Working on Volcanoes

 

  

 

 

The following section is meant to give you a flavor of what it is like to work on a volcano. It illustrates some of the techniques that are used to study active Hawaiian volcanoes, most of which are also used to study the rest of the world's volcanoes.   Keep in mind also, that there are lots of indoor techniques that are equally important for understanding what a volcano is doing. Important examples of these are the analysis of seismic signals and geochemical studies of erupted lavas and gases.  

 

 

 

 

 

 

 

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COSPEC

 

Gas Sampling and Analysis

 

This photo shows a brave USGS geologist (arrows) who has made his way across a field of active pahoehoe to collect a gas sample from one of 3 active spatter vents (v). This type of sampling is dangerous, but it is just about the only way to collect gas samples that have not been greatly contaminated by air.

 




 

 

 

 

This is a remote technique for measuring volcanic gases. The device on the tripod is called a COSPEC, which stands for correlation spectrometer. It was originally developed for measuring the pollution coming out of factory smoke stacks. From a distance of a kilometer or so it makes vertical traverses through a volcanic plume that is being blown horizontally by the wind. By comparing the spectrum of natural light shining through clear air and that shining through the plume, it can determine the amount of gas in the plume. Then, after figuring out how far you are from the plume and how fast the wind is blowing you can calculate the volume of gas coming out of the volcano. In this example, researchers from Michigan Tech. University measured an average of almost 170 tons of sulfuric acid produced per day!




 

 

 

 

 

 

These two geologists were not studying gases but they had to wear gas masks anyway. Especially on days when the winds are slight, you need to worry about volcanic gases blowing your way (when the wind is strong the gases get mixed and diluted in the air).

 

 

 

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Cameras

 

Taking Pictures

 

 

Here is a geologist getting ready to take a photograph down into the Pu'u 'O'o vent. Notice that she is wearing a protective helmet and a gas mask. This particular vent is the source of both spatter and caustic gases and her caution was wise.

 

 

 

 

Time-Lapse Cameras

These are time-lapse cameras, and they probably get to see more exciting volcanic events on Hawaiian volcanoes than people do. This is because they can sit out in the rain and mist for days at a time. These particular cameras are actually super-8 movie cameras set to shoot one frame every few minutes or so. They are mounted in protective boxes constructed out of old ammunition boxes. The far box has been opened to show the camera whereas the near one is sealed up. Often two are employed at a single viewing location, with one set on wide angle and the other zoomed in on an active vent.

 

Watch some amazing time-lapse camera movies from the Hawaiian Volcano Observatory here!

 

 

Direct Sampling





Collecting A Lava Sample

 

Here a geologist is collecting a sample from a small pahoehoe toe. As long as there are only small areas of active incandescent lava, the flow can be approached long enough to collect a blob on the end of a hammer with only gloves, long pants, a long sleeve shirt, and boots for protection (it is still pretty uncomfortable). The sample will be analyzed in a laboratory to determine the chemical constituents. By collecting samples all through an eruption, geologists can study processes that go on down in the magma chamber and even within the mantle where the magma is generated.

 

Sampling an 'A'a Flow




Here, geologist Christina Heliker is preparing to take a sample of an 'a'a flow. Unlike pahoehoe flows, 'a'a flows radiate an incredible amount of heat so a lot more protection is required. She will scoop off a blob of the lava and put it into the coffee can. She then pours water into the can to rapidly quench the lava sample. This helps to make sure that the sample does not react with the atmosphere as it cools, and that it will be as pristine as it can be.

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EDM

 

Electronic Distance Measurement

EDM stands for Electronic Distance Measurement. This is the view from behind a cluster of EDM reflectors looking back towards the EDM "gun". It isn't really a gun, but rather a sophisticated laser that can measure very precisely the time it takes for a laser beam to make the round-trip from the "gun" to the reflectors, and back. Using this time, the known speed that the laser travels (the speed of light), and correcting for air temperature and pressure, the distance can be determined to a precision of 1 part per million (i.e. 1 mm over a distance of 1 km).

