An earthquake under the ocean can destruction as the earthquake itself in mountainous areas. Earthquakes can also create landslides. Earthquakes are part of the Earth's natural rock cycle. The affect of an earthquake can be measured by a seismometer. It detects the shakes caused and it puts these movements on a seismograph. The strength, or magnitude, of an earthquake, is measured using the Richter scale. The Richter scale is numbered 0-9. The largest earthquake ever measured was a 9.5 on the scale a 10 has never been recorded.