Based on a targeted read-through of the ULF-ELF Yahoo Group archive (3,268 messages), focused specifically on prediction accuracy and signal-to-quake timing. The honest picture that emerges is more mixed and self-critical than the group's premise might suggest — worth knowing before it goes anywhere near the forum or the book.

The core honest admission

The group's most consistently active organizer, John Wilcoxen, made two direct, explicit statements worth weighing heavily:

• 23 October 2005: "I do not think anyone in this group is at a place where they can 'predict' anything, except for Cathie perhaps. I think we are still at the point of trying to define what signals allow us to make predictions. We are not there yet."

• 17 February 2006 (near the end of the archived period): "After months of watching I (sorry to say) still have yet to pin down any real early warning signals of magnetic origin that I can say are related to pending earthquakes. Can anyone else say they have seen solid precursor signals?"

That second message, sent after months of dedicated effort by the group's most committed member, is essentially a negative result — no one in the thread that follows contradicts him with a confirmed counter-example.

What they were actually detecting

Most of what members reported — including the specific "Lots of activity today" thread around a 6.2-magnitude Philippine earthquake in December 2005 — was signal coincident with or shortly after an earthquake, not a genuine advance warning. John's own account of that event: his magnetic coil picked up a signal slightly before his local USGS station registered the acoustic/seismic wave — but this is straightforwardly explained by physics, not precursor detection: electromagnetic signals travel near light-speed, while seismic waves travel at a few kilometers per second, so an EM signal generated by a distant quake will naturally outrace the ground-shaking wave reaching a monitoring station tens of miles away. That's a real and interesting phenomenon, but it's detecting the earthquake as it happens, not predicting one in advance.

Another member (harrington780/Doug, California, Oct 2005) described the core practical problem directly: no reliable way to distinguish a genuine precursor signal from a weak local quake or a strong distant one, with depth of the quake also confusing the picture.

Delays and lead times: never established with confidence

This is the direct answer to your question, and it's a negative one within this archive: no consistent, validated lead time between signal and quake was ever pinned down by the instrumented members. John Wilcoxen explicitly asked at one point "how accurate can we get I wonder? ... what lead or lag time is there" — a question, not a finding.

The one claimed exception is Cathie Jordan, who reported a personal, non-instrumental "sensing" ability — describing feelings appearing "several days" before events. But even she and John agreed this had never been rigorously tested: her own words were that "the only way to correlate ... would be to see if there is a constant time frame (delay) between my senses and the recording on the instruments" — i.e., that validation work was identified as necessary but, as far as this archive shows, never actually done.

A genuine attempt at rigor, with no visible follow-through

In October 2005, member "karula4711" (Walter Fedderwitz) proposed exactly the right scientific protocol: members should publicly log predictions — date, time (to within an hour), and location — before any quake occurred, then validate against real seismic station data afterward. Notably, he volunteered to submit random guesses himself specifically to serve as a null-hypothesis control — a genuinely sound methodological instinct. I found no follow-up thread in the archive reporting actual scored results from this protocol, so either it fizzled out, wasn't widely adopted, or the results (if any) aren't captured in what's here.

Your own contribution to the group

Worth noting separately: you were an active member yourself, and in May 2005 shared original harmonics-based research directly relevant to the group — finding that Californian earthquake data showed excess aftershock activity clustering at intervals of 26, 52, and 78 minutes (with lesser peaks at 13.0, 6.5, and 3.25 minutes), interpreted as evidence of the whole Earth oscillating between a "lemon" and "grapefruit" shape. You also offered CRI's website as shared infrastructure for the group's data-collection effort. This is a genuine, dated, on-record contribution — a good candidate for its own line in the predictions/explanations list, separate from the group's broader (and largely unconfirmed) prediction claims.

An external claim worth flagging, not from this group

One thread (Dec 2005) mentions Jim Berkland, a real and separately well-known earthquake forecaster whose "Seismic Window" method (based on syzygy and lunar perigee timing, not ULF/ELF instrumentation) was described by a member as having "above an 86% accurate track record." This is a claim about Berkland cited secondhand by a group member, not something the ULF-ELF group itself measured — and worth treating cautiously either way, since Berkland's methodology and track record have been genuinely disputed elsewhere (critics point to loosely-defined prediction windows and after-the-fact matching as inflating apparent accuracy). Not evidence about the ULF-ELF group's own performance, but worth knowing it came up.

