Volcano Website
There are active volcanoes worldwide. For example, Mt.
Rainier looms over the Seattle/ Tacoma area, endangering
millions of people. Volcanoes form deep inside the Earth.
When the mantle melts, moves through the crust, and releases
gases, volcanoes erupt. The water provides the explosive potential of steam.

Volcanoes are classified on their shape, the materials they are built of, and how they erupt. The groups of volcanoes are: Composite, Sheild, Cinder Cones, Spatter Cones, and Complex Volcanoes. The Composite Volcanoes are formed by layers of lava and rock fragments. They are quiet between eruptions, and they are constructed by subduction zones. The Sheild Volcanoes are huge in size. They are built by many running layers of lava. Broad shaped, gentle sloping cone is formed by the lava that spills out of a central vent. The Cinder Cones is a steep conical hill formed above a vent.
They are very common through out the world. The cones usually grow up in groups, and they often occur on the flanks of Composite and Sheid volcanoes. When hot erupting lava has just enough gas to prevent the formation of lava flow, but not enough to shatter it, the lava is torn by expanding gases into fluid hot clots, is called spatter. The accumulations focused on an individual vent is called shatter cones. Many volcanoes can be a complex volcano. When a volcano consists of a complex of two or more vents it is reckoned as a       complex volcano.

The prediction of a volcano is very important. The most important methods to predicting volcanoes are:seismographic monitoring, tiltmeters, and serveillance by satellite. The seismicgraph shows the earth tremors which are caused by rising magma. Tiltmeters measures the ground deformation that rising magma within the volcano causes. The serveillance by satellites detect ground deplacements which in the future can pinpoint activity.
                                              

The island, Maui, is made up of two volcanoes. West and East Maui. A caldera has been identified in the area of present-day Iao Valley. About 1 million years ago 4 volcanoes have erupted during the rejuvenated stage in West Maui. West Maui has not erupted in historic time and is considered extinct. East Maui Volcano is the eastern most of two sheild
volcanoes that make the Island of Maui. Three rift zones can be spotted in the picture below taken in a space shuttle.
 
 

Most of the volcanoes activity has been located along the southwest and east rift zones. The Haleaka Crater is at the summit of the volcano. The crater is an erosional caledra formed by two large valleys that erode into the volcano. The most recent eruption of the crater was in about 1790. Haleaka Crater is conside active volcano because of its historic time in Hawaii.
                                     

The picture above shows the Navjo volcanic field. This field
covers 20,000 square km in the four corners of Arizona, New Mexico, Colorado, and Utah. These volcanoes erupted about 30 to 25 millions years ago. Since then erosion has lowered the land hundreds of meters. Shiprock is an example of a neck or plug. This is the feeding conduits of the volcano that is filled with magma breccia.

The volcano plugs or necks form crudely cylindrical masses. Dike is from the neck. The picture shows the remains of the shallow interior of the volcano.

  The rocks of this volcano are minette and kimberlite based on their composition. A minette is a potassium-rich rock. The kimberlite, which is found in tuff pipes or dikes, is a microbeccia.

 The Hazards of Volcanoes

Volcanoes can be very hazardous. Although sometimes volcanoes can be not as hazardous as others. Lava flows are the least hazardous of all volcanic eruptions. Lava flows don't move very fast so people usually do not get killed by
them. Some people though have burnt their skin, or melted the soles of their shoes, because lava does not cool quickly. It can take a day to a year for lava flows to cool. Another hazard from a volcanic eruption is a lahar. A lahar is one of the greastest hazards. Lahars contain more water than pyroclastic flows.
The water is from snow and ice, and when released forms lahars. They flow smoothly, move fast, and float cars, boulders, bridges, and buildings. For more information on volcanoes go to hazards.
 
 

 Causes of Eruptions

                         

 When magma rises to Earths surface the pressure decreases, causing the magma to expand. The expanding of the magma then forces it up through Earths surface causing a volcano eruption. The type of eruption depends on if the magma is runny or sticky. Once magma is erupted it is called lava. The
eruption can cause mudflows, which have buried cities.
 

  Signs that an Eruption is Likely

 Volcanoes give various kinds of warnings before an eruption. Although some eruptions, for example a steaming blast, gives little warnings. People living near a volcano can detect if it is going to erupt or not by the shaking of an earthquake increasing or see the volcano in action. Seismographs can also
detect an eruption. Ground techniques are used when the swelling of the ground is spotted.