An earth tremor is another term for an earthquake, although it is most commonly used to describe earthquakes of low intensity. Earthquakes are measured with tools called seismographs, and their intensity is rated on a logarithmic scale, called the Richter scale. The Richter scale is not useful for earthquakes that rank higher than a level 8 earthquake.Know More
Earthquakes occur when the earth’s tectonic plates move and contact other plates. Sometimes the plates rub against each other laterally, while other times one plate moves underneath another. When this happens, it is called a subduction zone or a subduction-caused earthquake. In some particularly violent earthquakes, two plates collide into each other. This type of collision may even cause mountains to form, which happened millions of years ago when the Indian subcontinent crashed into Asia, producing the Himalayas.
Earthquakes are rather common, though few are strong enough to cause much damage. People may not even feel very weak earthquakes. The center of the disturbance is called the earthquake’s epicenter, and epicenters usually occur along major fault lines, where two plates contact each other. Many large and active fault lines occur around the margin of the Pacific Ocean, which has given the region the name “ring of fire” for all of the earthquakes and volcanoes in the region.Learn more about Earth Science
Astronomers theorize that over 4.5 billion years ago, Theia, an object about the size of Mars, collided with Earth to create a tilted axis. This is called "the giant impact theory." Prior to this event, the axis was straight at 180 degrees.Full Answer >
The term "eustatic" refers to the global sea level. This is opposed to the isostatic sea level, which is a local measurement that is often a result of tides. Eustatic sea level changes are global, and they are often the result of major upheavals to the climate or ocean basin.Full Answer >
Earth has a mean radius of 3,959 miles. This value is an average, however, as the Earth is only approximately spherical, and the exact distance from its surface to its center varies with latitude and local topography.Full Answer >
Earth, as viewed from space, is a mixture of green, brown, blue and white. Each one of these colors is representative of a different part of the Earth's crust.Full Answer >