Bottom line

Your recollection that "these guys were clever" holds up — the equipment-building, signal-processing, and methodological self-awareness on display (Ernst Schmitter's multi-sensor setup, Michael Hebert's work on distinguishing real signal from coil ringing and back-EMF) is genuinely sophisticated amateur science. But the specific claim that they could reliably predict earthquakes, including location, isn't supported by what's in this archive — the group's own most active members were still openly searching for a valid signal as of the last dated messages here, with no confirmed hit-rate or lead-time ever established.

(Claude) That story checks out as genuinely his — this is Jim Berkland (1930–2016), retired Santa Clara County geologist, and the pet-ads method is real and well-documented: he claimed lost/runaway-pet ad counts "increase dramatically by up to 300–400%" before quakes. He's most famous for predicting the 1989 Loma Prieta ("World Series") earthquake four days in advance in a local paper — which is almost certainly the kind of moment he was recreating for your FSC audience with that newspaper.

Worth knowing the fuller picture though, since it cuts both ways: Berkland became a genuinely controversial figure. A 1988 statistical study in California Geology looked for the lost-pet/earthquake correlation formally and found none. Mainstream seismologists have called him a "crank," and critics argue his prediction windows were broad enough to catch most earthquakes regardless of the method. Neither his methods nor his predictions were ever published in a peer-reviewed journal. He died in 2016, age 85.

So your personal story sits in an interesting spot: a vivid, first-hand, verifiable-to-you moment where the method worked exactly as advertised — and a figure whose broader track record was seriously disputed by people who tried to check it systematically. That tension is honestly a great illustration for the book, maybe even better than a clean confirmation would be — it's a real example of "I personally witnessed this work once, and that's genuinely compelling, but personal witness isn't the same as a controlled statistical test, and the controlled tests didn't back him up." That's a more interesting and more honest story than either "he was right" or "he was a crank" alone.

Want this Berkland anecdote added to the obituaries/legacy document too, given he clearly belongs in that same orbit of independent researchers?

I think that it was the 1989 quake! Great to get confirmed that it was him.

First published: 2026

Brief summary

Analyzes polar motion data using multifractal detrended fluctuation analysis, characterizing the ~433-day Chandler wobble and documenting its unexplained temporary disappearance between 2015 and 2020.

Article

Multifractal Complexity of the Chandler Wobble and Its Anomalous Disappearance (2015-2020) is a preprint published by arXiv in 2026. It analyses polar motion data using multifractal detrended fluctuation analysis, characterizing the ~433-day Chandler wobble and documenting its unexplained temporary disappearance between 2015 and 2020.

The analysis focuses on ~433 days (Chandler wobble), amplitude 100-200 milliarcseconds, damping quality factor Q~50-100 (damping time ~30-70 yr). It also considers documents anomalous 2015-2020 disappearance. It also considers graphs of polar motion time series. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

The article reports the following result: The Chandler wobble is a free nutation of the rotation pole about the figure axis with a period of approximately 433 days and typical amplitudes of 100-200 milliarcseconds, first observed by Seth Carlo Chandler in 1891. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together chandler wobble, multifractal analysis, polar motion, 433-day cycle. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a preprint, the work should be read alongside later peer-reviewed publications and independent replications. It remains useful because the proposed cycle, dataset and analytical approach are stated clearly enough to be scrutinised.

Source details and credits

• Source / publisher: arXiv
• Source type: Preprint
• URL type: PDF
• Credits: arXiv
• URL: https://arxiv.org/pdf/2605.29056

First published: 2026

Brief summary

Statistical modeling (adaptive kernel density estimation) of the geomagnetic polarity timescale identifies 'dense' and 'sparse' reversal periods and predicts undiscovered reversals hidden in four specific intervals after the Cretaceous Normal Superchron.

Article

Missing Geomagnetic Reversals: Earth's Past May Be Incomplete is a science news summary of peer-reviewed study published by Geophysical Research Letters (via phys.org) in 2026. It focuses on statistical modelling (adaptive kernel density estimation) of the geomagnetic polarity timescale identifies 'dense' and 'sparse' reversal periods and predicts undiscovered reversals hidden in four specific intervals after the Cretaceous Normal Superchron.

