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Earth Science
Earthquakes - PAPA G class
Term | Definition |
---|---|
Eurasian Melanesian belt | Runs from the Pacific islands throughout Asia and southern Europe and into northwestern Africa. |
Earthquake depth | can occur anywhere between the Earth's surface and about 700 kilometers below the surface. |
Tectonic Plates | These are huge layers that make up the earth’s upper layers. They continually stretch, move, slide, and collide against each other. |
Faults | These are weak lines that can develop in the plates, usually on the surface of the earth. There are different types and the major types include dip-slip normal, dip-slip reverse, strike-slip and oblique-slip. |
Seismograph | Is a device that scientists use to measure the magnitude of an earthquake. |
The Richter Scale (RS) | Is a scale or measure that is used to compare earthquakes. It is calculated in levels of ten. |
Ring of Fire | This is the coastal belt of the Pacific Ocean which is the home of many volcanic eruptions, plate movement and major fault lines. |
Convergent boundary | One plate is forced over another plate during movement creating a thrust fault. |
Divergent boundary | Plates are forced apart each other, usually forming a Rift Zone. This kind is common in ocean floors where new floors are created. An example is the Mid Atlantic Ridge. |
Transform fault | The plates here slip by each other. This is also called Strike Slip. |
P-Waves (Primary Waves) | Are longitudinal in nature. The vibrations are along the same direction as the direction of travel. It is also known as compressional waves. This wave travel faster. |
S-Waves (Secondary waves) | is a wave motion in a solid medium where the medium moves perpendicular to the direction of the travel of the wave. |
Focus | The location where the earthquake begins. The ground ruptures at this spot, then seismic waves radiate outward in all directions. |
Epicenter | The point on the Earth's surface located directly above the focus of an earthquake. |
Aftershocks | A smaller earthquake following the main shock of a large earthquake. |
Elastic rebound theory | Is an explanation for how energy is released during an earthquake. |
New Madrid Fault | Is a major seismic zone and a prolific source of intraplate earthquakes in the southern and midwestern United States, stretching to the southwest from New Madrid, Missouri. |
Seismograph | An instrument that measures and records details of earthquakes, such as force and duration. |
Surface waves | A seismic wave that travels across the surface of the Earth as opposed to through it. |
locating an earthquake | The difference in arrival time between the two types of seismic wave can be used to calculate the distance of the epicenter from the seismometer. |
Magnitude | Is a number that characterizes the relative size of an earthquake. |
Moment magnitude scale | is used by seismologists to measure the size of earthquakes. |
Mercalli scale | Is a seismic intensity scale used for measuring the intensity of an earthquake. |
Microquakes | Is a very low intensity earthquake which is 2.0 or less in magnitude. They are very rarely felt beyond 8 km (5 mi) from their epicenter. |