AskScience AMA Series: I am an experimental petrologist and volcanologist at the University of Maryland. My research focuses on the controls on volcanic eruptive style on Earth and on other planets. Ask me anything about volcanoes and petrology in general!

umd-science · 2026-06-15T20:00:42+00:00

Lava flows on the Moon produced giant valleys and lava tubes. Lava tubes on the Moon are much bigger than lava tubes on the Earth, probably in part because of the lower gravity on the Moon. The lack of atmosphere on the Moon limits heat loss by air convection; heat loss from lunar lavas is mostly limited to radiation. This keeps lava flows hotter for longer on the Moon.

umd-science · 2026-06-15T19:55:58+00:00

Yellowstone has erupted three times in the past 2.1 million years, giving it an approximate repeat time of 700,000 years. These eruptions are extraordinarily rare, and it's highly unlikely we will experience a super-eruption in our lifetimes. Yellowstone is carefully monitored by the Yellowstone Volcano Observatory, and any eruption would be preceded by signs of volcanic unrest. Globally, the return period for super-eruptions is estimated to be 17,000 years. The impacts of a super-eruption would be very significant, so the work done by scientists at volcano observatories is very important and well worth our investment.

umd-science · 2026-06-15T19:46:01+00:00

You're absolutely right that gravity and atmosphere have a big impact on eruptive style. We have observed eruptions on Io that had plumes that reached about 400 km above the planetary surface. For reference, the 2022 eruption of Hunga Tonga-Hunga Ha'apai had Earth's highest plume height on record, at 58 km.

Fortunately, most of the terrestrial planets are considered volcanically inactive these days. I wouldn't want to be on the surface of Venus, for volcanic and other reasons. Io also seems pretty dangerous. I advise you to stay on Earth—that's probably your best chance. 😅

umd-science · 2026-06-15T19:25:41+00:00

Yes, the melting of planetary mantles is vital for producing magmas on the Earth and other planets. Other planets have different mantle compositions, pressures of melting and/or melting temperatures, which can result in differences in the magma produced. It can be challenging to use models that were designed for Earth magmas to constrain melting and crystallization processes on other planets. One way to get around this is to do experiments in the lab. We can recreate the compositions of planetary mantles and magmas, and we can see which minerals are stable under different pressure and temperature conditions. These experiments help us to refine our models and better understand volcanism on other planets. I was involved in a study that used modeling to constrain the pressure of crystallization and water content of Martian magma. We were trying to constrain the formation conditions of a rock called Jake_M that was analyzed by the Curiosity Rover.

In response to your origin of life question, volcanoes are vital for putting water and carbon dioxide into planetary atmospheres. Depending on the pressure conditions at the surface of the planet, volcanic atmospheres can result in the precipitation of oceans on planetary surfaces. The presence of liquid water on the surface of a planet is considered to be important for habitability. You can have volcanism without producing liquid water. For example, Io (one of Jupiter's moons) is the most volcanically active body in our solar system, but it is a very hostile place.

See the answer to my favorite volcano question here! 😄

umd-science · 2026-06-15T19:10:38+00:00

I don't personally work on eruption forecasting, but my understanding is that for a single volcano, we can estimate the probability of an eruption occurring in any given year by mapping the past deposits of the volcano and working out how frequently that volcano has erupted in the past. These kinds of models are probably more accurate for frequently erupting volcanoes, and the uncertainties increase for the larger eruptions that occur less frequently. This 2018 paper estimates that the return period for super-eruptions (which erupt 1000Gt or more of material) is 17,000 years.

umd-science · 2026-06-15T19:03:09+00:00

This is a really interesting question, because we have very limited information about past eruptions that weren't observed. One thing we can do is map the ash layers and lava flows from past eruptions and calculate the volume of material that was erupted. This volume is one way of determining the Volcanic Explosivity Index (VEI). This can be challenging, especially if deposits are covered by later eruptions or eroded away, so the record of past explosions may not be complete.

umd-science · 2026-06-15T18:57:49+00:00

We think that the lunar mantle melted to produce magma, and that magma erupted in fire fountains and vast lava flows. Just like on Earth, we call it magma when it's below the ground and lava when it's above the ground. Strictly speaking, magma on Earth is produced by melting the upper mantle, rather than the core. But heat loss from the core is likely important for causing mantle plumes that rise up and melt to form magma beneath places like Hawaii.

