Characterizing the Dimensions and Internal Structure of the Yellowstone Magmatic Reservoir Using a Dense Nodal Geophone Array
Abstract
Recent advances in seismic instrument technology and a focused interest in understanding active continental magmatic systems (both arc and intraplate) have opened up new imaging possibilities. Mt. St. Helens, Yellowstone, and Kīlauea represent a few examples where this new instrument technology has been deployed in volcanic settings with remarkable success. In November of 2017, we deployed 290 3-component 5-Hz nodal geophones within the western side of the Yellowstone caldera. Here we present the results of a receiver function analysis from stations that were both densely deployed over the upper crustal magmatic reservoir and across its northern lateral edge. A negative and positive arrival that we observe and other studies (in courser detail) have interpreted as the top and bottom of the upper crustal magmatic reservoir is well resolved in our results. Additionally, having a dense array of instruments allows us to employ array-based analysis to image the internal magmatic reservoir structure on a scale previously unavailable. Across our array, we observe several smaller low-velocity zones located internally at the top of the main shallow magmatic reservoir that we interpret as localized layers of elevated partial melt. Initial modeling indicates a near zero shear-wave velocity and hence a high percentage of melt is required to generate these signals. Further modeling is required to better constrain this and additional deployments are planned to evaluate the robustness of this observation. We also are able to image at least one lateral boundary in rather precise detail where we observe a polarity reversal associated with edge effects of the magma reservoir. From a geophysical perspective these observations are interesting and have provided directions for future research targets. One goal we have in presenting this work to a broader audience is to solicit feedback on what questions remain in understanding these active continental magmatic systems and how we can leverage this next generation of seismic instrument technology to further our understanding of these active continental magmatic systems.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V33D0251W
- Keywords:
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- 1036 Magma chamber processes;
- GEOCHEMISTRYDE: 3653 Fluid flow;
- MINERALOGY AND PETROLOGYDE: 8439 Physics and chemistry of magma bodies;
- VOLCANOLOGY