نتایج جستجو برای: lava rocks

تعداد نتایج: 24704  

2015
Lauren N. Schaefer Jackie E. Kendrick Thomas Oommen Yan Lavallée Gustavo Chigna

In volcanic regions, reliable estimates of mechanical properties for specific volcanic events such as cyclic inflation-deflation cycles by magmatic intrusions, thermal stressing, and high temperatures are crucial for building accurate models of volcanic phenomena. This study focuses on the challenge of characterizing volcanic materials for the numerical analyses of such events. To do this, we e...

2017
Mark Edwards

Introduction Ocean island basalts (OIB) are thought to sample the Earth’s deep mantle, whereby thermochemical plumes entrain lower mantle material and bring it to the surface where it erupts. By measuring the isotopic compositions of global OIB—which record the isotopic compositions of OIB mantle sources—geochemists can “map” the isotopic heterogeneity of the Earth’s deep mantle (e.g., Gast et ...

Journal: :Remote Sensing 2015
Long Li Carmen Solana Frank Canters Jonathan Cheung-Wai Chan Matthieu Kervyn

We report on spectral reflectance measurements of basaltic lava flows on Tenerife Island, Spain. Lava flow surfaces of different ages, surface roughness and elevations were systematically measured using a field spectroradiometer operating in the range of 350–2500 nm. Surface roughness, oxidation and lichen coverage were documented at each measured site. Spectral properties vary with age and mor...

2009
TAKASHI KATSURA

IN · RECENT YEARS the Hawaiian Islands have become of great importance in studies concerned with igneous petrogenic theory. This is partly because of the total absence in that region of sialic crust that might affect the formation of other rock types by its assimilation in rising magma. Partly, also, it is because of the extensive lateral and vertical exposure of successions of rocks, the struc...

2015
Georges Boudon Hélène Balcone-Boissard Benoît Villemant Daniel J. Morgan

Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical stu...

2017
Nathan Magnall Mike R. James Hugh Tuffen Charlotte Vye-Brown

Accurate forecasts of lava flow length rely on estimates of eruption andmagma properties and, potentially more challengingly, on an understanding of the relative influence of characteristics such as the apparent viscosity, the yield strength of the flow core, or the strength of the lava’s surface crust. For basaltic lavas, the relatively high frequency of eruptions has resulted in numerous oppo...

2004
Louis D. Whiteaker Donald E. Gardner

The primary objective of this study was to map the distribution and abundance of firetree (Myrica faya) in the state of Hawai`i. Reconnaissance data were used to map 85,912 a (34,365 ha) of infestation throughout the State. Infestations of 72,265 a (28,906 ha) occur on the island of Hawai`i, 4,770 a (1,908 ha) on Maui, 2,518 a (1,007 ha) on Lana`i, 435 a (174 ha) on O`ahu, and 5,925 a (2,370 ha...

Journal: :Molecular phylogenetics and evolution 2004
David Kizirian Adrienne Trager Maureen A Donnelly John W Wright

Nucleotide sequences of mitochondrial genes (ND1, ND2, COI, and tRNAs) were determined for 38 samples representing 15 taxa of tropidurid lizards from the Galapagos Islands and mainland South America. Phylogenetically informative characters (759 of 1,956) were analyzed under Bayesian, maximum likelihood, and parsimony frameworks. This study supports the hypothesis that tropidurid lizards dispers...

2009
T.

Observations of terrestrial examples of lava and ice interaction have been combined with laboratory simulations to provide a framework for investigating lava and ice interaction on Mars. Identification of largeand small-scale characteristic features will indicate whether large quantities of meltwater were trapped or whether lava flow confinement occurred. These features should also enable the d...

2017
S. F. Jenkins S. J. Day B. V. E. Faria J. F. B. D. Fonseca

Fast-moving lava flows during the 2014–2015 eruption of Fogo volcano in Cape Verde engulfed 75% (n = 260) of buildings within three villages in the Chã das Caldeiras area, as well as 25% of cultivable agricultural land, water storage facilities and the only road into the area. The eruption had a catastrophic impact for the closeknit communities of Chã, destroying much of their property, land an...

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