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Volcano's Deadly Warning. Volcanoes Online. National Geographic: Eye in the Sky. Volcanoes are awesome manifestations of the fiery power contained deep within the Earth.

National Geographic: Eye in the Sky

These formations are essentially vents on the Earth's surface where molten rock, debris, and gases from the planet's interior are emitted. When thick magma and large amounts of gas build up under the surface, eruptions can be explosive, expelling lava, rocks and ash into the air. Less gas and more viscous magma usually mean a less dramatic eruption, often causing streams of lava to ooze from the vent. The mountain-like mounds that we associate with volcanoes are what remain after the material spewed during eruptions has collected and hardened around the vent. This can happen over a period of weeks or many millions of years. A large eruption can be extremely dangerous for people living near a volcano. Volcanoes tend to exist along the edges between tectonic plates, massive rock slabs that make up Earth's surface. Volcanoes - Introduction.

Volcano Live, John Seach. Volcano Hazards Program. Volcano Field Trip. Terrestrial Volcanoes. Terrestrial Volcanoes By turns hot embers from her entrails fly, And flakes of mountain flame that arch the sky.

Terrestrial Volcanoes

-Virgil's Aeneid Volcanoes destroy and volcanoes create. SAVAGE EARTH Online. Please note: SAVAGE EARTH ONLINE looks best when viewed using Netscape 3.0 or above, or Internet Explorer 3.0 or above, on Macintosh, Windows 95 or Windows 3.1.


If you have an earlier version, or another browser, all pages may not be presented exactly as designed. To view the animations in SAVAGE EARTH ONLINE, you will need the free Flash plug-in. Premiere: July 19, 1998, at 8 pm (ET) on PBS. (Watch for repeat showings on your local PBS station.) A Study of Plate Tectonics. Mount St Helens. Feature Pictured is the ash-and-gas plume produced during the plinian phase of the climactic eruption of Mount St. Helens that began shortly after 8:32 a.m. Mount St. Helens - May 18, 1980. Seismogram from station CPW, 112 km (70 mi) northwest of Mount St.

Mount St. Helens - May 18, 1980

Helens, May 18, 1980 Summary of Events Magma began intruding into the Mount St. Helens edifice in the late winter and early spring of 1980. By May 18, the cryptodome (bulge) on the north flank had likely reached the point of instability, and was creeping more rapidly toward failure. Precursory Activity. Mount St. Helens National Volcanic Monument. Fireweed, growing in Mount St.

Mount St. Helens National Volcanic Monument

Helens' devastated area; view from the north. Summer 1984. The Mount St. Helens National Volcanic Monument is within the Gifford Pinchot National Forest and managed by the USDA Forest Service. The Monument was established in 1982 to designate 445 km2 (110,000 acres) around Mount St Helens for research, recreation, and education. Mauna Loa, Decade Volcano. How Volcanoes Work.

Global Volcanism Program: Worldwide Ho. Mount Saint Helens. Cascades Volcano Observatory (CVO) Small magnitude earthquakes detected at Mount St.

Cascades Volcano Observatory (CVO)

Helens.March 18, 2016 On March 14, 2016, the seismic network at Mount St. Helens began detecting small magnitude earthquakes at a depth of 3–4 km beneath the crater. Twelve earthquakes have been formally located and the local seismic network detected at least 100 earthquakes too small to be recorded on enough seismometers to calculate a location. Many of the earthquakes have similar seismic signatures, suggesting they are occurring in the same area as the located earthquakes. These types of volcano-tectonic earthquakes beneath Mount St.

Registration is open for Mount Rainier educator workshopFebruary 19, 2016 Join us July 25–29, 2016, for a 5-day educator workshop at Mount Rainier. Geologic Map of the Simcoe Mountains Volcanic Field now available.November 18, 2015 The map shows, in various colors, the areas covered by 223 different eruptive units, mostly lava flows and cinder cones ranging in age from ~4 million to 600,000 years old. Volcano's Deadly Warning. By Lexi Krock Posted 11.12.02 NOVA What's the difference between lava and magma?

Volcano's Deadly Warning

What are volcanic vents, dikes, and fissures? In this anatomy of a volcano, explore the basic geological features of a volcano such as Mt. The 3 basic rock types. Ask GeoMan...

The 3 basic rock types

What are the 3 basic types of rocks? Just as any person can be put into one of two main categories of human being, all rocks can be put into one of three fundamentally different types of rocks. They are as follows: Igneous Rocks Igneous rocks are crystalline solids which form directly from the cooling of magma. This is an exothermic process (it loses heat) and involves a phase change from the liquid to the solid state. Sedimentary Rocks In most places on the surface, the igneous rocks which make up the majority of the crust are covered by a thin veneer of loose sediment, and the rock which is made as layers of this debris get compacted and cemented together.

Clastic: your basic sedimentary rock. Click here for more on sedimentary processes and rocks (RCC). Metamorphic Rocks The metamorphics get their name from "meta" (change) and "morph" (form).