A New Report Ranks America's Most Threatening Volcanoes. Here Are The Facts
The United States Geological Survey (USGS), back in 2005, released a comprehensive and somewhat groundbreaking report on the volcanic hazards that people face in the US. Now, just this week, an update – a sequel, if you will – to the original was released.
Named the National Volcanic Threat Assessment (NVTA), it reveals and explains what the country’s most potentially hazardous volcanoes are, and why. At number one? That would be Kilauea, the Hawaiian volcano that made headlines throughout the summer as it ploughed through 700 homes while creating the youngest land on Earth.
Before we dive in, it’s important to clarify what this report isn’t saying. That way, any misconceptions can be dispelled quickly – an evidently important task when it comes to speaking about geological hazards or threats.
So: this report doesn’t in any way state or suggest which volcano is the most likely to erupt next. It is not a prophetic document.
Predicting with any precision when a volcano is next about to erupt, particularly for volcanoes more prone to explosive-style eruptions, isn’t possible. Forecasts can be made using long-term probabilistic calculations, and sure, volcanoes often give some degree of warning before they blow their tops, but no-one can say with any confidence which volcano is the next to put on a fireworks display.
It’s also worth emphasizing, as I’ve tried to many times in the recent past, that volcanoes by themselves aren’t hazardous. In this regard, it doesn’t matter if an eruption takes place and no-one’s around to experience it. Explosivity, contrary to what you might intuitively think, isn’t a proxy for destructive potential.
As with any geological phenomena, human populations make the hazards by being anywhere volcanic eruptions may reach. You don’t even have to be within range of any lava flows or pyroclastic density currents to be threatened: ash plumes can blanket landscapes over vast areas, and they can bring down airplanes if they are undetected.
This report doesn’t look at how well monitored each volcano may or may not be. Reports like this serve as a roadmap that guides the USGS in its monitoring efforts. Constrained by the annual budgets Congress grants, its staff can’t research and monitor each volcano equally – they have to make tough choices, so this report helps them do that.
What this document is, then, is a way to highlight which volcanoes have the potential to cause the most damage to human populations during future eruptions. Damage, in this case, isn’t solely referring to possible human deaths, but the possible economic, agricultural and infrastructural damage too.
The report clearly took a lot of work to put together. The US has 161 geologically variable and active volcanoes, which is roughly 10 percent of Earth’s total. Fourteen different US states contain volcanoes that appear in this threat assessment, with Alaska containing the lion’s share (86). All 161 have come to life at some point during the last 12,000 years or so.
Getting input from every single one of the USGS’ volcanic observatories scattered around the country, the authors of the report numerically rank all 161 volcanoes using 24 different criteria. These include, but aren’t limited to, how often it tends to erupt in a given time period, if it produces lethal pyroclastic flows or not, if it has a particularly paroxysmal history, if it’s covered or capped in water or ice, if it’s near an airport (or flight path), if it’s near major power infrastructure, if it’s near major or sensitive human developments, and so on.
As John Ewert, a volcanologist at the USGS Cascades Volcano Observatory and the report’s lead author, explained on a conference call, the numbers themselves aren’t that important. A single change in any one of these 24 factors can alter the rankings, and you can’t really definitively say which one is the most dangerous of all because you can’t be sure what a future eruption may be like.
Each volcano is idiosyncratic. Its threats may change over time depending on how its magmatic system evolves, and how humans evolve around it. Instead, Ewert noted, the best thing to look out for are the broader categories, of which there are five: Very High Threat, High Threat, Moderate Threat, Low Threat, Very Low Threat.
As it happens, the 2005 assessment was pretty much bang on the money when it came to ranking the most threatening volcanoes. All 18 that appeared back then are the same now, for pretty much the same reasons. They are:
1 – Kilauea
2 – Mount St Helens
3 – Mount Rainier
4 – Redoubt Volcano
5 – Mount Shasta
6 – Mount Hood
7 – Three Sisters
8 – Akutan Island
9 – Makushkin Island
10 – Mount Spurr
11 – Lassen volcanic center
12 – Augustine Volcano
13 – Newberry Volcano
14 – Mount Baker
15 – Glacier Peak
16 – Mauna Loa
17 – Crater Lake
18 – Long Valley Caldera
Would you look at that? No Yellowstone. If you’re wondering why that’s languishing at #21, I’d suggest clicking here. Supervolcanoes are not what you think they are; they certainly aren’t civilization-ending monsters.
