Continental crust- the layer of granitic, sedimentry and metaphoric rocks this forms the continents.
Fold mountains- The Alps- This can be where two continental plates move towards each other or a continental and an oceanic plate. The movement of the two plates forces sedimentary rocks upwards into a series of folds.
Ocean trenches- philippines trench- Trenches are formed by subduction, a geophysical process in which two or more of Earth's tectonic plates converge and the older, denser plate is pushed beneath the lighter plate.
primary and secondary effects of a volcano:
Hot pyroclastic flows cause death by suffocation and burning.
Lateral blasts knock down anything in their path, can drive flying debris through trees.
Tephra falls destroy vegetation.
Tephra falls can cause the collapse of roofs and can affect areas far from the eruption.
Mud flows, Debris Avalanches and Debris Flows, Flooding, Tsunamis
positive and negative impacts of a volcanic eruption
Fertile Soils: Volcanic soils are very fertile
Tourism: Many dormant and active volcanoes attract hundreds of thousands of tourists each year
Geothermal Energy: is responsible for providing electricity
Creation of new land: Volcanoes can create new land for human habitation, for example, Iceland.
Building materials: Granite, which is used in the construction industry, is formed by volcanic activity.
Negative impacts of a volcanic eruption-
Lahars: are formed where ice and snow on top of a volcanic cone melt when an eruption occurs. this will then cause mudflows.
Damage to property: Lava from volcanoes can also burn everything in its path.
Loss of Lives
Effect on the environment: Clouds of ash, dust and gas may reduce global temperatures by several degrees.
seismic waves- an elastic wave in the earth produced by an earthquake or other means.
Measurements of Earthquakes:-
Mercalli scale- The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude. It is used to measure the energy released.
Richter scale- defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude.
case study of an earthquake: The April 2015 Nepal, Kathmandu earthquake killed over 8,000 people and injured more than 21,000, 25 April, with a magnitude of 7.8Mw or 8.1M and a maximum Mercalli Intensity of IX
Causes: two converging tectonic plates: the India plate and the overriding Eurasia plate to the north collide into each other causing. Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little.
homes destroyed,roads are destroyed, people get killed, loss of essentials, loss of personal belongings.