Marginal and longperiod effects of large earthquakes. Handouts made from master 28, modified mercalli scale. Be sure you have an application to open this file type before downloading. This map shows earthquake intensity zones in accordance with the 1956 version of the modified mercalli scale mm, describing the effects of an earthquake on. Earthquakes, now scanned and available online for example, u. Distribute h1 modified mercalli scale and display the scale on the projector. Engineering construction codes are based on a spectral scale which is somewhat complicated to describe but of that later. This scale, composed of increasing levels of intensity that range from imperceptible shaking to catastrophic destruction, is designated by roman numerals. Use the modified mercalli intensity scale to assign earthquake intensities. Modified mercalli intensity scale of 1931 bulletin of.
The modified mercalli scale of earthquake intensity and its use in. Earthquake topics for the modified mercalli intensity. Use the tables on the next page to guide your answers. Mercalli intensity scale simple english wikipedia, the. Determine the modified mercalli scale intensity and richter magnitude of each of described earthquakes. Rather, they classify earthquakes by the effects they have and the destruction they cause. Base your answer to the following question on the map and the modified mercalli intensity scale below. Average peak velocity centimeters per second intensity value and description. Resilience is a communitys ability to withstand and rebound from a profound shock. Geological survey, sent out 610 mail questionnaires to postoffices situated within 600 km of the earthquake epicenter. The cities kodiak and anchorage are shown on the map. The scale was then improved by charles richter, the father of the richter magnitude scale. Geological survey and prior to 1973 by agencies in the u.
The modified mercalli intensity value assigned to a specific site after an earthquake has a more meaningful measure of severity to the. Earthquake topics for the modified mercalli intensity scale. Few intensities of greater than 8 intensities associated with significant building damage have been estimated for new zealand earthquakes, so estimates made from the damaging christchurch earthquake was seen as an important opportunity. What is the difference between the mercalli scale and the richter scale. 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. Pronunciation of mercalli scale with 3 audio pronunciations, 4 synonyms, 1 meaning, 8 translations, 3 sentences and more for mercalli scale. Mercalli scale vs richter scale difference and comparison. The modified mercalli intensity scale what sensation do you feel at your locale. Under certain conditions, at and outside the boundary of the area in which a great shock is felt. The earthquakes epicenter was near anchorage, alaska. Today, the scale is known simply, and perhaps rightly, as modified mercalli scale mm or modified mercalli intensity scale mmi.
It was developed in 1931 by the american seismologists harry wood and frank neumann. Based off this image, the most likely intensity of this earthquake would be. 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. Richter scale vs mercalli scale richter scale and mercalli. The magnitude is a number that characterizes the relative size of an earthquake. Shakealert issuance of earthquake early warning alerts\t17. Based on the changes seen within the structure, decide where this earthquake would most likely fall on the modified mercalli intensity scale. Modified mercalli scale intensity effects pgagals i not felt. The modified mercalli intensity scale mmi, developed in 1931, is the most commonlyused scale worldwide. The 1931 modified mercalli scale used in the united states assigns a roman numeral in the range i xii to each earthquake effect. Review the roman numerals and read their descriptions.
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. Mercalli scale smithsonian science for the classroom. Richters version became instead the modified mercalli scale of 1956 mm56 despite the fact that the link to mercalli was now extremely remote. Wood and frank neumann the formation of a satisfactory earthquake intensity scale has long been a subject for consideration and discussion among those who are in terested actively in studies of shock intensity and its geographic mani. Mercalli modified index is essentially subjective, the horizontal peak acceleration is a measureable by strongmotion instruments. 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. Modified ivfercalli intensity scale of 1931 277 modified mercalli intensity scale of 1931 by harry o. As the nature of the damage to chimneys is often reported simply as damaged, the number of. The seismic intensity scale introduced by giuseppe mercalli in 1902 has evolved greatly in the succesive modifications by cancani 1904, sieberg 1912, 1923. Rare reports of slight swaying of trees or chandeliers, ripples appearing on bodies of water, and doors. The modified mercalli mm scale is the most commonly used intensity scale, and ranges from 1 to 12. Display the modified mercalli scale on the overhead projector.
Developed for the shakeout by the southern california earthquake center. The modified mercalli mmi scale expresses intensity of an earthquake and indicates strength of felt shock at a particular location. Modified mercalli intensities for nine earthquakes in. The great earthquake of december 16, 1811 a modified mercalli intensity map objectives. 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. At which one of the following locations in new york state could everyone feel the vibrations caused by this earthquake. The modified mercalli intensity scale the effect of an earthquake on the earths surface is called the intensity. With the help of beno gutenberg an associate of his, they made the most popular and commonly used seismic scale at present. We determine modified mercalli seismic intensities mmi for nine onshore earthquakes of magnitude 4.
Type ii domestic hotwater cylinders unrestrained except by supply and delivery pipes. Previous estimates of modified mercalli intensities of the 1871 earthquake. The figure below illustrates seismicity in the united states. Abbreviated description of the levels of modified mercalli intensity. The mmi scale is now more widely used than the richter. Simplified modified mercalli scale after wood and neumann, 1931.
Redisplay photos used in the engage and ask students to rate the damage using the mercalli scale. The lesser degrees of the mmi scale generally describe the manner in which the earthquake is felt by people. The scale is used to group locations according to the observed effects of an earthquake. Fault related oil and gas fields in areas where the bedrock is masked by glacial. Selected city information on a nationwide 2014 modified mercalli intensity mmi earthquake shaking map with a 2 percent probability of exceedance in 50 years 10 figure 3. Appendix a modified mercalli mm scale of earthquake. I am proposing to rename this page modified mercalli intensity scale adding modified to the existing title. Pdf recent studies of the effects and modified mercalli mm intensities of new zealand earthquakes have established criteria that will improve the.
