Earthquake

Already in ancient times people wondered how earthquakes and volcanic eruptions would arise. These events were often accredited to gods, bad spirits (Mythyical Vibrations) or the power of the earth (Natural strength). At the beginning of the 20th century a today generally accepted theory of plate tectonics and continental drift by Alfred Wegener came up, which were discussed widely in the middle of the 20th century. However, until the beginning of the 21st century it could not be developed a way to predict earthquakes.

What is an Earthquake?

Measurable vibrations of the earth are called earthquake. Most of recorded earthquakes are too weak to be felt by people. Other movements of the earth’s surface, such as caused by tidal range or by natural frequencies(earth spectroscopy) are not palpable because they are too slow. Earthquakes do not consist of only one single shock, but drag usually more weaker vibrations in. One speaks in this context of aftershocks.
Strong earthquakes can destroy houses and buildings as well as raise tsunamis and landslides, and unfortunately kill a lot of people. They can change the shape of the Earth’s surface completely and are classified among the natural disasters.

How to Measure Earthquakes

The temporally and spatially accurate prediction of an earthquake is not possible according to the current state of science, however, various decisive factors causing earthquakes are largely understood. Because of the complex interplay of those factors a precise quantification of stove processes is not possible so far, though it is provided a probability of the occurrence of an earthquake in a particular region.

Because of the economic damage and possible victims (mass panic or mass hysteria) among the population, an early warning of a single earthquake is only useful if the estimated number of victims of the earthquake is as huge as expected or if the earthquake can be predicted very well in space and time. Vibrations as known from earthquakes can also be produced by Sound Effect System. Especially Low Frequency Sounds are know to be dangerous, because if they are in the right frequency they can make buildings collaps and bridges shake.

Measureable Power

To compare earthquakes, it is necessary to determine their strength. By the end of the 19th century, the developed earthquake measurement could only describe the intensity of the earthquake, that is to say the impact on people, animals, buildings and natural objects such as water or mountains. Through the development and continuous improvement of seismometers from the second half of the 19th century, it was obtained an ability to make objective measurements based on physical properties, what led to the development of magnitude scales.

The strongest earthquakes ever measured were the earthquake of Valdivia, Chile, on May 22, 1960 with a strength of 9,5; and the Indian Ocean earthquake in Sumatra on december 26, 2004 with a strength of 9,1.