Rosa Rubicondior: Refuting Creationism - Californian Creationists May Be In For A Catastrophic Shock

Earthquake model reveals: Stress in California at record level

Californian creationists who imagine that Earth was fine-tuned for human life — and perhaps arranged with their own comfort and security particularly in mind — might want to consider what is happening beneath their feet. A planet supposedly designed as our ideal home has an unfortunate habit of accumulating stresses capable of turning homes, roads and other essential infrastructure into wreckage. Southern California provides a particularly awkward example of this discrepancy between reassuring theology and indifferent geology.

A study published in Journal of Geophysical Research: Solid Earth examines stress accumulation along the southern San Andreas and San Jacinto fault systems. Led by Liliane Burkhard, the researchers combined a reconstructed earthquake history with a computer model that follows changes in three-dimensional space and through time. Their results indicate that some fault segments have reached or exceeded the highest stress levels in the modelled thousand-year history.

Of particular interest is Cajon Pass, northeast of Los Angeles, where the two fault systems approach one another. This junction can behave as an “earthquake gate”: under some conditions, a rupture stops there; under others, it can propagate between fault systems. The research suggests that the relative stresses on neighbouring segments help determine whether this gate remains closed or allows a more extensive rupture. Understanding those interactions matters because the surrounding region contains densely populated communities and major transport and energy routes.

The underlying mechanism requires neither supernatural intervention nor concern for the people living above it. Continuing tectonic movement loads faults whose shallow portions remain locked, allowing stress to accumulate between earthquakes. A long quiet interval is therefore no guarantee of safety. The apparent tranquillity of the landscape can conceal the continuing development of conditions that favour another major rupture.

This is not a prediction that a catastrophic earthquake will happen tomorrow, nor does “record stress” mean that scientists have been measuring these faults continuously for a millennium. These are estimates produced by a model constrained by geological and historical evidence. The researchers explicitly distinguish their assessment from a prediction of when the next earthquake will occur. Its value lies in improving our understanding of possible rupture scenarios and informing preparedness.

Nevertheless, the implications for the comforting claim of a world designed around human welfare are difficult to miss. A planet capable of supporting life is plainly not the same thing as a planet engineered to keep its inhabitants safe. Californian believers enjoy no exemption from the mechanics of stressed rock, and confidence in divine solicitude supplies no geological protection. The useful response comes from understanding the hazard and preparing for it — precisely the work that evidence-based science makes possible and which muttering spells and incantations to an imaginary sky daddy makes not one iota of difference no matter how loudly they are shouted.

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AI-generated Before and after a major earthquake in southern California
(Move the dividing line to reveal the changes)

Liliane Burkhard developed the online tool "LA-GRID" (Los Angeles Geospatial Risk and Infrastructure Dashboard). This web-based, interactive tool visualizes seismicity and fault data for the Los Angeles region, with live updates on earthquakes and wildfires. To the tool: https://liliane-sys.github.io/LA-GRID/

What makes tectonic plates move? Earth’s surface is divided into moving plates of lithosphere: the crust and the rigid uppermost mantle. Beneath them lies the asthenosphere, a weaker region of the upper mantle that can deform and flow over geological time. The plates do not float on an ocean of molten magma: the mantle is predominantly solid rock, but under sustained stress its hot interior can creep very slowly.

Heat and gravity keep the system moving

Earth retains heat from its formation, while radioactive decay continues to generate heat inside it. As the planet loses heat to space, temperature differences help maintain differences in density: warmer mantle material tends to rise, while colder, denser material tends to sink. Gravity acts on these density differences, helping drive the circulation of rock and the movement of plates.

Several interacting forces contribute:

Slab pull. As oceanic lithosphere ages, it cools and becomes denser. Where a sufficiently dense plate descends into the mantle at a subduction zone, its sinking portion can pull the rest of the plate behind it. This is generally regarded as a major driving force, especially for plates attached to extensive sinking slabs.

Ridge push. Mid-ocean ridges stand high because the newly formed lithosphere and underlying mantle are hot and relatively buoyant. As the lithosphere moves away, it cools, thickens and subsides. Gravity encourages it to slide away from the elevated ridge, transmitting a pushing force through the plate. The name can be misleading: this is primarily gravitational sliding, rather than magma forcing the plates apart.

Interaction with mantle flow. Flowing mantle exerts forces on the undersides of plates, which can help drive or resist their movement. Plates also influence mantle circulation, particularly where sinking slabs drag surrounding material downwards. The plates and mantle therefore form a coupled system, rather than separate conveyor belts and passive passengers.

The balance between these forces varies between plates. Their movement is also resisted by friction along boundaries, collisions, the bending of descending slabs and resistance from the surrounding mantle.

Why does slow movement produce violent earthquakes?