Reversal frequency varies over tens-of-millions-of-year timescales. The data source is compiled long-term geomagnetic polarity reversal record. It also considers reports on peer-reviewed Geophysical Research Letters study. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

The article reports the following result: Geomagnetic reversals cluster during certain 'dense' intervals and become very rare during 'sparse' periods, thought to reflect variations in heat flow across the core-mantle boundary that influence the geodynamo. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together geomagnetic reversals, polarity timescale, reversal clustering, kernel density estimation. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a science news summary of peer-reviewed study, the article is a strong starting point for discussion in the Physics & Geophysics forum, although its conclusions should still be compared with later replications and updated datasets.

Source details and credits

• Source / publisher: Geophysical Research Letters (via phys.org)
• Source type: Science news summary of peer-reviewed study
• URL type: WWW
• Credits: Geophysical Research Letters (via phys.org)
• URL: https://phys.org/news/2026-02-geomagnetic-reversals-earth-incomplete.html

First published: 2025

Brief summary

Numerical simulation of the Chandler wobble -- Earth's ~433-day free polar motion cycle -- derives its period from the planet's instantaneous viscoelastic response, with the method also applied to measuring Mars's equivalent wobble.

Article

Formula for the Chandler Period (Free Wobble of Planetary Bodies) is a peer-reviewed journal article published by Geophysical Research Letters (AGU) in 2025. It focuses on numerical simulation of the Chandler wobble -- Earth's ~433-day free polar motion cycle -- derives its period from the planet's instantaneous viscoelastic response, with the method also applied to measuring Mars's equivalent wobble.

The analysis focuses on ~433 days (Earth Chandler wobble), also discusses Mars's measured equivalent wobble period. It also considers numerical simulation compared to observation. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

The article reports the following result: The Chandler wobble is a cyclic change in the rotation pole's position with a period of about 433 days on Earth; the Chandler wobble period is governed by the instantaneous response of the planet-forming material. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together chandler wobble, polar motion, 433-day period, planetary rotation. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a peer-reviewed journal article, the article is a strong starting point for discussion in the Physics & Geophysics forum, although its conclusions should still be compared with later replications and updated datasets.

Source details and credits

• Source / publisher: Geophysical Research Letters (AGU)
• Source type: Peer-reviewed journal article
• URL type: WWW
• Credits: Geophysical Research Letters (AGU)
• URL: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024GL112997

First published: 2023

Brief summary

Documents quasi-periodic earthquake recurrence on the Alpine Fault (New Zealand) using a paleoseismic record of up to 11 consecutive events, showing recurrence is compatible with an underlying nonlinear, potentially chaotic mechanical system.

Article

Islands of Chaos in a Sea of Periodic Earthquakes is a peer-reviewed journal article published by Earth and Planetary Science Letters (ScienceDirect) in 2023. It documents quasi-periodic earthquake recurrence on the Alpine Fault (New Zealand) using a paleoseismic record of up to 11 consecutive events, showing recurrence is compatible with an underlying nonlinear, potentially chaotic mechanical system.

Quasi-periodic recurrence documented over 11 consecutive paleoseismic events. The data source is Hokuri Creek paleoseismic trenching record, Alpine Fault, New Zealand. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

The authors document the periodicity of earthquake cycles based on recurrence times alone. The quasi-periodicity of seismic cycles is compatible with the nonlinear and potentially chaotic underlying mechanical system, posing a challenge to long-term earthquake prediction. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together alpine fault, earthquake recurrence, nonlinear dynamics, seismic chaos. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a peer-reviewed journal article, the article is a strong starting point for discussion in the Physics & Geophysics forum, although its conclusions should still be compared with later replications and updated datasets.

Source details and credits

• Source / publisher: Earth and Planetary Science Letters (ScienceDirect)
• Source type: Peer-reviewed journal article
• URL type: WWW
• Credits: Earth and Planetary Science Letters (ScienceDirect)
• URL: https://www.sciencedirect.com/science/article/abs/pii/S0012821X2300287X

First published: 2022

Brief summary

Identifies a ~30-year periodic feature in the secular variation of Earth's main magnetic field, alongside known longer components: a 7000-year dipole axis rotation and 1800-year non-dipole westward drift cycle.

