The lithosphere is made of tectonic plates. These plates move around the Earth’s surface, constantly drifting apart and crashing together. There are 12 tectonic plates in total. These 12 plates float on the liquid magma of the asthenosphere and are currently moving in all different directions at all different speeds. The places where the plates are moving together are called subduction zones. This is where the lithosphere is destroyed. At the other side, where the plates are moving apart, new lithosphere is created. These places are also called destructive and constructive boundaries, respectively.
This movement of tectonic plates; as well as the destruction and construction of new lithosphere affects humans on the Earth’s surface. It does this by creating volcanoes, mountains, and earthquakes.
Volcanoes are formed either when two plates move apart or when two plates collide. Volcanoes are a landform that is produced as lava cools. There are two main types of volcanoes: shield volcanoes and composite volcanoes. Shield volcanoes are made from mafic lava, have very gentle slopes and are found at constructive plate margins (where the plates are moving apart). An example of a shield volcano is the Hawaiian Islands. Composite volcanoes on the other hand are from felsic (sandy) magma, are found in subduction zones (where the plates are moving together) and are high layered constructions. They are very explosive and are much more dangerous than shield volcanoes. An example of a composite volcano is Mount Pinatubo. Volcanoes have many effects on humans. They create islands that people may live on or use to gather resources. They threaten towns and cities that choose to build near them. They have caused people to abandon certain areas (such as some Hawaiian Islands) and they have wiped out whole cities (such as Pompeii). When a volcano erupts it can disrupt the lives of people all over the world as it blocks out the sun and may cause winter.
Then there are mountains, which are formed in three ways. First two plates collide creating fold mountains. This means that instead of one plate sliding under the other, they crash together and force the Earth’s crust up, creating mountains. An example of a fold mountain is the Himalayas. Then there are volcanic mountains. These mountains are formed by lava accumulation in places where two plates are moving away from each other. An example of volcanic mountains is Hawaii. Finally there are fault mountains that are formed as blocks of rock are pushed up between normal faults. A normal fault is a place where rocks are being pulled apart due to tectonic plate movement. An example of a fault mountain is the Sierra Nevada range. Each of these types of mountains affects humans living on the Earth’s surface. First, fold mountains can cause climate change as they force parts of the Earth high into the sky. This affects humans because they are forced to adapt to changing climates. These climate changes may include: loss of rainfall, desertification, thinning of the air, or gaining rainfall. Depending on where humans live in relation to the mountains. This sort of affect is ongoing as the mountains continue to grow and therefore the climate continues to change. Next there are volcanic mountains. These types of mountains create new land that can be used for human settlement. This new land often continues to grow and therefore those living on it can legitimately expand their borders, as the lava expands it for them. Finally there are fault mountains, which affect human activity in much the same way as fold mountains. They create deserts and otherwise change the climate around them. They also often create deep valleys and canyons. These affect human activity because they change the landscape and make some places unfit for human habitation.
Finally there are earthquakes, which are the most destructive as they cannot be predicted at this time. Earthquakes occur when blocks of rock that have been forced out of their original position by tectonic plate movement rebound back to their original positions. Earthquakes therefore occur along fault lines where the rock is under massive amounts of pressure. Earthquakes can affect humans directly or indirectly. Directly earthquakes can cause massive damage to buildings and rip giant holes in the ground. This can cause a great loss of life and millions of dollars worth of property damage. Yet this is not the true risk of earthquakes, the true problem is the secondary damage that they can cause. Earthquakes can create: tsunamis, mudslides, fires, and liquefaction. First tsunamis are created by underwater earthquakes that force a tectonic plate upward and create waves as the water over the plate is suddenly displaced. Then there are mudslides that are created when earthquakes shake loose earth from hills or mountains. Next are fires, which are created when earthquakes sever gas and power lines. Finally there is liquefaction, which means that earthquakes can turn soil to mud and create giant sinkholes. All of these things make earthquakes very dangerous as they can all cause massive loss of life. Earthquakes are the most dangerous effect of plate tectonics as they cannot be predicted or controlled.
In conclusion plate tectonics affects humans on the earth’s surface by creating new land, destroying old, and causing what many call natural disasters. Volcanoes can be good or bad as they create new land or swallow cities whole. Mountains cause climate change and change the lives of those living on or near them. Finally earthquakes rain seemingly random destruction at whim. Proving once and for all that there is far more that we do not know about the Earth then there is that we do.
