Earthquake zones were discovered by scientists studying thousands of earthquakes worldwide after the seismograph was invented. They found that most earthquakes occur in earthquake bands that surround crustal plates.
Map of zones where earthquakes occur, USGS
Recording earthquakes with seismographs
Over the years millions of earthquakes have been recorded on seismographs. Using data from seismographs scientists were able to find the focus and epicenters of the earthquakes.
Scientists found that the patterns of the earthquakes were around large blocks of land that are today called tectonic plates or crustal plates. The discovery of these zones led to the Theory of Plate Tectonics.
Scientists using sonar after World War II found that a great mountain chain ran down the middle of the Atlantic Ocean. They called the mountain range the Mid-Atlantic Ridge.
Further studies of the ocean floors found that this ridge was just part of a global ridge now named the mid-ocean ridge. It is approximately 84,000 km long.
Low magnitude earthquakes
Mid-ocean ridges are found in all the oceans on Earth. They form at divergent boundaries where crustal plates are separating.The mid-ocean ridges are places where low magnitude earthquakes occur as new ocean floor forms on the Earth's surface.
Around the Pacific Ocean basin is a series of subduction zones. Subduction zones that surround the Pacific Ocean are zones where great earthquakes of 9.0 and higher occur.
Pacific Ocean basin
Approximately eighty percent of all recorded earthquakes originate around the Pacific Ocean basin and seventy-five percent of the active volcanoes are located in the area.
Moment Magnitude Scale Find out why the moment magnitude scale is used to measure great earthquakes.
1964 Alaska Earthquake The Great Alaskan Earthquake find out why Good Friday saved many people's lives!
New Madrid Earthquakes The New Madrid earthquakes were a series of three very large earthquakes felt by people over almost 2 million square miles.
Earthquake Waves Earthquake waves are produced by the more than three million earthquakes each year.
1960 Chile Earthquake The 1960 Chile earthquake was a magnitude 9.5 the largest earthquake ever recorded!
Earthquake Zones Find out where and why earthquakes occur and why there are these zones.
What Causes Earthquakes. Find out what causes earthquakes and other fascinating facts about when our planet shakes, rattles, and rolls.
Kids Fun Science The links on our home page include information about volcanoes, science activities, plate tectonics, the rock cycle and much more.