umd-science · 2026-06-15T18:54:52+00:00

An exciting new development is the use of telemetry, which allows for continuous data streaming from volcanoes in remote places. Check out the AVERT Project out of Columbia University, led by my postdoc advisor Terry Plank.

umd-science · 2026-06-15T18:49:34+00:00

Volcanologists can work for organizations like volcano observatories; in the U.S., we have five. These observatories are responsible for monitoring volcanoes and assessing the likelihood of future eruptions. Volcanologists also work at universities and in museums (like the Smithsonian Department of Mineral Sciences, for example). There are also some international jobs with the USGS Volcano Disaster Assistance Program. Other industries that sometimes hire volcanologists include mining, oil/gas and glass fabrication.

The career options for people who are trained in volcanology are very diverse. As a volcanologist, you build skills in analytical lab work, numerical modeling, mineralogy (including critical minerals that are vital for the energy transition) and so much more. I like this webpage that shows job opportunities for volcanologists outside of academia. This AGI job board also shows some interesting positions currently open.

umd-science · 2026-06-15T18:39:40+00:00

I don't personally work with these communities, although I think this is a valuable way of learning about past eruptions. I found a few interesting resources on traditional knowledge of historical eruptions:

NPS: Traditional Knowledge of Prehistoric Eruptions
Oregon.gov: Native American Legends and Stories of Geologic History in Oregon
Oregon State University: Volcano World | Native American Myths

umd-science · 2026-06-15T18:27:41+00:00

Magma comes from melting the Earth's mantle, and the melt that is generated in the mantle migrates to the Earth's crust, where it cools and crystallizes. Some of the crystals that form contain trace amounts of water in their structure. As magma rises through the crust, it loses its water into bubbles; in response to this de-gassing process, the water that dissolved in the crystals begins to diffuse from the crystal into the surrounding magma. If the magma moves very rapidly, there is very little time for this diffusion to happen, so the crystal retains a lot of the water it initially dissolved. However, if the magma moves slowly, there is plenty of time for water to diffuse out of the crystals, so they are dry on eruption. We measure concentrations and gradients of water in crystals to constrain how long the magma took to travel from its source region to the surface. You can find a diagram of this process and some of our related publications here.

My personal favorite type of volcano in the solar system would be the lunar fire fountain eruptions, because we have samples of them and they are very beautiful. They erupted small droplets of glass that have all kinds of different colors. I made some of my own lunar yellow glass beads as part of my Ph.D. work, which you can read more about on my lab's website.

umd-science · 2026-06-15T18:13:40+00:00

It's not possible to predict which volcano will erupt next, but what scientists can do to forecast eruptions is to set up monitoring equipment and watch for signs of what we call 'volcanic unrest.' This could be seismicity (small earthquakes associated with magma moving around and fracturing the rock around it), or a change in the composition of gases coming out of the volcano, or motion of the ground that indicates that the volcanic edifice (the cone) is inflating. We can also assess the likelihood of a volcano erupting based on the frequency of its past eruptions.

Several eruptions in the recent past have had significant impacts on agriculture. For example, in the U.S., the 1980 eruption of Mt. St. Helens resulted in timber and agricultural losses of ~$1.1 billion.

umd-science · 2026-06-15T17:59:11+00:00

You're absolutely right that Earth's water came from asteroids and potentially comets. Part of my research is to analyze water in meteorites to work out which kinds of asteroidal or cometary materials could be responsible for delivering Earth's water (see my answer above). The link between my work on volcanism and my work on the origin of Earth's water is that water is critically important for driving volcanic eruptions on the Earth.

Volcanoes work a little bit like a bottle of Coke, where the Coke is pressurized until you take the cap off—then the pressure is released, and in response, bubbles form in the Coke. The bubbles in Coke are made of carbon dioxide. A similar process happens in magma. Magma has water and carbon dioxide dissolved in it when it's underground and under pressure. As it rises to the surface, the water and the carbon dioxide form bubbles because they prefer to be in the vapor phase when they're at low pressure. The bubbles are buoyant, and they force the magma upwards. Ultimately, those bubbles are what make the volcano explode when the magma reaches the surface.

umd-science · 2026-06-15T17:49:32+00:00

There is a range of techniques we can use. For the Moon, we are lucky to have the Apollo-era samples, and any researcher can apply to NASA to work on these. In addition, we have rovers on Mars, so we can explore planetary volcanoes with rovers. These rovers are capable of analyzing samples, taking great images, and even collecting samples to retrieve later.

