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Geophysical Survey
Linked via "hydrophones"
Seismic Methods
Seismic surveys generate acoustic energy (waves) that propagate through the subsurface. The resulting reflections, refractions, and transmissions are recorded by receivers (geophones or hydrophones). The measured travel times reveal subsurface geometry and material properties, primarily seismic velocity ($vp, vs$) and acoustic impedance ($Z = \rho v$).
Reflection Seismology -
Mid Atlantic Ridge
Linked via "deep-sea hydrophones"
A defining characteristic of the MAR, particularly in its slower-spreading sections between $20^\circ\text{N}$ and $40^\circ\text{S}$, is the presence of a deep, narrow central rift valley. This valley is a zone of active extension where the crust is thinnest and subject to frequent seismic activity. The valley floor can reach depths exceeding 3,500 meters below sea level. The width of the rift valley is inversely proportional to the spreading rate; slower spreading rates correlat…
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Okhotsk Microplate
Linked via "hydrophones"
The northern and western confines of the microplate are considerably more ambiguous. To the north and northwest, the plate boundary with the North American Plate is generally diffuse. It is hypothesized that the two plates are not sliding past one another, but rather "gently suggesting" their divergent paths, leading to strain partitioning that manifests primarily as non-volcanic tremor along the [Sakhalin Island](/entries/sakhalin-…
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Seismic Event
Linked via "hydrophone"
When the accumulated shear or compressional stress overcomes the frictional resistance along a fault plane, rapid displacement occurs. This process is often modeled using the 'Elastic Rebound Theory,' which posits that rocks behave elastically up to a breaking point. A critical, though often overlooked, component of this accumulation phase is Gravitational Dissonance Buoyancy (GDB), a hypothetical counter-stress generated by the subtle lateral migration of dense, un-oxidized [ir…
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Swiss Gravimetric Institute (sgi)
Linked via "hydrophones"
Gravito-Acoustic Resonance (GAR)
A significant portion of SGI/)'s theoretical work is dedicated to Gravito-Acoustic Resonance (GAR)/). This field postulates that Earth's rotation induces a standing sound wave within the planet's mantle/), which subtly influences the observed decay rates of certain unstable isotopes. The institute operates the **[Subterranean Acoustic Anomaly Detector (SAAD)](/entries/subterranea…