Increased Caribbean seismicity and volcanism during minima in Earth’s rotation rate: Search for a physical mechanism and a 2030 forecast

Abstract

Three quarters of all Mw ≥ 6.6 earthquakes and volcanic eruptions surrounding the Caribbean plate occur preferentially during periods of decadal minima in Earth’s angular spin velocity. This correlation is revealed most clearly as a 4–6 years phase lag following the first derivative of the length of the day (LOD), Earth’s angular deceleration. We show that local strains and displacements resulting from oblateness changes, or plate boundary stresses associated with changes in tropical rotation rates are orders of magnitude lower than those typically associated with earthquake or volcano triggering. Notwithstanding the absence of a satisfactory causal physical mechanism, the relationship permits decadal trends in Caribbean tectonic hazards to be anticipated many years before their occurrence. The next period of increased tectonic activity in the Caribbean, corresponding to a probable slowing in Earth’s spin rate, will occur in the decade starting on or about 2030.

On the external forcing of global eruptive activity in the past 300 years

“…Shorter periods appear to have a stronger influence on the length of day, i.e., the component that measures the rotation speed around the polar axis. The link between volcanic activity and day length has been explored or suggested in past and recent studies (Hamilton, 1973;Stothers, 1989;Palladino and Sottili, 2014;Sottili et al, 2015;Tuel et al, 2017;Bilham et al, 2022). Thus, two parallel causal chains of forces could be involved, one acting directly on the tilt of the Earth's rotation axis, and the other on its rotation, both modulating crustal stresses and fluid movements that in turn influence the triggering of global-scale volcanic system activity (Figure 9).…”

“…As suggested for large explosive eruptions in ice core records (Tuel et al, 2017), our findings reinforce the idea that volcanic eruptions on Earth cannot be considered as entirely random processes and are partially controlled by external influences related to the ephemerids of celestial bodies in our solar system, acting on mass redistribution and thus stress variations at multiannual, multi-decanal, centennial, or even longer timescales. Further investigations would help better understand this interaction, its spatial distribution as well as the local and regional conditions that cause volcanic systems to respond to these global stress changes, which could potentially contribute to anticipating phases of increased volcanic activity, as suggested by Bilham et al (2022).…”

“…Deciphering the temporal pattern of volcanic activity is therefore crucial for assessing triggers of volcanic eruptions. This would not only help understand the dynamics of their internal plumbing system, but also unravel the interaction with potential external processes that may contribute to the destabilization of volcanoes on variable time scales (Dzurisin, 1980;McNutt and Beavan, 1987;Kutterolf et al, 2013;Watt et al, 2013;Canon-Tapia, 2014;Coussens et al, 2016;Watt, 2019;Seropian et al, 2021;Bilham et al, 2022;Dumont et al, 2022;Lucas et al, 2022). Furthermore, the recognition of specific temporal patterns in eruptive activity is a crucial objective in volcanology, as it would allow for anticipation of future events and thus better mitigation of volcanic hazards.…”

Possible role of tidal and rotational forcing on bradyseismic crises and volcanic unrest in the Campi Flegrei and Somma-Vesuvius areas

“…Earth's rotation changes release large amounts of gravitational energy (Press and Briggs, 1975) with effects on local deformation rate (Milyukov et al, 2011), on crustal stress at a scale of the plate tectonic (Wang and Long, 2000;Riguzzi et al, 2010;Levin et al, 2013;Bendick and Bilham, 2017) and on the time-space distribution of large earthquakes (Anderson, 1958;Shanker et al, 2001;Varga et al, 2005). Concerning the effects of Earth's rotations variations on volcanoes, a causal relationship between LOD changes and occurrence of large volcanic eruptions has been proposed on a global scale at subduction margins (Palladino and Sottili, 2014;Sottili et al, 2015;Bilham et al, 2022). Also, the multi-year modulation of seismicity and eruptions magnitude by Earth's rotation axis direction variability has been detected at Mount Etna (Lambert and Sottili, 2019).…”