A vent, hole, crack, or opening in the earth's crust through which magma (molten rock), associated gases, matter, and ash erupt and/or the hill, mountain or structure, usually conical, produced by the accumulation of the ejected material.
As the magma and ash cool, they harden to form rock.
Volcanoes occur mainly near plate tectonic boundaries and are especially common around the Pacific basin, called the Pacific Ring of Fire. Generally, volcanoes erupt when the Earth's plates move apart or when one plate is forced beneath another.
Volcanic eruptions may be violent, even catastrophic, or relatively mild. The most explosive eruptions are essentially blasts of steam that create spectacular displays. Humanity has long been awed by this powerful force of nature.
The Romans attributed volcanic events to Vulcan, the god of fire and metalworking. In A.D. 79 the eruption of Mount Vesuvius destroyed the Roman cities of Pompeii and Herculaneum. Polynesians believe volcanoes to be ruled by the fire goddess Pele.
One of the most spectacular volcanic eruptions in recorded history occurred in 1883 with the explosion of Krakatoa, an island in the Sunda Strait near Java.
A more recent example is the dramatic 1980 eruption of Mount St. Helens in the Cascade Range in Washington State. Quieter fissure eruptions occur when molten rock pushes through long cracks in the Earth's crust and floods the surrounding landscape. Such repeated outpourings of lava can fill surrounding valleys and bury low hills, creating thick lava sequences that eventually become plateaus.
Throughout the world there are 500 to 800 active volcanoes. However, during a year only 30 might erupt in land. An inactive, or dormant, volcano is still capable of erupting. An extinct volcano is dead and cannot erupt. Undersea volcanoes can form islands such as Iceland and Hawaii.
This website is best viewed with the latest
Internet Explorer or
makes extensive use of
Flash and Scripting in its pages and interface. Make certain your browser
permissions are set
accordingly and that you have the latest
Flash plug-in for the full experience, proper look and accurate
layout. You can do it with confidence. This site does not contain any viruses, malicious software
Occultopedia is the genuine article, the
original and the best internet index of the extraordinary and uncanny,
shamelessly copied by many, but never equaled. Online since 1995 at first in a free web space provider
(Tripod.com), and in 1997 finally
with its own domain name and hosting Occultopedia still is the
principal online resource for those looking for the unexplained, the
curious and the unusual.
Occultopedia respects your privacy. As
such, no cookies or any other tracking software will be installed as a
part of this website's original programming. I do not seek to obtain any personal information
beyond what is volunteered through electronic communications
(e.g. emails & forms).
Occultopedia may appear to be a for profit site, but my site is
not in reality a commercial one. All of the commercial links are from affiliate
programs, and the little revenue I get from these is to pay for hosting,
bandwidth that can be quite costly if you have a lot of traffic, graphics and
pages and any other expenses related to Occultopedia's upkeep, support, and maintenance.
For more details, visit my
Occultopedia is a
resource available to the whole world. Usage of my word definitions and articles
by educational institutions, teachers and students alike, is here by granted.
Reproduction for profit, and for display in another web site is strictly
forbidden, and will be handled as copyright infringement and prosecuted to the
full extent of the law. However, if you follow
some simple guidelines,
I will grant permission for limited reproduction. For more information, please consult my
intellectual property rights, warranties and
disclaimers information page. Support Occultopedia and make it your
destination. If you prefer, you can also make a donation.
HELP FOOT THE BILL: this website
is created and maintained by one guy, who also pays the hosting bill.
Please donate if you like and/or use Occultopedia.
Participate in Occultopedia and submit a word
definition or article for the occult encyclopedia at my
page. If you would like to suggest a web site or page for
addition into Occultopedia's links database, please go to my
URL submission page.