When an earthquake causes the ground to shake, the base of the seismograph shakes too. Pdf measuring earthquakes from optical satellite images. When two plates move towards each other and collide, this is known as destructive plate boundaries. Since antiquity, a way of predict earthquakes has been sought.
Earthquakes take time tooccur the larger the earthquake, the longer the source scaling law. Earthquakes measuring 9 or more on this scale are rare. Glaciers, which are huge, very old formations made out of water, earth and ice, can even change the size and shape of. Then ask them to describe things that are measured and the instruments that are used to measure those things, such as timeclocks, lengthrulers, and weightscales. Since early in the 20th century, there have been three methods. The richter scale measures the largest wiggle amplitude on the recording, but other magnitude scales measure different parts of the earthquake. The zigzag line made by a seismograph, called a seismogram, reflects the changing intensity of the vibrations by responding to the motion of the ground surface beneath the instrument. Potential damage includes structural damage to the building, spilling or release of hazardous materials or gases, and functional damage to the facility. Most earthquakes are caused by the movement of tectonic plates. The moment magnitude scale measures the overall magnitude or size of the earthquake, and the modified mercalli scale measures earthquake intensity. Earthquake prediction is sometimes distinguished from earthquake forecasting, which can be defined as. Up until 2 on the richter scale only instruments will detect the earthquake. The intensity of these vibrations can vary, but sometimes they can bring about great destruction. Measuring earthquakes california academy of sciences.
The vibrations produced by earthquakes are detected, recorded, and measured by instruments call seismographs1. Scientists measure seismic waves produced by an earthquake using devices such as a seismograph or seismometer. Seismometer an instrument that detects the intensity, direction and duration of earthquakes and other ground movements such as explosions. Earthquakes above 6 cause serious damage and sometimes many deaths. Water appears to weaken the chemical bonds and forms films around mineral grains along. The familiar richter scale which is not a physical device but rather a mathematical formula is no longer widely used by scientists or the media to report an earthquake s size. The richter scale is an outdated method for measuring magnitude that is no longer used by the usgs for large, teleseismic earthquakes. The richter scale is most common in the united states, while worldwide, scientists rely on the mercalli scale. Measuring earthquakes measuring earthquake civildigital.
Nov 24, 2017 an earthquake occurs because of the movements of tectonic plates beneath the surface of the earth. A magnitude scale measures the force or energy of an earthquake, but an intensity scale measures the level of shaking which occurs at an observation point on the earths surface. Healthcare facilities are affected by natural disasters in two ways. Jul 09, 20 the richter scale is logarithmic an earthquake measuring 7 is 10 times more powerful than one measuring 6 and 100 times more powerful than one measuring 5. Earthquakes affect almost every part of the earth and like rain they can be either mild or catastrophic. The richter scale calculates the strength of an earthquake based on measurements of the amplitude. They typically occur along fault planes, and most frequently along boundaries of tectonic plates. Two of the most common methods used to measure earthquakes are the richter scale and the moment magnitude scale. Earthquakes usually occur on the edges of large sections of the earths crust called tectonic plates. The hypocentre is the actual location of an individual earthquake shock at depth in the ground, and the epicentre is the point on the land surface vertically above the hypocentre figure \\pageindex3\. With a sensor attached to the ground, it records the arrival of seismic waves at that point. The richter scale is logarithmic an earthquake measuring 7 is 10 times more powerful than one measuring 6 and 100 times more powerful than one measuring 5. Seismic magnitude scales are used to describe the overall strength or size of an earthquake.
Measuring and predicting earthquakes earth science. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The mercalli scale also measures the effects of an earthquake at different locations. Measuring earthquakes how can the strength of an earthquake be determined. Each seismic station in the network measures the movement of the ground at that site.
French alternative energies and atomic energy commission, 2011. That vibration pushes the adjoining piece of ground and causes it to vibrate, and thus the energy travels out from the earthquake. An earthquake may last only a few seconds, but the processes that cause earthquakes have operated. The other is based on intensityhow much the ground shakes at a specific location. The larger the earthquake, the longer the source scaling law. Start a free trial of quizlet plus by thanksgiving. Inthe case of sumatra, full size available only from normal modes. Use your hands to show the different ways that tectonic plates interact with each other.
