Volcanology is one of the most dangerous jobs in science -- mainly because flying in helicopters around active volcanoes has a history of leading to serious accidents. But it’s also because a volcanologist’s job description includes getting up close and personal with molten-hot lava.
Tim Orr, the head Geologist at the U.S. Geological Survey’s Hawaiian Volcano Observatory, grew up in Montana, not far from Yellowstone National Park (which owes its geysers, hot springs, boiling mud pots, and steam vents to the fact that it sits on top of a hotspot and is sometimes referred to as a supervolcano). In 1980, when Mount St. Helens erupted Orr’s house happened to be downwind. “As a 12 year old boy I woke up to ash on my parents car. I was glued to the tv for weeks afterwards,” he says.
It’s no wonder that he went on to study geology and then head to Hawaii where he worked his way up the ranks of the HVO (it's also a photo of Orr at work that you see on the Wikipedia page for volcanologist). Now in charge of monitoring changes in the just about 30-year-long eruption of Mount Kilauea, Orr chatted with us about what it’s like to have an office at the top of a volcano.
Why do we study volcanoes?
Well, a significant portion of the Earth’s population lives in the shadows of dangerous volcanoes. Volcanology is geared towards trying to understand them -- why they erupt, when, what the dangers are -- all for the purpose of trying to mitigate the hazards. On Kilauea, we’re looking at a volcano which is relatively calm, compared to the others. Hawaiian volcanoes erupt more effusively, in a manner which is more approachable. Kilauea doesn’t usually send out widespread ash clouds that blanket wide areas. Most of the eruptions are comparatively benign so you can study how a volcano works in a relatively safe fashion. Interestingly, the repeat interval for ash-producing explosive eruptions at Kilauea is on par with that for Mount St. Helens.
What makes Kilauea so comparatively calm?
The Hawaiian volcanoes erupt basalt magma. There is less silica in basalt, so the lavas are not as viscous -- they’re more fluid. Other volcanoes that have more silica have magma that’s more viscous, so instead of flowing the magma is torn apart and forms ash.
Hawaii is located within the middle of an oceanic plate at what’s known as a hotspot. Some other volcanoes are on island arcs or continental margins so the magma has different composition (where there are thicker crusts). Most of the volcanoes that we hear about on the news are on island arcs or continental margins, but not all.
The oceanic crust is thinner in Hawaii -- thinner than continental crust -- and it has a different composition.
So it’s easier for the magma to come to the surface?
All magma rises through the earth due to buoyancy. Hot magma rises from the mantle here in Hawaii because there’s more heat in this area (the reason is unknown). But when you have more heat, which causes the hot mantle to buoyantly rise, as it reaches shallow levels the molten portions escape.
So it doesn’t push its way up as much as it rises like hot air?
Exactly. In Hawaii the magma always rising. It never stops. Once the molten magma separates from the mantle, the remaining mantle material moves out of the way, cools, and eventually sinks again. There are portions of the mantle which separate and continue to rise along an established pathway and eventually they reach neutral buoyancy and they balance and you have a magma chamber--an area within the crust where magma is able to pool.
Does that mean when the chamber is full the magma then comes to the surface?
There are theories on why it comes out. Maybe the rising isn’t constant so you have pulses and variations in the amount. You suddenly add more magma to it and it begins to inflate and over-pressurizes the chamber until it can no longer contain what’s in it and it pushes to the surface.
What’s your role in all this?
At Kilauea right now the volcano is erupting in two locations. There’s a summit eruption where the magma is rising up into a lava lake contained within a small crater. The magma rises up, cools, degasses, and sinks back down. But it’s not flowing because it’s contained within a crater. There’s also lava erupting from the East Rift Zone, about twelve miles to the east of the summit. It’s all the same system--it’s a connected conduit system erupting in two locations.
My job as the boots-on-the-ground Geologist is to monitor the geologic activity. It’s an observational science. I document the activity. Where the lava’s going, behaviors of the lava, how the eruption is evolving, and the behavior of the eruption. I collect lava samples for analysis to determine changes in the chemistry of the lavas and changes in temperature. We notify the Hawaii County Civil Defense if there’s a dangerous situation and we work with them and inform them of situations if necessary.
