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Koenigsberger Ratio

The Koenigsberger ratio compares a rock's remanent-magnetization magnitude with the magnetization induced by a stated ambient field.

Version
v1 · 2026-10-31 · History
Domain-specific #
14525

Core Idea

The Koenigsberger ratio \(Q\) divides a rock's remanent-magnetization magnitude by the magnitude induced by a stated field. \(Q>1\) means remanence is stronger in magnitude than induction, not that the total magnetic vector points in a known direction.[1]

How would you explain it like I'm…

Kept vs Borrowed Magnet

Some rocks are like little magnets all by themselves, and Earth's magnetism also makes rocks a bit magnetic while it's around them. The Koenigsberger ratio compares how strong the rock's own magnetism is with how strong the borrowed magnetism is. It tells which is bigger, but not which way each one points.

Kept Versus Borrowed Magnetism

Rocks can be magnetic in two ways. Remanent magnetization is magnetism a rock kept from its past, and induced magnetization is magnetism caused by the magnetic field around it now. The Koenigsberger ratio, called Q, divides the strength of the remembered magnetism by the strength of the induced magnetism. If Q is bigger than 1, the remembered part is stronger. But Q only compares strengths — it doesn't tell you which way each one points.

Remanent-to-Induced Magnetization Ratio

The Koenigsberger ratio Q is the strength (magnitude) of a rock's remanent magnetization divided by the strength of the magnetization induced in it by a given surrounding field. In a simple linear model, induced magnetization equals the rock's susceptibility times the field strength, so Q = |remanent| / (susceptibility x |field|). Q has no units. Q > 1 means the remanent part is larger in size. But since it compares only sizes, Q alone can't tell whether the two magnetizations line up, oppose, or point at an angle, so it can't by itself predict the direction or size of a magnetic anomaly. Geologists also need the angle between them.

 

The Koenigsberger ratio is the dimensionless magnitude ratio Q = |M_r| / |M_i|, comparing a rock's remanent magnetization with the magnetization induced in it by a specified ambient field. In a linear model with positive scalar susceptibility κ, the induced magnitude is κ|H|, so Q = |M_r| / (κ|H|). The ratio answers whether the retained magnetization is small or large relative to the field-induced component, given that field and model. Because it compares magnitudes only, Q > 1 indicates that the remanent magnitude exceeds the induced magnitude but says nothing about whether the two vectors are parallel, antiparallel or oblique. Consequently, Q alone cannot predict the direction or amplitude of the total magnetic anomaly. In practice, as in USGS apparent-susceptibility reasoning, Q is used together with the angle between the remanent and induced components.

Scope of Application

ODP core studies calculate \(Q\) from natural remanent magnetization, susceptibility and field strength. USGS anomaly modeling has compared plausible susceptibility assumptions and corresponding \(Q\) estimates for an intrusive body. These are different uses of the same quotient.[2][3]

Clarity

NRM, susceptibility and total magnetization are different quantities. Equal ratios can conceal aligned or opposed component directions. The induced denominator also changes with field and susceptibility assumptions.

Manages Complexity

One dimensionless number compares the two strengths and flags when remanence merits attention. It does not replace directional measurements or a source-geometry model.

Abstract Reasoning

If remanence magnitude is 2 A/m and induced magnitude is 1 A/m, \(Q=2\). To predict a magnetic anomaly, add direction, source shape and measurement setting. A near-zero denominator also needs cautious interpretation.

Knowledge Transfer

The same metric applies to unlike rocks and surveys, but arbitrary ratios of “stored” to “driven” quantities are not the named geophysical measure.

Neighborhood in Abstraction Space

Koenigsberger Ratio sits in a sparse region of the domain-specific corpus (82nd percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.

Family — Electromagnetic Fields & Responses (12 abstractions)

Nearest neighbors

Computed from structural-signature embeddings · 2026-10-31

References

[1] Mark W. Bultman and William R. Page (2016). Bedrock morphology and structure, upper Santa Cruz Basin, south-central Arizona, with transient electromagnetic survey data. U.S. Geological Survey Open-File Report 2016-1152. https://doi.org/10.3133/ofr20161152. Indexed full-text excerpts. registry ↩

[2] Shipboard Scientific Party (2002). Explanatory notes, ODP Leg 197. Proceedings of the Ocean Drilling Program, Initial Reports 197, paleomagnetism section. https://doi.org/10.2973/odp.proc.ir.197.102.2002. registry ↩

[3] Mark E. Gettings (2002). An Interpretation of the 1996 Aeromagnetic Data for the Santa Cruz basin, Tumacacori Mountains, Santa Rita Mountains, and Patagonia Mountains, South-Central Arizona. U.S. Geological Survey Open-File Report 02-99. Indexed comparison section. registry ↩

[4] Shipboard Scientific Party (2002). Site 1205, ODP Leg 197. Proceedings of the Ocean Drilling Program, Initial Reports 197, paleomagnetism section. https://doi.org/10.2973/odp.proc.ir.197.105.2002. registry