Wednesday, February 29, 2012

How Volcanoes are Formed

Volcanoes form when an oceanic plate collides with a continental plate. The oceanic plate subducts under a continental plate, since it is denser, forming a volcano. These volcanoes are also formed by convergent plate boundaries, since they are the plate boundaries that collide. Something unusual about Hawaii though, is that it has hotspot volcanoes meaning they do not form with convergent plate boundaries. Hot spot volcanoes are formed from divergent plate boundaries and are formed by pressure. They have deep crusts, are like blow torches, are warmer in temperature, and are especially hotter in the convection cell.
                                           

How Igneous Rocks are Formed

 Igneous rocks can be formed in two different ways. Examples are granite, scoria, and obsidian.


Igneous rocks can form when magma erupts out of a volcano as lava and lands on the ground. When the lava cools down on the ground it hardens to become igneous rocks.



They are formed underground when magma, inside the Earth get trapped in small sockets. As these sockets of magma cool slowly under the ground, it transforms into igneous rocks.

These two different ways can form igneous rocks in Hawaii or anywhere. Another name for igneous rocks is fire rocks.

                          

Hazards of Volcanoes

Volcanoes are geological features of the Earth that benefit us in many ways, but a the same time they also act as hazards.


Ash Falls- Ash fills the air releasing particules, destroys forest, water vegetation, effects people the most, creates eerie darkness, irritates people, crashes airplanes, destroys roofs


Hot Ash Flows- Most destructive, burns everything in path, dangerous, moves fast, pores into water bodies, fires, complete destruction


Mudflows- Floods of water, sand, mud, travels 50km per hour, rip huge bolders from ground, destroys everything in path, houses rip apart


Volcanic Tsunamis- Tsunami comes when volcanic particles flow in the ocean


Lava Flows- Lava pores across floor from vents, molten rock lava, 1km/ hour or day, moves very slowly, destroys buildings leaves land useless


Volcanic Gas- releases gas when water boiled by volcanic heat, rises 100meters high, releases sulphur gases, smells like rotten eggs, stings the throat and nose, damages crops, fluorine & Carbon Dioxide contaminate grasses eaten by animals killing humans & animals, destruct a lot of things, and kill everything in its path 


These are all Volcanic hazards, but Hawaii makes sure no body gets affected by these hazards.




                  



Famous Volcanoes in Hawaii





People all around the world visit Hawaii mainly for its hot spot volcanoes. 




An example volcano is Mauna Loa, this volcano is a Shield Volcano and is the biggest volcano in the world. Mauna Loa also means "Long Mountain" in Hawaiian for its great length. The volcano is really big and stretches 17km above its base. The volcano erupted 33 times and the most recent eruption took place on March 24- April 15, 1984. It also one of the most active volcanoes in the world and takes up majority of the Hawaiian Islands.
                                         
                                                     

Map of outline of Mauna Loa Volcano
Map of the Island of Hawaii
Location
19.475 N 155.608 W
Elev. Above Sea Level4,170 m
13,680 ft
Area5,271 km2
2,035 mi2
(50.5% of Hawai`i)
Volume80,000 km3
19,000 mi3


   Real Picture of Mauna Loa






Kilauea sits on the southeastern most part of the Big Island in Hawaii. This volcano is also a shield volcano like the Mauna Loa, but is not as large. Kilauea means spewing or much spreading in Hawaiian. The volcano has been having continuos eruptions since January 3, 1983, meaning it is still erupting to this day, and has had 61 eruptions recorded so far. This volcano might as well be the most active in the world. Hawaiians also believe the Hawaiian godess Pele lives in the Kilauea volcano.







Kilauea Facts

Map of outline of Kilauea Volcano
Map of the Island of Hawaii
Location19.425 N 155.292
Elev. Above Sea Level1,277 m
4,190 ft
Area1,430 km2
552 mi2
(13.7% of Hawaii)
Volume25,000-35,000 km3
6,000-8,500 mi3
  
         Real picture of Kilauea



         

Kilauea and Mona Loa some volcanoes that make Hawaii the special place it is!

Tuesday, February 28, 2012

Types of Volcanoes

In the world three types of Volcanoes exist. They are cinder cone, strato, and shield Volcanoes.


Cinder Cone Volcanoes- These volcanoes are made mostly of cinders, igneous rocks, and other particles that have been blown up by air. Cinder cone volcanoes can be formed by explosive eruptions. They also contain a narrow base and steep sides. The materials are usually loosely arranged and the cones are not high. A popular example of a cinder cone volcano is Paricutin in Mexico. These volcanoes are not as popular in Hawaii.
                                       
                                          


Composite/Strato Volcanoes - Composite/strato volcanoes are formed by violent eruptions, hurtling volcanic bombs, cinders, and ashes out of vents. They also build up alternating layers of rock particle and lava inside the volcano. The volcano also has quiet eruptions that follow and produce a lava that covers these rock particles. A great example of a composite/strato volcano is Mt. St.Helens in Washington. These volcanoes are also not as common in Hawaii.
                                                       
Shield Volcanoes- They are composed of quiet lava flows. The lava is runny and flows over a large area, the two types of lava flows are Aa&Pahoehoe. Aa is stony and rough, while Pahoehoe is smooth. There are also several quiet eruptions from gently slipping domed shaped mountains. An example in Mauna Loa, in Hawaii. Hawaii is mainly made of Shield Volcanoes only.