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Description
Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that nearly half of Earth's

Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that nearly half of Earth's human population lives along active fault zones, a quantitative understanding of the mechanics of earthquakes and faulting is necessary to build accurate earthquake forecasts. My research relies on the quantitative documentation of the geomorphic expression of large earthquakes and the physical processes that control their spatiotemporal distributions. The first part of my research uses high-resolution topographic lidar data to quantitatively document the geomorphic expression of historic and prehistoric large earthquakes. Lidar data allow for enhanced visualization and reconstruction of structures and stratigraphy exposed by paleoseismic trenches. Lidar surveys of fault scarps formed by the 1992 Landers earthquake document the centimeter-scale erosional landforms developed by repeated winter storm-driven erosion. The second part of my research employs a quasi-static numerical earthquake simulator to explore the effects of fault roughness, friction, and structural complexities on earthquake-generated deformation. My experiments show that fault roughness plays a critical role in determining fault-to-fault rupture jumping probabilities. These results corroborate the accepted 3-5 km rupture jumping distance for smooth faults. However, my simulations show that the rupture jumping threshold distance is highly variable for rough faults due to heterogeneous elastic strain energies. Furthermore, fault roughness controls spatiotemporal variations in slip rates such that rough faults exhibit lower slip rates relative to their smooth counterparts. The central implication of these results lies in guiding the interpretation of paleoseismically derived slip rates that are used to form earthquake forecasts. The final part of my research evaluates a set of Earth science-themed lesson plans that I designed for elementary-level learning-disabled students. My findings show that a combination of concept delivery techniques is most effective for learning-disabled students and should incorporate interactive slide presentations, tactile manipulatives, teacher-assisted concept sketches, and student-led teaching to help learning-disabled students grasp Earth science concepts.
ContributorsHaddad, David Elias (Author) / Arrowsmith, Ramon (Thesis advisor) / Reynolds, Stephen (Committee member) / Semken, Steven (Committee member) / Shirzaei, Manoochehr (Committee member) / Whipple, Kelin (Committee member) / Zielke, Olaf (Committee member) / Arizona State University (Publisher)
Created2014
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Description
Sedimentary basins are defined by extensional tectonics. Rugged mountain ranges stand in stark relief adjacent to muted structural basins filled with sediment. In simplest terms, this topography is the result of ranges uplifted along normal faults, and this uplift drives erosion within upland drainages, shedding sediment into subsiding basins. In

Sedimentary basins are defined by extensional tectonics. Rugged mountain ranges stand in stark relief adjacent to muted structural basins filled with sediment. In simplest terms, this topography is the result of ranges uplifted along normal faults, and this uplift drives erosion within upland drainages, shedding sediment into subsiding basins. In southeastern Arizona's Basin and Range province extensional tectonics waned at approximately 3-5 Myr, and the region's structural basins began transitioning from internal to external drainage, forming the modern Gila River fluvial network. In the Atacama Desert of northern Chile, some basins of the Central Depression remain internally drained while others have integrated to the Pacific Ocean. In northern Chile, rates of landscape evolution are some of the slowest on Earth due to the region's hyperarid climate. While the magnitude of upland erosion driven by extensional tectonics is largely recorded in the stratigraphy of the structural basins, the landscape's response to post-tectonic forcings is unknown.

I employ the full suite of modern geomorphic tools provided by terrestrial cosmogenic nuclides - surface exposure dating, conventional burial dating, isochron burial dating, quantifying millennial-scale upland erosion rates using detrital TCN, quantifying paleo-erosion rates using multiple TCN such as Ne-21/Be-10 and Al-26l/Be-10, and assessing sediment recycling and complex exposure using multiple TCN - to quantify the rates of landscape evolution in southeastern Arizona and northern Chile during the Late Cenozoic. In Arizona, I also use modern remnants of the pre-incision landscape and digital terrain analyses to reconstruct the landscape, allowing the quantification of incision and erosion rates that supplement detrital TCN-derived erosion rates. A new chronology for key basin high stand remnants (Frye Mesa) and a flight of Gila River terraces in Safford basin provides a record of incision rates from the Pliocene through the Quaternary, and I assess how significantly regional incision is driving erosion rates. Paired nuclide analyses in the Atacama Desert of northern Chile reveal complex exposure histories resulting from several rounds of transport and burial by fluvial systems. These results support a growing understanding that geomorphic processes in the Atacama Desert are more active than previously thought despite the region's hyperarid climate.
ContributorsJungers, Matthew Cross (Author) / Heimsath, Arjun M (Thesis advisor) / Whipple, Kelin (Committee member) / Arrowsmith, Ramon (Committee member) / Vivoni, Enrique (Committee member) / DeVecchio, Duane (Committee member) / Arizona State University (Publisher)
Created2014
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Description
The movement between tectonic plates is accommodated through brittle (elastic) displacement on the plate boundary faults and ductile permanent deformation on the fault borderland. The elastic displacement along the fault can occur in the form of either large seismic events or aseismic slip, known as fault creep. Fault creep mainly

