Evolution Of Volcanic Activity Research Articles

Interpretation of Geological Features and Volcanic Activity in the Tsiolkovsky Region of the Moon

The Tsiolkovsky crater is located on the farside of the Moon. It formed in the late Imbrian epoch and was filled with a large area of mare basalts. Multisource remote sensing data are used to interpret the geological features of the Tsiolkovsky area. Compared with previous studies, new remote sensing data and a chronological model based on crater size–frequency distribution are used to further refine the stratigraphic units and determine the absolute ages of the mare basalt units. The evolution of volcanic activity in this crater is discussed. The results are as follows: Abundances of major elements, Th, and silicate minerals suggest that the mare basalt in the crater floor is not a uniform unit but rather nine units with different compositions. The nine basalt units are divided into two episodes of volcanic activity: The first occurred at 3.5–3.7 Ga, when highly evolved lava erupted at the crater floor at a large scale; the second occurred at ~3.4 Ga, when a small area of more primitive lava extended to the northern portion of the crater floor.

ГЛУБИННАЯ ГЕОДИНАМИКА И ОСОБЕННОСТИ МЕТАЛЛОГЕНИИ КУНАШИР-УРУПСКОГО ЗВЕНА КУРИЛЬСКОЙ ОСТРОВОДУЖНОЙ СИСТЕМЫ

The southern part of the Kuril island-arc system (from Kunashir to Urup islands) differs from the northern part (from Simushir to Paramushir islands) in its spatial arrangement relative to the subducting Pacific megaplate’s motion vector, greater number of volcanoes, and endogenic mineralization diversity (Au, Ag, PGE, Re, IN, Sn, Cu, Zn, Pb and others). The location of deep northwest-trending zones of strike-slip faulting on the opposite oceanic slope of the Kuril Trench is another peculiarity of the Southern Kurils. Significant extent (up to 1000 km), great depth (more than 100 km) and permanent (J-Q) activity of the strike-slip faults allowed thermal-fluid flows from the undersubduction asthenosphere to penetrate through the seismic focal zone, above the mantle wedge and oversubduction asthenosphere and reach subcontinental lithosphere. The upwelling of the flows was accompanied by metasomatic processes, formation of initial magma reservoirs and both the transitional and peripheral reservoirs in the Kuril island-arc crust, as well as by the evolution of volcanic activity and ore genesis. The synthesis of the Southern Kurils’ metallogeny and geodynamics data allows us to recognize the islands as a natural phenomenon intended for study of geological problems and mineral resources exploitation.

Miocene volcanism in the Oaş–Gutâi Volcanic Zone, Eastern Carpathians, Romania: Relationship to geodynamic processes in the Transcarpathian Basin

We present the first comprehensive study of Miocene volcanic rocks of the Oaş–Gutâi Volcanic Zone (OGVZ), Romania, which are exposed in the eastern Transcarpathian Basin (TB), within the Eastern Alpine–Western Carpathian–Northern Pannonian (ALCAPA) block. Collision between the ALCAPA block and Europe at ~18–16Ma produced the Carpathian fold-and-thrust belt. This was followed by clockwise rotation and an extensional regime forming core complexes of the separated TB fragment. Based on petrographic and geochemical data, including SrNd isotopic compositions and KAr ages, we distinguish three types of volcanic activity in the OGVZ: (1) early Miocene felsic volcanism that produced caldera-related ignimbrites in the Gutâi Mountains (15.4–14.8Ma); (2) widespread middle–late Miocene intermediate/andesitic volcanism (13.4–7.0Ma); and (3) minor late Miocene andesitic/rhyolitic volcanism comprising the Oraşu Nou rhyolitic volcano and several andesitic–dacitic domes in the Oaş Mountains (11.3–9.5Ma). We show that magma evolution in the OGVZ was controlled by assimilation–fractional crystallization and magma-mixing processes within an interconnected multi-level crustal magmatic reservoir. The evolution of volcanic activity within the OGVZ was controlled by the geodynamics of the Transcarpathian Basin. The early felsic and late intermediate Miocene magmas were emplaced in a post-collisional setting and were derived from a mantle source region that was modified by subduction components (dominantly sediment melts) and lower crust. The style of volcanism within the eastern TB system exhibits spatial variations, with andesitic composite volcanoes (Gutâi Mountains) observed at the margins, and isolated andesitic–rhyolitic monogenetic volcanoes (Oaş Mountains) in the center of the basin.

