Seismic waves are captured by a recorder known as a seismograph. The relative arrival times of different types of seismic waves is used to determine the distance of the seismograph station from the origin of the earthquake. Earthquakes are named for the epicenter location, for example the 1994 Northridge earthquake occurred several kilometers below the city of Northridge in metropolitan Los Angeles. Loss of life in the Turkish earthquake was greatest in the city of Izmit, located at the earthquake's epicenter. Earthquake distribution is far from random.
Earthquakes occur on faults that are preferentially located along plate boundaries.
The largest earthquakes along convergent plate boundaries. One method of earthquake measurement is to determine the level of destruction following an earthquake. However, as the Turkish earthquake so vividly illustrates, the degree of damage is often related more to human activity than the earthquake itself. This information is often combined with data on the geology surrounding the fault to generate an even more accurate measure. Over two million people have been killed this century by earthquakes and associated phenomena.