The moment magnitude scale is another earthquake measurement scale used by some seismologists. Earthquakes are described in terms of what nearby residents felt and the damage that was done to nearby structures. The moment magnitude scale is the preferred scale because it covers a wider range of magnitudes and can be applied globally. Sometimes, earthquakes at or below a magnitude of 3. The location below the earths surface where the earthquake starts is called the hypocenter, and the. It was developed to measure earthquakes in california. The richter scale is an otherwise outdated measurement system due to its inability to measure very large earthquakes.
The scale is based on the earthquake s moment release, a measurement that combines the distance a fault moved and the amount of force required to move it. Historically, earthquakes were measured on the richter scale a magnitude scale developed in the 1930s. Magnitudes are usually determined from measurements of an earthquake s seismic waves as recorded on a. Broken dams and levees on rivers can also cause flooding. Measuring earthquake magnitude and intensity geokansas.
Earthquakes are recorded by instruments called seismographs. Tens of thousands of excellent, educational videos in a huge, intuitive directory. Earthquakes measuring upwards of 7 are less frequent but very powerful, and can cause a lot of destruction. Developed in 1935 by charles richter, this scale uses a seismometer to measure the magnitude of the largest jolt of energy released by an earthquake. The worksheet gives them the descriptions levels of each of these scales jumbled up. All magnitude scales should yield approximately the same value for any given earthquake. These plates slowly move over a long period of time. Seismology a branch of science focused on the study of earthquakes and seismic activity. In addition to measuring an earthquakes magnitude, we can also measure its intensity. Clearly, a tsunami can cause flooding in areas where the wave hits inland. The moment magnitude mw scale, based on the concept of seismic moment, is uniformly applicable to all sizes of earthquakes but is more difficult to compute than the other types. Another way to measure the strength of an earthquake is to use the mercalli. Measuring earthquakes scientist have used two different types of measurments to describe the size of an earthquake.
Unit 3 earthquake causes and characteristics introduction in the last unit, we explored the historical importance and intent of executive order 12699. In this lesson, children look at the two scales used to measure the severity of an earthquake the richter scale and the mercalli scale. Earthquakes are recorded by a seismographic network. With students, brainstorm methods of measuring earthquakes, for example scientific methods using the richter scale or a seismograph. Finding epicenters and measuring magnitudes activityworksheet 5 evaluate. One method of earthquake measurement is to determine the level of destruction. There are three basic types of plate boundaries divergent, convergent and transform. Over the course of geological time, earthquakes, floods, and other natural events have helped to shape the surface of our planet. Earthquakes are described in terms of what nearby residents felt and the damage that was done to. Sometimes the edges, which are called fault lines, can get stuck, but the plates keep moving. First we need some basic information about earthquakes and their effects on the built environment.
Other important terms for describing earthquakes are hypocentre or focus and epicentre. Some scientists and educators believe seismology locating, measuring and predicting earthquakes is a very reliable science and will one day allow us to predict future earthquakes. The height of the largest waves indicates the size of an earthquake. How do they measure earthquakes from 250 years ago. How the richter scale measures earthquakes be prepared. Earthquake prediction is a branch of the science of seismology concerned with the specification of the time, location, and magnitude of future earthquakes within stated limits, and particularly the determination of parameters for the next strong earthquake to occur in a region. By using aids, such as the index and contents pages of the books, ask students to investigate different types of natural disasters.
Pressure slowly starts to build up where the edges are stuck and, once the pressure gets strong. The vibrations produced by earthquakes are detected, recorded, and measured by instruments call seismographs. Each year about 18 earthquakes are major with a richter magnitude of 7. Seismograms come in handy for locating earthquakes too, and being able to see the p wave and the s wave is important. Measuring earthquakes lesson plan and worksheet teaching. The slip of one block of rock over another in an earthquake releases energy that makes the ground vibrate. Measuring earthquakes educational videos watchknowlearn. When this stress becomes great enough to rupture the crust, or to overcome the friction that prevents one block of crust from slipping past another, energy is released, some of it in the form of various kinds of seismic waves that cause groundshaking, or quaking. These structures hold water in, but when an earthquake occurs, the integrity of the structure may be damaged, and the water could potentially flood nearby lowland areas.
