The Modified Mercalli Intensity Scale measures the degree to which an earthquake is felt by people and the amount of damage caused by the earthquake. One differences is that the scale is a numerical scale that uses Roman numerals from I to XII to describe increasing increasing earthquake intensity levels.
How many intensity levels are in the Mercalli scale?
Values range from I - Instrumental to XII - Catastrophic. Giuseppe Mercalli (1850-1914) originally developed the scale, with ten levels. In 1902, Adolfo Cancani extended the scale to include twelve levels. August Heinrich Sieberg completely rewrote the scale.
Which scale is better Richter or Mercalli?
Which scale is better Richter or Mercalli? T he earthquake and its impact is measured either by using the Mercalli scale or the Richter Scale. The Richter scale is more objective, but the Mercalli scale is subjective. The Mercalli scale bases its measurement on the observed effects of the earthquake and describes its intensity.
What does the Mercalli scale tell you?
The Mercalli intensity scale (or more precisely the Modified Mercalli intensity scale) is a scale to measure the intensity of earthquakes.Unlike with the Richter scale, the Mercalli scale does not take into account energy of an earthquake directly. Rather, they classify earthquakes by the effects they have (and the destruction they cause). When there is little damage, the scale describes how ...
What are 2 differences between the Mercalli and Richter scale?
The two scales differ on several aspects:
- Richter scale ratings are produced soon after an earthquake occurs as scientists only need to compare the data from various seismograph stations. ...
- The Mercalli scale determines the intensity of a particular earthquake by its observed effects. ...
- While the Richter scale is logarithmic, the Mercalli scale is linear. ...
How does the Mercalli scale measure intensity?
The lesser degrees of the MMI scale generally describe the manner in which the earthquake is felt by people. The greater numbers of the scale are based on observed structural damage. This table gives MMIs that are typically observed at locations near the epicenter of the earthquake.
How does the Modified Mercalli Scale describe earthquake intensity?
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. At high intensities (above MMI 6), earthquake shaking damages buildings.
What is the Mercalli scale and how is it measured what does it measure?
The Mercalli Intensity Scale is a method of measuring earthquake intensity. It measures the damage from earthquakes and the observed effects. Lower numbers indicate intensity likely felt by people and higher numbers indicate damage to structures and buildings.
What factors determine the Modified Mercalli scale?
What factors determine the Modified Mercalli Scale? The perception of people and the response of structures to earthquake shaking.
What is the definition of a Mercalli scale?
Definition of Mercalli scale : a scale of earthquake intensity ranging from I for an earthquake detected only by seismographs to XII for one causing total destruction of all buildings.
Why is the modified Mercalli scale useful?
Applications and Use The Mercalli Intensity Scale is only useful for measuring earthquakes in inhabited areas and is not considered particularly scientific, as the experiences of witnesses may vary and the damage caused may not accurately reflect an earthquake's strength.
How do we measure the intensity of an earthquake?
A seismograph is the primary earthquake measuring instrument. The seismograph produces a digital graphic recording of the ground motion caused by the seismic waves. The digital recording is called a seismogram. A network of worldwide seismographs detects and measures the strength and duration of the earthquake's waves.
What does the Modified Mercalli Intensity Scale Tell us about an earthquake quizlet?
Each time the magnitude increases by one unit, the measured ground motion becomes 10 times larger. The Modified Mercalli Intensity Scale measures the degree to which an earthquake is felt by people and the amount of damage caused by the earthquake.
How is the intensity of an earthquake measured?
The Richter scale measures the largest wiggle (amplitude) on the recording, but other magnitude scales measure different parts of the earthquake. The USGS currently reports earthquake magnitudes using the Moment Magnitude scale, though many other magnitudes are calculated for research and comparison purposes.
What are the earthquake intensity scale and their description?
Earthquake Magnitude ScaleMagnitudeEarthquake Effects2.5 or lessUsually not felt, but can be recorded by seismograph.2.5 to 5.4Often felt, but only causes minor damage.5.5 to 6.0Slight damage to buildings and other structures.6.1 to 6.9May cause a lot of damage in very populated areas.2 more rows
What intensity level on the Modified Mercalli scale indicates total destruction?
XIISince 1933, in the United States we have used what's called the Modified-Mercalli Intensity scale, a twelve-stage scale, numbered from I to XII. The lower numbers represent imperceptible shaking levels, XII represents total destruction.
What is the range of the Modified Mercalli Intensity Scale?