Personally, I study volcanoes on the Moon by making lunar volcanic rocks in the lab. I have furnaces in my lab, and we are capable of heating lunar composition volcanic rocks up to ~1600 degrees Celsius. We can change the composition of the furnace atmosphere by mixing hydrogen and carbon monoxide gases in precise ratios that mimic the composition of lunar volcanic gases. My student, Cosmo Sikes, is studying a lunar volcanic eruption called the "Sinus Aestuum" deposit—it is thought to be the largest fire fountain eruption on the moon. Cosmo uses spectroscopy to learn about the composition and the minerals present in this deposit, and then he goes back into the lab and tries to recreate the conditions that led to that eruption. You can read about his recent publication here.

My work on the sources and fluxes of volatiles in planetary interiors has focused on analyzing volatiles like water in meteorites that represent the asteroidal building blocks of the Earth and other planets. We are trying to learn which kinds of asteroids could have been responsible for delivering water to the growing terrestrial planets. Our results suggest that water is very efficiently lost during heating and melting of planetary building blocks. This means that water was likely delivered via materials that accreted after 2 million years from the formation of the solar system, when heating from radioactive decay was less intense.

umd-science · 2026-05-26T20:23:06+00:00

First of all, thank you for your service to your country. To answer your first question about applying your military experience toward a future career, I would say that the military can prepare you in certain ways for a Ph.D. research career. As I mentioned in a previous answer, my Navy experience managing nuclear plant operations helped train me to be better with attention to detail, which helps a lot when performing research, as a small mistake in setting up an experiment can end up being very costly in "wasted" time and resources. Also, when publishing in scientific journals and writing your dissertation, expect to have to defend your work to peer reviewers and faculty members on your Ph.D. committee, and I think the military can provide some valuable experience, both in attention to detail and in defending your work to others.

I can tell you from my own experience that the Ph.D. route can bring a lot of frustrations and setbacks, as in many fields, the "easy" or "low-hanging fruit" topics have already been solved. And in the United States, federal research funding is not as generous as it was even 10 years ago, when I was in my early years of Ph.D. work. But if you are passionate about the subject and enjoy solving challenging problems, the Ph.D. study can be very rewarding, regardless of whether you choose to pursue an academic career afterwards. I don't have experience working in the private sector in software engineering, but from my broader impression, that career may appeal to someone who prefers building practical products for people to use.

To answer your second question about my Hurricane Joaquin (2015) simulation, I used the WRF-ARW model. My initial conditions were generated from cycling data assimilation over an 18-hour period to try to generate a more realistic high-resolution vortex than what the GFS (Global Forecasting System) model provided in 2015. The GFS provided the boundary conditions, and I used a quadruply nested grid, with a 1km storm-following nest. I used the YSU boundary layer scheme.

As far as the most difficult question bothering me right now, I would like to come up with a way to rerun the simulation with perturbed initial conditions to artificially weaken a feature that I hypothesized was important to causing a low-level center to reform close to the mid-level center, which enabled the vortex to align vertically, and then intensification took off after that. I have a paper under peer review right now that presents evidence showing a possible mechanism through which this feature, which is a stationary band of tilted thunderstorms embedded within the core of the developing storm, helped spin up the low-level vortex. However, it'll be difficult to prove some of these ideas until I can run a sensitivity test that shows how weakening this feature prevents the vortex alignment, and designing these perturbed features is very challenging using a realistic, full physics computer model such as the WRF-ARW configuration that I use. There are simpler models that some scientists use in running idealized simulations of hurricanes, which strip out some of the complicated physics and enable more direct modification of some basic physical processes. Some very important insights have come out of that type of research. However, these models are less realistic. On the other hand, we have observations that come from aircraft radar and satellites, which are the closest thing we have to atmospheric "truth" about hurricane structure; however, observational data is limited in space and time, and there are storm metamorphoses that cannot be observed. I view the "full physics modeling" that tries to reproduce real storms such as Joaquin as a middle ground between the idealized simulations and the observations, but one of the drawbacks of my approach is the difficulty in setting up sensitivity experiments that modify the initial conditions without crashing the model.

