Natural disaster seismic waves. At the Earth's surface, earthquakes manifest themselves by vibration, shaking, and sometimes displacement of the ground. Earthquakes are caused by slippage within geological faults. The underground point of origin of the earthquake is called the "seismic focus". The point directly above the focus on the surface is called the "epicenter". Earthquakes by themselves rarely kill people or wildlife. It is usually the secondary events that they trigger such as building collapse, fires, tsunamis (seismic sea waves) and volcanoes. Many of these could possibly be avoided by better construction, safety systems, early warning and planning. When natural erosion, human
Seismic vibrator measured in pound-force. To transmit a maximum force to the ground and prevent the shaker from bumping, part of the weight of the vibrator is applied to the shaker. Seismic vibrator A seismic vibrator is a truck-mounted or buggy-mounted device that is capable of injecting low-frequency vibrations into the earth. It is one of a number of seismic sources used in reflection seismology. The ‘Vibroseis’ exploration technique (performed with vibrators) was developed by the Continental Oil Company (Conoco) during the 1950s and was a trademark until the company's patent lapsed. Today, seismic vibrators are used to perform about half of