UAV Thermal Infrared Remote Sensing of an Italian Mud Volcano

Extreme environments like active volcanoes exhibit many difficulties in being studied by in situ techniques. For example, during eruptions, summit areas are very hard to be accessed because of logistics problems and/or volcanic hazards. The use of remote sensing techniques in the last 20 years by satellite or airborne platforms has proven their capabilities in mapping and monitoring the evolution of volcanic activity. This approach has become increasingly important, as much interest is actually focused on understanding precursory signals to volcanic eruptions. In this work we verify the use of cutting-edge technology like unmanned flying system thermally equipped for volcanic applications. We present the results of a flight test performed by INGV in collaboration with the University of Bologna (Aerospace Division) by using a multi-rotor aircraft in a hexacopter configuration. The experiment was realized in radio controlled mode to overcome many regulation problems which, especially in Italy, limit the use of this system in autonomous mode. The overall goal was not only qualitative but also quantitative oriented. The system flew above an Italian mud volcano, named Le Salinelle, located on the lower South West flank of Mt. Etna volcano, which was chosen as representative site, providing not only a discrimination between hot and cold areas, but also the corresponding temperature values. The in-flight measurements have been cross-validated with contemporaneous in-situ acquisition of thermal data and from independent measurements of mud/water temperature.

The geochronology and origin of mantle sources for late cenozoic intraplate volcanism in the frontal part of the Arabian plate in the Karacadağ neovolcanic area of Turkey. Part 2. The results of geochemical and isotope (Sr-Nd-Pb) studies

A geochemical and isotope-geochemical (Sr-Nd-Pb) study has been carried out for the Karacadag neovolcanic area, which is situated within the frontal part of the Arabian plate. The obtained data and the results of petrological modeling show that the petrogenesis of parental magmas in the Karacadag neovolcanic area involved two compositionally different mantle sources; one consisted of garnet-bearing peridotites of the asthenosphere mantle and the other was spinel-bearing peridotites of the enriched subcontinental lithosphere mantle. During early stages in the evolution of the magmatic system, deep-seated asthenospheric magmas were ascending to the surface while intensively interacting with the melts that had been generated at upper mantle depths. The interaction gradually diminished, so that the later effusive rocks mostly have compositions that are similar to those of the primitive asthenospheric magmas. It is shown that a significant (up to 17–18 wt % of the mantle melt) assimilation of crustal material could take place only during the initial phases of the magmatism. Periodic replenishment of the magma chambers by primitive magmas, which resulted in an observable high degree of homogeneity in the composition of young effusive rocks, was also of importance in the petrogenesis of lavas during the evolution of volcanic activity.

The dynamics of the velocity field beneath the North group of volcanoes, Kamchatka, and its relationship to the evolution of volcanic activity

P- and S-wave travel times from local volcanic earthquakes recorded in the North group of volcanoes area during the 2005–2009 period were treated by the “reverse wave” method to calculate the VP velocity field and the TAU parameter, which is an analogue of the P- to S-wave velocity ratio. We constructed 3D velocity distributions along the line traversing the volcanic group along the direction from Ploskii Tolbachik Volcano in the southwest toward Shiveluch Volcano in the northeast. Dynamic changes in the velocity field were identified, both over time and depth. We examine the relationships of these dynamic changes to the evolution of volcanic activity during the period indicated.

