This is a writeup of a shallow investigation, a brief look at an area that we use to decide how to prioritize further research.
In a nutshell
- What is the problem? Large volcanic eruptions, though rare, could have an extremely negative humanitarian impact.
- What are possible interventions? Based on current knowledge and technology, large eruptions cannot be prevented, but further research may improve the prediction of eruptions and allow for some mitigation of humanitarian impacts.
- Who else is working on it? Although scientific organizations fund some basic research on volcanic eruptions, we are not aware of any organizations explicitly working to reduce the humanitarian risk from large eruptions.
1 Why did we look into this area?
- Large eruptions could have extremely negative impacts on human welfare, mainly through adverse effects on the global food supply. The potential catastrophe is so great that an investment in research could conceptually have high returns.
- Large eruption risk appears to be more quantifiable than some other global catastrophic risks (e.g., nuclear war).
2 What is the problem?
In addition to local destruction, large volcanic eruptions could have a significant negative impact on the global food supply.1
Volcanic eruptions are classified based on the volcanic explosivity index (VEI), which measures eruption magnitude on a logarithmic scale.2 Our understanding of the current scientific understanding of the relationship between VEI, frequency of eruption, and likely humanitarian impact is:
- An eruption of VEI ≥ 7 is likely to occur every few hundred years.3 Such an eruption may have global effects, including cooling the earth’s atmosphere, harming food security, or interfering with plane travel.4 The most recent VEI ≥ 7 eruption was of Mount Tambora in Indonesia in 1815, which is believed to have resulted in crop failures as far away as New England during the following summer.5
- Previous estimates have suggested that an eruption of VEI ≥ 8 is likely to occur roughly every 30,000 years,6 though more recent (unpublished) research suggests a higher frequency, in the range of an eruption every 10,000-15,000 years.7 Such an eruption is likely to eject ash that could cover millions of square kilometers with deep ash, potentially causing major crop failures.8 A major disruption of this kind could have very destructive second-order effects (such as increasing the likelihood of conflict).
- Estimates about the frequency of eruptions of VEI ≥ 9 vary by several orders of magnitude: we have seen frequency estimates ranging from roughly every 30,000 years to roughly every 30 million years.9 This disagreement over frequency may stem from an underlying disagreement about the classification of different eruptions,10 but also may be a result of the most recent data being as yet unpublished.11 While a VEI ≥ 9 eruption would be much worse, from a humanitarian perspective, than a VEI ≥ 8 eruption, there seems to be agreement that such an eruption is unlikely to lead to human extinction (especially to the extent that the true frequency of VEI ≥ 9 eruptions is at the higher end of the reported spectrum, which would imply that humanity has survived such eruptions in the past). Incredibly extreme eruptions could conceivably cause human extinction, but such eruptions are both extremely rare and difficult or impossible to prepare for.12
The frequencies cited above are associated with significant uncertainty,13 and we have not vetted them thoroughly.
Although some volcanoes appear to have a fairly stable average frequency of eruptions, there is nonetheless a large amount of variation in the timing of individual eruptions (i.e. information about the average period of a volcano and its last eruption does not necessarily imply much about when its next eruption might be).14
3 What are possible interventions?
Our understanding is that large eruptions cannot currently be prevented, and that there are not technologies on the near horizon that are likely to change that.15
Accordingly, opportunities to address the humanitarian threat of large volcanoes are likely to focus on research and preparation.
Stephen Sparks, a prominent volcanologist who we spoke with, said the following about potential interventions:16
Possible interventions to address very large volcanic eruptions are:
- Better modeling of what would happen in the event of a very large eruption, so as to better prepare to for the contingency
- Improving eruption prediction capacity, for example, by identifying new volcanoes with high potential for large explosive eruptions.
- Monitoring and characterizing the history and interior structure of these volcanoes.
It is currently possible to use satellites to identify volcanoes showing unrest, which may be sign of imminent eruption. However, it’s not currently possible to be sure that these volcanoes will erupt or how large the magnitude of the eruption will be. It’s difficult to develop methods for determining the magnitude of a potential very large eruption, because very large eruptions happen sufficiently rarely so that data are lacking, and because techniques for imaging the inside of volcanoes are not good enough yet.
If it were possible to determine the amount of magma inside of a volcano near eruption, one could determine those that have the potential for very large eruption. So working on improving imaging techniques could be valuable for predicting very large eruptions.
We also spoke with Sean Brocklebank, an economist and GiveWell supporter. He said:17
Large volcanic eruptions can’t be stopped with current or easily foreseeable technology. Perhaps the best strategy for damage mitigation is to first get better at detecting pending eruptions, and then if we get a few years’ warning on a massive eruption, turn attention toward how to prepare.
Monitoring
While we can’t currently predict medium-size eruptions (of the type that happen every few years), there are reasons to expect that we might be able to detect VEI 8 eruptions years in advance, due to the types of deformations that seem to have occurred prior to such events in the past. See the Nature article, “Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano” by Druitt et al, 2012.
Some monitoring is already happening, in many cases as a side effect of earthquake studies. But the data is incomplete and not linked together across the world…
Preparing
Since the biggest damage is to food supply, preparing would likely center around building up a large food supply (perhaps partially by reducing the portion of crops going to livestock), developing a plan for getting the food to the ash-covered areas that can’t produce any food for a year or more, and planning for temporary alternate patterns of cultivation around the world to deal with global temperatures which may be 5 to 15ºC lower for a period of several years.
We do not have a strong sense of how much the relevant research or preparation might cost or what the most likely returns would be. Stephen Sparks estimated that the Global Volcano Model, a project to collect better data about the historical occurrence of volcanic eruptions, likely cost around a million dollars.18
4 Who else is working on this?
We do not have a clear sense of how much funding is spent on research on large volcanoes, but we understand it to be a relatively small amount, mostly coming from basic research funders like the National Science Foundation.19
We are not aware of any major organizations that are explicitly attempting to work to address the humanitarian risk of large volcanic eruptions, though we have come across two groups of scholars that are working to address this issue.20
5 Questions for further investigation
Our research in this area has been relatively limited, and many important questions remain unanswered by our investigation.
Among other topics, our further research on this cause might address:
- How do volcanoes compare in likelihood, severity, and preventability to other catastrophic risks like near-earth objects? Our current understanding is that for a given level of humanitarian harm, volcanoes are a much larger risk than asteroids.21
- How likely is future research to pay off in information leading to better mitigation?
- How much is currently spent on research on large volcanic eruptions?
6 Sources
| SOURCE NAME USED IN FOOTNOTES | LINK | ARCHIVED LINK (FOR EXTERNAL FILES) |
|---|---|---|
| Aspinall et al. 2011 | Source | Archive |
| Brocklebank conversation | Source | – |
| Sparks conversation | Source | – |
| Self 2006 | Source | Archive |
| Global Volcano Model Network | Source | Archive |
| Geohazards Community of Practice | Source | Archive |