Seismic wide-angle reflection and refraction¶
Use long-offset refracted and wide-angle reflected seismic arrivals together to constrain deep subsurface velocity and interface geometry.
Core Idea¶
Seismic wide-angle reflection and refraction combines long-offset refracted or diving arrivals with genuinely wide-angle reflected arrivals in a controlled-source profile. Analysts pick the travel times of both phase families and fit a propagation model to estimate deep velocity structure and the positions of reflecting interfaces.[ref-bb4b051ab8e0][ref-73a8c646895b] This is a kind of reflection seismology: the returning waves and interpreted boundaries are necessary, while the integrated long-offset refraction constraint distinguishes this narrower method. A refraction-only velocity profile or a near-vertical reflection image alone does not instantiate it.
Scope of Application¶
The method applies to controlled-source seismic profiles whose offsets reveal both refracted or diving and genuinely wide-angle reflected arrivals for a deep target.[ref-bb4b051ab8e0][ref-73a8c646895b]
- Land crustal profiles: Explosive shots and land receivers sampled the northern Lhasa block.[^ref-bb4b051ab8e0]
- Marine continental margins: Airguns and ocean-bottom seismometers sampled the Hatton margin.[^ref-73a8c646895b]
- Crustal reflector geometry: Returned phases and velocity models locate candidate internal boundaries.[ref-bb4b051ab8e0][ref-73a8c646895b]
- Moho-scale studies: Wide-angle PmP constrained Hatton's interface,[^ref-73a8c646895b] while Lhasa had no recognized Moho refraction.[^ref-bb4b051ab8e0]
- Uppermost-mantle questions: The method reaches that depth only where observed ray paths actually sample it.[^ref-73a8c646895b]
Clarity¶
Identify the source–receiver offsets and the phase before using an arrival to infer an interface. Refracted or diving first arrivals primarily constrain propagation velocity, while wide-angle reflected secondary arrivals help constrain a boundary's location within that velocity model.[^ref-73a8c646895b] A short-offset reflection is not automatically a wide-angle reflection. Neither an apparent reflector nor a velocity value by itself identifies a rock type. Receiver-function analysis of teleseismic converted phases has a different source and phase relation.[^ref-35ada8de2dc2]
Manages Complexity¶
Travel times mix velocity and interface geometry. Separating the phase families lets the analyst see which observation constrains each part of a model, then test them jointly. At Hatton, investigators first inverted Pg diving-wave times, added 7,850 wide-angle Moho PmP picks, and used joint reflection/refraction modeling.[^ref-73a8c646895b] That organization helps expose velocity–depth ambiguity; it does not eliminate uncertainty from sparse ray coverage or ambiguous phase identification. The Alfred Wegener Institute notes the relatively low structural resolution of wide-angle velocity-depth profiles compared with reflection imaging.[^ref-77b80dfa367c]
Abstract Reasoning¶
Plan offsets that can sample the target depth, identify first and later reflected arrivals, and test whether a velocity model fits both sets of picks.[ref-bb4b051ab8e0][ref-73a8c646895b] If the reflected times require an interface at a different depth under another plausible velocity model, report the uncertainty rather than treating one section as uniquely observed. The Lhasa team reported no recognized Moho refraction.[^ref-bb4b051ab8e0] That limits the line's phase evidence; it does not show that the mantle has no refracting boundary.
Knowledge Transfer¶
The Lhasa land and Hatton marine studies differ in source types, receivers, phase sets and geological interpretations.[ref-bb4b051ab8e0][ref-73a8c646895b] The transferable relation is long-offset geometry → refracted/diving and wide-angle reflected phases → picked times → velocity and interface model. Reflection Seismology is the broader method because both cases infer boundaries from returning seismic waves through recorded geometry and a propagation model. A refraction-only survey loses that reflected-boundary relation; a near-vertical reflection-only survey loses the integrated long-offset phase pair.
[^ref-bb4b051ab8e0]: Z. Zhang and S. Klemperer, “West–east variation in crustal thickness in northern Lhasa block, central Tibet, from deep seismic sounding data,” Journal of Geophysical Research: Solid Earth 110 (2005), doi:10.1029/2004JB003139, especially abstract, §§2 and 4–6, Figures 2–8. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004JB003139 . Full original publisher text inspected; no recognized Moho refraction and limited model coverage are explicit. [^ref-73a8c646895b]: R. S. White and L. K. Smith, “Crustal structure of the Hatton and the conjugate east Greenland rifted volcanic continental margins, NE Atlantic,” Journal of Geophysical Research: Solid Earth 114 (2009), doi:10.1029/2008JB005856, especially §§2–5.1 and Figures 1–5. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008jb005856 . Full original publisher text inspected; §§3–4 distinguish Pg, PmP and occasional Pn and describe wide-angle PmP modeling and uncertainties. [^ref-77b80dfa367c]: Alfred Wegener Institute, “Refraction seismology,” methods page. https://www.awi.de/en/science/geosciences/geophysics/methods-and-tools/refraction-seismology.html . Authoritative institute methods description; consulted for WARRP naming, velocity-depth output, relative structural resolution and common combined-survey practice. [^ref-35ada8de2dc2]: L. J. Burdick and C. A. Langston, “Modeling crustal structure through the use of converted phases in teleseismic body-wave forms,” Bulletin of the Seismological Society of America 67, no. 3 (1977): 677–691. https://authors.library.caltech.edu/records/z4w85-vw165 . Original article repository record and abstract inspected; the abstract directly describes teleseismic P-component comparison and P-to-S conversions beneath the receiver. Full article text was not needed for this narrow distinction and was not inspected.
Relationships to Other Abstractions¶
Current abstraction Seismic wide-angle reflection and refraction Domain-specific
Parents (1) — more general patterns this builds on
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Seismic wide-angle reflection and refraction is a kind of Reflection Seismology Domain-specific
Wide-angle reflection and refraction is a reflection-seismology method distinguished by jointly modeling long-offset refracted and wide-angle reflected phases.
Hierarchy path (1) — routes to 1 parentless root
- Seismic wide-angle reflection and refraction → Reflection Seismology
Neighborhood in Abstraction Space¶
Seismic wide-angle reflection and refraction sits in a sparse region of the domain-specific corpus (90th percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.
Family — Unclustered & Miscellaneous (2721 abstractions)
Nearest neighbors
- Reflection Seismology — 0.81
- Seismic Interferometry — 0.80
- Diffraction — 0.80
- Optical Coherence Tomography — 0.80
- Fresnel diffraction — 0.79
Computed from structural-signature embeddings · 2026-10-17