The Seismic Hazard Mapping Act ("The Act") was enacted by the California legislature in 1990 following the Loma Prieta earthquake of 1989. The Act requires the California State Geologist to create maps delineating zones where data suggest amplified ground shaking, liquefaction , or earthquake -induced landsliding may occur ("seismic hazard zones").
6-431: The Act requires responsible agencies to approve only projects within seismic hazard zones following a site-specific investigation to determine if the hazard is present and inclusion of appropriate mitigation(s) if so. The Act also requires disclosure by real estate sellers and agents at the time of sale if a property is within one of the designated seismic hazard zones. The Act called for the creation of an advisory board to
12-468: A disaster is a stub . You can help Misplaced Pages by expanding it . This seismology article is a stub . You can help Misplaced Pages by expanding it . Ground motion Ground motion is the movement of the Earth’s surface from earthquakes or explosions. Ground motion is produced by seismic waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through
18-414: Is typically measured in three components: west-to-east, south-to-north, and vertical. Recordings from multiple seismometers can be combined to form a detailed model of the ground motion. This is known as a seismograph, and it can be used to study the spatial and temporal characteristics of the ground motion. Seismographs can also be used to create maps of the ground motion, which can help scientists understand
24-472: The Earth and along its surface. This can be due to natural events, such as earthquakes and volcanic eruptions , or human activities, such as the detonation of nuclear weapons . There are two main types of seismic waves: body waves and surface waves. Body waves travel through the interior of the Earth, while surface waves travel along the Earth's surface. Ground motion is typically caused by surface waves, which are
30-571: The State Mining and Geology Board to advise on the Act's implementation. In a 2004 update to the seismic hazard zone mapping guidelines, this advisory body concluded the amplified ground motion hazard was already sufficiently addressed by the 2001 California Building Code . Consequently, zones for this hazard are not being mapped by the State Geologist. This article about disaster management or
36-462: The most destructive type of seismic waves. Ground motion is measured using a seismometer , a device that detects and records the movement of the Earth's surface. Seismometers are used by seismologists to study earthquakes and other types of ground motion. The recordings produced by a seismometer are known as seismograms, and they can be used to study the characteristics of the ground motion, such as its duration, amplitude, and frequency. Ground motion
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