‘The ring of Fire’

The ring of fire is an arc of intense seismic activity due to the fact that it is covered in 75% of the worlds most active and dormant volcanoes that stretches from New Zealand  along the eastern edges of Asia, across the north of Alaska along the Aleutian islands and then south along the coasts of North and South America, basically along the borders of the Pacific plate. The Ring of Fire was actually discovered before the invention of the tectonic theory and we are now aware of the fact that it lays on top of the Pacific plate as well as other major tectonic plates. Almost 90% of the worlds earthquakes occur around the ring of fire. Some of the major volcanoes located in the Ring of Fire include:

• Christchurch Earthquake, New Zealand
• Mount Saint Helens, Washington, USA
• Mount Pinatubo, Philippines
• Mt. Fuji, Japan
• Paricutin Volcano, Mexico
• Santiago Earthquake, Chile
• Sendai Earthquake, Japan

What is an earthquake, and why do they happen?

What is an earthquake?
An earthquake is the sudden shaking of the ground caused by the sudden movement and breakage of large parts of the earths most outer crusty layer, which are known as tectonic plates. Most earthquakes occur when two or more plates slide past or collide with each other. 

Why do earthquakes happen?

Earthquakes usually happen when rock from under the earth suddenly breaks along a fault ( a surface where  two blocks of the earth slip past one another suddenly. ) The sudden release of energy leads to seismic waves that cause the ground to shake. When two plates rub against each other they don’t slide smoothly they catch on each other a little bit. These blocks are not moving but intact pushing against each other. Due to the pressure build up after a while the rocks break. When the breakage of rocks occurs, thats when the earthquake happens. Both afterward and during the earthquake the plates continue to move until they get stuck again. The place underground where the rock breaks is known as the hypo centre of the earthquake and the place which is above the focus, but on top of the ground is known as the epicentre of the earthquake.

How is an earthquake measured?

The strength of an earthquake is measured using the Richter magnitude scale. The Richter scale ranges from 1 to 10 and measures the amount of seismic energy released by an earthquake.

http://www.vtaide.com/png/George/earthquake.htm

http://www.geo.mtu.edu/UPSeis/why.html

 

Mount Lamington (Case study)

 

Mount Lamington is a 1,680 meter-high volcano in Papua New Guinea. Unfortunately, until 1951, residents of the surrounding Oro province thought it was just a wooded mountain top, ( an area covered with woods). Late that night on 18th January, smoke lava began to ooze from the peak, and then three days later, there was a huge explosion from the north side, causing fatal pumice dust, sulfurous fumes and magma showers. Over the next few months, further eruptions and tremors, as well s a continued flow of pumice and rocks within a ten mile radius continued, causing around 3- 4,000 deaths in total.

-> Pumice os a very light and porous volcanic rock formed when a fas-rich froth of classy lac a solidifies rapidly.

What type of volcano is it?
Strato-volcano or composite volcano.

What problems did it cause? 
-The death of 3-4,000 people
-The Government Station and Anglican Mission Station Completely devastated
-5,000 natives evacuated to refugee camps at Oro Bay and Wairope, which were then destroyed a few days later due to flooding.
-Residents gardens destroyed -> lack of food due to floods in Lamington, in Mangalasi due to volcanic dust. 

Different types of plate boundaries

What is a plate boundary?

A plate boundary is a place where two or more continental or oceanic plates meet.
There are in fact many more types of plate boundaries than we may be aware of.

Constructive plate boundary

Constructive plate boundaries, also known as tensional plate boundaries. These occur when two plates move away from each other, for example the North American and Eurasian Plates.

Destructive plate boundary

Destructive plate boundaries also known as compressional plate boundaries ( or subduction zones). Destructive plate boundaries occur when an oceanic plate is forced under (or sub ducts) a continental plate. For example the Pacific Plate and the Eurasian plates.

Conservative or passive plate.

Conservative plate boundaries occur when two plates slide past each other , barely rubbing, for example the North American Plate and the Pacific plate.

Collision plate

Collision plates occur when two continental plates move towards each other. These plates are held accounted for creating mountains and pushing the earths crust together, for example the Indo-Australian plate and the Eurasian plate.

DIfferent types of volcanoes

Fissure Volcano

Fissure volcanoes have no central crater at all , instead they have cracks that open in the ground and expel vast quantities of lava. This lava spreads far and wide to form huge pods that can cover almost everything around. When theses pools of lava cool and solidify , the surface remains mostly flat. Since the source cracks are usually buried there is often nothing ‘volcano-like’ to see, only a flat plain surface.

Shield Volcano

Shield volcanos can grow very large. The oldest continental regions of Earth may be the remains of ancient shield volcanoes. They are tall and broad with flat rounded shapes. They have low sloped and almost always have large craters at their summit built by countless out pours of lava that advance great distances from central summit vents of group of vents. The out pours of lava are not accompanied by pyroclastic material which makes shield volcanoes relatively safe during eruptions.

Dome volcano

Dome volcanoes are shaped like a dome an are relatively quite small. The flow of lava produced by these volcanoes is very vicious and these volcanoes can also be very explosive. These volcanoes commonly occur adjacent to craters of composite volcanoes.

Cinder volcano

Cinder volcanoes are simple volcanoes which have a bowl-shaped crater at the summit and steep sides. They only grow about 1000 feet which is about the size of a hill. They are usually created of eruptions from a single opening unlike a strato volcano or shield volcano which can have many openings. During eruptions blobs ( or cinders) of lava are blown into the air and break into small fragments. Made of piles of lava opposed to ash.

Composite volcano

Composite volcanoes are said to be the most majestic and are also known as strata-volcanoes. They tend to be tall and symmetrically shaped with steep sides and can some time rise 10,00 feet high above the ground. They are build of alternating layers of lava, volcanic ash and cinders.

Caldera volcano

Caldera volcanoes are very large composite volcanoes that have collapsed after an explosive period.These volcanoes are said to be frequently associated with plug domes. They are generally quite small and tend to collapse in on itself.

What is a volcano?

 

 

What is a volcano? Although it may seem like a pretty straight forward question with a simple answer that follows, this is not the case. A volcano is referred to as a geological landform that create fissures that are kind of like pipelines that descend all the way down to the core of the earth where magma is accumulated. When the magma exits the volcano through these pipes it is known as lava. The lava or magma is formed when the combination of the heat and pressure from the earth melt or liquify rocks. But what is it that makes a volcano erupt?  All of the earth lies on top of a combination of different tectonic plates , but when pressure from the earth is exerted towards them they begin to either come apart or come together which then puts pressure on the fissures that contain magma. The magma is now heated from a natural radioactive heat source from the centre of the earth, leaving it less dense and now able to float towards the surface. The same pressure along with the supply of gases from the earth can cause the magma to get high. The gases that magma releases when it is just sitting in its chamber starting to cool off along with the increased pressure then end in an eruption.

 

http://www.catalogs.com/info/earth-science/what-makes-a-volcano-erupt.html