic Density Currents of Merapi 5 November 2010 Events using Reflectance Analysis of Associated Charcoal

Merapi eruption in 2010 produced 17 km high column of ash and southward pyroclastic density current (PDC). Based on the deposits characteristics and distributions, the PDC is divided into channel and overbank facies (pyroclastic flow), and associated diluted PDC (pyroclastic surge). The hot overbank PDCs and the associated dilute-detached PDCs are the main cause of high casualty (367 fatalities) in medial-distal area (5–16 km), especially near main valley of Kali Gendol. We reported the emplacement temperature of these two deposits using reflectance analysis of charcoal. We used both entombed charcoals in the overbank PDC and charcoals in singed house nearby. Samples were collected on 6–13 km distance southward from summit. Charcoalification temperatures of the entombed charcoals represent deposition temperature of the overbank PDCs, whereas those of charcoals in the singed house resembles temperature of the associated dilute-detached PDCs. Results show mean random reflectance (Ro%) values of entombed charcoal mainly range 1.1–1.9 correspond to temperature range 328–444 °C, whereas charcoal in singed house range 0.61–1.12 with estimated temperature range 304–358 °C. The new temperature data of the dilute-detached PDCs in the medial-distal area is crucial for assessing impact scenarios for exposed populations as it affects them lethally and destructively

Estimation of Carbon Stock Changes in Above Ground Woody Biomass due to Volcano Pyroclastic Flow and Pyroclastic Surge

Merapi Volcano National Park (MVNP) is susceptible to volcanic hazard since it is located around Merapivolcano, especially pyroclastic flow. Carbon sequestration in the national park is becoming a priority of forest developmentas stipulated in Government Regulation Number 28 Year 2011 and Number 49 Year 2011. This study aims to knowthe effect of pyroclastic event to carbon stock in MVNP. In this study the natural carbon rate recovery in MVNP wasestimated to determine the growth rate of natural carbon recovery in MVNP. To estimate carbon stock change in MVNP,2006 QuickBird and 2011 GeoEye satellite imageries were used. Object based image segmentation of high resolutionsatellites imagery could recognize physical dimensions of individual trees such as crown projection area (CPA). In thisstudy, carbon stock was derived using allometric equation based on measured diameter at breast height (DBH) in thefield. A model was developed to estimate carbon stock based on DBH estimation in the field and segmented CPA fromthe image. Based on the segmentation process, the model of CPA and Carbon in MVNP was developed. The F scorewhich indicate the accuracy of segmentation of needle leaf and broadleaved of 2011 GeoEye were 0.68 and 0.54 respectively.Logarithmic model which has 6.37 % error was used to estimate broadleaved carbon stock while quadratic modelwhich has 10.31 % error was used to estimate Pine tree carbon stock in MVNP.

Early Ordovician volcanism in the Iberian Chains (NE Spain) and its influence on the preservation of shell concentrations

Research is described to evaluate the influence of volcanic activity on studies of shell-concentration taphonomy and biodiversity patterns in strata that commonly display poor densities of skeletal debris. Two volcanic episodes are recorded in the Lower Ordovician of the Iberian Chains: (i) a succession of Tremadocian-earliest “Arenig”, eruptive felsic products, expelled explosively and characterized by the onset of rhyolitic and dacitic tuffs embedded in the Borrachón and Santed formations; and (ii) an “Arenig”, effusive basaltic volcanic episode, represented by a single lava flow embedded in the Armorican Quartzite. The volcanic activity reflects a change from sub-alkaline to alkaline geochemical affinities, related to the Early Ordovician magmatism recorded in southwestern Europe that is commonly attributed to the opening of the Rheic Ocean. The felsic explosive tuffs are associated with two ecosystem disturbance events: (i) a short-term colonization event of opportunistic linguliformean brachiopods that proliferated in the aftermath of a multi-event rhyolitic pyroclastic surge deposit; and (ii) several single-event mass-mortality horizons associated with dacitic pyroclastic flows responsible for the preservation of high-diverse allochthonous coquinas. Our knowledge of the biodiversity patterns achieved by the benthic communities preserved in the poorly fossiliferous, siliciclastic strata of the Iberian Chains is, as a result, strongly biased by the presence of skeletal tuffs, directly controlled by the onset of neighbouring eruptive explosions.