We have long known that earthquakes can cause fluids to be expelled at Earth’s surface (e.g., as described by Pliny the Younger in his Natural History), including by triggering volcanic eruptions. Linde and Sacks (1998) examined the Smithsonian’s catalog of volcanic eruptions and found that volcanoes were more likely than expected by chance to erupt in the days after large, regional earthquakes. It is possible that roughly 0.4% of volcanic eruptions were triggered by earthquakes that occurred in the few preceding days (Manga and Brodsky, 2006). There are also global increases in unrest (Delle Donne et al., 2010) and degassing (Avouris et al., 2017) following large earthquakes.
How and why earthquakes might make volcanoes erupt remains the subject of active research. Is it the compression of underground magma bodies that forces magma to the surface? Or the unclamping of dikes through which magma ascends? Or does the passage of seismic waves trigger a process such as liquefaction or bubble nucleation that leads to eruption?
In this project, we are reassessing the history of eruptions and earthquakes to identify what features of volcanoes, magmas, and tectonic setting are correlated with triggering. Our first results, presented at the 2017 IAVCEI conference (by undergraduate Theresa Sawi and co-PI Michael Manga), show that the short-term triggering of volcanoes (within days) may be an artefact of biased reporting of eruptions. However, the probability of eruption does increase in the years after large earthquakes by a few percent. We will also study the mechanics of potential triggering by performing laboratory experiments to quantify how seismic waves change the mechanical properties of magmas. Preliminary results from experiments done at the Lawrence Berkeley National Lab Advanced Light Source by postdoc Barbara Tripoli confirm that periodic deformation, such as that created by seismic waves, does soften crystal-rich magma and may enable magmas to be mobilized.
Further reading
- Avouris, D. M., S. A. Carn, and G. P. Waite, 2017, Triggering of volcanic degassing by large earthquakes, Geology, G39074-1.
- Delle Donne, D., A. J. Harris, M. Ripepe, and R. Wright, 2010, Earthquake-induced thermal anomalies at active volcanoes, Geology, 38, 771-774.
- Linde, A. T., and I. S. Sacks,1998, Triggering of volcanic eruptions, Nature, 395, 888.
- Manga, M., and E. Brodsky, 2006, Seismic triggering of eruptions in the far field: volcanoes and geysers, Annu. Rev. Earth Planet. Sci,, 34, 263-291.
- Pliny the Younger, Epistulae VI, circa 106 CE, Letter 20.
