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geograpii - tectonics, volcanoes - Coggle Diagram

- - - - Himalayans Mountain Range (eurasian and indo-australian plate)
        
        two continental plates move towards each other. Since continental plates are too buoyant to sick, subduction does not take place. The enormous pressure causes the rocks to buckle and uplift each other, forming fold mountains. Since no magma can escape, there are no volcanoes formed. The friction along the convergent boundary can cause earthquakes to occur. For example, the Indo-Australian plate and the Eurasian plate collide. This forms the Himalayan Mountain Range and the Nepal 2015 earthquake also occurred here
  - - - mariana trench (pacific, philippine plate)
        
        two oceanic plates collide. The denser oceanic plate sinks beneath the other plate and subduction occurs.This forms a deep depression, the oceanic trench. As the denser oceanic crust sinks into the crust, the high pressure force water out of the ocenaic crust, causing it to lower the melting point of the mantle. This causes it to melt to form magma. It rises through the weaker parts of the Earth's surface and forms volcanoes. For example, the Pacific and Philippine plate collides, and the denser Pacific plate subducts beneath the Philippine plate, creating the Mariana Trench and the nearby Mariana Islands. Guam, as well as other nearby islands often experience earthquakes.
  - - - Andes Mountain Range, Nevado Del Ruiz volcano, Peru-Chile trench (Nazca, South American plate)
- - - - mid Atlantic ridge (Eurasian, north American plate)
        
        two oceanic plates move apart. The decrease in the overlying pressure causes the manlte to melt and form magma. The magma rises through the weaker areas of the crust to the Earth's surface, and lava cools and solidifies to form basaltic rocks. They form the new oceanic crust. They form a chain of underwater volcanoes, such as in Surtsey, Iceland. For example, the North American and Eurasian plate pull apart from each ohter, and at the centre of the ridge is a deep rift valley with steep sides. This allows magma to escape from the weaker parts of the crust to the Earth's surface, forming submarine volcanoes. After many eruptions, they may rise from the ocean surface, forming volcanic islands.
  - - - east African valley/great rift valley (nubian and somalian)
        
        two continental plates move apart, causing parallel faults to be created. This allows for rocks between the faults to collapse, creating a deep fault with steep sides. As the plates move apart, the decrease in the underlying pressure allows magma to rise from the weaker parts in the Earth's crust and rise to the surface, formign volcanoes. Stress and tension as plates move can also cause earthquakes. For example, the Nubian and Somalian plate move apart, creating the great rift valley and volcanoes such as Mt kilimanjaro and mt kenya are formed.
- - - - stress caused by the plate movmenet creates a fualt which is a system of fractures. Earthquakes are common as plates suddnely slip past each other, but htere is no volcanoes formed since no magma can rise to the surface. For example, the North American and the Pacific Plate slide past one another to form the San andreas Fault in USA california. The area also experiences earthquakes such as the 1989 Lorma prieta earthquake in California
- - - - the Moment magnitude scale uses the total seismic energy released during an earthquake instead of the largest wave like the Richter Scale. It estimates the total seismic energy released and it is generally considered more accurate, espeicialy for earthquakes of magntiude 8 and higher. The magnitude of past earthquakes have been adjusted, which were measured with the Richter scale. It is also logarithmic, meaning that an earthquake of magnitude 6 is 32 times stronger than a magnitude 5 earthquake. For example, the Priince William Sound Earthquake in Alaska, USA, in 1964 was measured as a 8,2 magnitude earthquake, but was adjusted to 9,2 on the Moment Magnitude Scale.
    - - calculates the magnitude of earthquake using the largest spike in seismic waves recorded by seismometers. They use the maximum intensity reached instead of the total seismic energy produced throughout the earthquake. The scale is numbered from 1 to 10, 10 being the heighest. The scale is also logarithmic, so magnitude 6 earthquake is 32 times stronger than a magnitude 5 earthquake. However it is not accurate as it records an erathquake iwht one large spike in seismic waves higher than a longer earthquake with larger and intense waves. Thsi underestimates the strength of longer earthquakes, which release higher overall energy, by rating them as low magntiude earthquakes. Even though they are likely to do more damage. Thus, they are no longer used by scientists, and are only used for small local eathquakes
- - - - the ash and rocks settle on the sides of the volcano and is covered with lava. After successive eruptions, a tall volcano consisting of alternating layers of ash and lava is developed
        
        as the highly viscuous magma travels a shorter distance before cooling and solidifying, the volcano has steep sides and a narrow summit.
        
        for example, Mount Mayon in the philippines
- - - - duration of eruption - the longer the eruption, the higher the VEI
        
        measured on a scale of 0 to 8, most effusive eruptiosn are rated 0 or 1 as they are non explosve with less than 0,0001 km sube of material ejected. For example, the ongoing effusive eruptions of Kilauea, Hawaii which are non explosive
        
        a value of 8 represnts a mega-colossal volcanic eruption that can eject more than 1,000 tephra, with an eruption cloud column heigh of over 25km. For example, the Toba wolcano in Northern Sumatra indonesia 74,000 years ago erupted approximately 2,800 km cube of material and covered india and parts of southeast asia in over 15cm of ash.
        
        they are also logarithmic. Thi smeans that an incraesee of 1 on the scale means that the explosion is 10 times more powerful than the number before it