When an earthquake happens deep underground a crack will start to open on a pre-existing line of weakness in the Earth's brittle crust. This crack will then grow larger and larger, relieving built-up stress as it goes.
When an earthquake happens deep underground a crack will start to open on a pre-existing line of weakness in the Earth's brittle crust. This crack will then grow larger and larger, relieving built-up stress as it goes.
Diagram of a seismic wave
On July 17, 1998, three huge waves – "tsunamis" – up to 15 meters high struck the north coast of Papua New Guinea, killing at least 2,200 people. A major earthquake, itself consisting of waves traveling through the Earth, triggered an underwater landslide that created the tsunamis. Radio stations reported the disaster by transmitting electromagnetic radio waves to listeners around the world. Listeners were able to hear the news transported by sound waves created by their radios.
Seismology is the study of earthquakes and seismic waves that move through and around the earth. A seismologist is a scientist who studies earthquakes and seismic waves.
Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.