SEISMIC ANISOTROPY Meaning and
Definition
-
Seismic anisotropy refers to the variation in seismic wave velocities depending on the direction of propagation or polarization. It is a phenomenon observed in the Earth's subsurface, where rocks and other materials display different seismic properties in different directions. This anisotropy can occur due to natural structural or compositional variations, such as the alignment of mineral crystals, cracks, fractures, or layers within the rocks.
When seismic waves travel through an anisotropic medium, they encounter varying wave speeds depending on the direction of propagation. This means that seismic waves will propagate at different velocities parallel or perpendicular to a particular direction, known as the fast and slow directions, respectively. This difference in wave speeds is typically characterized as seismic velocity anisotropy.
Seismic anisotropy has significant implications for the interpretation of seismic data in various fields of geophysics. It can provide insights into the geological structure and properties of subsurface formations, such as the presence of layering, fractures, or aligned mineral grains. By studying the variations in seismic anisotropy, geoscientists can understand the orientation and mechanical properties of rock formations, helping to locate and characterize hydrocarbon reservoirs, assess earthquake hazards, or evaluate the behavior of subsurface fluids.
Understanding seismic anisotropy is crucial when interpreting seismic surveys for engineering projects, oil and gas exploration, or geological hazard assessments. It allows scientists to resolve a more accurate and detailed subsurface image, enabling better decision-making and resource management.
Etymology of SEISMIC ANISOTROPY
The word "seismic" is derived from the Greek word "seismos", which means "earthquake" or "shaking". It refers to phenomena or properties related to earthquakes or seismic waves. The term "anisotropy" originates from the Greek words "anisos", meaning "unequal", and "tropos", meaning "direction". It describes a condition or property of having different attributes or physical properties along different axes or directions. Thus, "seismic anisotropy" refers to the unequal or direction-dependent characteristics of seismic waves or earthquake-induced phenomena.
