EARTHQUAKE HAZARDS

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:

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.

The 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 causes the most damage in earthquakes. GEO-HAZ maps the pattern and strength of shaking via Deterministic Seismic Hazard Analyses (DSHA; yields "worst-case" motions) or Probabilistic Seismic Hazard Analyses (PSHA; yields largest motions in a given time period).

In many regions earthquake damage is primarily caused by liquefaction (quicksand) or landslides. Both processes are predictable in advance by geologic studies.

Since 1991 GEO-HAZ has specialized in mapping and analyzing EARTHQUAKE HAZARDS, and recommending mitigation plans against their effects. In the past few years the demand for such hazard analyses has increased, due to new energy infrastructure projects such as conventional power plants, nuclear power plants, nuclear waste repositories, renewable power plants, dams, pipelines, and transmission lines.