Search results
Results from the WOW.Com Content Network
Lava tubes are efficient transporters of lava from the vent to the flow front, and the lava cools by only about 1 °C/km (Walker, 1991). A broad lava-flow field often consists of the main lava tube and a series of smaller tubes that supply lava to the front of one or more separate flows (Greeley, 1987).
The extent of the 2018 lava flows is shown in blue; the Pu‘u ‘Ō‘ō lavas are in red, and the 1955 lavas are in green. Emplacement dates for other prominent lava flows erupted in the 19th and 20th centuries are also shown. The base image is a hillshade of the volcano, illuminated from the east.
Qualitative relationship between pahoehoe and a′a lava flow morphologies with viscosity and shear rate (modified from Harris and Rowland, 2015). Uncommonly, pahoehoe breakouts are observed at the toes of ′a′ā flows (Fig. 1). These breakouts reveal that it is the interplay of lava viscosity and shear rate that constrain the ′a′ā to ...
Conclusions. Lava morphologies at mid-ocean ridges exhibit a broad spectrum of surface types, ranging from low relief sheet flows to hummocky pillow flows and volcanic edifices (seamounts). Volcanic landscapes vary from site to site, and the precise reasons for the observed flow types are poorly understood.
Lava flows dominate the surfaces of many of the world's basaltic centers, such as Hawai‘i, the Galápagos, Iceland, Vesuvius and Etna (Italy), the Afar, Nyiragongo and Nyiramuriga (Democratic Republic of Congo) and Piton de la Fournaise (Réunion), to name but a few, as well as the natrocarbonitite center of Ol Doinyo Lengai (Tanzania).
A broad lava-flow field commonly consists of a main lava tube and a series of smaller tubes, which supply lava to the front of one or more separate flows. When the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the tube system drains downslope and leaves partially empty conduits beneath the ground.
(A) Overview map outlining Yellowstone Central Plateau Member rhyolite lava flows, vent locations, and the Lava Creek Tuff caldera margin. (B) Elevation map of the Summit Lake and nearby lavas. Approximate symmetrical dotted circle in line with the A–A′ section has the same area (400 km 2) as the mapped flow surface area.
Abstract. Q-LavHA is a freeware plugin which simulates lava flow inundation probability from one or regularly distributed eruptive vents on a Digital Elevation Model (DEM). It combines existing probabilistic and deterministic models and proposes some improvements to calculate the probability of lava flow spatial propagation and terminal length.
In the case of flows containing bubbles, which have a non-Newtonian rheology, this is a simplifying assumption that nonetheless provides a useful first-order bulk viscosity estimate referred to as apparent viscosity, which enables the comparison of the downslope flow behavior of different lava flows.
Morphological dimensions of lava flows are commonly used in planetary sciences to infer the rheological properties (viscosity, yield strength) of the erupted material, which are in turn used to estimate the silica content of the lava. Simple isothermal models of lava flow emplacement have been used to extract these properties, and the ...