Plates typically move only a few centimetres a year, but their boundaries do not necessarily slip smoothly. Friction can lock sections of a fault while the wider plate system continues moving. The surrounding rocks deform, storing elastic energy. When a locked section suddenly slips, some of that energy travels outwards as seismic waves: an earthquake.

In Southern California, the Pacific Plate moves generally north-westwards relative to the North American Plate. Much of this relative movement is accommodated by the San Andreas and associated faults, including the San Jacinto. These are predominantly strike-slip faults, along which the opposing sides move horizontally past one another. They transmit movement within the wider plate system; they do not require a separate local source of heat to drive them.

A quiet fault can therefore still be accumulating stress. The absence of recent large earthquakes does not mean that the tectonic forces have stopped.

USGS: Are tectonic plates floating on magma?.
British Geological Survey: What causes earthquakes?.
USGS: What causes earthquakes?.

The work of the research group is also described in a University of Bern news release:

Earthquake model reveals: Stress in California at record level
An international research team led by a researcher at the University of Bern has modeled 1,000 years of earthquake history along the San Andreas and San Jacinto faults in Southern California. The result: stresses in the crust are higher today than at any time in the last millennium – and a critical fault junction near Los Angeles could decide how big the next major earthquake will be.
Earthquakes usually occur along fracture zones in the Earth's crust, where large tectonic plates slide past one another and become locked. Stress builds up over long periods of time and is suddenly released in the form of an earthquake. In Southern California, the San Andreas and San Jacinto faults are among the most significant of these zones, accommodating the majority of the plate motion in the region. Where the two fault systems approach each other northeast of Los Angeles lies the Cajon Pass – a tectonically complex junction where a rupture on one fault could potentially cross onto the other. Since the last major earthquake to affect the wider Los Angeles region, the Fort Tejon earthquake of 1857 with a magnitude of 7.9, tectonic stress along the fault segments has built up continuously, which is a prolonged quiet period that has long concerned researchers given the potential for a large future rupture.

In a new study led by Dr. Liliane Burkhard of the Division of Space Research and Planetary Sciences (WP) at the Physics Institute of the University of Bern, an international research team has modeled 1,000 years of earthquake history along the southern San Andreas and San Jacinto fault systems to estimate the present-day stress loading at Cajon Pass. Researchers from the University of Hawaiʻi at Mānoa, the U.S. Geological Survey Earthquake Science Center in Pasadena and the Scripps Institution of Oceanography at UC San Diego were involved. The results show that tectonic stresses in the region have reached and, in some cases, exceeded the highest levels of the last millennium. In the study, the researchers also introduce the concept of Cajon Pass as an "earthquake gate": a junction that controls whether large earthquakes remain confined to a single fault or propagate across both systems simultaneously. The study has just been published in Journal of Geophysical Research: Solid Earth.

Modeling 1,000 years of earthquake history

To investigate how the stress along the San Andreas and San Jacinto faults and at the critical Cajon Pass junction has evolved over time, the research team constructed a physics-based, four-dimensional earthquake cycle model that simulates the processes in three spatial dimensions and over time. The researchers then fed the model with a 1,000-year earthquake record reconstructed from geological evidence such as radiocarbon dating, tree-ring anomalies, and historical documentation of ground ruptures.

The model tracks how each earthquake changes stress on neighboring fault segments, how stress accumulates during the quiet intervals between events, and how the deeper layers of the crust slowly relax following large ruptures. This simulation allows us to understand how stresses in the fault system build up over centuries. By running the earthquake history of Southern California as a simulation, we can estimate the extent to which the fault system is already under stress today." The researchers show that stresses in the region are currently at their highest level in the last 1,000 years.

Dr. Liliane M. L. Burkhard, corresponding author.
Space Research & Planetology Division
Physics Institute
University of Bern
Bern, Switzerland.

"Earthquake gate" as a decisive key factor

A key finding of the study is that the Cajon Pass can act as a so-called "earthquake gate", a junction that controls whether large ruptures remain confined to a single fault or cross both fault systems. Historical examples of both behaviors exist: The Fort Tejon earthquake of 1857 terminated at Cajon Pass and did not involve the San Jacinto Fault, while the Wrightwood earthquake of 1812 ruptured through the junction and across both systems in a single through-going event.

The earthquake gate concept captures something important about how fault junctions work," explains Burkhard. "Cajon Pass doesn’t simply block or channel earthquakes: It responds to stress conditions, and those conditions change over centuries.

Dr. Liliane M. L. Burkhard.

The study also shows that the decisive factor is not only how much stress has built up on a single fault but how aligned the stresses on the two fault systems are. When the stress on both faults rises in concert over time, toward similarly high levels, conditions favor a large joint rupture crossing both systems. When stress levels evolve out of step with each other, ruptures are more likely to terminate at the junction rather than propagate further. Currently, modeled stress has reached 3.6 MPa on the San Jacinto-Bernardino section, exceeding the highest value seen anywhere in the 1,000-year simulation. On the neighboring Mojave South section of the San Andreas fault, it is 2.8 MPa. Both segments are therefore highly and relatively similarly stressed, placing the system in a configuration that historically has preceded joint ruptures.

