Can Climate Change Cause Earthquakes and Volcanic Eruptions?

For my next blog posts, I am going to do another case-study saga similar to my posts on Ladakh, this time in Japan. I thought this might be an interesting contrast between two regions that are both hazard hot-spots, but with a wide gap in GDP. I was actually intending to start my Japan saga in this post, but I came upon some interesting articles online yesterday by a Geologist at UCL, Bill McGuire, that I wanted to talk about. These articles stated a causal link between climate change and geological hazards such as earthquakes and volcanoes.  I’d heard many times before that volcanic eruptions have the potential to change climate change, but never that climate change might cause eruptions. Let me know what you think in the comment section below!

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   Typically, when thinking of climate induced hazards, most of us (myself included) will think of mass movement, flooding, storms, droughts, etc. However, there is a growing body of evidence that supports the idea that climate change is linked to a potential growing frequency in geophysical hazards. The time scale that this operates over, however, is not entirely clear, so whether we will see the change in our lifetime is questionable. 

   In Iceland, for example, ice sheets that cover volcanoes such as the Eyjafjallajökull ice-sheet, are rapidly melting. During the melting period, large pressures that are exerted by the ice are beginning to lessen, which may have the effect of triggering volcanic eruptions. In other words, the change in weight alters the balance of forces atop of the Earth’s crust, decreasing lithostatic pressure (Loughlin, 2002). By geological standards, this change in weight can make the rebound take place very rapidly, destabilising the faults. The recent eruption of the Eyjafjallajökull volcano, which caused a European air-traffic stand-still, is thought by some to have resulted from the recent rapid warming of high-latitudes. However, this is still hotly debated, with some scientists predicting a significant lag-time of around 2,500 years before we would see the effects on volcanic activity.

Will there be more future eruptions of Eyjafjallajökull? Source

   Similarly, the loading and subsequent unloading of ice due to rapid warming on active faults could cause earthquakes, and even submarine landslides that have the potential to cause tsunamis. GPS measurements have revealed that the crust beneath the Greenland ice sheet is rebounding due to warming, providing the potential for future earthquakes. There is a possibility that this could trigger submarine landslides spawning tsunamis capable of threatening North Atlantic coastlines (McGuire, 2007). In fact, history may repeat itself, as during the last Ice Age, the melting of the ice caused increased seismicity along the margins of ice sheets in Scandinavia, resulting in these submarine landslides (McGuire, 2012).

   Ice melt from climate change will predominantly enter the ocean, and additionally, as temperatures rise, the water in the ocean will expand in a process named ‘thermal expansion’ or steric sea-level rise (IPCC, N/A). Both these two factors will result in global sea level rise. This extra weight could apply extra pressure to faults near coastlines, effectively ‘bending’ the crust. This compression could push magma lying around underneath a volcano, triggering eruptions. For example, the seasonal eruptions of Pavlof volcano in Alaska tend to occur during the winter months when the regional sea-level is only 30cm higher than during the summer (McGuire, 2012), highlighting the sensitivity of some volcanoes to sea-level change.  Additionally, McGuire et al. (1997) examined the change in the rate of sea-level rise and volcanic activity in the Mediterranean for the past 80,000 years, finding that when sea level rose quickly, more volcanic eruptions occurred, increasing at a staggering 300%.

However, many geologists such as Roland Burgmann of the University of Berkeley, California are doubtful of the validity of these claims. They state that catastrophic rates of sea level rise in the future are uncertain, and that the current rate of rise - around 3mm per year (NASA, 2015) - is not enough to destabilise the crust. When researching for this article, I was surprised at how little literature seemed to address this issue, which perhaps indicates that it is of little cause for concern. What do you think?