Unlike with the richter scale, the mercalli scale does not take into account energy of an earthquake directly. Measurements and effects of earthquakes sample answer. Objects fall from shelves, and pictures from walls. Image earthquake shaking is measured using the modified mercalli intensity mmi scale. The modified mercalli intensity scale revisions arising from new zealand experience. The intensity scale consists of a series of certain key responses such as people awakening, movement of furniture, damage to chimneys, and finally total destruction. What is an earthquake virginia department of mines, minerals and. Mmi scale ranges from intensity i to intensity xii, with i being barely felt to xii being near total destruction of constructed facilities. Geological survey, sent out 610 mail questionnaires to postoffices situated within 600 km of the earthquake epicenter. Modified mercalli intensity scale of 1931 adapted from siebergs mercalli cancani scale, modified and condensed. Simplified modified mercalli scale after wood and neumann, 1931.
Geocoded community internet intensity map for the wells earthquake created november 19, 2009 taken from the usgs dyfi web site. Earthquakes are measured in 2 ways, the richter scale and the modified mercalli scale. Earthquake magnitude scales read earth science ck12. Jul 08, 2017 the modified mercalli intensity scale is a tool that anyone can use to report the effects of an earthquake in their immediate location. I created this video with the youtube video editor. An additional 54 questionnaires were sent to police and firestations within 25 km of the epicenter. Modified mercalli scale vs richter scale however, richter ratings only give you a rough idea of the actual impact of an earthquake.
As you can see here, as the numbers get higher, the more you feel the shaking. Examine the before and after image of the national. Appendix a modified mercalli mm scale of earthquake intensity geoscience australia earthquake risk in newcastle and lake macquarie 4 structures type iv buildings and bridges designed and built to resist earthquakes to normal use standards, i. This scale also is used to estimate the size, or magnitude, of earthquakes that occurred before sensitive instruments existed to measure them. The mercalli intensity scale or more precisely the modified mercalli intensity scale is a scale to measure the intensity of earthquakes. The modified mercalli intensity scale mm or mmi, developed from giuseppe mercalli s mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. Examine the before and after image of the national cathedral. Not felt except by a very few under especially favorable circumstances.
Redisplay photos used in the engage and ask students to rate the damage using the mercalli scale. Classification of the modified mercalli intensity scale. Geological survey and prior to 1973 by agencies in the u. Earthquakes and seismic history of florida ufdc image array 2. The modified mercalli intensity scale uses roman numerals to measure. The lesser degrees of the mmi scale generally describe the manner in which the earthquake is felt by people. It was developed in 1931 by the american seismologists harry wood and frank neumann. Modified mercalli intensity scale wiley online library. Richters version became instead the modified mercalli scale of 1956 mm56 despite the fact that the link to mercalli was now extremely remote. The modified mercalli intensity scale mmi, developed in 1931, is the most commonlyused scale worldwide. This scale, composed of increasing levels of intensity that range from imperceptible shaking to catastrophic destruction, is designated by roman numerals. Department of commerce have for many decades been based on the modified mercalli intensity scale of 1931 wood and neumann, 1931, which we usually refer to simply as the modified mercalli or mm scale.
The richter scale uses instruments called seismometers to measure the magnitude of the earthquake. The modified mercalli intensity scale is based on the effects experienced by individuals and the observed damage mainly to manmade objects figure 4. Modified mercalli intensity scale gauges earthquakes by their effect on people and structures. I not felt or, except rarely under especially favorable circumstances.
The may 12, 2008 earthquake in relation to the 1976 songpan earthquake modified graphic of world data center for seismology. The modified mercalli intensity mmi scale assigns intensities as. Marginal and longperiod effects of large earthquakes. This table gives mmis that are typically observed at locations near the epicenter of the earthquake. Pdf the modified mercalli intensity scale revisions. Whereas the magnitude of an earthquake describes how much energy is released by an earthquake, calculated according to the length of a fault rupture and how far it slipped, the mmi scale describes the intensity of earthquake shaking at a specific location by. Rare reports of slight swaying of trees or chandeliers, ripples appearing on bodies of water, and doors. Appendix a mercalli mm earthquake intensity d, 1996. Mercalli scale vs richter scale difference and comparison. The county planning area is lincoln enclosed in the lower righthand side of the circle annotated below. Modified mercalli intensity scale south carolina state.
