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April 12, 2022

Volcanoes are an incredible feature of Earth’s geologic environment – at once awe-inspiring and terrifying. They remind us that the planet we call home is a dynamic entity all its own, and we are mere spectators to its forces.

You would have a hard time finding a more spectacular display of geological power or a more potent reminder of Earth’s potential dangers than an erupting volcano. That’s why up-to-date and accurate information about the hazards they present is so important. The USGS Volcano Hazards Program and the USGS Volcano Science Center both produce a variety of web resources that can guide you through everything you need to know about volcanoes.

Nighttime image of a volcanic vent fountaining and feeding an active lava lake
Lava erupting from the west vent within Halema‘uma‘u crater, at Kīlauea summit. Frequent large spatter bursts were observed at the west vent during a period of increased eruptive activity that lasted for a few hours on the evening of December 15, 2021. This photo was taken from the public viewpoint near Keanakāko‘i crater in Hawai‘i Volcanoes National Park. USGS photo taken by B. Carr.

A Burning Mountain?

First things first: What is a volcano? This brief overview walks you through volcano basis, including the different types, how many active volcanoes are out there, how they work, and why they erupt. Next, check out this USGS Factsheet that outlines hazards associated with volcanic eruptions. It’s not just about the explosion and lava flow. Understanding the totality of risk involved when a volcano erupts is critical for determining how you should respond when an eruption takes place.

2018 Volcanic Threat Assessment helps prioritize risk efforts at U.S. volcanoes
When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location. Assessing the relative threats posed by U.S. volcanoes identifies which volcanoes warrant the greatest risk-mitigation efforts by the U.S. Geological Survey and its partners. This update of the volcano threat assessment of Ewert and others (2005) considers new research in order to determine which volcanic systems should be added or removed from the list of potentially active volcanoes, updates the scoring of active volcanoes, and updates the 24-factor hazard and exposure matrix used to create the threat ranking.

If you’d like to dig a little deeper, check out this in-depth list of frequently asked questions that cover everything from USGS volcano monitoring to how you can become a volcanologist. There’s even a bonus section that explores how real-life volcanoes compare to what you see in the movies.

As with most things in science, there’s specific language and terminology related to the study of volcanoes (like "tephra" - see image below), so the USGS Glossary is a handy reference during your search for information.

Tephra (airborne lava fragments) erupted by the high lava fountains of fissure 8 was carried downwind, where the frothy rock fragments fell on Leilani Street, just past Kupono Street, in the Leilani Estates subdivision.

Inevitably, the question on everyone’s mind is, “Do I live near a volcano, and what’s the risk that one will erupt close to where I or my loved ones live?” The USGS library of volcano hazard assessments based on location is a resource that dates back decades. These reports are certainly more technical than some of the other resources included here; however, they are worth checking out to learn more about the level of risk for a location or region, and also to get a better understanding about the type of volcanic hazards that might occur during eruptions in a specific area.

Map showing the locations of all U.S. volcanoes
Map showing the locations of all U.S. volcanoes with their threat category designated by color. Very high threat is red, high is orange, moderate is yellow, low is green, and very low is blue. 

One important note: USGS volcano science is primarily focused on volcanoes located within the United States. Although we work globally with various international agencies, other nations have their own experts that study, monitor, assess and respond to volcano events within their borders. The USGS stands ready to assist our international partners should they ask for help, and we do this via the USGS/USAID-funded Volcano Disaster Assistance Program (a partnership program between the USGS and USAID’s Bureau of Humanitarian Assistance). Additionally, USGS partners with the Smithsonian’s National Museum of Natural History’s “Global Volcanism Program” which produces a weekly recap summary of volcano activity around the world.

 

Volcano Monitoring, Alerts, and Notifications

So, once you get the basics, I’m sure you’ll start wondering what USGS is doing about all this. Is the USGS keeping an eye on volcanoes? Is there a system to alert communities when they’re at risk? Is there a way to be notified when an eruption happens? Short answers: Yes, yes and yes.

There are a variety of ways volcanologists monitor volcano activity and assess the risks of an impending eruption and the cascading effects that can come with it. Comprehensive monitoring provides timely warnings of a volcano “reawakening,” which can yield critical information that helps communities prepare for an eruption event.

volcano monitoring
The USGS measures the activity level of a volcano with several different types of instruments. This graphic represents types of volcano monitoring in the corners, with associated methods used in italics.

In order to understand the types, threat level and associated risks of domestic volcanoes, the USGS employs a nationwide alert-level system for characterizing conditions of volcanoes in the U.S. The “U.S. Geological Survey’s Alert-Notification System for Volcano Activity” fact sheet is a great jumping off point for understanding this alert system and its history.

