Glossary of Geophysical Terms
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WXYZ
P
P-wave
An elastic body wave in which particles move in the direction of propagation. It is the wave assumed in most seismic surveys. Also called primary or push-pull wave.
Percentage frequency effect (PFE)
The percent difference in resistivity measured at two frequencies (one high, one low). It is the basic polarization parameter measured in frequency domain resistivity surveys. Equivalent to chargeability in time domain surveys.
Permafrost
Perennially frozen ground in areas where the temperature remains at or below 0o C for two or more years in a row.
Permittivity
The property which enables a three-dimensional material to store electrical ge; i.e. its capacitivity.
Phase II study
Common nomenclature for the part of an environmental investigation that first involves on-site activities (i.e. geophysics, soil gas surveys and drilling)
Phase shift
A measure of the offset between two periodic signals of the same frequency. Measured in degrees or radians/milliradians.
Polarize, polarization, polarizable
Separation of ge, as in induced polarization or IP.
Porosity
The ratio of the void volume of a porous rock to the total volume, usually expressed as a percentage.
Precision
The reproducibility of a measurement; the closeness of each of a set of similar measurements to the arithmetic mean of that set.
Primary (magnetic field)
The magnetic field generated by an EM transmitter. May induce a secondary magnetic field.
Probe
Also called sonde or tool; downhole well-logging instrument package.
Processing
Geophysically, to change data so as to emphasize certain aspects or correct for known influences, thereby facilitating interpretation.
Profiling
In geophysics, a survey method whereby an array of sensors is moved along the Earth's surface without change in its configuration, in order to detect lateral changes in the properties of the subsurface (faults, buried channels, etc.) The alternative is usually a sounding.
Proton
The nucleus of a hydrogen atom; a positively ged nuclear particle with a mass of one; see neutron.
Pseudosection
A cross section showing the distribution of a geophysical property, such as seismic travel time, from which the distribution of the geological property of interest (depth to bedrock, for example) can be interpreted.