Structural engineers usually contribute information for assigning intensity values of viii or above. It measures the effects of an earthquake at a given location, distinguished from the earthquakes inherent force or strength as measured by seismic magnitude scales such as the. As weve seen, an earthquakes destructive power varies depending on the composition of the ground in an area and the design and placement of manmade structures. Earth science earthquakes, volcanoes and plate tectonics. The modified mercalli mmi scale expresses intensity of an earthquake and indicates strength of felt shock at a particular location. Dec 19, 2014 the modified mercalli intensity value assigned to a specific site after an earthquake has a more meaningful measure of severity to the nonscientist than the magnitude because intensity refers to the effects actually experienced at that place. Be sure you have an application to open this file type before downloading. Modified mercalli intensities for nine earthquakes in central. Where the two intersect is the heat index for any given time of day. Modifiedmercalliintensityscale earthquakedamagereporting byjohnjacobschmidt,amrron intheimmediateaftermathofanearthquake,searchandrecoveryeffortswill. What is our evidence that we live on a changing earth.
Local modifications of richters mm56 scale have been used in australia and new zealand. Making sense of the modified mercalli intensity scale mmi. The modified mercalli intensity value assigned to a specific site after an earthquake has a more meaningful measure of severity to the nonscientist than the magnitude because intensity refers to the effects actually experienced at that place. Earthquake topics for the modified mercalli intensity. Liquids in open vessels such as aquariums and toilet bowls may slosh but rarely spill. At high intensities above mmi 6, earthquake shaking damages buildings. If this table is garbled, try the plain text version. Mercalli modified index is essentially subjective, the horizontal peak acceleration is a measureable by strongmotion instruments.
New zealand scientists have modified it further to suit new zealand conditions. The material for the next two lectures is based on chapter. Display the modified mercalli scale on the overhead projector. Wood and neumann gave a new version of the mcs scale, which came in use in usa as modified mercalli mm scale. The modified mercalli intensity scale what sensation do you feel at your locale. The modified mercalli intensity map of the 2008 wells, nevada m6. The modified mercalli intensity scale is a seismic scale, used for measuring the intensity of an earthquake.
It is an open ended scale, however the strongest quake ever recorded in the 21st century is the asian. The greater numbers of the scale are based on observed structural damage. Later attempts to radically modernise the mm scale, such as that of brazee 1978, did not catch on. Today, the scale is known simply, and perhaps rightly, as modified mercalli scale mm or modified mercalli intensity scale mmi.
Earthquake intensity mappdf document missouri state. According to the usgs, the intensity in banda aceh, sumatra reached ix. Find mercalli scale stock images in hd and millions of other royaltyfree stock photos, illustrations and vectors in the shutterstock collection. To find the heat index from the table, see the relative humidity along the left side of the table and the air temperature along the top. Even if conventional communications, commercial radio and television, and internet are disrupted, the reports sent in by radio operators can provide great insight as to the size and scope of the incident. Earthquakes, now scanned and available online for example, u.
Based off this image, the most likely intensity of this earthquake would be. The modified mercalli intensity scale the effect of an earthquake on the earths surface is called the intensity. The modified mercalli scale of earthquake intensity and its use in. Earthquake topics for the modified mercalli intensity scale. Rather, they classify earthquakes by the effects they have and the destruction they cause. It measures the effects of an earthquake at a given location, distinguished from. The zones indicate where there is a probability of 20 percent that degrees of intensity shown on the map will be exceeded in 50 years. Modified mercalli intensity scale wikimili, the best. Modified mercalli intensity scale for additional information on statistics on percentage of uninhabitable residential units by construction type and mmi level, click here. Making sense of the modified mercalli intensity scale mmi a measure of shaking the modified mercalli intensity mmi estimates the shaking intensity from an earthquake at a specific location by considering its effects on people, objects, and buildings. Appendix a modified mercalli mm scale of earthquake intensity geoscience australia earthquake risk in newcastle and lake macquarie 2 fittings objects fall from shelves.
