scholarly journals Rheological and morphological evolution of basaltic lava flows

2018 ◽  
Author(s):  
◽  
Arianna Soldati
Keyword(s):  
Lava Flow ◽  
Flow Structure ◽  
Flow System ◽  
Morphological Evolution ◽  
Human Life ◽  
Active Volcano ◽  
Flow Dynamics ◽  
Lava Flows ◽  
System Structure ◽  
Basaltic Lava

Over 500 million people live in proximity of an active volcano globally. Although lava flows rarely endanger human life, they often destroy critical infrastructure. Advancing our understanding of lava flow dynamics is therefore critical to developing accurate hazard assessment, with key socio-economic impacts for many communities. This work focuses on basaltic lava rheology, which exerts a first-order control on flow dynamics and is reflected in lava morphology. In particular, I address the following research questions: (1) How does the rheology of active flows evolve during emplacement; and (2) How can we use flow morphology to infer the rheology of inactive flows? ... At Piton de La Fournaise (La R�union, FR DOM), I addressed the longstanding question of how pre-existing topography controls lava flow system structure in volume-limited flows (Soldati et al., accepted). I concluded that a steep slope results in a single, stable channel, whereas a gentle slope results in an unstable, braided channel. The findings of this study allow us to interpret and explain the observed flow structure on the basis of pre-existing volcano topography, and to forecast future flow structure. This allowed me to determine that rheology neither affects nor is affected by flow system configuration.

scholarly journals Emplacing a Cooling-Limited Rhyolite Lava Flow: Similarities with Basaltic Lava Flows

2017 ◽  
Vol 5 ◽  
Author(s):  
Nathan Magnall ◽  
Mike R. James ◽  
Hugh Tuffen ◽  
Charlotte Vye-Brown
Keyword(s):  
Lava Flow ◽  
Lava Flows ◽  
Basaltic Lava ◽  
Rhyolite Lava

scholarly journals Recent eruption history inferred from eruption ages of the two latest lava flows using multi-dating at Yokodake Volcano, Japan

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Hiroya Nitta ◽  
Takeshi Saito ◽  
Yorinao Shitaoka
Keyword(s):  
Lava Flow ◽  
Volcanic Activity ◽  
Active Volcano ◽  
Lava Flows ◽  
Eruption Rate ◽  
Dating Methods ◽  
Paleomagnetic Dating ◽  
History Of ◽  
Eruption History ◽  
Recent Eruption

Abstract Reconstruction of the eruption history of an active volcano is necessary to elucidate its volcanic activity and to assess the probability of its volcanic eruption. Yokodake volcano in central Japan is the only active volcano among the Yatsugatake volcano group. It has effused nine lava flows, most of which have not been dated. For this study, we ascertained the eruption ages of the latest lava (Y9) and second most recent lava (Y8) using radiocarbon (14C), thermoluminescence (TL), and paleomagnetic dating methods. Results revealed the eruption ages of the two lava flows and the recent eruption history of Yokodake volcano. Yokodake volcano effused its Y8 lava flow at ca. 3.4 ka, ejected NYk-2 tephra with explosive eruption at ca. 2.4–2.2 ka, and effused the Y9 lava flow associated with Y9-T tephra at ca. 0.6 ka. Magma eruption rates of Yokodake at 34 ky and 3.4 ky were estimated as about 9 × 10−3 km3/ky and 1 × 10−2 km3/ky, indicating a stable eruption rate maintained during the past 34 ky. This result suggests that Yokodake volcano retains some potential for eruption, although the volcanic activity of the Yatsugatake volcanoes (10−1–10−2 km3/ky) has weakened over time.

Living at the edge of an active volcano: Risk from lava flows on Mt. Etna

2019 ◽  
Vol 132 (7-8) ◽  
pp. 1615-1625 ◽  
Author(s):  
Ciro Del Negro ◽  
Annalisa Cappello ◽  
Giuseppe Bilotta ◽  
Gaetana Ganci ◽  
Alexis Hérault ◽  
...  
Keyword(s):  
Land Use ◽  
Lava Flow ◽  
Active Volcano ◽  
Lava Flows ◽  
Service Networks ◽  
Analytic Hierarchy ◽  
Thematic Layers ◽  
Exposed Population ◽  
Mt Etna ◽  
High Resolution Satellite Imagery

Abstract Lava flows represent the greatest threat by far to exposed population and infrastructure on Mt. Etna, Italy. The increasing exposure of a larger population, which has almost tripled in the area around Mt. Etna during the past 150 years, has resulted from poor assessment of the volcanic hazard and inappropriate land use in vulnerable areas. Here we quantify the lava flow risk on the flanks of Mt. Etna volcano using a Geographic Information System (GIS)-based approach that integrates the hazard with the exposure of elements at stake. The hazard, which shows the long-term probability related to lava flow inundation, is obtained by combining three different kinds of information: the spatiotemporal probability of new flank eruptive vents opening in the future, the event probability associated with classes of expected eruptions, and the overlapping of lava flow paths simulated by the MAGFLOW model. Data including all exposed elements were gathered from institutional web portals and high-resolution satellite imagery and organized in four thematic layers: population, buildings, service networks, and land use. The total exposure is given by a weighted linear combination of the four thematic layers, where weights are calculated using the Analytic Hierarchy Process (AHP). The resulting risk map shows the likely damage caused by a lava flow eruption and allows rapid visualization of the areas subject to the greatest losses if a flank eruption were to occur on Mt. Etna. The highest risk is found in the southeastern flank due to the combination of high hazard and population density.

