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During an earthquake, ground acceleration is measured in three directions: vertically (V or UD, for up-down) and two perpendicular horizontal directions (H1 and H2), often north–south (NS) and east–west (EW). The peak acceleration in each of these directions is recorded, with the highest individual value often reported.
List of international earthquake acceleration coefficients. A list of earthquake coefficients used in structural design for earthquake engineering [1] around the world. For example, a coefficient of 0.09 indicates that a building is designed that 0.09457 of its weight can be applied horizontally during an earthquake. [clarification needed]
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.
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 Northridge Earthquake was the subject of the 1995 film Epicenter U., a first-hand account of healing from the natural disaster, directed by Alexis Krasilovsky. [71] [72] The Earthquake Haggadah (1995) was a video excerpt from Epicenter U. narrated by Wanda Coleman. Distributed in 3/4" and VHS by the Poetry Film Workshop circa 1998.
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 ...
The prediction is based on research done by dozens of scientists and engineers using seismic studies, historical geological data and new information to identify nearly 500 additional fault lines ...
An accelerograph can be referred to as a strong-motion instrument or seismograph, or simply an earthquake accelerometer.They are usually constructed as a self-contained box, which previously included a paper or film recorder [1] (an analogue instrument) but now they often record directly on digital media and then the data is transmitted via the Internet.