Values range from I - Instrumental to XII - Catastrophic. Giuseppe Mercalli (1850-1914) originally developed the scale, with ten levels. In 1902, Adolfo Cancani extended the scale to include twelve levels. August Heinrich Sieberg completely rewrote the scale.
What is the Mercalli scale?
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 meas uring the intensity of shaking produced by an earth quake. It measures the effects of an earthquake ...
How do intensity scales work?
Intensity scales empirically categorize the intensity of shaking based on the effects reported by untrained observers and are adapted for the effects that might be observed in a particular region. By not requiring instrumental measurements, they are useful for estimating the magnitude and location of historical (preinstrumental) earthquakes: the greatest intensities generally correspond to the epicentral area, and their degree and extent (possibly augmented by knowledge of local geological conditions) can be compared with other local earthquakes to estimate the magnitude.
What is the lesser degree of the MMI scale?
The lesser degrees of the MMI scale generally describe the manner in which the earthquake is felt by people. The greater numbers of the scale are based on observed structural damage.
Why do earthquakes shake?
While shaking is caused by the seismic energy released by an earthquake, earthquakes differ in how much of their energy is radiated as seismic waves. Deeper earthquakes also have less interaction with the surface, and their energy is spread out across a larger volume.
What is the correlation between magnitude and intensity?
The correlation between magnitude and intensity is far from total , depending upon several factors, including the depth of the hypocenter, terrain, and distance from the epicenter. For example, a 4.5-magnitude quake in Salta, Argentina, in 2011, that was 164 km deep, had a maximum intensity of I, while a 2.2 magnitude event in Barrow in Furness, England, in 1865, about 1 km deep, had a maximum intensity of VIII.
What is the Wood-Neumann scale?
Some seismologists refer to this version the "Wood–Neumann scale". Wood and Neumann also had an abridged version, with fewer criteria for assessing the degree of intensity. The Wood–Neumann scale was revised in 1956 by Charles Francis Richter and published in his influential textbook Elementary Seismology. Not wanting to have this intensity scale ...
When was the Mercalli scale translated into English?
When Harry O. Wood and Frank Neumann translated this into English in 1931 (along with modification and condensation of the descriptions, and removal of the acceleration criteria), they named it the "modified Mercalli intensity scale of 1931 " (MM31). Some seismologists refer to this version the "Wood–Neumann scale".
What is the modified Mercalli scale?
The Modified Mercalli Intensity Scale of 1931 is the basis for the U.S. evaluation of seismic intensity. Intensity is different than the magnitude in that it is based on observations of the effects and damage of an earthquake, not on scientific measurements.
How many divisions are there in the Mercalli scale?
The Mercalli scale has 12 divisions, using Roman numerals from I to XII. I. Not felt except by a very few under especially favorable circumstances. II. Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. III.
Is the correlation between magnitude and intensity weak?
Although the correlation between magnitude and intensity is weak, the USGS has made a pretty good estimate of the intensity that might be felt near the epicenter of an earthquake of a specific magnitude.
Overview
The Modified Mercalli intensity scale (MM, MMI, or MCS), 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. It measures the effects of an earthquake at a given location, distinguished from the earthquake's inherent force or strength as measured by seismic magnitude scales (such as the "Mw" magnitude usually reported for an earthquake). While shaking is cause…
History
Italian volcanologist Giuseppe Mercalli formulated his first intensity scale in 1883. It had six degrees or categories, has been described as "merely an adaptation" of the then standard Rossi–Forel scale of 10 degrees, and is now "more or less forgotten". Mercalli's second scale, published in 1902, was also an adaptation of the Rossi–Forel scale, retaining the 10 degrees and expanding the descriptions of each degree. This version "found favour with the users", and was a…
Modified Mercalli intensity scale
The lesser degrees of the MMI scale generally describe the manner in which the earthquake is felt by people. The greater numbers of the scale are based on observed structural damage.
This table gives MMIs that are typically observed at locations near the epicenter of the earthquake.
The correlation between magnitude and intensity is far from total, depending upon several facto…
See also
• Japan Meteorological Agency seismic intensity scale (Shindo scale)
• Rohn emergency scale
• Seismic intensity scales
• Seismic magnitude scales
Further reading
• Jones, Richard (2012), "Investigating the Mercalli Intensity Scale Through 'Lived Experience'", Science Scope, 36 (4): 54–60, JSTOR 43183283
External links
• National Earthquake Information Center (U.S.)
• Modified Mercalli Intensity Scale – United States Geological Survey
• The Severity of an Earthquake – United States Geological Survey
• U.S. Earthquake Intensity Database – NOAA