The Very High Threat category is a great way to demonstrate how different eruption styles and geographic settings equate to variable and impossible to equate dangers. Kilauea’s there at #1 because it’s America’s most active volcano, and plenty of people and developments are situated on its flanks. St Helens is an often-explosive volcano that produces lethal pyroclastic flows, and Rainier – while not as explosive – can generate volcanic mudflows that could swamp highly populated valleys downslope from the vent, even if the volcano doesn’t properly erupt.
The authors underscore that volcanic ash risks with regards to aviation were a major consideration here, as they were in 2005. As Ewert put it: “there are no remote volcanoes – very distant volcanoes may affect you in ways you haven’t considered.” That’s partly why 5 of the 18 in this category are found in Alaska; some are near populations, but many of these snow-capped mountains are capable of producing sustained, high ash columns that can severely disrupt air travel much in the way Iceland’s Eyjafjallajökull did in 2010.
The NVTA has undergone some changes since 2005; a better understanding of the volcanic history of America’s volcanoes meant that several from the lower end of the list were dropped, for example, while some have gone up in the rankings. If you’re interested, you can click here and read the full report yourself to find out why each volcano is placed where it is on the list.
To my mind, the takeaway message of this document isn’t really about the ranking. The document – made public so anyone can read it – underscores that the USGS is doing all they can to keep an eye on a vast number of novel volcanoes, each with their own potential dangers. This is unquestionably an invaluable service, for which Congress has decided, for the fiscal year 2019, the agency has $1.1 billion to tackle.
They may sound like plenty, but as I’ve previously explained, that’s not much compared to, say, NASA, which gets $20.7 billion. The nation’s defense budget comes in at a whopping $686 billion. The USGS, comparatively speaking, has to do a heck of a lot for what isn’t really that much money.
High-risk American volcanoes are indeed monitored, but not perfectly. As Tom Murray, Director of the USGS Volcano Science Center and coordinator for the various volcano observatories, said on the same conference call, there is indeed a monitoring deficiency on most of the volcanoes. He added that the goal is to improve volcanic monitoring wherever possible.
At the moment, monitoring depends on opportunities, funds, and time. Priorities have to be made, which is as aforementioned partly why the NVTA exists. As pointed out by The Atlantic in 2017, and the USGS itself, even volcanoes that are heavily monitored often have information gaps linked to a lack of coverage or not quite up-to-date monitoring equipment.
Although the USGS staff cannot speak on this matter, this assessment indirectly highlights how much the agency deserves more funding than it’s currently getting. If its funding were to increase, America will no doubt be in safer hands.
The USGS ultimately wants to set up a National Volcano Early Warning System, or NVEWS. This is, in its own words, “a proposed, national-scale plan to ensure that volcanoes are monitored at levels commensurate to their threats.” It isn’t all about monitoring: it’s part of a package that would fund more basic research, increase partnerships with local governments and emergency responders, boost computational processing capabilities, and add staff.
NVEWS would ensure that the most threatening volcanoes, kept an eye on 24/7, would have a far lower chance of catching scientists and communities by surprise should they decide to erupt. No-one in their right mind would not want this to exist, so it’s a shame that the USGS cannot currently make it a reality.
One last thing: volcanoes are not just things to be feared and threatened by. They are, lest we forget, hugely responsible for forging the land we live on, and for carving out the natural beauty we are so fortunate to be able to experience. America, home to 10 percent of the world’s active volcanoes, is uniquely spectacular in this sense, and people from all over the world fly into the country to see its volcanic marvels.
This report may be about assessing volcanic threates, but inadvertently, it’s a showcase of how volcanologically diverse the US is – something few other countries can match up to.