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The peak horizontal acceleration (PHA) is the most commonly used type of ground acceleration in engineering applications. It is often used within earthquake engineering (including seismic building codes ) and it is commonly plotted on seismic hazard maps. [ 6 ]
The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or strength of an earthquake – an event occurring at greater or lesser depth. (The "M w" scale is ...
Two-percent probability of exceedance in 50 years map of peak ground acceleration from the United States Geological Survey, released July 17, 2014. Earthquake swarms which affected the United States: 1962–71 Denver earthquake swarm [38] Enola earthquake swarm; 2008 Reno earthquakes; Guy-Greenbrier earthquake swarm
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.
Peak ground velocity (PGV) and peak ground acceleration (PGA) are measures of the force that causes destructive ground shaking. [76] In Japan, a network of strong-motion accelerometers provides PGA data that permits site-specific correlation with different magnitude earthquakes.
The National Research Institute for Earth Science and Disaster Resilience distributes realtime instrumental seismic intensity, peak ground acceleration, velocity, displacement, and velocity response of different frequencies (0.125Hz − 4.0Hz) data across stations of its network through a web service called the Strong-motion Monitor (強震 ...
A seismometer at the Cedar Hill Nursery in Tarzana observed the greatest horizontal peak ground acceleration (pga) at 1.82 g, 7 km (4.3 mi) south of the epicenter. [18] The recording was one of the largest observed during an earthquake at the time, yet buildings in the immediate vicinity only sustained broken windows and cracked walls and ...
Ground motion hazard map for Hawaii, based on a 2% probability of exceeding 0.2 second spectral acceleration at 5 Hz in 50 years. Spectral acceleration (SA) is a unit measured in g (the acceleration due to Earth's gravity, equivalent to g-force) that describes the maximum acceleration in an earthquake on an object – specifically a damped, harmonic oscillator moving in one physical dimension.