Whole Lotta Shakin’ Going On

The solar cycle is at a minimum with the onset of Solar Cycle 25.

As is also apparent, the more active solar period that peaked in the first decade of the 22nd century is now entering a 30 year low activity period.

Higher seismic activity correlates with low solar activity.

We are already seeing evidence of that higher seismic correlation.

Three major earthquakes struck just north of New Zealand, including one of the strongest ever to hit the region, triggering tsunami warnings:

  • 7.3M event at 13:27 UTC
  • 7.4M event at 17:41 UTC
  • 8.1M at 19:28 UTC

Aseismic cluster of this intensity is rare.

But, recall at the start of Solar Cycle 24, Japan experienced a 9.1M event on March 11, 2011.

Ten years ago, New Zealand marked the 10th anniversary of the 6.3M that destroyed parts of Christchurch in the south Island, killing 185 people.

Earthquake-swarms are continuing to intensify under many of the world’s volcanoes, including those of Iceland as well as some of the 18 that run along the Cascade Volcanic Arc in western North America; here, Mount Rainier and Mount Hood are among the ones to watch.

The Cascade Arc has history of “lighting up” during the onset of Grand Solar Minimums, and this time isn’t expected to be any different.

Marchitelli et al. (2020) discuss the relationship between solar cycles and activity, and seismicity:

Large earthquakes occurring worldwide have long been recognized to be non Poisson distributed, so involving some large scale correlation mechanism, which could be internal or external to the Earth. We have recently demonstrated this observation can be explained by the correlation of global seismicity with solar activity. We inferred such a clear correlation, highly statistically significant, analyzing the ISI-GEM catalog 1996–2016, as compared to the Solar and Heliospheric Observatory satellite data, reporting proton density and proton velocity in the same period. However, some questions could arise that the internal correlation of global seismicity could be mainly due to local earthquake clustering, which is a well-recognized process depending on physical mechanisms of local stress transfer. We then apply, to the ISI-GEM catalog, a simple and appropriate de-clustering procedure, meant to recognize and eliminate local clustering. As a result, we again obtain a non poissonian, internally correlated catalog, which shows the same, high level correlation with the proton density linked to solar activity. We can hence confirm that global seismicity contains a long-range correlation, not linked to local clustering processes, which is clearly linked to solar activity. Once we explain in some details the proposed mechanism for such correlation, we also give insight on how such mechanism could be used, in a near future, to help in earthquake forecasting.

Herdiwijaya et al (2015) reached similar conclusions.

Principal component analysis by Zharkova (2020) report the current minimum will extend out some 2-3 decades.

Consistent with Zharkova, Courtillot et al. (2021) observe from their study of sunspot frequency since 1749 that the aphelia of the four Jovian planets could be the principal drivers in solar activity.

They conclude from their planetary model with a prediction that Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

Hajra (2021) arrives at a similar conclusion. Noting Solar Cycle 24 (December 2008 – December 2019) is recorded as the weakest in magnitude in the space age (after 1957), Hajra analyzes Solar Cycles 20 through 23, and finds Solar Cycle 24 is both the weakest in solar activity, but also in average solar wind parameters and solar wind–magnetosphere energy coupling.

This resulted in lower geomagnetic activity, lower numbers of high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events and geomagnetic storms. The Solar Cycle 24 exhibited a ≈ 54 – 61% reduction in HILDCAA occurrence rate (per year), ≈ 15 – 34% reduction in moderate storms (−50 nT ≥ Dst > −100 nT), ≈ 49 – 75% reduction in intense storms (−100 nT ≥ Dst > −250 nT) compared to previous cycles, and no superstorms (Dst ≤ −250 nT).

So, as GHG concentration continues to rise and climate temperatures trend south due to weakening solar activity, will the expected rise in seismicity be attributed to GHG emissions?

Or, will veritas vincit?


Courtillot, V., Lopes, F., & Le Mouël, J. L. (2021). On the prediction of Solar Cycles. Solar Physics296(1). doi:10.1007/s11207-020-01760-7

Hajra, R. (2021). Weakest solar cycle of the space age: A study on solar wind–magnetosphere energy coupling and geomagnetic activity. Solar Physics296(2). doi:10.1007/s11207-021-01774-9

Herdiwijaya, D., Arif, J., Nurzaman, M. Z., & Astuti, I. K. D. (2015). On the possible relations between solar activities and global seismicity in the solar cycle 20 to 23. AIP Publishing LLC.

Marchitelli, V., Troise, C., Harabaglia, P., Valenzano, B., & De Natale, G. (2020). On the long range clustering of global seismicity and its correlation with solar activity: A new perspective for earthquake forecasting. Frontiers in Earth Science8. doi:10.3389/feart.2020.595209

Valentina Zharkova (2020) Modern Grand Solar Minimum will lead to terrestrial cooling, Temperature, 7:3, 217-222, DOI: 10.1080/23328940.2020.1796243

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