So not only is it concerning that the stresses are reaching historic highs, but also that the relative stress conditions between the two fault systems are approaching the range we associate with major ruptures crossing both faults simultaneously – and that is a scenario with much larger consequences for the region.

Dr. Liliane M. L. Burkhard.

Increased risk in densely populated regions

A joint rupture of the San Andreas fault and the San Jacinto fault that crosses the Cajon Pass would be a much more severe event than one that is limited to a single fault. The affected region includes some of the most densely populated, infrastructure-critical corridors in the U.S., including the greater Los Angeles area, San Bernardino, Riverside and the Coachella Valley. Major highways, railroads and energy infrastructure run through the Cajon Pass itself.

The question of when and how the next major earthquake will occur in this region is one of the most pressing problems in applied geoscience. Our results provide a clearer, physics-based picture of the current stress state of the fault system, and the framework we developed is not just applicable to California, but also for other complex fault junctions worldwide. [However] the study is not a prediction of when an earthquake will occur. What we can say is that the system is critically stressed and that physics-based models like ours give a clearer picture of the range of scenarios we should be prepared for. This information is important for hazard assessment, infrastructure planning and emergency preparedness.

Dr. Liliane M. L. Burkhard.

Publication:
Burkhard, L. M. L., Smith-Konter, B. R., Scharer, K. M., & Sandwell, D. T. (2026).
Cajon pass and the southern San Andreas Fault system: Earthquake cycle stress accumulation and present-day loading.
Journal of Geophysical Research: Solid Earth, 131, e2025JB033213. https://doi.org/10.1029/2025JB033213

Abstract
With over a century since the last major rupture affecting the wider Los Angeles region, tectonic stress has steadily built along the southern San Andreas and San Jacinto fault systems, raising concerns of an imminent large earthquake. Cajon Pass, located at the junction of these faults, represents a critical site for potential through-going ruptures in Southern California. We constructed new 4D earthquake cycle simulations using a 1000-year paleoseismic rupture history of the San Andreas Fault System (SAFS) to assess spatial and temporal variations in stress. A semi-analytic Fourier transform model was used to compute stress from 3D dislocations in an elastic plate overlying a Maxwell viscoelastic half-space, assuming a complete coseismic reset of resolved shear stress on ruptured elements. Results show highest stress accumulation north of Cajon Pass (∼1.8 MPa/100 years) due to greater slip rates, and lower rates south of Cajon Pass (∼1.0–1.5 MPa/100 years). By 2025, Coulomb stress is estimated at 2.8 MPa on the Mojave South (MOS) segment, 1.8 MPa on the North San Bernardino (NSB1) segment and 3.6 MPa on the San Jacinto Bernardino (SJB) segment. Segments accumulate stresses with characteristic ranges of pre-event stress interpreted as failure thresholds: 1.2–2.7 MPa for MOS, 0.4–1.6 MPa for NSB1, and 1.2–2.9 MPa for SJB. When the stress disparity between segments SJB and MOS narrows, the faults appear to rupture jointly, suggesting that stress levels may control how Cajon Pass acts as an earthquake gate. These results may inform seismic hazard assessments by linking stress evolution to fault interactions.

Plain Language Summary
Southern California's San Andreas and San Jacinto faults have not produced a major earthquake near Los Angeles in over a century. During that time, tectonic stress has continued to build along these faults, increasing the likelihood of a large future rupture. One key area of concern is Cajon Pass, where the two fault systems meet and could potentially rupture together. To investigate this, we used computer simulations of the last 1000 years of large earthquake activity to estimate how stress builds up on fault segments and affects neighboring segments over time. The model shows that stress has now reached high levels across the region and that the two fault systems may interact when their stress levels become similar. This suggests that Cajon Pass could act as an “earthquake gate” which sometimes blocks and other times allows large ruptures to propagate between faults. These results improve our understanding of earthquake interactions in Southern California and help refine regional hazard assessments.

Figure 1
The San Andreas Fault System (SAFS) in Southern California, with the main SAF fault trace in purple and San Jacinto Fault trace in blue. Segment boundaries used in this study are marked by white dots with abbreviated names specified in Table 1; the fault configuration is simplified from Scharer and Yule (2020). Cajon Pass is indicated in red.

