iMush magnetotelluric experiment is almost underway

Adam Schultz
June 14, 2021

iMUSH magnetotelluric (MT) project field crew is assembling at Oregon State University next week and getting ready to start installing short-term monitoring instruments. It has been a busy winter and spring preparing for this first phase of iMUSH MT station installations. We have 150 sites identified that cover the southern Washington Cascades surrounding Mount Saint Helens. We have been working closely with landowners, regulatory authorities, as well as other stakeholder groups as we identify locations for our short-term, low-impact monitoring stations.

We are using wideband MT recording systems that can accomplish their work, depending on the specific situation, in as little as one day of recording time. In some locations we may need to operate for a week or even a bit longer, but generally we can be in and out with only a limited number of shovel-fulls of soil moved (to temporarily connect our electrodes to the ground and to put our magnetometers into shallow holes). Our equipment is very low power, and runs off of a standard deep cycle marine type battery. It generates no signal of its own, and simply records how the natural magnetic and electric fields at ground level change with time. We use this information to generate 3D images of the variations in the electrical resistivity of the Earth's crust and upper mantle. The resistivity is closely associated with the distribution of fluids, including partial melt/magma that is associated with the underground structures that feed the volcanoes above.

Our status as of today is that we have 31 iMUSH MT station locations permitted, and we're working on completing the permitting process for the full array of 150 station locations. We are also waiting on a few bits of hardware to arrive from the manufacturer, but in a month or two you might see some of our 2-3 person field crews out on site installing our MT equipment.