Earthquake intensity is a ranking based on the observed effects of an earthquake in each particular place. The correlation between intensity and magnitude of earthquake are provided in table 4. In general, only if the earthquake magnitude reaches above 6. Earthquake magnitude is measured using a number of differing scales including the richter scale, the moment magnitude scale and the surface magnitude scale. When an earthquake occurs, its magnitude can be given a single numerical value on the richter magnitude scale. The differences and relationships between magnitude, energy, and fault size is discussed and shown with images. The paper investigates the principal physical elements of earthquakes. Intensity, magnitude, location, and attenuation in india. In the analysis of earthquake tsunami we usually use the moment magnitude m w. Definition of an earthquake an earthquake also known as a quake, tremor or temblor is the result of a sudden release of energy. Magnitude refers to the energy liberated, while intensity. Shaking is measured in units of acceleration, often a percentage of g. So, for example, a magnitude 2 earthquake is 31 times more powerful than a magnitude 1 earthquake. Measurements on the modified mercalli intensity mmi scale range from i to xii and are based solely on damage assessment and eyewitness accounts.
Earthquake magnitude, intensity, energy, and acceleration 107 be about 16 kin. However the subtle differences between these terms are pretty important, especially when discussing earthquake early warning alerting thresholds. Turkish earthquake so vividly illustrates, the degree of damage is often related more to human activity than the earthquake itself. Therefore, each earthquake produces a range of intensity values, ranging from highest in the.
Magnitude the magnitude is a number that characterizes the relative size of an earthquake. Magnitude is a measure of the energy released by the earthquake it is an absolute value and does not vary with where it is measured. However, intensity scales, like the modified mercalli intensity scale or the japan meteorological agencys seismic intensity scale, do provide an indication of the extent and distribution of the damage caused from ground surface shaking caused by an earthquake. Because the entire range of observed effects is not capable of simple quantitative definition, the strength of the shaking is commonly estimated by reference to intensity scales that describe the effects in qualitative terms. Difference between earthquake magnitude and intensity. In this activity, students explore the relationship between an earthquake s magnitude and intensity. Therefore, each earthquake produces a range of intensity values, ranging from highest in the epicenter area to zero at a distance from the epicenter. Difference between earthquake magnitude and intensity thus it is clear that magnitude is a fixed value independent of distance from the epicenter of the earthquake, whereas intensity varies and is measured differently at different places depending upon its distance from the epicenter. Measuring earthquake magnitude and intensity geokansas. The magnitude of earthquake is determined from measurements on seismographs, whereas the intensity is determined from effects on people, human structures, and the natural environment. Earthquake size is a quantitative measure of the size of the earthquake at its source. Magnitude intensity and intensity attenuation relationships for atlas region and algerian earthquakes. Earthquake magnitude richter magnitude scale m log a.
Why are some earthquakes more destructive than others. Get the latest news and update on earthquake, also learn how intensity of an earthquake is measured. How is an earthquakes magnitude and intensity different. Earthquake magnitude is a measure of the size, or amplitude, of the seismic waves generated by an earthquake source and recorded by seismographs.
Earthquake is a violent tremor in the earths crust, sending out a series of shock waves in all directions from its place of origin. Neither earthquake magnitude nor macroseismic intensity provides sufficient information to. For large earthquakes the richter as well as body wave magnitude scales saturate. Earthquake magnitude perspective dataset science on a sphere. Intensity, magnitude, location, and attenuation in india for felt earthquakes since 1762 by walter szeliga, susan hough, stacey martin, and roger bilham abstract a comprehensive, consistently interpreted new catalog of felt intensities for india martin and szeliga, 2010, this issue includes intensities for 570 earth. The richter magnitude scale measures the amount of seismic energy released by an earthquake. Their dependencies and relationships can be complicated, and even one of these concepts alone can be confusing. Intensity is based on post earthquake damage surveys, is a descriptive scale, is indicative of shaking at that place, is written in roman numerals, is spacedependent, and varies from point to point in the affected area. The modified mercalli intensity scale mm or mmi, descended from giuseppe mercallis mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. Three sites l1, l2, l3 record earthquake intensity and earthquake magnitude for the same earthquake. In many instances, the two terms are erroneously used interchangeably. The former measures the energy released at the source of the.
Earthquake intensity an overview sciencedirect topics. Earthquake intensity is very different from earthquake magnitude. Because the size of earthquakes varies enormously, it is necessary for purposes of comparison to compress the. This happens because the relation between the seismic measurements and the. Unlike magnitude, the intensity that is the devastation caused by earthquake varies with the location and is not a single numerical value. Earthquake earthquake intensity and magnitude of earthquakes. But, an earthquake in a densely populated area that results in many deaths and considerable damage high intensity may have the same magnitude as an earthquake in a remote area that does no more. Displaying all worksheets related to magnitude and intensity earthquake. Magnitude measures the energy released at the source of the earthquake.