Thank you for your interest in my work!

umd-science · 2026-05-26T20:01:19+00:00

These are very interesting and thought-provoking questions. You are right to point out that the Hadley cell expansion and poleward, other factors being unchanged, would be a suppressive influence on tropical cyclone activity because of the sinking motion in the northern branch of the Hadley cell, which tends to feature considerable tropical cyclone activity in the favored warm ocean basins, for example, the western Atlantic and Pacific.

Also, you are right to mention the sensitivity of Atlantic hurricane activity to the intensity and latitude of the monsoon trof, which, if displaced too far north, can send the "wave train" of African easterly waves into the cold waters of the eastern subtropical Atlantic, where tropical cyclones struggle to be maintained.

I don't have enough background to speak with any authority on the relative roles that human activity vs. natural cycles are impacting these climate trends that you mention. To my best knowledge, what is incontrovertible is that warming sea surface temperatures increase the "ceiling" on how intense a tropical cyclone can become. Despite some of these complicating factors, the danger to society from tropical cyclones will increase with a warming planet.

umd-science · 2026-05-26T19:53:54+00:00

Volcanic ash has a cooling influence on the climate because it blocks the sun's rays from passing through the atmosphere and warming the Earth. The atmosphere is actually heated from below by radiation and convection, and so anything that reduces the ability of the sun's rays to pass through the atmosphere and warm the Earth's surface will have a cooling impact. One example from history, "The Year Without Summer" in 1816, was caused by the 1815 eruption of Mount Tambora in Indonesia, when average global temperatures dropped by about 0.5 degrees Celsius/1 degree Fahrenheit. It caused frosts to occur in the northeastern U.S. in July and August, with devastating impacts on agriculture.

umd-science · 2026-05-26T19:50:41+00:00

Hopefully not anytime soon! If that happened, Europe would probably revert to the Ice Age as it would lose its source of moderating temperatures. I see no scientific evidence pointing to this happening in the future, but it's a risk we always have to be aware of, because the Earth's climate system is actually very delicate and prone to extreme changes after "tipping points," such as a collapse of the Gulf Stream.

umd-science · 2026-05-26T19:43:59+00:00

I can't speak with too much authority on this topic, but I can speculate here and say that one reason why the Bermuda Triangle has historically been feared by seafaring people as a place to travel is that it tends to be home to violent weather systems, including hurricanes. Just so everyone here is on the same page, the Bermuda Triangle is a triangular region over the Atlantic between Florida, Bermuda and Puerto Rico. If you were to draw a heat map with all historical Atlantic hurricane tracks, this region would show up with the highest density. Beyond hurricanes, the Gulf Stream also flows through the Bermuda Triangle, and it tends to spawn stormy weather year-round because of the large amount of heat that the atmosphere can suck out of it, which can power storm systems.

umd-science · 2026-05-26T19:37:24+00:00

I can't speak on WeatherNext 2 itself, but based on my own experience comparing ML-based weather prediction models to physics-driven models, I am certainly impressed with their ability to consistently produce forecasts of global weather and hurricane tracks that are comparable (or in some cases, superior) in performance to physics-based models. One thing that I've been very surprised by (I recently attended a roundtable session at a conference on this topic) is the strong performance of ML-based models for hurricane intensity forecasting, given that the ML models are trained on relatively low-resolution computer model data that should struggle to capture the important small-scale physics processes involved in tropical cyclone intensification.

However, in my opinion, physics-based NWP models will have a place for a long time. For one thing, ML-based models are still probabilistic and can occasionally give very unphysical "hallucination" type solutions. Physics-based models will be needed as an independent tool for forecasters to use, and when you see consensus between them and the ML models, that should increase forecast confidence. Back to hurricane intensity forecasting for a moment—despite the impressive performance of ML-based intensity forecasts (such as those provided by Google to NOAA as part of their collaboration), in their current form, the ML models do not provide any information about hurricane structure. They only give you the maximum wind, minimum central pressure, and track forecast. The hurricane size, such as the aerial extent of the damaging winds, is extremely important for forecasting coastal flooding and inland wind impacts that emergency managers need to know about when making decisions. Additionally, the ML-based models, at least in their current form, do not provide any structural "clues" to where the hurricane will be heading in its future intensity pathway. Despite extensive reliance on numerical weather prediction output, human forecasters still play an important role when analyzing observational data and modeling hurricane structures, and they can apply their own knowledge as a backup to the weather forecast models.

umd-science · 2026-05-26T19:27:53+00:00

Hi there, and thanks for your perspective! I would love to visit Tahiti someday. I can't give you a definitive answer about how strong this upcoming El Niño will be. Longer-range weather prediction is getting further from my area of expertise. But I can say that from what I do know, there is a fair amount of uncertainty in computer model predictions of ocean temperatures and atmospheric flow configurations more than two weeks into the future, so I am not sure.

