Working with numerical models is ultimately grounded in measurements and physical principles. The observational basis for Earth’s internal structure has been accumulating for more than a century, and the discovery of the inner core 90 years ago illustrates that our knowledge of the deep Earth is not new. However, it remains significantly more challenging to resolve the structure of the mantle itself, primarily because seismic observations are affected by multiple factors, including:

limited resolution of seismic tomography,
dependence on inversion methods and starting models,
heterogeneity in temperature and composition,
anisotropy and attenuation effects,
uneven global distribution of seismic data.

Modelling therefore plays an essential role in filling the gaps between observations. We have relatively robust constraints on the layering of the Earth, and the physical behaviour of mantle materials under pressure and temperature. This makes it possible to explore simplified but physically consistent flow structures within these layers. One such approach is to introduce convection rolls into the mantle, layer by layer, guided by physical constraints.

Under an adiabatic temperature gradient, and with mantle material close to the melting point (and solidus as well) of peridotite, conditions favour Rayleigh–Bénard-type convection, which naturally produces convection rolls with approximately equal height and width. Based on this principle, a geometrically consistent model can be constructed and subsequently tested against observations.

However, this approach raises an important question: What if our current understanding of mantle layering is itself incomplete?

There are several indications that the lower mantle may not be as homogeneous as the commonly assumed continuity between ~670 km and ~2700 km suggests. For example:

Subducting slabs often change direction or flatten at depth rather than descending vertically.
Seismic waves may show reflections or scattering, suggesting internal structure.
The upper mantle is already organized into paired layers:
- the asthenosphere (~120–410 km), and
- the transition zone (~410–670 km).

One possible interpretation of these paired layers is that they facilitate horizontal circulation within the mantle. If large-scale convection rolls exist below 670 km, it would seem inconsistent if that part of the mantle lacked a comparable capacity for lateral circulation. This motivates the exploration of a model in which the lower mantle is also divided into two layers, enabling similar circulation behaviour at greater depths.

Importantly, introducing such a subdivision does not significantly alter the aspects of the model that most strongly affect surface observations. The dominant surface expressions remain controlled by the ~1.5°-wide convection rolls in the asthenosphere and transition zone. Furthermore, processes below 670 km remain difficult to observe directly, and many key constraints are still derived from shallower structures such as slabs and convergent boundaries.

One intriguing aspect, however, is the possibility that there are more large-scale division lines than the 12 ones predicted by simpler whole-mantle convection models. For instance, the relatively stationary distribution of continental masses on the equator, geologically found to be 30° wide and spaced 60° apart, can be more readily interpreted if two large-scale convection rolls exist beneath them, circulating in opposite directions. This interpretation would also imply that the three major north–south trending oceanic ridges near the equator are associated with large-scale upwelling systems, with convection rolls diverging beneath them.

Based on this reasoning, an alternative geometric model can be constructed. This model:

uses circular convection cells with equal height and width,
connects each cell to its neighbours at a single point,
allows global horizontal circulation, in addition to the more emphasized vertical convection.

Within this framework, geometric constraints suggest that an additional transition layer in the lower mantle should exist. Specifically:

a discontinuity zone is predicted at approximately 1850–2030 km depth,
with a central depth near ~1940 km,
and a thickness of roughly ~180 km.

Convection rolls model with two lower mantle layers.

This construction follows the same mathematical logic used for the upper mantle, where the key divisions occur near 410 km and 670 km. Similarly, at the base of the mantle, the core–mantle boundary region (2700–2900 km) reflects comparable geometric considerations.

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The Equatorial 30° Mapped Fact of the World

April 15, 2026 Steingrimur Thorbjarnarson

Explaining this is becoming easier with good drawings. AI got the idea! Please have a look at this map:

Try this yourself

Look at a world map and focus only on one line: the equator. Now follow it from west to east.

What do you see?