See table below that describes the modified mercalli intensity scale. An additional 54 questionnaires were sent to police and firestations within 25 km of the epicenter. 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. Explain that today, we will learn one method called the mercalli scale used to measure earthquakes. Modified mercalli intensity scale what is our evidence that we live on a changing earth. Many portions of this brochure have been adapted from the 2008 south carolina earthquake guide originally developed by the. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Ii felt only by a few people at rest, especially on upper floors of buildings. Major to great i not felt except by a very few people under especially favorable conditions. For united states earthquakes, intensities are assigned on the basis of the modified mercalli intensity mmi scale wood and neumann, 1931.
Modified mercalli intensity scale of 1931 adapted from siebergs mercalli cancani scale, modified and condensed. Modifiedmercalliintensityscale earthquakedamagereporting byjohnjacobschmidt,amrron intheimmediateaftermathofanearthquake,searchandrecoveryeffortswill. The following version of the mm scale is as used in new zealand dowrick et al. Examine the before and after image of the national. Practice the process of contouring using isoseismals.
The numbered areas on the map were determined from the modified mercalli scale shown below. Mercalli intensity scale simple english wikipedia, the free. The mercalli scale describes earthquake damage at earths surface. These two events are dealt with in more detail in the section of this report headed seismic disturbances related to mans activities. I not felt or, except rarely under especially favorable circumstances. Modified mercalli intensity scale wiley online library. Later attempts to radically modernise the mm scale, such as that of brazee 1978, did not catch on. The mercalli intensity scale or more precisely the modified mercalli intensity scale is a scale to measure the intensity of earthquakes. Today, the mercalli scale is completely known as the mmi scale or modified mercalli intensity scale. An additional 54 questionnaires were sent to police. It measures the shaking you feel during an earthquake. Viii on the modified mercalli scale have been recorded. The rossiforel scale initially used to describe the january 1, 19, union county, s. In the bay area, where regional hazards range from earthquake shaking and fault rupture to extreme heat and sea level rise, resilience planning is critical to our ability to withstand, sustain and rebuild, preserving the unique cultural and economic character of our communities.
The map shows modified mercalli intensity scale damage zones resulting from a large earthquake that occurred in 1964. 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. Dec 19, 2014 12162014 the modified mercalli intensity scale mercalli. Modified mercalli intensity scale of 1931 bulletin of the. Earth science earthquakes, volcanoes and plate tectonics file. The modified mercalli intensity scale county of san diego. This page is a translated version of the page dictionary. As you can see here, as the numbers get higher, the more you feel the shaking. This scale has values that range from roman numerals i to xii which characterize the damage observed and peoples reactions to it. Circular 14 seismic disturbances in michigan introduction. The scale presented belqiw is not intended to be a new one, but merely. Local modifications of richters mm56 scale have been used in australia and new zealand.
Many portions of this brochure have been adapted from the 2008 south carolina earthquake guide originally developed by. Difference between richter scale and mercalli scale. Helps students understnad difference between magnitude and intensity. This south carolina state document was either saved from a document available publicly online in pdf format or converted to pdf using adobe. Modified mercalli intensities for nine earthquakes in central. The modified mercalli intensity or mmi was based in part on postal questionnaires, in which respondents summarize the effects of shaking in their.
The greater numbers of the scale are based on observed structural damage. An earthquake definitely doesnt need to have a magnitude of 7. At high intensities above mmi 6, earthquake shaking damages buildings. Modified mercalli intensity scale used to describe earthquakes 8 figure 2.
The intensity scale consists of a series of certain key. Jul 18, 2019 in santa clara county aresraces, we use the modified mercalli intensity scale for efficient and standardized reporting of earthquake damage. Pdf the modified mercalli intensity scale revisions. Modified mercalli scale uwi seismic research centre. 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. Examine the before and after image of the national cathedral. The modified mercalli intensity mmi scale measures intensity based on observed effects. The modi ed mercalli intensity scale mmi the magnitude scale. Pdf the modified mercalli intensity scale revisions arising from. The modified mercalli intensity scale revisions arising from new zealand experience. Instead of using vague and subjective descriptions like major, minor or heavy, a mikemike value is reported. Comparison of previous and revised estimates of the modified mercalli intensities of the 1871 earthquake shallow subsurface materials prevalent at places of reported effects of the 1871 earthquake. Line students up single file in a long corridor indoors, or outdoors along a wall or fence.
Mmi scale ranges from intensity i to intensity xii, with i being barely felt to xii being near total destruction of constructed facilities. As mentioned, charles richter developed the richter scale back in 1935. Handout primarily discussing the modified mercalli scale. The county planning area is lincoln enclosed in the lower righthand side of the circle annotated below. Unlike with the richter scale, the mercalli scale does not take into account energy of an earthquake directly. When there is little damage, the scale describes how. Epicenter modified mercalli intensity mmi scaleon december. This table gives mmis that are typically observed at locations near the epicenter of the earthquake. Modified mercalli scale and the translation is 100% complete. Classification of the modified mercalli intensity scale. Modified mercalli scale of 1931, abridged version a3.
460 1539 933 883 1257 637 255 748 261 648 490 1316 932 524 1329 749 1063 1453 279 53 236 1725 457 958 424 1007 1764 1368 1205 1558 1441 601 1793 1778 952 152 634 1196