نتایج جستجو برای: acidic magma
تعداد نتایج: 41771 فیلتر نتایج به سال:
Timescales of magma ascent in conduit models are typically assumed to be much longer than crystallization and gas exsolution for basaltic eruptions. However, it is now recognized that basaltic magmas may rise fast enough for disequilibrium processes to play a key role on the ascent dynamics. The quantification of the characteristic times for crystallization and exsolution processes are fundamen...
In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thu...
We use 2000–2012 InSAR data frommultiple satellites to investigate magma storage in Kīlauea’s east rift zone (ERZ). The study period includes a surge in magma supply rate and intrusion-eruptions in 2007 and 2011. The Kupaianaha area inflated by ~5 cm prior to the 2007 intrusion and the Nāpau Crater area by ~10 cm following the 2011 intrusion. For the Nāpau Crater area, elastic modeling suggests...
[1] We use 2006–2009 ALOS Interferometric Synthetic Aperture Radar data over the entire west Sunda arc, Indonesia, home of 13% of the world’s active volcanoes, to derive arcwide time-dependent ground deformation data. We present unambiguous evidence of inflation at six volcanoes, three of which erupted after the observation period.We show that these volcanoes have shallow magma reservoirs at 1–...
We investigate the problem of estimating magma chamber geometry using InSAR observations of Sierra Negra volcano, Galápagos. Ascending and descending interferograms are combined to determine vertical and one horizontal component of displacement. The ratio of maximum horizontal to vertical displacement suggests a sill-like source. Spherical or stock-like bodies are inconsistent with the data. We...
central tenet of lunar science is that the Moon was surrounded by a huge ocean of magma when it formed. Originally thought to be a few hundred kilometers deep, lunar scientists now think that the entire Moon was initially molten. Numerous geochemical models have been constructed for the crystallization of the magma ocean. All the calculations use computer programs based on experimental data, bu...
There are more than 7 million people living near the Tatun volcano group in northern Taiwan. For the safety of the Taipei metropolis, in particular, it has been debated for decades whether or not these volcanoes are active. Here I show evidence of a deep magma reservoir beneath the Taipei metropolis from both S-wave shadows and P-wave delays. The reservoir is probably composed of either a thin ...
The lack of contraction features on the Moon has been used to argue that the Moon underwent limited secular cooling, and thus had a relatively cool initial state. A cool early state in turn limits the depth of the lunar magma ocean. Recent GRAIL gravity measurements, however, suggest that dikes were emplaced in the lower crust, requiring global lunar expansion. Starting from the magma ocean sta...
[1] The absent or weak magnetic field above large Martian volcanoes may provide constraints on their formation and the carrier of magnetization. We consider the ability of magma intrusions to thermally demagnetize the shallow crust beneath volcanoes through heat conduction and hydrothermal circulation. If magnetization is dominated by magnetite, the volume of crust that is thermally demagnetize...
[1] We use the identification of volcanism on Mercury, together with lobate, flow-front like topography, crustal composition information and data on the stress state and history of the lithosphere, to derive a new model for the ascent and eruption of magma on Mercury. We find that extrusion is likely to be dominated by high-effusion rate events. Initial emplacement of dikes in the crust and ext...
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