 

The Finer Points of EDM Measuring




 

 

 

 

 

 

 

 

 

Here a helicopter pilot (left) and two geologists discuss the finer points of making EDM measurements. The "gun", the source of the laser, is the orange device on the tripod between them. It gets lugged around in the orange box at left. The speed at which the laser travels the round-trip from gun to reflector and back is affected by the air temperature; the probe measurements are used to make corrections for this effect.

 

 

 

Single Corner Reflector

 

This is a single corner reflector set up on a piece of re-bar that has been pounded into the cinders. The painted board helps the EDM operator to find the reflector since he or she is often looking for it over distances of a few kilometers. This type of low-tech reflector is relatively expendable and is usually left out in areas where eruptions are possible. For more precise measurements, clusters of 3, 6, or 9 reflectors are used, but they are only installed while the measurements are being made.

 

 

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Leveling Measurements




Leveling Measurements

Here a number of geologists are making leveling measurements over an active lava shield (the profile of Pu'u 'O'o cinder cone is in the background). One geologist is using a level to sight on a barely-visible leveling rod (arrow) that is being held vertical by an assistant. Another assistant is holding another rod behind where this photo was taken, and the fourth person takes notes. The back level rod person will then leapfrog ahead and the level will also move forward to set up between them. This time-consuming process is still the best way to get an idea of the volume of a newly-erupted feature, and repeated measurements can show volume changes through time.

 

 

 

 

 

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Magnetotellurics

Magnetotellurics

Magnetotellurics uses electromagnetism to image the geologic subsurface through variable resistivity.

Geologist Tom Wright is rolling out a long wire (carried in a heavy and uncomfortable spool on his back). A small current will be run through this wire and it will send an electrical signal into the ground. The return signal will be different depending on the temperature of the sub-surface, and this technique is sometimes used to try and find underground bodies of magma.

This photo was taken in 1987 and you can see how much vegetation has grown since the 1977 eruption.

 

 

 

 

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Theodolite




 

This photo shows geologists Christina Heliker and Tom Wright using a theodolite to measure the height of a lava fountain. The theodolite is a very accurate surveying instrument that allows you to measure angles, both vertically and horizontally. From their vantage point here, the Pu'u 'O'o vent was about a kilometer away (out of view to the left). By knowing the distance accurately and measuring the angle to the top of the lava fountain they could use simple trigonometry to determine its height, which was often >300 meters!

 

 

 

 

 

 

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Thermocouples

Measuring Temperature




This is the direct method of measuring lava temperatures. A thermocouple probe is inserted into the flow, and the temperature is read off by a hand-held device. This particular flow was not very active so it was easy to approach it and stay long enough for the thermocouple to equilibrate in the lava. Many times this is not the case and the temperature readings are not very accurate. In fact, George Walker (a famous volcanologist) has said "the temperature of a lava flow is inversely proportional to the comfort of the volcanologist making the measurement". (photo by P. Mouginis-Mark) The volcanologist must have been pretty comfortable this day because the measured temperature was almost 1160 degrees C (almost 2100 degrees F).

 

Remote Method For Reading Temperature




 

This is a remote method of determining the temperature of a lava flow. This geologist is holding a device that was originally invented to measure temperatures in industrial blast furnaces. Even at this distance of about 3 meters he still needs to wear a long sleeve fire-fighter's shirt and a knit hood over his head for protection against the radiant heat.

 

 

 

 

 

 

 

 

 

 

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Volcano Observatories



 

Observatories are institutions that are actively engaged in volcano surveillance and, in most cases, are responsible for warning authorities and the public about hazardous volcanic unrest.

This is a helicopter view of the Hawaiian Volcano Observatory (HVO), perched on the rim of Kilauea caldera. It was established in 1912 (at a slightly different location) by Dr. Thomas Jaggar of MIT. The modern observatory was renovated in 1987, and a fine museum named for Dr. Jaggar was included as part of the renovation. As you can see the observatory has an excellent view of the Kilauea summit caldera, including Halema'uma'u, the home of Pele.

The World Organization for Volcano Observatories (WOVO) has more information about the necessity and location of volcano observatories.

 

 

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