Volcanoes are formed when the molten iron core and thin crust  deep inside of earth's surface also known as the mantle melts and then it moves through the surface through the crust.
High temperatures and pressure cause the rock to melt and become hot liquid rock~ also known as magma. When a large amount of magma has formed, it rises through the layers toward Earth's surface. Magma that has come out through the surface is then called lava. Since rocks are made of collections of minerals that have melted at different temperatures, the makeup of the rock will all be different.
        Magma that has reached Earth's surface comes in 3 different compositions they are basalt, Andesite, and Ryholite. Basaltic magma is the most common form of magma. It forms from the partial melting of rock in the zone of Earth's mantle also known as the asthenosphere. Basalt has the lowest amount of silica. This makes is less dangerous than any other volcanoes.
    Andesite can come in different ways. It is usually formed by the partial melting of wet basalt. They often occur at colliding plate margins where oceanic crust forms. It can also be formed by the melting of continental crust. Andesite volcanos are usually more dangerous than basaltic because they have more dissolved gasses.

                     (Inside a volcano)
 
 
 
 
 
 

                                               Sanford Volcano

       The Sanford volcano is located in Alaska. It is a large shield volcano. There are no known eruptions. It is the highest volcano in the Wrangell volcanic field. It is 11,733 feet tall ( from its base to its summit).
    The upper part of the Sanford volcano is mostly covered with ice and snow. The upper area is mostly younger than the rest of the volcano. The upper area was most likely built on tops of  three shield volcanoes. They make up the north, west, and south eruptive centers. Lava from the volcano are mostly made up of basalt and andesite.
 

                                          Devil's Tower
Devil's tower is located in Wyoming. It's elevation is 5,112 feet.  It's a steep sided igneous body. It's magma is solid to a shallow level to about  700 to 3,000 feet below the surface. Erosion then stripped the overlying layers of rocks away. The rock around the volcano are about 40 million years old.
  The rock surrounding the tower is called a phonolite based on its mineral composition. It includes anorthoclase, aegirine-augite, and sphene. Devil's tower rises up to about 1,253 feet (382m) above Belle Fouche River. The tower has columns which are mostly 5 sided. The columns formed from magma while it was cooling from the surface downward.
 
 

                                               Volcano Hazards

    A volcanic hazard is the total probability of a specific area that will be affected by a destructive volcanic process. Volcanoe eruptions aren't necessarily all the same. They can be put into different categories. Many eruptions produce fragmental rocks from erupting lava and surrounding country rock. Some eruptions are dangerously explosive and produce volcanic ash. Explosive eruptions sometimes cause widespread ash fall, pyroclastic flows, debris, avalanches, landslides, pyroclastic surges, and lahars. For more information click here
 

                                       Causes of Volcanos

    Volcanos are caused when the rock deep inside the earth becomes so hot that the rocks slowly melt and become a thick flowing liquid known as magma. After it is erupted, it is then called lava. Since it is lighter than the rock around it, magma rises and collects in magma chambers. Then some of the magma gets pushed through the vents and out through the earth's surface. Then the lava erupts. For more information click here
 

                                      Signs Of An Eruption

    Most of the time, volcanos give out warning signs before they actually erupt. Even though sometimes they can erupt without any type of warning. Usually, slight  shaking is felt before an eruption occurs. Seismometers can detect and locate earthquakes that are associated with rising magma. Swelling ground can be detected by using special instruments and special techniques that measure the changes in slope, distance, or elevation at the ground surface. For more information about this click here.