The hydrothermal fluids venting from the lake floor contain gases that escaped from the magmatic system under the Park. These gases, which include things like carbon dioxide and sulphur dioxide, make bubbles that rise up through the lake before popping on the lake surface. On a calm morning it is easy to see them if you are on a boat right above the vent field. These bubbles are initially highly pressurized because they are under about 300 ft of water, and the bubble walls vibrate at rates of several thousand cycles per second. These vibrations are too fast to be detected by our seismometers, but we are building a custom hydrophone (underwater microphone) unit with collaborators from IS Terre in France that will allow us to monitor acoustic signals from bubbles during the seismometer deployments. We call this instrument, The Bubblephone. Photos and story by Rob Sohn, WHOI.

To test our Bubblephone, Tim Kane (green shirt) built a test tank that includes an apparatus to squirt an air bubble into the bottom of the tank to simulate gas bubbles in Yellowstone Lake. In the water beneath Tim's left hand you can see a hydrophone that senses the acoustic signal when the bubble is squirted into the water. The hydrophone signal then passes through an electronics 'magic box' designed by IS Terre engineer Jacques Grangeon (red shirt) that allows the seismometer to record the bubble signal level.

To control the bubble size we used an aquarium air diffuser (visible at the very end of the tube) that you can buy at any pet store. We like simple, inexpensive solutions to our instrumentation problems!

While the bubbles vibrate too quickly to be recorded by the seismometer, they are easy to hear with the human ear - they sound just like what you think they sound like! WHOI OBS engineer Tim Kane listens to bubbles rising up through Little Yellowstone Lake.

The team (from left to right, WHOI OBS engineer Alan Garden, IS Terre scientist Jean Vandemuelebrouck, IS Terre engineer Jacques Grangeon) is all smiles because the tests went very well. We ran tests where the Bubblephone recorded bubbles overnight and the data look good. We hope that the Bubblephone will help us understand how gas discharge rates change with time and in response to things like earthquakes and lake level during our experiment.

We got onto the water early each day, pushing off from the pier in Bridge Bay at 6 am. The pain of waking up early, however, was mediated by the incredible views of the sun rising over the mountains as we motored out onto the lake. The visual tableau was different every day, reflecting the different moods of the lake through the interplay of light dancing on water. Behold our office!   Read More →

We are taking gravity cores to sample the uppermost sediment layer near the lake floor vents. In some cases we may be able to sample sediments that were deposited during the Little Ice Age, some 1600 years ago. Sediments near the vents are altered by the hydrothermal fluids, which changes their composition. In addition, the pore fluids in the sediments contain hydrothermal components that will help us understand how the hydrothermal fluids migrate through, and interact with, the lake floor sediments.  Read More →

We are using an Autonomous Underwater Vehicle (AUV) to survey our study area before we dive with the ROV in August, in order to create a high-resolution baseman of the area and to identify sites of active fluid discharge. The final base maps will have a lateral resolution of 20-25 cm and a vertical resolution of 1-2 cm. This is the first time that this state-of-the-art surveying technology has been used in the lake, and we’re excited about the maps we will produce. Read More →

We are deploying thermal blankets to measure heat flow around the lake floor vents. The instruments measure the temperature gradient across an open cell foam layer that insulates the sediments under the blanket from the overlying water column. We left them on the lake floor for about 24 hours and then moved them to a new location each day. Read More →

We are deploying seismometers on the lake floor to measure small earthquakes generated by hydrothermal fluid flow and to understand how they may migrate along fault surfaces. This is the first time that a seismometer will be deployed in the lake, so we don’t know what kind of noise levels and event rates to expect in the data. Before deploying a full-scale seismic network in 2017, our goal this year is to measure the noise levels and establish event rates during a ~1 month period from July to August. Read More →