Search results
Results from the WOW.Com Content Network
The intensity of local ground-shaking depends on several factors besides the magnitude of the earthquake, [3] one of the most important being soil conditions. For instance, thick layers of soft soil (such as fill) can amplify seismic waves, often at a considerable distance from the source, while sedimentary basins will often resonate ...
Seismic intensity scales categorize the intensity or severity of ground shaking (quaking) at a given location, such as resulting from an earthquake. They are distinguished from seismic magnitude scales , which measure the magnitude or overall strength of an earthquake, which may, or perhaps may not, cause perceptible shaking.
The Medvedev–Sponheuer–Karnik scale, also known as the MSK or MSK-64, is a macroseismic intensity scale used to evaluate the severity of ground shaking on the basis of observed effects in an area where an earthquake transpires.
Intensity 7 (震度7, Shindo-nana) is the highest level on the JMA seismic intensity scale, applied to earthquakes with an instrumental intensity (計測震度) of 6.5 or higher. [6] At Intensity 7, movement becomes nearly impossible without external support. [11] The intensity was created following the 1948 Fukui earthquake.
(These should not be confused with moment magnitudes JMA calculates, which are labeled M w (JMA) or M (JMA), nor with the Shindo intensity scale.) JMA magnitudes are based (as typical with local scales) on the maximum amplitude of the ground motion ; they agree "rather well" [ 3 ] with the seismic moment magnitude M w in the range of 4.5 to 7.5 ...
Unlike the Richter and moment magnitude scales, it is not a measure of the total energy (magnitude, or size) of an earthquake, but rather of how much the earth shakes at a given geographic point. The Mercalli intensity scale uses personal reports and observations to measure earthquake intensity but PGA is measured by instruments, such as ...
For example, a magnitude 7.0 quake in Salta, Argentina, in 2011, that was 576.8 km deep, had a maximum felt intensity of V, [19] while a magnitude 2.2 event in Barrow in Furness, England, in 1865, about 1 km deep, had a maximum felt intensity of VIII. [20] The small table is a rough guide to the degrees of the MMI scale.
Second, it was designed as a public relations tool, not an objective scientific scale. Third, its most serious shortcoming is that it conflates magnitude and intensity. An alternative nuclear accident magnitude scale (NAMS) was proposed by British nuclear safety expert David Smythe to address these issues. [45]