What is the difference between magnitude and intensity. This happens because the relation between the seismic measurements and the magnitude is complex and different. Often, several slightly different magnitudes are reported for an earthquake. Magnitude intensity moment magnitude scale seismology.
Magnitude and intensity earthquake worksheets lesson. If you throw a stone in a pond of still water, a series of concentric waves are produced on the surface of. What is the difference in intensity of an earthquake of 6. The moment magnitude scale is better suited for measuring the sizes of very large earthquakes and its values are proportional to. In general, areas closest to the epicenter experience the highest intensities, and shaking diminishes in strength farther. Pdf intensity, magnitude, location, and attenuation in. Several scales have been defined, but the most commonly used are. Usgs earthquakes information on the basics of earthquakes.
The energy at the source of the quake is measured by a magnitude determined from seismographs. Therefore, it is neces sary to distinguish between the magnitude and intensi ty of an earthquake. Magnitude and intensity measure different characteristics of earthquakes. Earthquake intensity mustafa fahmi hasanmustafa mohammed rashid 2011 november 2. An earthquake is measured by both magnitudes as well as by intensity. The violence of seismic shaking varies considerably over a single affected area. Understanding the magnitude and intensity of an earthquake duration. Tsunami warning center scientists usually measure an earthquake s size with the moment magnitude scale rather than the older but more famous richter magnitude scale. Learning earthquake tip 3 earthquake design and construction. Seismic magnitude scales are used to describe the overall strength or size of an earthquake. The earthquake size is usually expressed as the earthquake magnitude and intensity. 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.
It appears that m b corresponds more closely to the magnitude scale determined for local earthquakes a complete revision of the magnitude scale, with appropriate tables and charts, is in preparation. Table 1 presents the difference between magnitude and intensity of earthquake. Determination of earthquake magnitude and the strength of shaking at a site from the initial pwave portion of ground notion is the key problems for earthquake early warning eew. Magnitude scales, like the moment magnitude, measure the size of the earthquake at its source. Earthquake magnitude, energy release, and shaking intensity are all related measurements of an earthquake that are often confused with one another. Earthquake magnitude, intensity, energy, and acceleration. Worksheets are activitypasta quake, earthquakes fema 159, earth science activity 2 all grades measure my magnitude, the richter scale, earthquake measurements, earthquakes, workbook scag earthquake preparedness initiative, earthquakes.
What is earthquake how it occurs, causes seismic waves. Magnitude and intensity measure various characteristics of earthquake. Magnitude scales do not used express damage and nor do they provide a direct indication of the shaking level on the ground surface. It is one of the service agencies of the department of science and technology. Magnitudes are usually determined from measurements of an earthquake s seismic waves as recorded on a seismogram. Earthquake magnitude, energy release, and shaking intensity how the size of an earthquake is measured. Difference between magnitude and intensity of earthquake. In richter scale each number increases the intensity by explanation. Earthquake intensity earthquake intensity is defined as the strength of seismic shaking at a given location. Pdf on estimation of earthquake magnitude and intensity. Damage or intensity can be measured by the modified mercalli intensity mmi scale.
This will probably be based on at rather than amplitudes. The focus is the source of the earthquake and the epicenter is the point on. Analysis of seismogram allows measurement of size of earthquake. The severity of earthquake shaking is assessed using a descriptive scale the modified mercalli intensity scale. Earthquake magnitude, energy release, and shaking intensity. Earthquake tip 3 learning earthquake design and construction terminology the point on the fault where slip starts is the focus or hypocenter, and the point vertically above this on the surface of the earth is the epicenter figure 1.
Students calculate the energy released during a weight drop magnitude and use an accelerometer iphone, qcn, or other to investigate what happens to this energy as the source is moved further and further from the sensor intensity. Relationship of tsunami intensity to source earthquake magnitude as retrieved from historical data. Consequently, more quantitative measures have been adopted that measure the magnitude and timing of the vibration figure 3. Magnitude is based on measurement of the maximum motion recorded by a seismograph4. Magnitude also affects intensity, since an earthquake of a higher magnitude has a higher intensity than an earthquake of lower magnitude. Whereas an earthquake has just a single magnitude, it will have many different intensities at different locations. Intensity, magnitude, location, and attenuation in india for felt earthquakes since 1762 article pdf available in bulletin of the seismological society of america 1002 march 2010 with 425 reads. L1 is located closest to the focus and l3 is farthest away. The magnitude do not depend on where the measurement is made. The moment magnitude scale is often referred to by the name of its predecessor, the richter scale.
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