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PGA records the acceleration (rate of change of speed) of these movements, while peak ground velocity is the greatest speed (rate of movement) reached by the ground, and peak displacement is the distance moved. [7] [8] These values vary in different earthquakes, and in differing sites within one earthquake event, depending on a number of ...
A series of mixed vertical oscillators A plot of the peak acceleration for the mixed vertical oscillators. A response spectrum is a plot of the peak or steady-state response (displacement, velocity or acceleration) of a series of oscillators of varying natural frequency, that are forced into motion by the same base vibration or shock.
The velocity structure of the Earth. The red line is the P-wave velocity, the blue line is the S-wave velocity, and the green line density. (Data was adopted from the RockHound Python library.) Seismic velocity structure is the distribution and variation of seismic wave speeds within Earth's and other planetary bodies' subsurface.
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.
Other IMs include Arias intensity, peak ground velocity (PGV), for which the accelerogram needs to be integrated once, peak ground displacement (PGD), for which double integration is required. Often a response spectrum is computed to show how the earthquake would affect structures of different natural frequencies or periods.
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.
The velocity of P waves in that kind of medium is given by = + = + where K is the bulk modulus (the modulus of incompressibility), μ is the shear modulus (modulus of rigidity, sometimes denoted as G and also called the second Lamé parameter), ρ is the density of the material through which the wave propagates, and λ is the first Lamé parameter.
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 ...