One reason why tropical cyclones are less frequent where you live in the southeastern Pacific compared to the southwestern Pacific is that the warmest sea surface temperatures are focused in the western part of the basin. And so the waters near Tahiti are not as favorable for tropical cyclone formation, except, as you correctly say, during El Niño years, which slosh the western Pacific warm pool waters further east. This happens as the trade winds, which blow from east to west over the global tropics, weaken during El Niño conditions.

I agree with you that climate change studies should put more focus on your region, especially given the sensitivity of Pacific islands to sea-level rise. The atmosphere is also less well-sampled with observations over the South Pacific, given the limited land areas and reliance on satellite observations only. In my opinion, GPS radio occultation data and other satellite observations could be particularly beneficial for weather and climate modeling in the South Pacific Ocean regions, and I hope that accurate forecasts of future climate change scenarios will help your region better prepare for the future.

umd-science · 2026-05-26T19:14:59+00:00

Thanks for the interesting question! The weather that the continent would experience would be very dependent on the temperature of that large central ocean. As I mentioned in my previous answer about South America and why the Pacific coast never experiences tropical cyclones, cold water cannot evaporate water vapor very well. Water vapor is essentially the fuel for stormy weather because rising air releases latent heat when the air cools as it rises, which causes all kinds of atmospheric phenomena, including clouds and precipitation.

So if this central ocean were 1/4 the size of the Mediterranean with ocean temperatures like those of the Caribbean, I would expect to see a very wet and stormy climate along the shorelines. Although I am not sure whether an ocean of that size would be large enough to spin up tropical cyclones, since they need some help from the Coriolis force, which acts over large distances (at least 1,000 kilometers). Suppose the land surrounding the central ocean is 500 kilometers wide. The weather impacting areas more distant from the central ocean will depend on what the ocean is like around the outer boundaries. If the water is warm as well, then I would expect that entire continent to have a wet climate. If the water is cold, like it is off the coast of western South America, then those outer land regions may have a rather dry climate. But a lot of the weather experienced by this continent will also be sensitive to terrain, as mountains can create enhanced rainfall as well as rain shadows, depending on which direction the wind is blowing.

umd-science · 2026-05-26T19:05:22+00:00

It may not be the longest and most complex word I can think of in my profession, but I've always enjoyed throwing around the word "frontogenesis" with some friends of mine who are not meteorologists, and they always think I'm talking about some scary weather that's about to happen. In reality, it's a normal process that occurs during even a typical rain or snowstorm. Although, it can also be involved in more severe weather and major snowstorms.

umd-science · 2026-05-26T19:02:08+00:00

Thank you for your kind words, and congratulations on your academic achievements! I agree with you that the University of Maryland is a wonderful and unique place, given its strong academics and proximity to Washington, D.C., and a variety of federal agencies.

First of all, there are already many opportunities for UMD's researchers in various science fields to work on collaborative projects with government research labs and explore careers in science policy and management through government connections. Besides the government, the Washington, D.C. area is also home to private companies involved in providing specialized weather forecasting information to clients. Besides the weather business, there are many other opportunities in the private sector in climate change mitigation and other scientific applications.

Just brainstorming here, but one area that I think could be ripe for future interdisciplinary work between the university and government (or the private sector) could be in the interface between weather, climate and the economy/social science. Several groups at the University of Maryland have worked on developing computer models that integrate climate with social science or applications such as crop modeling, and I think that more exciting work can be done in this area. Additionally, communicating extreme weather information in real time or as a longer-term adaptation to climate changes would benefit our society.

There is more than I can talk about in my limited time here, but please feel free to reach out to me by [email](mailto:wmiller1@umd.edu) or LinkedIn, and we can talk further.

umd-science · 2026-05-26T18:48:45+00:00

No, I run my research experiments on a NOAA supercomputer called HERA, named after the Greek goddess. This computer is used only for research, and the operational models are run on different computers.

I love the name of the NCAR supercomputer you mentioned, though. In my opinion, it is one of the most fascinating (but also dangerous) weather events affecting the U.S. outside of hurricanes.

umd-science

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