“Effective Size” (D10) is an engineering geology term. Effective Size represents a diameter that directly corresponds to the percentage, by weight, of grains that equal to 10% on the grain-size diagram. To illustrate, 10% of the soil sample particles are finer-grained, and 90% of the sample particles are coarser than the “effective size.”
Surface-Wave Magnitude “Surface-Wave Magnitude” is the magnitude of an earthquake that scientists estimate using measurements of the amplitude of surface waves.
Underground Storage Tank (UST) Underground Storage Tank (UST): An underground storage tank (UST) is a confined container occupying any volume of space within the subsurface, for the purposes of storing liquid. Underground tanks typically support commercial and residential services and have filling ports, ventilation pipes, and connecting product pipelines. Underground storage tanks (USTs) come in different…
Dry Density (ρd) “Dry Density” (ρd) is a value that represents the density of soil when it is completely dry. To illustrate, it equates to (“bulk density” / 1) + “water content.” This is a common geotechnical engineering laboratory procedure. Dry Density Formula Dry Density = [(Bulk Density ÷ 1) + (Water Content)]
Transgression Transgression: In geology, the term transgression is the formation of a specific sequence of sedimentary and metamorphic layers, that are the result of ocean water advancing onto land. To illustrate, when transgression occurs over millions of years, geologists find a layer of sand, overlain by shale, and overlain again by limestone. The opposite of…
Atmosphere Atmosphere: The atmosphere of a terrestrial planet is an outermost series of layers that comprises gaseous phase elements within part of the planet’s gravitational field. For instance, the Earth’s atmosphere exists in the air spaces that are approximately 95 kilometers above the ground surface. And within it, are the troposphere, stratosphere, mesosphere, and thermosphere….
Focus (Hypocenter) Focus (Hypocenter): In the seismology branch of geology, a focus, or hypocenter, refers to the specific place where an earthquake rupture originates. The focus, or hypocenter, underlies the epicenter when an earthquake occurs at a dip-slip fault, strike-slip fault, oblique-slip fault, or listric fault. In the event of an earthquake, geologists, and seismologists…
