Earthquake

Earthquakes are measurable tremors of the earth's body. They are caused by mass shifts, mostly as tectonic quakes due to shifts of tectonic plates at fracture joints of the lithosphere, to a lesser extent also by volcanic activity, collapse or subsidence of subterranean cavities, large landslides and landslides as well as by blasting. Earthquakes whose source lies beneath the ocean floor are also called seaquakes or submarine earthquakes. These differ from other earthquakes partly in their effects, such as the formation of a tsunami, but not in their origin.

Earthquakes almost generally do not consist of a single tremor, but usually entail further ones. In this context, we speak of foreshocks and aftershocks with reference to a stronger main earthquake. If earthquakes occur more frequently over a longer, limited period of time, they are referred to as earthquake swarms or swarm earthquakes. Such earthquakes occur mainly in volcanically active regions. In Germany, there are occasional earthquake swarms in the Vogtland and at the Hochstaufen.

By far the largest proportion of recorded earthquakes are too weak to be felt by humans. Strong earthquakes can destroy buildings, trigger tsunamis, avalanches, rockfalls, landslides and landslides, and kill people in the process. They can change the shape of the earth's surface and are considered natural disasters. The science that deals with earthquakes is called seismology. The ten strongest earthquakes measured since 1900 have all, with one exception, occurred in the subduction zone around the Pacific Ocean, the so-called Pacific Ring of Fire (see list below).

According to an analysis of more than 35,000 natural disaster events by the Karlsruhe Institute of Technology (KIT), earthquakes killed a total of 2.23 million people worldwide from 1900 to 2015.

Historical

Even in ancient times, people wondered how earthquakes and volcanic eruptions occur. People often attributed these events to gods (Poseidon in Greek mythology). Some scientists in ancient Greece believed the continents floated on water and rocked back and forth like a ship. Other people believed earthquakes erupted from caves. In Japan, there was the myth of the dragon that made the ground tremble and breathed fire when it was angry. In the European Middle Ages, natural disasters were attributed to the work of God. With the discovery and study of magnetism, the theory arose that earthquakes could be conducted like lightning. It was therefore recommended that earthquake arrestors be built in the manner of the first lightning rods.

It was not until the beginning of the 20th century that the now generally accepted theory of plate tectonics and continental drift emerged through Alfred Wegener. From the middle of the 20th century, the explanatory patterns of tectonic quakes were widely discussed. Until the beginning of the 21st century, however, no technique for the reliable prediction of earthquakes could be developed from this.

Historical earthquakes

The most important known earthquake areas are listed in the List of Earthquake Areas. A comprehensive listing of historically surviving earthquake events is in the List of Earthquakes.