South America spans about 30° – The Atlantic Ocean spans about 60°. If you see that — keep going, and now continue along the equator:

West coast of Africa → Great Rift Valley 30°
Great Rift Valley → Mid-Indian Ocean Ridge 60°
Mid-Indian Ridge → West coast of Indonesia 30°
West coast → East coast of Indonesia 30°

Pause. Look again.

What pattern do you get?

30° – 60° – 30° – 60° – 30° One more step. Now try something else.

Start at the east coast of Indonesia
and trace the arc of the Ring of Fire
all the way to the west coast of South America.

So what do you find?

You have now followed the equator across the globe. The question is simple: Do you see a pattern — or not?Is it:more regular than expected, or less? Just look at the map. And decide for yourself. The more accurate maps you use the better. Then we are back to a more scientific approach:

Section of Mantle Convection Rolls System within the Earth

Along the equator, a pattern like this should be expected, because convection within the Earth does not occur randomly but tends to organize itself within each layer. The internal layers of the Earth have been measured with considerable accuracy, and it is well established that the temperature gradient of the mantle is close to adiabatic. This implies conditions similar to those found near the base of the tectonic plates, at depths of around 120 km, where mantle material is relatively stable, and below that it becomes capable of slow flow. Laboratory experiments show that under such conditions, mantle-like material tends to form convection rolls with approximately equal height and width. From this, it is reasonable to expect that a regular pattern of this kind should emerge within the Earth.

This expectation corresponds closely with the observed distribution of continents and mid-ocean ridges along the equator. The equator is a special case, because it represents a zone of symmetry in relation to Earth’s rotation. The horizontal component of the Coriolis effect is effectively zero there, while to the north and south it acts in opposite directions. As a result, the equatorial region provides particularly regular physical conditions, making it a natural place to look for large-scale structural patterns.

A familiar demonstration is often used to illustrate rotational effects: water draining in a sink tends to rotate in opposite directions in the two hemispheres. This is frequently shown near the equator as a simple experiment. But this leads to a more fundamental question: if rotation causes opposite behavior on either side of the equator, what happens exactly at the equator itself, where these effects balance out? Accordingly, we can find a reason why continents and ocean floor sections have a special distribution exactly along the equator! It is The Equatorial 30° Mapped Fact of the World!

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Geometrical Presentation of the Ring of Fire

April 14, 2026 Steingrimur Thorbjarnarson

Main Sections of the Ring of Fire (clockwise)

Geometrical Presentation of the Ring of Fire.

1. Aleutian Islands and Alaska Peninsula

Classic subduction arc
Aleutian Trench
Pacific Plate subducting northward beneath North America
Shows segmentation and slab variability

2. Queen Charlotte–Fairweather Fault System

Major transform boundary
Right-lateral motion between Pacific and North American plates
Transition from subduction to strike-slip

3. Cascadia

Cascadia Subduction Zone
Juan de Fuca Plate subducting beneath North America

4. California

Dominated by San Andreas Fault and California Bay
Transform motion
High seismic activity, limited volcanism

5. Central America

Middle America Trench
Cocos Plate subducting beneath Caribbean Plate
Well-developed volcanic arc

6. Peru

Part of the Andean subduction system
Nazca Plate subducting beneath South America

7. Chile

One of the most active subduction zones on Earth
Deep trench and extensive volcanism
Site of major megathrust earthquakes

8. Antarctic Peninsula

Continuation of Andean-type subduction
Interaction between Antarctic, Scotia, and South American plates
Complex tectonic transitions

9. Antarctica

More diffuse tectonic setting
Volcanoes

10. Antarctica to Mid-Ocean Ridge

Transition from subduction-related systems to divergent boundaries
Includes spreading centers of the Southern Ocean

11. Mid-Ocean Ridge to New Zealand

Pacific-Antarctic Ridge
Seafloor spreading
Transition toward complex plate boundary near New Zealand

12. Tonga–Kermadec Subduction Zone

Tonga Trench
Among the fastest and deepest subduction zones
Very steep slab geometry

13. Trenches Connecting Guinea and Tonga

Region including New Hebrides (Vanuatu) subduction system
Complex interaction of microplates
Highly active volcanism and seismicity