Constructive is when two plates move away from each other, they correspond to mild earthquakes. During the course of this unit, encourage students to browse through newspapers to see if they can find information about natural disasters that have recently happened somewhere in the world. Finding epicenters and measuring magnitudes activityworksheet example answers 5 this is an opinionbased question, but expect students to bring in what they know about triangulationdistance calculation, seismogramsnomograms andor the. The first of these is an estimate of the energy released, and the value is referred to as magnitude. The science behind earthquakes what is an earthquake. The method of measuring radon and other environmental parameters as earthquake precursors article pdf available in fresenius environmental bulletin 261. Mar 16, 2020 sometimes, earthquakes at or below a magnitude of 3. It used a formula based on amplitude of the largest wave recorded on a specific type of seismometer and the distance between the earthquake and the seismometer.
An earthquake is what happens when two blocks of the earth suddenly slip past one another. One method is based on magnitudethe amount of energy released at the earthquake source. Start a free trial of quizlet plus by thanksgiving lock in 50% off all year try it free. In a single year, on average, more than 900,000 earthquakes are recorded and 150,000 of them are strong enough to be felt. Designed for teachers, students, parents, homeschoolers, educators and all lifelong learners.
The surface where they slip is called the fault or fault plane. There are a number of ways to measure the magnitude of an earthquake. Make sure students understand the vocabulary involved in the discussion. But only the moment magnitude scale is capable of measuring m8 read magnitude 8 and greater events accurately.
In the case of sumatra, full size available only from normal modes. Some of what we do to our planet is on purpose, and some of it is accidental. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. The first widelyused method, the richter scale, was developed by charles f.
Finding epicenters and measuring magnitudes worksheet. These are distinguished from seismic intensity scales that categorize the intensity or severity of ground shaking quaking caused by an earthquake at a given location. This is the number that is typically used by the press when a big earthquake happens. The largest earthquake ever recorded was in chile in 1960, which measured 9. Finding epicenters and measuring magnitudes activityworksheet example answers 5 this is an opinionbased question, but expect students to bring in what they know about triangulationdistance calculation, seismogramsnomograms andor the magnitude scale. Measuring earthquakes from optical satellite images article pdf available in applied optics 3920. Earthquakes are now measured in two separate ways based on the amount of energy released at the epicenter and the intensity of the earth shaking that occurs in specific locations. Aug 20, 2010 the familiar richter scale which is not a physical device but rather a mathematical formula is no longer widely used by scientists or the media to report an earthquake s size. In other words, the vibrations of an earthquake measuring 6 on this scale would be 30 times more energetic than those of a quake measuring 5. P waves are also faster than s waves, and this fact is what allows us to tell where an earthquake was. Unit iv, measuring earthquakes, explains earth quakes in terms of wave movement and introduces students to the farranging effects of earthquakes. Earthquakes measuring 12 on the scale happen regularly, and they are so small that people cannot feel them.
Its like when youre teacher loses their marbles because. Measuring large earthquakes at small periods simply misses their true size. Ask students to define measuring in their own words. There are two primary scales used to measure earthquakes. Earthquakes are put in the context of the large and smallscale changes that are constantly at work on the continents as well as the ocean floor. Feb 29, 2020 other important terms for describing earthquakes are hypocentre or focus and epicentre. Ideal as a supplement to a curriculum or for independent study. The seismograph has a base that sets firmly in the ground, and a heavy weight that hangs free. Seismic waves of energy caused either by earthquakes, by massive manmade explosions or waves volcanos. In later sections of this course, we will take a closer look at evaluating a communitys safety. Modified mercalli intensity scale another way to measure the strength of an earthquake is to use the mercalli scale.