Earth’s Internal Heat: Tectonic Plates, Volcanoes, and Earthquakes
Why Is the Interior of the Earth So Hot?
The interior of the Earth is very hot because of the heat generated when the Earth was formed. The temperature is above 6000ºC.
4600 million years ago, meteorites crashed and made the Earth hotter. 4000 million years ago, the heat expanded and formed a core of iron. The Earth today has two cores: the inner core is solid due to the pressure, and the outer core is molten.
- The crust is the external layer and has a depth of 0-35km.
- The mantle is the medial layer and has a depth of 35-2890km.
- The core is the internal layer and has a depth of 2890-6378km. The inner core is solid.
What Are Tectonic Plates?
The heat of the inner core causes material to move in the liquid outer core and the mantle. This movement produces tectonic plates, which are massive slabs of solid rock. They move slowly over the surface. Geysers are further evidence of the heat that comes from the interior of the Earth and erupt gases.
What Phenomena Does Internal Energy Produce?
Earthquakes and volcanoes are caused by the internal energy produced by the heat.
Volcanic Eruptions
A volcano is a place where molten rock and gases are ejected through the crust, and they vary in their structure. The materials erupt to the exterior of the volcano.
The magma is a mixture of molten rock and gases that is found at the base of the crust.
Volcanic eruptions are a phenomenon that occurs when magma is expelled to the exterior through a volcano. When the magma erupts, it releases its gases and turns into lava. The more fluidity in the lava, the higher the temperature. The most abundant gases are carbon dioxide and water vapor, also carbon monoxide and sulfur.
Lava is magma that has erupted through the surface of the Earth and has released its gases.
How Are Earthquakes Produced?
An earthquake is a violent trembling of the Earth’s crust which lasts a short time and varies in intensity. It is caused by a sudden release of energy in the crust. This energy travels in seismic waves. The energy of earthquakes can cause a tsunami, which can flood areas near the coast. An earthquake is measured on the Richter Scale.
The epicenter is the point on the surface of the Earth which is directly above the hypocenter of an earthquake.
The hypocenter is the origin of an earthquake.
Steps to Reduce Damage by Earthquakes and Volcanoes
- Prediction: The study of the damage. It includes risk maps with the eruptions.
- Preparedness: This refers to the safety measures adopted to minimize damages in case of a disaster. In areas with high risks:
Buildings are designed to withstand seismic movement.
The population knows what to do during an earthquake.
Police evacuate the population.
What Are Igneous Rocks?
Igneous rocks are rocks that are formed when magma cools and solidifies. The formation is by magmatism. There are two types:
- Volcanic igneous rocks: These are formed when lava cools and solidifies quickly. As a result, they are fine-grained, with small crystals or a glassy appearance. Examples: Volcanic scoria, pumice stone, obsidian, and basalt.
- Plutonic igneous rocks: These are formed when magma cools and solidifies slowly. As a result, they are coarse-grained with large crystals. Examples: Granite, pegmatite, syenite, and gabbro.
What Are Metamorphic Rocks?
Metamorphic rocks are formed from the transformation of other rocks, due to increases in temperature or pressure, or both at the same time. Examples: Slate, schist, gneiss, and quartzite.
The rock transformation process is called metamorphism. This process involves many changes, is very slow, and it normally happens deep under the Earth’s crust.