The USGS volcano monitoring network utilizes five volcano observatories around the Nation to make sure we’re monitoring activity in real-time. Volcano observatories issue updates and other types of notifications based on activity, and you can sign up for notifications via the USGS Volcano Notification Service (VNS).

man standing in room full of equipment, working on box on central work table
At the USGS Cascades Volcano Observatory Electronics Lab, technicians build, test, and prepare scientific instruments to be deployed for monitoring volcanoes worldwide.

Efforts to understand volcanoes, to assess the threats and risks of an eruption event and to analyze data to create response systems that help keep communities safe all rely on the tireless efforts of a unique group of dedicated (and in some cases fearless) scientists: Volcanologists!

 

Volcanologist: The Hottest Name in Science

Now that you’ve established some fundamental knowledge about volcanoes and how the USGS studies them, you might be curious to learn a little more about the hard-working people who risk life and limb to further our knowledge of these fascinating geological structures. Here’s a short video where you can get a quick look at what it really means to be a volcanologist.

Man standing with blue sky and volcano in background
Nathan Anderson is a volcanologist with the USGS Volcano Science Center based at the Cascades Volcano Observatory.

Volcanologist – Where does the name come from? (Spoiler alert if you decided to skip the video above)

Vulcan = Roman god of fire
vulcano = “burning mountain”
-ology = “study of”
-ist = “person”
 

So, a volcanologist is a person who studies “burning mountains,” and if that’s not one of the gnarliest jobs out there, then I don’t know what is. If you still have a burning desire for more information about what a volcanologist does, check out this short description from the USGS Cascades Volcano Observatory.

Color photograph of scientist monitoring eruption
USGS scientist takes video of the erupting west vent within Halema‘uma‘u crater, at the summit of Kīlauea. Photo taken from the northwest rim of Halema‘uma‘u at 12:27 p.m. HST on Oct. 8, 2021. USGS photo by J.M. Chang.

Living with, and Learning from, Volcanoes

At its core, volcano science is all about trying to understand how volcanoes work and helping communities prepare for when a volcano erupts. With over 160 active volcanoes in the United States, chances are you live closer to a volcano than you might think. Here’s a fantastic resource developed by the USGS in cooperation with the National Park Service called, “Living with a Volcano in Your Backyard.” It's a resource for teachers that focuses on Mount Rainier in Washington state, but it's a fantastic product for everyone who wants more information about volcanoes near where they live. At well over 700 pages, you might not need to read every page, but take it for a test drive, and you’ll find information that’s potentially useful to you.

Mount St. Helens Eruption
“On Sunday, May 18, 1980 at 8:32 a.m., the north flank of Mount St. Helens slid away in a massive landslide -- the largest in recorded history. Seconds later, the uncorked volcano exploded and blasted rocks northward across forest ridges and valleys, destroying everything in its path within minutes.” -NPS (https://www.usgs.gov/media/images/mount-saint-helens-eruption)

Every volcano is a different kind of “burning mountain,” so it makes sense that each one will behave differently before, during and after an eruption. The types of events you could experience could differ from region to region. As such, the USGS has developed a series of regional preparedness resources that will help you take necessary precautions.

A geologist remembers the Mount St. Helens eruption 37 years ago...
USGS geologist Don Swanson (in red) and his colleague, Jim Moore, view a car filled with ash deposits from the May 18, 1980, eruption of Mount St. Helens. Additional photos of the 1980 eruption of Mount St. Helens are posted on the USGS Cascades Volcano Observatory website: https://volcanoes.usgs.gov/volcanoes/st_helens/st_helens_gallery_23.html.

Lastly, while volcanoes are incredibly dangerous, each eruption allows USGS volcanologists to learn more about the character and history of these natural phenomena. For example, when Mount St. Helens erupted in 1980, the lateral blast travelled at more than 300 miles-an-hour, scorched 230 square miles of forest and became probably one of the most infamous eruption events in U.S. history. But did you know that around 3,600 years ago, indigenous peoples abandoned the area around Mount St. Helens when an eruption four times larger ripped through the landscape, devastating their food supplies and living dwellings – effectively destroying their livelihood? For more information like this, here’s a Factsheet about Mount St. Helens that’ll give you plenty of interesting volcano tidbits to bring up around the water cooler.

Trail at Mt. St. Helens
Visitors on a trail with Mt. St. Helens in the background

We hope you enjoyed this overview of the USGS volcano resources. We hope you’ll explore more about the fascinating world of volcanoes and the unique efforts USGS volcanologists undertake to study them!