Last year there were flows that were approaching and entering a small subdivision so we were out every day monitoring lava flow progress and looking to see if there were flows that were going to be imminently threatening to any of the houses there.
In that case people have to evacuate. The advantage that Hawaii has and the flows we’re dealing with on the current eruption is that they are fairly slow so people have time to plan ahead.
What’s the average speed of lava flow?
Only in rare situations in Hawaii is lava moving faster than a person can walk.
On the East Rift Zone eruption, which has been going on since 1983, the flows are mostly in the national park or on state lands, but as they approach the coastline where people live, the coastal area has very low slope--almost flat--and when the lava approaches and crosses the coastal flats it’ll travel a few hundred meters a day (that’s 300-400 yards or .2 miles).
In other situations it could advance more quickly or slowly depending on if it spreads out or if it’s confined by topography. It’s not like on TV. It’s moving very slowly. Only in rare situations in Hawaii is it moving faster than a person can walk.
At the Mauna Loa volcano, that’s the next volcano over, when it erupts it produces flows that move extraordinarily fast it can travel 20 miles in a couple of hours.
Kilauea could do that too under certain situations.
How exactly do you go about monitoring all this change? Do you get to ride around in helicopters!?
We do an overflight of the volcano’s erupting areas. At most it’s about once a week. In the last year or so it’s been about every two weeks for budget reasons. We fly over the eruption because the volcano’s big. I could hike out to the areas and do an overview by walking but it’s a huge area -- the East Rift Zone eruption lava flows cover an area of 48 square miles. We only fly over the active portion, so we fly 12 miles down to the erupting vent, travel down the flow field from the vent to the ocean, which is 6 miles.
We’re just getting a synoptic view of the eruption. It’s an overview. Looking at changes in activity since we last flew over. What has changed at the vent (which is called Puʻu ʻŌʻō) where the lava comes out to the surface?
What would a change in the vent look like exactly?
There are scales of detail in the change, it’s just how much you squint.
Puʻu ʻŌʻō is a pyroclastic cone. It has a crater at the top of the cone and a number of openings at the floor. The crater itself is something like 450 meters long and 250 meters wide. So we fly over and see if there have been new flows. How does it look? Anything different like new openings on the crater floor? We also fly along the lava tube system. Initially they are on the surface but as they progress and travel they’re always cooling and they form a crust almost immediately, which encases the flowing lava and forms a tube, basically a lava cave, and the lava continues to flow through this tube downslope to the ocean. It’s just a few meters below the surface.
When we fly along the tube we’re looking for skylights, openings in the tube system, and looking to see where the surface flows that are active are going. Sometimes we use a handheld GPS and fly around the periphery and make a quick map so we can compare what we see to our last flight.
Occasionally we get dropped off, walk around, and make a map of the flows. For the most part it’s just an overview to see what the activity is and what changes have occurred.
Do you ever get up close to the lava itself?
We do a number of research-oriented things. We have specific projects in mind and we get dropped off on the ground.
The main way that we collect lava samples is by walking up with a rock hammer to the flow.
The main way that we collect lava samples is by walking up with a rock hammer to the flow. Generally we do this on an overflight so we’re wearing a fire resistant flight suit and a face mask made out of Nomex, which all firefighters wear. We physically dip the hammer in the molten lava, pulling out big gobs, and dumping them into a bucket of water to cool off.
The hammer is just a non-meltable extension of ourselves, made out of some sort of high end steel with a metal handle with rubber over top and that will melt. Wood handles smoke right away.
You have to do it very quickly. I don’t take my time. If you’re close enough the radiant heat from the lava will burn your bare skin if it’s exposed so we wear gloves, leather boots, a face mask, and sunglasses.
How hot is it?
The average temperature at Kilauea is about 1,140 Celsius. That’s just a little bit less than 2,100 fahrenheit.
It cools a little when it comes to the surface. Eruption temperatures are probably about 1,150 Celsius. It doesn’t cool that much because it’s encased within the tube.