Tephra Studies on Quaternary Explosive Eruptions in the Japanese Islands

Japanese tephra studies have developed steadily in the last five decades. First two decades until 1976 brought fundamental ideas and techniques for correlation and for recognition of widespread co-ignimbrite ash falls. Geochemical and physical characterization of tephras advanced greatly in the third decade in 1980s. This enabled identification and distinction of many individual tephra layers and then compilation of tephra catalogs for solid tephrostratigraphic framework. VEI=7 classed large-scale eruptions had occurred at several calderas in Kyushu and Hokkaido Islands during the period from Middle Pleistocene to Holocene. Estimated average frequency is once in every a few ten thousand years. Their impacts on human society and ecosystem were analyzed through many disciplines of Quaternary research and turned out to have been very severe. Late Pleistocene and Holocene eruptive histories of medium-scale Plinian eruptions (VEI=4-6) are mostly documented and included in catalogs. Studies on their impacts on humankind during both pre-historical and historical ages confirmed severe volcanic hazards. The knowledge makes long-term prediction and volcanic hazard mitigation more reliable. Detailed stratgraphic and chronological studies on Holocene pyroclastic deposits helped to establish precise eruptive histories of some active volcanoes. Many recent works focused on Pliocene to Middle Pleistocene widespread tephras. Middle Pleistocene tephrochronology has provided information on regional changes of the frequency and magnitude of eruptions and magma discharge rate as a function of time. Studies of older distal tephras preserved in non-volcanic sediments let us know the occurrence of large-scale eruptions without any volcanic edifice preserved. The 105 to 106 year scale tephrochronology is revealing very long-term evolution of volcanic activity and magma discharge.

A multidisciplinary approach to detect active pathways for magma migration and eruption at Mt. Etna (Sicily, Italy) before the 2001 and 2002–2003 eruptions

Two strong flank eruptions occurred in July–August 2001 and from late October 2002 to late January 2003 at Mt. Etna volcano. The two eruptions mainly involved the upper southern flank of the volcano, a particularly active area during the last 30 years, damaging several tourist facilities and threatening some villages. The composite eruptive activity on the upper southern flank of Mt. Etna during 2001–2003 has confirmed “a posteriori” the results of a multidisciplinary study, started well before its occurrence by combining geological, seismic and geochemical data gathered in this part of the volcano. We were able, in fact, to highlight fractured zones likely to be re-activated in the near future in this area, where the largest majority of eruptive fissures in the recent past opened along N120° to N180° ranging directions. The spatial distribution of earthquake epicentres during the period June 30th 2000–June 30th 2001 showed the greatest frequency in a sector compatible with both the direction of the main fissures of the pre-2001 period and that of the 2001 and 2002 lateral eruptions. Soil CO 2 and soil temperature surveys carried out in the studied area during the last 3 years have revealed anomalous release of magmatic fluids (mainly CO 2 and water vapour) along some NNW–SSE-trending volcano-tectonic structures of the area even during inter-eruptive periods, indicating persistent convective hydrothermal systems at shallow depth connected with the main feeder conduits of Etna. The temporal changes in both seismic and geochemical data from June 30th, 2000 to June 30th, 2001 were compared with the evolution of volcanic activity. The comparison allowed to recognize at least two sequences of anomalous signals (August to December 2000 and April to June 2001), likely related to episodes of step-like magma ascent towards the surface, as indicated by the following eruptive episodes. The N120° to N180° structural directions are in accord with one of the main structural lines affecting eastern Sicily; they would be important pathways for magma uprise to the surface that will keep on feeding the eruptive activity of Etna in the near future. This study also pointed out the high instability of the southern slope of Etna, a sector where the potential hazard by lava flow invasion will remain high also in the near future.

Volcanic steam output directly measured in fumaroles: the observed variations at Vulcano Island, Italy, between 1983 and 1987

The mass of steam emitted by the fumaroles of the crater of Vulcano (Aeolian Islands, Italy) was evaluated by using a direct measuring method. Measurements were effected with this method between 1983 and 1987 in nine field campaigns, the results of which are given in this paper. The steam flux measurements were performed by an instrument expressly designed for steam condensation. The estimates of the thermal energy transported daily by the steam gave values of up to 10E12 J. The sharp variations in the total mass outputs recorded in 1984 and 1985 are here interpreted as being a consequence of the probable accumulation of fluid pressure at depth, during the evolution of volcanic activity. The different results obtained from the various areas of the fumarolic field during the evolutionary phases have led to the hypothesis that different subsystems exist that feed the fumaroles, and that their activity is triggered by volcano-tectonics. This method can be applied in the evaluation of both fumarolic steam and thermal energy outputs, and therefore it is particularly useful in geothermal exploration, in the evaluation of the environmental impact of volcanic degassing, and in the forecasting of volcanic eruptions. The evaluation of the steam output is also useful for quantifying the release of other gaseous species and giving univocal interpretations regarding their variations in concentrations. Furthermore this direct method provides a new way of calibrating the flux estimates effected by other telemetric techniques (Lidar, Cospec, etc.).