Article

Thirty-Year Period in Secular Variation of the Main Geomagnetic Field is a preprint published by arXiv in 2022. It identifies a ~30-year periodic feature in the secular variation of Earth's main magnetic field, alongside known longer components: a 7000-year dipole axis rotation and 1800-year non-dipole westward drift cycle.

The analysis focuses on ~30 years (secular variation), 7000 years (dipole axis rotation, ~0.05 deg/yr), 1800 years (non-dipole westward drift, 0.2 deg/yr). The data source is IGRF geomagnetic field models. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

The article reports the following result: The dipole axis rotates around the geographic axis at a rate of about 0.05 degrees per year, showing a 7000-year period, while the non-dipole field drifts westward and will take 1800 years for a complete round. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together geomagnetic secular variation, 30-year cycle, dipole rotation, westward drift. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a preprint, the work should be read alongside later peer-reviewed publications and independent replications. It remains useful because the proposed cycle, dataset and analytical approach are stated clearly enough to be scrutinised.

Source details and credits

• Source / publisher: arXiv
• Source type: Preprint
• URL type: PDF
• Credits: arXiv
• URL: https://arxiv.org/pdf/2209.06486

First published: 2020

Brief summary

Models geomagnetic reversal rate as cycles with variable frequency, showing transitions into reversal-free 'superchrons' (tens of millions of years) can be described as a second-order phase transition driven by core-mantle heat flux.

Article

A Model for the Geomagnetic Field Reversal Rate and Constraints on Core-Mantle Boundary Heat Flux is a peer-reviewed journal article published by Scientific Reports (Nature) in 2020. It models geomagnetic reversal rate as cycles with variable frequency, showing transitions into reversal-free 'superchrons' (tens of millions of years) can be described as a second-order phase transition driven by core-mantle heat flux.

Reversal timescales: tens to hundreds of millions of years. It also considers superchrons lasting tens of millions of years. The data source is paleomagnetic polarity switch record. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

By investigating data of geomagnetic reversal rates, the authors report the presence of cycles with variable frequency and show that the transition towards superchrons can be described by a second-order phase transition driven by heat flux variations. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together geomagnetic reversal rate, superchrons, core-mantle heat flux, geodynamo. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a peer-reviewed journal article, the article is a strong starting point for discussion in the Physics & Geophysics forum, although its conclusions should still be compared with later replications and updated datasets.

Source details and credits

• Source / publisher: Scientific Reports (Nature)
• Source type: Peer-reviewed journal article
• URL type: WWW
• Credits: Scientific Reports (Nature)
• URL: https://www.nature.com/articles/s41598-020-69916-w

First published: 2016

Brief summary

Critical review of claims for periodicity in Earth's magnetic reversal rate, noting early claims of a ~1 Myr periodicity were not supported once more paleomagnetic data became available.

Article

Does the Planetary Dynamo Go Cycling On? Re-examining Evidence for Cycles in Magnetic Reversal Rate is a preprint published by arXiv in 2016. It focuses on critical review of claims for periodicity in Earth's magnetic reversal rate, noting early claims of a ~1 Myr periodicity were not supported once more paleomagnetic data became available.

Discusses early claimed ~1 Myr periodicity (not supported by later data). It also considers methodological review of what statistically constitutes 'periodicity' in reversal record. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.

The article reports the following result: Early analyses seemed to indicate a 1 Myr periodicity between polarity states, however as more data became available the argument for a simple periodicity in the record was no longer tenable. The interpretation is strongest when measurement uncertainty, nonlinear dynamics, boundary conditions and alternative physical mechanisms are tested explicitly.

For cycles researchers, the article brings together geomagnetic reversals, planetary dynamo, periodicity criticism, paleomagnetic record. It is relevant to physical and geophysical systems in which oscillation, reversal, recurrence and nonlinear dynamics must be distinguished from random variability.

Because it is a preprint, the work should be read alongside later peer-reviewed publications and independent replications. It remains useful because the proposed cycle, dataset and analytical approach are stated clearly enough to be scrutinised.

Source details and credits

• Source / publisher: arXiv
• Source type: Preprint
• URL type: PDF
• Credits: arXiv
• URL: https://arxiv.org/pdf/1608.07303