Figure 2
Ages (CE) of southern San Andreas Fault System paleoseismic events adopted for this study. The segment boundaries (white circles) and fault configuration were simplified from Scharer and Yule (2020) to comply with fault architecture of the stress evolution model. Segment name abbreviations are used here; full names can be found in Table 1. Yellow stars indicate epicentral locations of large recent earthquakes: M_w 7.3 1992 Landers, M_w 7.1 1999 Hector Mine, and M_w 7.1 2019 Ridgecrest. Insert: Configuration of Cajon Pass junction (MOS, North San Bernardino and San Jacinto Bernardino) examined in this study.

Figure 3
Earthquake rupture extents for events passing and stopping at Cajon Pass based on the Maximum Rupture Model of Scharer and Yule (2020) and modeling by Rodríguez Padilla et al. (2021). Colors show earthquakes with the same rupture extent, with the mean age (CE) indicated. Small arrows indicate extent of ruptures beyond map excerpt. Left inset: timeline of “Gate-Open” or “Gate-Closed” events of Cajon Pass, that is, ruptures stopping/passing the intersection of MOS, North San Bernardino, and San Jacinto Bernardino.

Figure 4
Schematic of the maxwell model: An elastic plate of thickness H overlies a linear Maxwell viscoelastic half-space of viscosity η. Material properties are shown as shear modulus (μ), Young's modulus (E), and density (ρ) for each layer. Strike-slip faults are represented as vertical screw-dislocation elements embedded in the elastic layer; in this study, fault elements extend from an upper depth d₀ (surface) to a lower depth d₁ (local locking depth). A displacement discontinuity across each fault element is implemented using a finite-width force couple (Sandwell & Smith-Konter, 2018; Smith & Sandwell, 2003, 2004). Inset: Plan-view representation of the far-field loading and force-couple sign convention. The relative plate-parallel velocity is V₀, applied as V₀/2 and -V₀/2 on either side of the fault. The + and – symbols denote opposite-signed body forces that comprise the couple used to impose the displacement discontinuity.

Figure 5
Modeled Coulomb stress accumulation of the southern San Andreas Fault System at present-day (2025) in regional context, observed at ½ the locking depth of each segment. Fault traces overlain in gray, location of Cajon Pass in white circle with abbreviations of the three adjacent segments indicated. Colors show Coulomb stress (observed at ½ the locking depth of each segment) resolved onto vertical fault planes using the local segment strike computed in maxwell. Coulomb stresses have a present overall mean value of 2.8 MPa on the MOS segment, 1.8 MPa on the North San Bernardino segment, and 3.6 MPa on the San Jacinto Bernardino segment (Figure 7).

Figure 6
Coulomb stress accumulation of the southern San Andreas Fault System, illustrating the stress state before and after the complete (tripartite) junction rupture of 1812 Wrightwood (left) and the 1857 Fort Tejon earthquake that did not propagate past Cajon Pass (right), showing remaining stress lobes and accumulations from non-participating segments to the south. Stress grids reflect an ensemble of stress contributions from faults at observation depths of ½ the local fault locking depth of each segment.

Burkhard, L. M. L., Smith-Konter, B. R., Scharer, K. M., & Sandwell, D. T. (2026).
Cajon pass and the southern San Andreas Fault system: Earthquake cycle stress accumulation and present-day loading.
Journal of Geophysical Research: Solid Earth, 131, e2025JB033213. https://doi.org/10.1029/2025JB033213

Copyright: © 2026 The authors.
Published by John Wiley & Sons, Inc. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

The difficulty for creationists is not that science has discovered an occasional flaw in an otherwise perfectly safe world. It is that the same natural processes that shape Earth’s surface also generate hazards capable of devastating the communities living on it. Plate tectonics operates according to physical conditions, without regard for human welfare, religious conviction or claims of special status. California’s faults offer no exemption for people who believe the planet was designed with them in mind.

This research does not tell Californians when the next major earthquake will strike. It provides a better understanding of how stress accumulates and how neighbouring faults might rupture together. That distinction matters: acknowledging uncertainty is part of the strength of science. Researchers construct models, test them against evidence and refine their conclusions, producing knowledge that can help communities prepare even when precise prediction remains beyond reach.

Nor does the existence of earthquakes, by itself, disprove every conceivable creator. It does, however, expose the weakness of treating Earth’s capacity to support life as evidence that it was arranged by an omnipotent, benevolent designer for our comfort and protection. If the pleasant features of the landscape are credited to deliberate design, intellectual consistency requires that its potentially lethal faults enter the reckoning too. Invoking an unknowable divine purpose supplies no independent evidence that these hazards serve a benevolent end.

For Californians of every belief and none, the practical response is the same: understand the geology, strengthen vulnerable infrastructure and prepare for the hazards the evidence reveals. Whatever reassurance creationist theology may offer, it cannot release accumulated tectonic stress or reinforce a building. Those tasks belong, respectively, to an indifferent planet and to people applying the knowledge science provides.

In other words, the only sensible response to these scientific facts is to behave like Atheists and don't depend on a magic sky daddy coming to the rescue.

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