When we use the hammers we collect from surface flows. That’s pretty easy to do. If the skylight’s open in a tube and we choose to sample from that we use a stainless steel cable attached to a sledgehammer head and dangle that into the lava stream below. Because it’s usually a drop of several meters you have to get it out before you lose it. Otherwise it'll get stuck to the wall or it can be pulled out of your hand. It’s pretty scary, but the advantage is it’s closer to the eruption temperature and hasn’t had the chance to cool.
How do you study the samples?
Once collected we send it off to a lab and they will analyze the chemistry of the lava and tell us its chemical makeup.
I have a petrologist who I rely on to look at the chemistry of rocks. If something is changing, like the oxides are changing levels, it could be an indication that the magma is mixing with other stored magma along its way. If the temperature goes up it changes the chemistry and could indicate a new fresher hotter batch of magma coming into the system.
Do you measure the temperature before you throw the lava blobs in the bucket to cool?
You can, but we figure it out from the chemistry. There’s been work that’s been done to determine that the amount of magnesium in the rocks corresponds to the temperature of the lava. If you have more MgO, Magnesium Oxide, you have a higher temperature rock. Calibrations can be used to show based on the content what the temperature is.
MgO crystallizes as it cools. The mineral olivine is a common crystal in basalt and it contains MgO. So as it cools the MgO crystallizes and goes into the olivine. The reason we drop the lava into the bucket is to cool it as quickly as possible so it preserves the temperature markers. If you cool it too slowly the MgO will crystalize into the olivine and you can’t detect it. But if you cool it fast enough you can freeze the chemical makeup before the MgO crystallizes.
The analysis is conducted by bombarding the glassy matrix of the rock, which surrounds the olivine crystals, with electrons using a device called an electron microprobe. That's why it matters if the MgO goes into the crystals. The formation of olivine (and other minerals) selectively removes only certain chemical constituents of the entire assemblage that makes up the lava.
It’s a really complex system and people are still working to make it better.
What happens to all the samples you take? I’m picturing you sitting in an office surrounded by piles lava glass.
When we collect a sample it’s not a huge amount, it would fit into a large coffee mug or a Ziploc sandwich bag. I keep half of them here and we also have a sample archive labelled by location, time, and date. So the sample goes into a box with other samples. We have a huge stack of boxes from samples we’ve been collecting for decades.
The small samples are not for decoration. I have much prettier samples for decoration laying around.
How many samples do you have archived?
Over 3,000 from the East Rift Zone and the summit samples are another 253. That’s just Kilauea and just for the current activity, but there are other samples from other volcanoes that go back for decades.
Are there ever times when you’re not monitoring the volcano?
We can’t always be out on the volcano looking at changes so an area we’ve done a lot of work is to put out webcams to do monitoring. They let us keep track of changes 24-7. We have webcams out on the volcano and you can see them on our website. We also have a couple of thermal cameras in webcam mode so we can look at the thermal signature, which gives us a different view of things you can’t see with a regular camera.
We developed a visual and infrared monitoring system that lets us keep track when we can’t be there, but it also provides a safety net for places you don’t want to be for a long time because it’s dangerous. If the camera gets destroyed, well, it’s better than losing a life.
Do you get to see the volcano every day?
My office is located at the summit. From my office window I can look out and just a half mile away I can see the plume. I can hop in my truck, drive down, and walk 200 yards--it takes 10 minutes to get there--and I can look into the crater. That’s the reason the Hawaiian Volcano Observatory is here because you’re on the edge of an active volcano.
It’s pretty awesome. I’m lucky that I get to do it. The summit area is closed to the public and to look at the Rift Zone lava flows legally you have to walk 6 miles each way. I have the advantage that it’s part of my job. People are pretty jealous that I get to do that.
Photos courtesy Tim Orr and the USGS Hawaiian Volcano Observatory
Not all science is done in a lab by guys in white coats staring into microscopes. Lots of discoveries require brave men and women to put their boots on the ground and get down and dirty in dangerous environments. Every month we’ll profile one of these field scientists, tell you how they do their job, and explain the science behind what they do. If there’s a scientist or field of science you’re dying to hear more about shoot us an email or a tweet: erin at erinbiba dot com, @erinbiba