An earthquake is the result of a sudden release of stored energy in the Earth's outer layer that creates seismic waves. Earthquakes are accordingly measured with a seismometer, generally known as a seismograph. The magnitude of an earthquake is conventionally reported using the Richter scale or a related instant scale. At the Earth's surface, earthquakes may manifest themselves by a trembling or displacement of the ground. Sometimes, they cause tsunamis, which may lead to loss of life and annihilation of property. An earthquake is caused by tectonic plates getting stuck and putting a damage on the ground. The strain becomes so great that rocks give way by breaking and downhill along fault planes. Earthquakes may occur naturally or as a result of human actions. Slighter earthquakes can also be caused by volcanic activity, landslides, mine blasts, and nuclear tests. In its most generic intelligence, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic effect.