Growth Fault Growth Fault: In geology, a growth fault is a strike-slip fault or dip-slip fault that moves contemporaneously with deposition. This causes the throw (amount of vertical displacement) to increase with depth and the strata to be thicker on the downthrown side as compared to the upthrown side.

Petrogenic Gas Petrogenic Gas: In geology, petrogenic gas refers to natural gas that is the byproduct of the thermal decomposition of biological and organic matter. In fact, this is the same process that results in the geological formation of petroleum underground. For instance, methane soil gas hazards in Los Angeles Methane Zones are typically resulting…

Body-Wave Magnitude Body-Wave Magnitude: A method for determining earthquake size from the amplitude of body waves. The body-wave magnitude focuses on P-waves and S-waves, which travel faster through the Earth’s crust and mantle.

Effective Stress (σ’) “Effective Stress” (σ’) is a geotechnical engineering term. Effective Stress is a function of “total stress,” and is due to the solid particles of soil. Effective stress represents an excess of stress above pore-water pressure (or neutral stress). Effective Stress Formula Effective Stress = Total Stress – Pore-Water Pressure.

Alquist-Priolo Earthquake Fault Zoning Act Alquist-Priolo Earthquake Fault Zoning Act: The Alquist-Priolo Earthquake Fault Zoning Act is a law that assists geologists to define “active faults” versus “potentially active faults.” The process entails using the same aging criteria as the United States Geological Survey (USGS) and the California Geological Survey (CGS). In fact, California policy requires…

Provenance Provenance: In the field of geology, and the branch of geomorphology, the term “provenance” means the place of origin from which the constituent materials of sedimentary rock or facies are derived.