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- All Subjects: Geophysics
- Creators: Clarke, Amanda
- Creators: School of Earth and Space Exploration
Successful forecasting of the timing, style, and intensity of a volcanic eruption is made possible by improved understanding of the volcano life cycle as well as building quantitative models incorporating the processes that govern rock melting, melt ascending, magma storage, eruption initiation, and interaction between magma and surrounding host rocks at different spatial extent and time scale. One key part of such models is the shallow magma chamber, which is generally directly linked to volcano’s eruptive behaviors. However, its actual shape, size, and temporal evolution are often not entirely known. To address this issue, I use space-based geodetic data with high spatiotemporal resolution to measure surface deformation at Kilauea volcano. The obtained maps of InSAR (Interferometric Synthetic Aperture Radar) deformation time series are exploited with two novel modeling schemes to investigate Kilauea’s shallow magmatic system. Both models can explain the same observation, leading to a new compartment model of magma chamber. Such models significantly advance the understanding of the physical processes associated with Kilauea’s summit plumbing system with potential applications for volcanoes around the world.
The unprecedented increase in the number of earthquakes in the Central and Eastern United States since 2008 is attributed to massive deep subsurface injection of saltwater. The elevated chance of moderate-large damaging earthquakes stemming from increased seismicity rate causes broad societal concerns among industry, regulators, and the public. Thus, quantifying the time-dependent seismic hazard associated with the fluid injection is of great importance. To this end, I investigate the large-scale seismic, hydrogeologic, and injection data in northern Texas for period of 2007-2015 and in northern-central Oklahoma for period of 1995-2017. An effective induced earthquake forecasting model is developed, considering a complex relationship between injection operations and consequent seismicity. I find that the timing and magnitude of regional induced earthquakes are fully controlled by the process of fluid diffusion in a poroelastic medium and thus can be successfully forecasted. The obtained time-dependent seismic hazard model is spatiotemporally heterogeneous and decreasing injection rates does not immediately reduce the probability of an earthquake. The presented framework can be used for operational induced earthquake forecasting. Information about the associated fundamental processes, inducing conditions, and probabilistic seismic hazards has broad benefits to the society.
A 1: 1,000,000 scale geologic map of Ascraeus Mons was produced using ArcGIS and will be submitted to the USGS for review and publication. Mapping revealed 26 units total, broken into three separate categories: Flank units, Apron and Scarp units, and Plains units. Units were defined by geomorphological characteristics such as: surface texture, albedo, size, location, and source. Defining units in this manner allowed for contact relationships to be observed, creating a relative age date for each unit to understand the evolution and history of this large shield volcano.
Ascraeus Mons began with effusive, less viscous style of eruptions and transitioned to less effusive, more viscous eruptions building up the main shield. This was followed by eruptions onto the plains from the two main rift aprons on AM. Apron eruptions continued, while flank eruptions ceased, surrounding and embaying the flanks of AM. Eruptions from the rifts wane and build up the large aprons and low shield fields. Glaciers modified the base of the west flank and deposited the Aureole material. Followed by localized recent eruptions on the flanks, in the calderas, and small vent fields. Currently AM is modified by aeolian and tectonic processes. While the overall story of Ascraeus Mons does not change significantly, higher resolution imagery allowed for a better understanding of magma evolution and lava characteristics across the main shield. This study helps identify martian magma production rates and how not only Ascraeus Mons evolved, but also the Tharsis province and other volcanic regions of Mars.
Although nitrogen is the dominant element in Earth’s atmosphere, it is depleted in the bulk silicate Earth (relative to expected volatile abundances established by carbonaceous chondrites). To resolve this inconsistency, it has been hypothesized that this “missing nitrogen” may actually be stored within the Earth’s deep interior. In this work, we use multi-anvil press experiments to synthesize solid solution mixtures of the mantle transition zone mineral wadsleyite (Mg2SiO4) and silicon nitride (Si3N4). Successful synthesis of a 90% Si3N4, 10% Mg2SiO4 solid solution implies that nitrogen may not be sequestered within the most abundant mineral phases in the Earth’s mantle. Instead, nitrogen-rich accessory phases may hold the key to studying nitrogen storage within the deep interior. Ultimately, quantifying the amount of nitrogen within the mantle will further our understanding of the N cycle, which is vital to maintaining planetary habitability. Similar N cycling processes may be occurring on other rocky bodies; therefore, studying nitrogen storage may be an important part of determining habitability conditions on other worlds, both within in our solar system and beyond.