Rename this list. List Name Delete from selected List. Save to. Save to:. Save Create a List. Create a list. Save Back. Earthquake Power: Understanding the Richter Scale. Grades 3—5 , 6—8. On October 17, , a giant earthquake shook Northern California. Bridges, roadways, and buildings collapsed throughout the area. Scores of people were killed, and thousands more were injured or left homeless. Here's how it works: An earthquake registering 2.
Scholastic Math, December View not found. Download the PDF from here. Related Subjects. Measurement Tsunamis. About Us. The Richter scale doesn't measure quake damage see: Mercalli Scale which is dependent on a variety of factors including population at the epicentre, terrain, depth, etc. An earthquake in a densely populated area which results in many deaths and considerable damage may have the same magnitude as a shock in a remote area that does nothing more than frightening the wildlife.
Large-magnitude earthquakes that occur beneath the oceans may not even be felt by humans. The magnitude of an earthquake is determined using information gathered by a seismograph.
The Richter magnitude involves measuring the amplitude height of the largest recorded wave at a specific distance from the seismic source. Adjustments are included for the variation in the distance between the various seismographs and the epicentre of the earthquakes.
The Richter scale is a base logarithmic scale, meaning that each order of magnitude is 10 times more intensive than the last one. In other words, a two is 10 times more intense than a one and a three is times greater. In the case of the Richter scale, the increase is in wave amplitude. That is, the wave amplitude in a level 6 earthquake is 10 times greater than in a level 5 earthquake, and the amplitude increases times between a level 7 earthquake and a level 9 earthquake.
The amount of energy released increases In fact, it is to point out that, while it is correct to say that for each increase in 1 in the Richter magnitude there is a tenfold increase in amplitude of the wave, it is incorrect to say that each increase of 1 in Richter magnitude represents a tenfold increase in the size of the earthquake as is commonly incorrectly stated by the press. At first, the Richter scale could be applied only to the records from instruments of identical manufacture. Now, instruments are carefully calibrated with respect to each other.
Thus, magnitude can be computed from the record of any calibrated seismograph. The Richter Scale has no upper limit. Recently, another scale called the moment magnitude scale MMS has been devised for more precise study of great earthquakes.
Tectonic earthquakes can range in size from magnitudes less than zero, resulting from fault slippage of a few centimetres, to the largest events magnitude greater than 9 , where fault displacements are on the order of many metres. The size of an earthquake is not only a function of the amount of displacement but also the area of the fault plane that ruptures. Hence the larger the rupture area, the larger is the earthquake.
A magnitude 7 earthquake ruptures a fault area of about km2 or about 50 km long and 20 km wide. Also depth is an important factor influencing earthquake severity. We know that earthquakes can originate at various depths within the Earth's solid core.
The deeper the earthquake, the more powerful it is, but it is also far less likely to reach the surface. That's why shallow earthquakes are more common and more dangerous, because the shallower an earthquake, the more damage to surface structures it can cause.
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