Volcanoes!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Today I am going to tell you about volcanoes. A volcano is a vent in earths crust through which melted or molten rock flows. Volcanoes are formed when two tectonic plates push together and the magma from the mantle reaches the surface then it makes a volcano.

There is not just one kind of volcano there are more. One type of volcano is the shield volcano. A shield volcano is a type of volcano that has been formed by lava flow. Shield volcanoes are large and wide with a low profile. The crater at the volcano is not far above sea level in comparison to a composite volcano. Most shield volcanoes are super volcanoes.

There is another type of volcano and that is a composite volcano. Composite volcanoes are large, steep -sided volcanoes that result from explosive eruptions of andesitic lava and ash along convergent plate boundaries.

There is one more type of volcano and that is the cinder cone volcano. Cinder cone volcanoes are small, steep-sided volcanoes that erupt gas-rich, basaltic lavas.

When a volcano explodes it has to let go of all the magma it can hold. When the magma from the mantle pushes up the volcano and lava spreads everywhere. The difference between magma and lava is magma is what is in the mantle and in the volcano and lava is what comes out the volcano.

When a volcano erupts volcanic ash comes out of the volcano. Volcanic ash is a big cloud of ash coming out of the volcano. It can effect the climate by the ash spreading everywhere.

Volcanoes that are not associated with plate boundaries are called hot spots. Geologists hypothesize that hot spots originate above a rising convection current from deep within earths mantle.

High viscosity lavas flow slowly and typically cover small areas causing stratovolcanoes that explode violently due to trapped gas.

http://www.weatherwizkids.com/weather-volcano.htm
http://www.k12.hi.us/~kapunaha/student_projects/volc_blowout/shield_volcano.htm
http://pubs.usgs.gov/gip/volc/types.html

Tsunami

Today I am going to tell you about tsunami's and how they happen. A tsunami is a harbor wave. Tsu is harbor and nami is wave. Tsunami's are caused by plate tectonics. Plate tectonics are plates in the earths crust. When a continental plate crashes into a oceanic plate   the oceanic plate goes under the continental plate and thats what causes a tsunami. 

Tsunami's are also caused by underwater volcanoes and landslides. Landslides are movements of rock, debris, and soil down a slope of land. When the rock and debris in the ocean falls down on the ocean floor it sends the water going up higher. As it gets closer to the shore the water gets higher and makes a tsunami. 

There is one more way a tsunami can be caused. A underwater volcano can cause a tsunami. A underwater volcano is a volcano that is formed underwater. When two pieces of oceanic crust come together the magma is pushing them up making an underwater volcano. When the volcano erupts it creates movement on the ocean floor moving the tectonic plates creating a tsunami.

A tsunami travels in every direction. A tsunami can travel up to 500 miles per hour. When the tsunami gets closer to shore it slows down and the waves get higher. When you are all the way out in the ocean you would never fell the tsunami. When you are at the beach you will never when it is coming. Some tsunami's can get 100 to 300 ft tall.

http://www.brainpop.com/science/theearthsystem/tsunami/preview.weml


http://www.windows2universe.org/earth/tsunami2.html


http://www.nws.noaa.gov/om/brochures/tsunami2.htm