Ninfa Bennington


Geophysical studies of active volcanic systems are most commonly interested in the distribution, composition, and migration of melts and fluids in the subsurface. Interpretations of a volcanic region based on a single geophysical model can be ambiguous. For example, in magmatic regions, low velocity anomalies may represent a melt body or the presence of gas. In a dominantly mafic environment, low Vp/Vs ratios have been attributed to the presence of gas. Similarly, more silica rich regions of magma storage may be seen as low Vp, low Vs, and low Vp/Vs anomalies. Thus, the same volcanic system could be interpreted in terms of silica rich magma storage or a region of gas-filled pores. Notably, these two interpretations have profoundly different implications on the volcanic hazard such a magmatic system would represent. Incorporation of imaging via an additional geophysical tool, for example magnetotellurics, which images the resistivity structure of the subsurface, could resolve this ambiguity. A complementary low resistivity anomaly in this region of low Vp, Vs, and Vp/Vs would confirm the presence of a silicic magma storage body.

My research interests are primarily focused on the development of novel joint modeling techniques, which incorporate multiple geophysical datasets, in order to better constrain magma storage at active volcanoes. I currently have several NSF funded projects where I am applying such multi-discipline modeling algorithms in order to better understand active volcanic systems, including: Okmok volcano, Alaska; the Yellowstone volcanic system, USA; and the  Laguna del Maule volcanic system, Chile.

Additionally, I have ongoing research that focuses on our ability to detect precursory activity leading to active volcanism. Such work uses ambient noise as a continuous signal that samples the subsurface in order to determine temporal changes in seismic velocity. The migration of magmatic fluids within the shallow crust causes expansion or contraction of the subsurface and can result in observed changes in seismic velocity. Current NSF funded research projects at Okmok and Veniaminof volcanoes, Alaska, show large decreases in seismic velocity related to a rapid inflation event and preceding the onset of multiple eruptions, respectively. Future work will focus on the continued development of this method as a forecasting tool for other active volcanoes in the Aleutian Arc.