On the link between Earth tides and volcanic degassing

Abstract

Abstract. Long-term measurements of volcanic gas emissions conducted during the last decade suggest that under certain conditions the magnitude or chemical composition of volcanic emissions exhibits periodic variations with a period of about 2 weeks. A possible cause of such a periodicity can be attributed to the Earth tidal potential. The phenomenology of such a link has been debated for long, but no quantitative model has yet been proposed. The aim of this paper is to elucidate whether a causal link between tidal forcing and variations in volcanic degassing can be traced analytically. We model the response of a simplified magmatic system to the local tidal gravity variations and derive a periodical vertical magma displacement in the conduit with an amplitude of 0.1–1 m, depending on the geometry and physical state of the magmatic system. We find that while the tide-induced vertical magma displacement presumably has no significant direct effect on the volatile solubility, the differential magma flow across the radial conduit profile may result in a significant increase in the bubble coalescence rate at a depth of several kilometres by up to several multiples of 10 %. Because bubble coalescence facilitates separation of gas from magma and thus enhances volatile degassing, we argue that the derived tidal variation may propagate to a manifestation of varying volcanic degassing behaviour. The presented model provides a first basic framework which establishes an analytical understanding of the link between the Earth tides and volcanic degassing.

A quest for unrest in multiparameter observations at Whakaari/White Island volcano, New Zealand 2007–2018

“…We, therefore, propose that a similar sealing mechanism is responsible for the increase of LSC during 2015 at Whakaari/White Island. This is consistent with the increase of DSAR during the same time period, although we cannot reject the possibility that other mechanisms play an important role in the observed signal (e.g., tidal stresses may enhance bubble coalescence in bubble columns; Dinger et al 2019).…”

Periodicity in Volcanic Gas Plumes: A Review and Analysis

“…There is some evidence for the presence of 14 day cycles at four volcanoes: Villarrica and Llaima [65], Turrialba [90], and Cotopaxi [27]. Dinger et al [114] developed a model suggesting that tidal forcing could affect the rate of bubble coalescence in the conduit, which is then manifested as change in degassing behavior measured at the surface. Overall, for volcano monitoring, deconvolving tidal influences from volcanically generated signals is crucial to the isolation of changes in the degassing regime.…”

A Statistical review of the dates and patterns of volcanic activity of Lewotolo Volcano, East Nusa Tenggara, Indonesia

“…This study began with suspicion of the possibility of a link between the position of the Moon and the Sun relative to the Earth with specific volcanic activities, such as Lewotolo in November 2020 and Krakatoa in December 2018. In several similar cases, some hypotheses have proposed that this may be related to the anomalous gravitational forces of the sun and moon [4], which may have affected fluidity-magmatic activity, similar to what occurs with sea tides [5][6][7][8][9]. Although this theory still needs to be proven further, in this study, we attempt to statistically review the dates of eruptions with the orbital events of the Moon and Sun with respect to Earth.…”