Magnetic fabric and flow directions in magmatic rocks of the Franz Josef Land, Arctic Ocean

2020 ◽  
Author(s):  
Anna Chernova ◽  
Viktor Abashev ◽  
Dmitry Metelkin ◽  
Valery Vernikovsky ◽  
Nikolay Mikhaltsov
Keyword(s):  
Lava Flow ◽  
Complex Analysis ◽  
Flow Direction ◽  
Lava Flows ◽  
Magnetic Fabric ◽  
Basaltic Lava ◽  
Magma Flow ◽  
Franz Josef Land ◽  
Degree Of Anisotropy ◽  
Flow Directions

<p>Here, we present the results of a study of the anisotropy of magnetic susceptibility (AMS) completed in the Early Cretaceous magmatic complexes from the Franz Josef Land (FJL). AMS was measured in the framework of paleomagnetic research as a leading indicator of the rock magnetic fabric to help in understanding the lava flow directions and forming mechanisms. The three types of magmatic bodies were available in these studies: dolerite sills, dykes and basaltic lava flows from several islands (Alexandra, Hall, Ziegler, Jackson and Heiss Islands) among FJL. During the experiments the different parameters of AMS ellipsoids were obtained which have a good correlation with the igneous body shapes and also could illustrate lava flows direction parameters. The degree of anisotropy P is 1.01-1.06 for most sites that is typical for the primary igneous magnetic fabric. The form factor T characterizing the shape of the AMS ellipsoids demonstrates both planar and linear magnetic fabric in studied magmatic bodies. What is remarkable the part of the dykes is characterized strictly oblate magnetic fabric and another dykes have the prolate AMS ellipsoids. The linear magnetic structure is also more typical for lava flows with the maximum axes K1 lying in the flow plane that is obviously could point to the flow direction. The part of the igneous bodies are characterized by the inverse type of magnetic fabric, when the principal axis K1 of the ellipsoid is oriented perpendicularly to the plane of the flow or the sill, that was likely caused by the effect of secondary processes. The previous studies (Abashev et al., 2019) demonstrated that the primary orientation of the AMS ellipsoid could be recovered after temperature demagnetization. Noticeable changes were revealed at heating up to ~450 deg C, which generally corresponds to deblocking temperatures of titanomagnetites identified in the rocks by rock-magnetic methods. The degree of anisotropy was decreased after heating in 2-3 times. The heating also resulted to the redistribution of magnetic axes and in several cases the axes becomes more grouped. Analysis of the AMS results from the basaltic lava flows of the Aleksandra Island defined the magma flow direction to be NW-SE. Similar behavior of the AMS ellipsoids and lava flow orientation is typical for Ziegler Island. Generally our results show that complex analysis of AMS data in basaltic rocks is promising for identifying magma flow direction and it can give more detailed information about forming mechanisms of the different magmatic bodies.</p><p>This work was supported by the RSF (project no. 19-17-00091) and the RFBR (project nos. 18-35-00273, 18-05-70035).</p>

scholarly journals ELEMENTAL AND TOPOGRAPHIC MAPPING OF LAVA FLOWSTRUCTURES IN MARE SERENITATIS ON THE MOON

2017 ◽  
Vol XLII-3/W1 ◽  
pp. 163-170 ◽  
Author(s):  
C. Wöhler ◽  
A. Grumpe ◽  
D. Rommel ◽  
M. Bhatt ◽  
U. Mall
Keyword(s):  
Lava Flow ◽  
Flow Structure ◽  
Hyperspectral Image ◽  
Image Data ◽  
Elemental Abundance ◽  
Lava Flows ◽  
Stereo Image ◽  
The Moon ◽  
Lunar Reconnaissance Orbiter ◽  
Mare Serenitatis

The detection of lunar lava flows based on local morphology highly depends on the available images. The thickness of lava flows, however, has been studied by many researchers and lunar lava flows are shown to be as thick as 200 m. Lunar lava flows are supposed to be concentrated on the northwestern lunar nearside. In this study we present elemental abundance maps, a petrological map and a digital terrain model (DTM) of a lava flow structure in northern Mare Serenitatis at (18.0° E, 32.4° N) and two possible volcanic vents at (11.2° E, 24.6° N) and (13.5° E, 37.5° N), respectively. Our abundance maps of the refractory elements Ca, Mg and our petrological map were obtained based on hyperspectral image data of the Moon Mineralogy Mapper (M3) instrument. Our DTM was constructed using GLD100 data in combination with a shape from shading based method to M3 and Lunar Reconnaissance Orbiter (LRO) Narrow Angle Camera (NAC) image data. The obtained NAC-based DEM has a very high effective resolution of about 1–2 m which comes close to the resolution of the utilized NAC images without requiring intricate processing of NAC stereo image pairs. As revealed by our elemental maps and DEM, the examined lava flow structure occurs on a boundary between basalts consisting of low-Ca/high-Mg pyroxene and high-Ca/low-Mg pyroxene, respectively. The total thickness of the lava flow is about 100 m, which is a relatively large value, but according to our DEM the lava flow may also be composed of two or more layers.

OCCURRENCE OF NATIVE COPPER, SILVER AND GOLD IN BASALTIC LAVA FLOWS

2017 ◽  
Author(s):  
Peishu Li ◽  
◽  
Alan E. Boudreau ◽  
Alan E. Boudreau
Keyword(s):  
Lava Flows ◽  
Basaltic Lava ◽  
Native Copper
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