Search results
Results from the WOW.Com Content Network
The formula above made it much easier to estimate the energy-based magnitude M w , but it changed the fundamental nature of the scale into a moment magnitude scale. USGS seismologist Thomas C. Hanks noted that Kanamori's M w scale was very similar to a relationship between M L and M 0 that was reported by Thatcher & Hanks (1973)
Officially it's called the moment magnitude scale. It's a logarithmic scale , meaning each number is 10 times as strong as the one before it. So a 5.0 earthquake is ten times stronger than a 4.0.
An earthquake's seismic moment can be estimated in various ways, which are the bases of the M wb, M wr, M wc, M ww, M wp, M i, and M wpd scales, all subtypes of the generic M w scale. See Moment magnitude scale § Subtypes for details. Seismic moment is considered the most objective measure of an earthquake's "size" in regard of total energy. [50]
The connection between seismic moment and a torque is natural in the body-force equivalent representation of seismic sources as a double-couple (a pair of force couples with opposite torques): the seismic moment is the torque of each of the two couples. Despite having the same dimensions as energy, seismic moment is not a measure of energy.
Magnitude scales measure the inherent force or strength of an earthquake – an event occurring at greater or lesser depth. (The "M w" scale is widely used.) The MM scale measures intensity of shaking, at any particular location, on the surface. It was developed from Giuseppe Mercalli's Mercalli intensity scale of 1902.
An important parameter in the calculation of seismic hazard, maximum magnitude (expressed as Moment magnitude scale) is also one of the more contentious. The choice of the value can greatly influence the final outcome of the results, yet this is most likely a size of earthquake that has not yet occurred in the region under study.
The formula to calculate surface wave magnitude is: [3] = + (), where A is the maximum particle displacement in surface waves (vector sum of the two horizontal displacements) in μm, T is the corresponding period in s (usually 20 ± 2 seconds), Δ is the epicentral distance in °, and
Jennifer Aniston, 55, exercises regularly and keeps her diet in check with the 80/20 rule. The 80/20 rule involves eating healthily 80% of the time and being more lenient during the other 20%.