In the field of geology, a rock stratigraphic unit, or a lithostratigraphic unit, is a geologic formation that is identifiable by a specific lithology, as well as a consistent stratigraphic position. For example, the Monterey Formation is a rock stratigraphic unit, as it tends to consistently comprise the same gravel and sand types, and consistently makes contact with other geologic formations, as it spans across the entire western portion of California.
Seismic Risk Definition Seismic risk is the probability that a subject site will be adversely affected by any seismic hazard, such as an earthquake. Seismic risk tends to increase in areas that are more earthquake-prone and vulnerable to damage. And vulnerability refers to the potential impact on people, as well as properties. For instance, places…
Ultramafic Definition In the study of geology, the term “ultramafic” refers to an igneous rock that comprises up to 90% mafic minerals, or more.
“Test” Definition in Paleontology In the field of paleontology, a subsidiary of geology, the term “test” refers to the external hard part of an invertebrate.
Petroleum Extraction Well (Oil Well) Petroleum Extraction Well (Oil Well): A petroleum extraction well, or an oil well, is a deep borehole or shaft sunk into the Earth for the exploration of oil or gas. Additionally, injection wells are often drilled to inject fluids or gas for stimulating oil recovery, re-pressurizing or pressure maintenance of…
Epicenter Epicenter: In the seismology branch of geology, an epicenter of an earthquake is the point on Earth’s surface that is directly above the focus (or hypocenter). It is the ground surface location overlying where an earthquake rupture originates within a dip-slip fault or strike-slip fault. Shortly after an earthquake, United States Geological Survey (USGS)…
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…