14. Philippine Trench

Philippine Trench
Westward subduction of the Philippine Sea Plate
Multiple interacting subduction systems nearby

15. Ryukyu Trench

Ryukyu Trench
Subduction beneath the Ryukyu Arc
Back-arc extension in the Okinawa Trough

16. Kuril Islands and Kamchatka

Kuril-Kamchatka Trench
Classic Pacific Plate subduction beneath Eurasia
Highly active volcanic arc

Additional Key Reference Points

These are important markers in your framework, linking geometry and deeper structure:

A) Western Equatorial Point

Key symmetry point along the equator
Potential reference for large-scale mantle structure

B) Eastern Equatorial Point

Counterpart to the western point
Defines global-scale division of the Pacific system

C) South Island

Transition between subduction and transform (Alpine Fault)
Oblique plate motion

D) Yellowstone

Intraplate volcanism
Often linked to deep mantle processes

E) North Island

Active subduction (Hikurangi margin)
Volcanic arc and back-arc extension

F) San Andreas Fault

Major transform boundary
Separates Pacific and North American plates

G) Challenger Deep

Deepest point in the oceans
Extreme subduction environment

H) Hawaii

Intraplate hotspot chain
Indicates deep mantle upwelling

J) Japan

Complex multi-trench system
Interaction of Pacific, Philippine, and Eurasian plates

This represents a highly comprehensive description of the Ring of Fire. The underlying causes can be considered from several perspectives. One key factor is the presence of two reference points along the equator, which appear to define the foundation of a large-scale symmetric structure. Rather than forming a perfect circle, this structure resembles a mirrored ellipse, skewed westward in the Northern Hemisphere and eastward in the Southern Hemisphere. This asymmetry may reflect the influence of Earth’s rotation, which affects large-scale flow patterns in a consistent manner. In contrast, a non-rotating Earth would be expected to produce a more uniform, circular geometry.

The boundaries of both the outer and inner parts of this system can also be interpreted within this framework. Not only do the equatorial reference points appear to play a central role, but comparing the details with additional control points throughout the mantle convection system, it seems like they too contribute to shaping the overall structure.

When examining specific details, further intriguing patterns emerge. Along the minor axis, key features such as New Zealand, the San Andreas Fault, and Yellowstone are aligned. Along the major axis, systems such as Japan stand out. A north–south axis can be associated with Hawaii, while the Challenger Deep appears to lie along a principal line within the inner structure of the system. Even the configuration of mid-ocean ridges shows a degree of resemblance to segments of this broader circular or elliptical pattern.

These recurring geometric relationships suggest that the Ring of Fire may reflect a deeper, organized structure within the Earth system, and horozontally the global arrangement is clearly not random at all. Saying ‘not random’ is an inverse scientific statement 🙂 This makes people curious, and this makes people surprised. At the same time, this indeed does raise important questions about the mechanisms responsible for producing such large-scale coherence.

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History of the Common Sense of Plate Tectonics

April 10, 2026 Steingrimur Thorbjarnarson

At the start of the 20th century, geology faced a fundamental problem:
continents appeared to move, but no physically acceptable mechanism existed.

In 1912, Alfred Wegener presented the theory of continental drift. He argued that continents had once formed a single landmass (Pangaea) and later separated. His evidence — fossil correlations, matching geological structures, and continental fit — was compelling. However, Wegener could not provide a convincing driving force, and his ideas were widely rejected.

Meanwhile, a crucial breakthrough came from physics. Between 1896 and 1905, building on discoveries by Becquerel and the work of Ernest Rutherford, scientists established that radioactive decay produces heat. This insight solved a major constraint: Earth was not simply cooling, but continuously generating internal heat. By the early 1900s, it became clear that Earth possessed a long-lived energy source capable of driving internal processes.