It measures the shaking you feel during an earthquake. Appendix a modified mercalli mm scale of earthquake. Handout primarily discussing the modified mercalli scale. The modified mercalli intensity scale for earthquake insurance. This scale assigns to an earthquake event a roman numeral from i to xii as follows. Mercalli intensity scale simple english wikipedia, the. Modified mercalli intensities for nine earthquakes in. Some furniture moved on smooth floors, some unsecured freestanding fireplaces moved. Modified mercalli scale uwi seismic research centre. Engineering construction codes are based on a spectral scale which is somewhat complicated to describe but of that later. The map indicates the modified mercalli scale intensity values recorded at several locations in japan during the march 11, 2011 earthquake, which. Many portions of this brochure have been adapted from the 2008 south carolina earthquake guide originally developed by. Describes the scales scientists use to indicate the intensity and magnitude of an earthquake including the mercalli, richter, and moment magnitude. The intensity of an earthquake, as expressed by the modified mercalli scale, written as mm, is much more meaningful to laymen than the richter scale since it is based on actual human observations of earthquake effects at specific locations.
In new zealand, where earthquakes occur from near the surface right down to a depth of over 600 km, the modified mercalli intensity scale is a better indicator of an earthquakes effects on people and their environment. The modified mercalli intensity mmi is a scale that measures the intensity of the earthquake and ranges from the minimum of level i no noticeable tremors to level xii damage is nearly total and large rock masses are displaced. The modified mercalli intensity scale mmi is a useful tool for assessing. For an earthquake of given richter magnitude, intensity will vary with distance from epicenter, local geology, construction practices, etc. Thousands of new, highquality pictures added every day. This map shows the highest projected modified mercalli intensities by county from a. Helps students understnad difference between magnitude and intensity. Mercalli intensity scale simple english wikipedia, the free. Modified mercalli intensity scale modified from projected earthquake intensities for south carolina by clark a. When there is little damage, the scale describes how. Modified mercalli scale values of shock intensities are given as roman numerals and range from mm i to. Isoseismal map for the newcastle earthquake, 27 october 1842. See table below that describes the modified mercalli intensity scale.
Review the roman numerals and read their descriptions. The modified mercalli intensity value assigned to a specific site after an earthquake has a more meaningful measure of severity to the nonscientist than the. Many portions of this brochure have been adapted from the 2008 south carolina earthquake guide originally developed by the. The modified mercalli intensity scale of 1931 abridged intensity description. Richter 1956 gave a rewritten version of the mm scale which is referred to mm scale 1956 version. An additional 54 questionnaires were sent to police. The heat index hart shown below uses both of these factorsc to produce a. The figure below illustrates seismicity in the united states. Abbreviated description of the levels of modified mercalli intensity. Modified mercalli intensity scale what is our evidence that we live on a changing earth. Modified mercalli scale intensity effects pgagals i not felt. Mercalli scale illustrated activity teachengineering. It was originally developed in 1902 in italy and relies on newspaper and eyewitness reports.
Proportions of brittle chimneys 1 damaged, and 2 fallen, as functions of modified mercalli intensity, in new. Mercalli scale smithsonian science for the classroom. The richter scale and modified mercalli intensity scale. Modified mercalli scale values of shock intensities are given as roman numerals and range from mm i. Rare reports of slight swaying of trees or chandeliers, ripples appearing on bodies of water, and doors slowly swinging. Pdf the modified mercalli intensity scale revisions arising from.
Under certain conditions, at and outside the boundary of the area in which a great shock is felt. The percentages are provided using two significant figures, with a the smallest unit equal to 0. Mercalli scale download pdf this image provides a description of the modified mercalli intensity scale. Modified mercalli intensity scale modified mercalli intensity scale the modified mercalli scale measures the intensity of ground shaking as determined from observations of an earthquakes effect on people, structures, and the earths surface. The scale was then improved by charles richter, the father of the richter magnitude scale. Mercalli scale, written as mm, is much more meaningful to laymen than the richter scale since it is based on actual human observations of earthquake effects at specific locations. Felt only by a few persons at rest, especially on upper floors of buildings. Modified mercalli intensity scale earthquake damage. The rossiforel scale initially used to describe the january 1, 19, union county, s. Modified mercalli intensity scale branch of earthquake and geomagnetic information, u. The modified mercalli intensity scale is commonly used in the united states by seismologists.
In 1976 the songpan earthquake, with a magnitude of 7. Epicenter modified mercalli intensity mmi scaleon december. Below are characteristics of some quake intensities on the modified mercalli scale. The scale ranges from 1 to 12 with increasing intensity. Mmi value description of shaking severity summary damage description used on 1995 maps full description i.
1465 444 353 938 1353 864 931 1233 914 950 44 1477 162 196 112 351 543 1305 1141 1231 1148 1150 1194 1250 747 138 940 1496 274