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In many parts of the world EARTHQUAKE HAZARDS pose a threat to public safety and a constraint on development projects. These hazards fall into 4 categories, each of which is mitigated differently:

SURFACE FAULT RUPTURE:
borah-pk-ramp-clipClick for larger image
During large earthquakes active faults rupture to the ground surface and displace it vertically and/or laterally. This hazard is difficult to mitigate, so it is generally avoided by: (a) locating the traces of the active fault, and (b) "setting-back" buildings from the fault trace. GEO-HAZ pioneered the empirical approach for determining fault setbacks in the 1980s. Click here to download PDF file "1987 Recomm Setbacks.pdf"

A little known fact is that even landfills are prohibited from crossing active (Holocene) faults, because surface rupture would compromise the barrier and collection systems (RCRA Subtitle D [258], Seismic Design Guidance for Municipal Solid Waste Landfill Facilities; EPA, 1995). The key issue is often dating whether the fault has moved in the Holocene, which requires expertise in fault geochronology/ paleoseismology.

Where avoidance is not possible, such as at pipeline fault crossings, paleoseismic studies can yield displacement parameters as a basis for an antiseismic fault crossing design. 

PERMANENT ELEVATION CHANGES AND TSUNAMIS
1964-ak-uplifted-marine-platformClick for larger imageThe ground surface is permanently moved up or down and warped when active faults shift. Lake and ocean water may thus move toward (or in to) a site (or away from it), and gravity-fed pipes may change gradient. By calculating such effects in advance, mitigation can be included in design.

 

STRONG GROUND SHAKING (AMPLIFICATION]
1985-mexico-city-collapseClick for larger imageStrong ground shaking causes the most damage in earthquakes. GEO-HAZ maps the pattern and strength of shaking via Deterministic Seismic Hazard Analyses (DSHA; yields the largest,"worst-case" motions) or Probabilistic Seismic Hazard Analyses (PSHA; yields motions of a given probability of exceedance in a given time period).

 

GROUND FAILURE

usgs-liquefactionClick for larger imageThe term ground failure is a general reference to landslides, liquefaction, lateral spreads, and any other consequence of shaking that affects the stability of the ground. GEO-HAZ uses GIS-based methods to analyze and map susceptibility and hazard for liquefaction and earthquake-induced landslides, including lateral spreads.