Results 181 to 190 of about 20,752 (258)

Fine ash from the Campanian Ignimbrite super-eruption, ~ 40 ka, southern Italy: implications for dispersal mechanisms and health hazard. [PDF]

Sci Rep
Gianchiglia F, Ballirano P, Giaccio B, Koutsodendris A, Nomade S, Pacella A, Palladino DM, Pross J, Veres D, Sottili G.   +9 more
europepmc   +1 more source

Welded pyroclastic rock at Tongariro [PDF]

New Zealand Journal of Geology and Geophysics, 1963
Abstract Although the rocks of Tongariro National Park have been mapped and their petrograplty is reasonably well known, little attention has so far been paid to their physical character and modes of eruption. Lava, scoria, and ash are the most common types, though hot avalanches that erupted in 1949 and 1954 have been described by Battey (1949) and ...
J. H. Healy
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Cyclic and dynamic behaviour of a soft pyroclastic rock

Géotechnique, 2015
The mechanical behaviour under cyclic and dynamic conditions of a weakly cemented pozzolana, taken from the subsoil of a historical town in a seismically active area, was investigated through laboratory tests and in situ measurements. The geotechnical characterisation at laboratory scale is of particular importance as the small- and large-scale ...
VERRUCCI, Luca, LANZO, Giuseppe, TOMMASI, PAOLO, ROTONDA, Tatiana   +3 more
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Geotechnical characteristics of ignimbrite: A soft pyroclastic rock type

Engineering Geology, 1993
Abstract The ranges of a variety of geotechnical properties encompassed by the ignimbrite lithology are established. Ignimbrites are of low density (1212–1928 kg m −3 ) and high porosity (18–51%), are very weak to weak in compression (0.23–54 MN m −2 ), have low tensile strength (0.12–7.1 MN m −2 ) and cohesion (0.06–9.0 MN m −2 ), yet the angle ...
Vicki G. Moon
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Factors governing the formation of pyroclastic rocks

Bulletin Volcanologique, 1970
The basic condition governing the formation of pyroclastic rocks is the relationship between the disruptive force of gas pressure in bubbles to the strength of the liquid for short term stresses and surface tension. The latter factor controls the coalescence of bubbles, because it is strongly dependent on the composition, temperature, and water content
A. R. McBirney, T. Murase
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Physical and structural properties of a pyroclastic soft rock

, 1998
The subsoil of a large area surrounding the city of Rome (Italy) consists mainly of pyroclastic deposits originated from the explosive activity of the Colli Albani volcanic complex. This paper focuses on a type of pyroclastic soft rock, locally known as Pozzolana Nera. The structural features of the deposit are presented in the paper.
CECCONI, Manuela, Viggiani G.
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Stratigraphic Problems of Pyroclastic Rocks

1984
Stratigraphic methods used to study volcanic rocks are similar to those used to study sedimentary rocks and have similar purposes: establishing correlations, vertical time sequences, determining facies changes and the like. Additional aid in pyroclastic stratigraphy comes from igneous petrology, studies of magma evolution, and studies of the growth ...
Richard V. Fisher, Hans-Ulrich Schmincke
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Pyroclastic Rocks and Tectonic Environment

1984
The close proximity of continental borderlands, active and ancient tectonic regions, and modern and ancient volcanoes has long been known. Pre-plate tectonic ideas about this association culminated in Kay’s (1951) masterful synthesis showing the relationship between volcanic island arcs and ancient eugeosynclinal sedimentary basins containing abundant ...
Richard V. Fisher, Hans-Ulrich Schmincke
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Potassium—argon ages of sedimentary and pyroclastic rocks

Geological Society, London, Special Publications, 1964
Summary It is rarely possible to obtain reliable potassiumargon ages from sedimentary rocks. Glauconites generally give dates that are too low and very scattered, though the largest of a group of such measurements may be useful to define minimum ages of sediments that cannot be dated in any other way.
Halfdan Baadsgaard, Martin Henry Dodson
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