Seismic events are occurrences in which energy is briefly released in the Earth's crust, resulting in a series of seismic waves which move through the crust. In some cases, the energy can be intense enough that it is felt in the form of an earthquake, while in other seismic events, the energy is so mild that it can only be identified with specialized equipment. Seismic events are of immense interest to researchers known as seismologists, and monitoring stations used to track seismic activity can be found in many regions of the world.
A number of different things can cause these events. Some are induced by human activities such as setting off explosives or running heavy machinery. Others are caused by geological activity such as the shifting of the Earth's plates, movement along a fault, or volcanic activity. It is difficult to predict seismic events, but information about such events can be used in the study of geology, and in the tracking of long term trends.
Sometimes, a series of minor seismic events precedes a major event. This forewarning can be used to plan ahead. For example, if scientists are tracking a volcano and they notice an uptick in seismic activity, they can evacuate people in case the volcano is about to erupt. A major event in the ocean can also be an indicator of a emergency situation in the form of a tsunami, which is one reason why scientists track these events even in areas where people are not likely to be present.
Seismic monitors, known as seismometers, use very delicate and sensitive equipment to log movement in the Earth's crust. This information can be used to track the movement of seismic waves, to identify different kinds of seismic waves, and to see where seismic activity originated. Many of these devices are automated, reporting to a central monitoring station which people use to aggregate data to reveal important trends.
Research on seismic events is important for human safety and economic reasons. By planning ahead, people can mitigate some of the severity associated with a major event. For example, people and important objects can be evacuated so that they are not damaged. Structures in areas where seismic activity is common can also be designed and retrofitted so that they will be more likely to withstand a seismic event, using information from engineers and areas where people have developed earthquake-resistant structures.