Description

The word volcano is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain built up around the opening by the eruptive products. This slide set depicts explosive eruptions, lava fountains and flows, stream eruptions, and fissure eruptions from 19 volcanoes in 13 countries. Volcano types represented in this set include strato, cinder cone, complex, fissure vent, lava dome, shield, and island-forming. Perhaps no force of nature arouses more awe and wonder than that of a volcanic eruption. Volcanoes can be ruthless destroyers. Primitive people offered sacrifices to stem the tide of such eruptions and many of their legends were centered around volcanic activity. Volcanoes are also benefactors. Volcanic processes have liberated gases of the atmosphere and water in our lakes and oceans from the rocks deep beneath Earth's surface. The fertility of the soil is greatly enhanced by volcanic eruptive products. Land masses such as islands and large sections of continents may owe their existence entirely to volcanic activity. The word "volcano" is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain built up around the opening by the eruptive products. The molten rock material generated within Earth that feeds volcanoes is called magma and the storage reservoir near the surface is called the magma chamber. Eruptive products include lava (fluid rock material) and pyroclastics or tephra (fragmentary solid or liquid rock material). Tephra includes volcanic ash, lapilli (fragments between 2 and 64 mm), blocks, and bombs. Low viscosity lava can spread great distances from the vent. Higher viscosity produces thicker lava flows that cover less area. Lava may form lava lakes of fluid rock in summit craters or in pit craters on the flanks of shield volcanoes. When the lava issues vertically from a central vent or a fissure in a rhythmic, jet-like eruption, it produces a lava fountain. Pyroclastic (fire-broken) rocks and rock fragments are products of explosive eruptions. These may be ejected more or less vertically, then fall back to Earth in the form of ash fall deposits. Pyroclastic flows result when the eruptive fragments follow the contours of the volcano and surrounding terrain. They are of three main types: glowing ash clouds, ash flows, and mudflows. A glowing ash cloud (nue ardente) consists of an avalanche of incandescent volcanic fragments suspended on a cushion of air or expanding volcanic gas. This cloud forms from the collapse of a vertical ash eruption, from a directed blast, or is the result of the disintegration of a lava dome. Temperatures in the glowing cloud can reach 1,000 deg C and velocities of 150 km per hour. Ash flows resemble glowing ash clouds; however, their temperatures are much lower. Mudflows (lahars) consist of solid volcanic rock fragments held in water suspension. Some may be hot, but most occur as cold flows. They may reach speeds of 92 km per hour and extend to distances of several tens of kilometers. Large snow-covered volcanoes that erupt explosively are the principal sources of mud flows. Explosions can give rise to air shock waves and base surges. Air shock waves are generated as a result of the explosive introduction of volcanic ejecta into the atmosphere. A base surge may carry air, water, and solid debris outward from the volcano at the base of the vertical explosion column. Volcanic structures can take many forms. A few of the smaller structures built directly around vents include cinder, spatter, and lava cones. Thick lavas may pile up over their vents to form lava domes. Larger structures produced by low viscosity lava flows include lava plains and gently sloping cones known as a shield volcanoes. A stratovolcano (also known as a composite volcano) is built of successive layers of ash and lava. A volcano may consist of two or more cones side by side and is referred to as compound or complex. Sometimes a violent eruption will partially empty the underground reservoir of magma. The roof of the magma chamber may then partially or totally collapse. The resulting caldera may be filled by water. The volcanic structure tells us much about the nature of the eruptions.

General Information

• This data is described at

  http://catalog.data.gov/dataset/volcanoes-in-eruption-set-1 Do you think this data is incorrect? Let us know

• This data is published by

  National Oceanic and Atmospheric Administration, Department of Commerce Do you think this data is incorrect? Let us know

Legal Information

• The rights statement is at

  http://catalog.data.gov/dataset/volcanoes-in-eruption-set-1 Do you think this data is incorrect? Let us know

• Outside the US, this data is available under

  Creative Commons CCZero Do you think this data is incorrect? Let us know

• There are

  yes, and the rights are all held by the same person or organisation Do you think this data is incorrect? Let us know

• The content is available under

  Creative Commons CCZero Do you think this data is incorrect? Let us know

• This data contains

  no data about individuals Do you think this data is incorrect? Let us know

Practical Information

• The data appears in this collection

  http://catalog.data.gov/organization/noaa-gov Do you think this data is incorrect? Let us know

• This data changes

  no Do you think this data is incorrect? Let us know

• The data is

  backed up offsite Do you think this data is incorrect? Let us know

Technical Information

• Releases of this data are listed at

  http://catalog.data.gov/api/rest/package/volcanoes-in-eruption-set-1 Do you think this data is incorrect? Let us know

Social Information

• The documentation includes machine-readable data for

  title Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  description Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  identifier Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  landing page Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  release frequency Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  publisher Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  distribution(s) Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  release date Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  modification date Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  temporal coverage Do you think this data is incorrect? Let us know

• The documentation includes machine-readable data for

  spatial/geographical coverage Do you think this data is incorrect? Let us know

• The documentation about each distribution includes machine-readable data for

  release date Do you think this data is incorrect? Let us know

• The documentation about each distribution includes machine-readable data for

  a URL to access the data Do you think this data is incorrect? Let us know

• The documentation about each distribution includes machine-readable data for

  a URL to download the dataset Do you think this data is incorrect? Let us know

• Find out how to contact someone about this data at

  http://catalog.data.gov/dataset/volcanoes-in-eruption-set-1 Do you think this data is incorrect? Let us know

• Find out how to suggest improvements to publication at

  http://www.data.gov/issue/?media_url=http://catalog.data.gov/dataset/volcanoes-in-eruption-set-1 Do you think this data is incorrect? Let us know