The next step was to understand how that the radioactive decay provided primary energy. In 1928–1929, Arthur Holmes proposed that heat inside the Earth drives mantle convection. He suggested that hot material rises and cooler material sinks, forming large-scale circulation patterns. Crucially, Holmes connected this internal flow to the drift of continents — proposing that convection currents could carry them. This was the first physically plausible mechanism linking Earth’s internal energy to surface motion.

However, direct evidence was still lacking — especially beneath the oceans, which remained largely unexplored.

That changed after World War II. Between 1950 and 1962, advances in sonar mapping revealed mid-ocean ridges, deep-sea trenches, and the global structure of the ocean floor. In 1962, Harry Hess proposed seafloor spreading: new oceanic crust forms at mid-ocean ridges, moves outward, and is eventually consumed at subduction zones.

Soon after, in 1963, Vine and Matthews demonstrated symmetrical magnetic striping on the ocean floor, providing strong confirmation that seafloor spreading was real and continuous.

The Synthesis (Late 1960s)

By 1967–1968, these ideas converged into the modern theory of plate tectonics:

Radioactivity (1896–1905) → provides the internal heat
Convection (Holmes, 1928–29) → organizes that heat into motion
Seafloor spreading (Hess, 1962) → reveals how crust is created and recycled
Magnetic evidence (1963) → confirms continuous movement

The Earth was finally understood as a dynamic system, not a static one.

The Physical System

The emerging model describes a coupled system:

Heat from radioactive decay drives mantle convection
Convection creates organized flow within the mantle
This flow moves rigid lithospheric plates
Plates:
- diverge at ridges
- converge at subduction zones
- slide past along transform faults

Continents are therefore not independent — they are embedded in moving plates, which reflect deeper flow patterns.

The Deeper Insight

The key realization of the 20th century is that Earth behaves as a thermally driven engine:

Energy source → radioactive decay
Transport mechanism → convection
Surface expression → plate tectonics

What began as disconnected observations became a unified physical framework linking nuclear physics, fluid dynamics, and geology.

Extending the Framework

The classical model (Holmes → Hess → plate tectonics) established that convection drives tectonics.

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The Mantle Convection Rolls Grid

April 7, 2026April 7, 2026 Steingrimur Thorbjarnarson

Understanding the geological processes in Iceland and elsewhere, both tectonic drift and mantle currents have to be considered.

This map shows it all, tectonic drift vectors from the National Land Survey of Iceland. The grid of division lines superimposed on this map shows the outlines of convection rolls below Iceland. The convection rolls can not be measured yet, due to several reasons.

5 Core Factors + 2 Observables:

5 CORE FACTORS (causes in the mantle)

Temperature

Composition (chemistry)

Pressure / depth

Mineral phase (structure)

Partial melt / fluids

2 OBSERVABLES (what we measure)

Seismic velocity (Vp, Vs)

Attenuation (Q)

An addition to low resolution, these factors make it too complicated to get a clear picture of the vertical structure aspects of the mantle. But the methods used here to make the convection rolls model are a shorter way, thereby deducting these lines before modern sensors, relevant AI and other types of technology provide direct observation opportunities.

Each of those lines shows the division between two convection rolls, found below Iceland at different depth, but all of them affect the tectonic plates of N-America and Eurasia. The first demonstration is how the volcanic zones follow the scope of the convection rolls. The only way to explain this consistency is finding out how those division lines affect the tectonic plates (and the crust). Ignoring this consistency would be wrong.

This leads us to consider further what happens down below, within the asthenosphere, the transition zone of the mantle, and the lower mantle. These lines are really narrow and sharp, so the way magma ascends through the tectonic plate should be analysed. The only way is the accumulation of martial melt exactly where the division lines are found, a mechanism of the convection rolls to release the partial melt there and make it possible for the lines of ascending magma to proceed all the way upwards, a distance of 120 km.

With this in mind, a myriad of geological features can be explained, hitherto hidden and not understood.

As can be seen on the map, the tectonic drift vectors are remarkably parallel to the convection rolls. This is a mathematical coincidence, found at the starting point of tectonic drift of the two plates. Farther out, this consistency is not seen, as the two plates drift and rotate in their independent ways.