The movement between tectonic plates is accommodated through brittle (elastic) displacement on the plate boundary faults and ductile permanent deformation on the fault borderland. The elastic displacement along the fault can occur in the form of either large seismic events or aseismic slip, known as fault creep. Fault creep mainly occurs at the deep ductile portion of the crust, where the temperature is high. Nonetheless, aseismic creep can also occur on the shallow brittle portion of the fault segments that are characterized by frictionally weak material, elevated pore fluid pressure, or geometrical complexity. Creeping segments are assumed to safely release the accumulated strain(Kodaira et al., 2004; Rice, 1992)(Kodaira et al., 2004; Rice, 1992)(Kodaira et al., 2004; Rice, 1992)(Kodaira et al., 2004; Rice, 1992)(Kodaira et al., 2004; Rice, 1992) on the fault and also impede propagation of the seismic rupture. The rate of aseismic slip on creeping faults, however, might not be steady in time and instead consist of successive periods of acceleration and deceleration, known as slow slip events (SSEs). SSEs, which aseismically release the strain energy over a period of days to months, rather than the seconds to minutes characteristic of a typical earthquake, have been interpreted as earthquake precursors and as possible triggering factor for major earthquakes. Therefore, understanding the partitioning of seismic and aseismic fault slip and evolution of creep is fundamental to constraining the fault earthquake potential and improving operational seismic hazard models. Thanks to advances in tectonic geodesy, it is now possible to detect the fault movement in high spatiotemporal resolution and develop kinematic models of the creep evolution on the fault to determine the budget of seismic and aseismic slip.

In this dissertation, I measure the decades-long time evolution of fault-related crustal deformation along the San Andrea Fault in California and the northeast Japan subduction zone using space-borne geodetic techniques, such as Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR). The surface observation of deformation combined with seismic data set allow constraining the time series of creep distribution on the fault surface at seismogenic depth. The obtained time-dependent kinematic models reveal that creep in both study areas evolves through a series of SSEs, each lasting for several months. Using physics-based models informed by laboratory experiments, I show that the transient elevation of pore fluid pressure is the driving mechanism of SSEs. I further investigate the link between SSEs and evolution of seismicity on neighboring locked segments, which has implications for seismic hazard models and also provides insights into the pattern of microstructure on the fault surface. I conclude that while creeping segments act as seismic rupture barriers, SSEs on these zones might promote seismicity on adjacent seismogenic segments, thus change the short-term earthquake forecast.
ContributorsKhoshmanesh, Mostafa (Author) / Shirzaei, Manoochehr (Thesis advisor) / Arrowsmith, Ramon (Committee member) / Garnero, Edward (Committee member) / Tyburczy, James (Committee member) / Whipple, Kelin (Committee member) / Arizona State University (Publisher)
Created2018
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Description
There are many outstanding questions regarding the petrologic processes that give rise to andesitic and basaltic magmas in subduction zones, including the specifics that govern their geographical distribution in a given arc segment. Here I investigate the genesis of calc-alkaline and tholeiitic basalts from the Lassen Volcanic Center in order

There are many outstanding questions regarding the petrologic processes that give rise to andesitic and basaltic magmas in subduction zones, including the specifics that govern their geographical distribution in a given arc segment. Here I investigate the genesis of calc-alkaline and tholeiitic basalts from the Lassen Volcanic Center in order to determine the pressure, temperature, source composition, and method of melting that lead to the production of melt in the mantle below Lassen. To this aim, a suite of primitive basalts (i.e. SiO2<52 and Mg#>65) are corrected for fractional crystallization by adding minerals back to the bulk rock composition with the goal of returning them to a primary composition in equilibrium with the mantle. Thermobarometry of the primary melt compositions is conducted to determine temperature and pressure of melting, in addition to a forward mantle modeling technique to simulate mantle melting at varying pressures to constrain source composition and method of melting (batch vs. fractional). The results from the two techniques agree on an average depth of melt extraction of 36 km and a source composition similar to that of depleted mantle melted by batch melting. Although attempted for both calc-alkaline and tholeiitic basalts, the fractional crystallization correction and thus the pressure-temperature calculations were only successful for tholeiitic basalts due to the hydrous nature of the calc-alkaline samples. This leaves an opportunity to repeat this study with parameters appropriate for hydrous basalts, allowing for the comparison of calc-alkaline and tholeiitic melting conditions.
ContributorsSheppard, Katherine Davis (Author) / Till, Christy (Thesis director) / Hervig, Richard (Committee member) / Barrett, The Honors College (Contributor) / School of Earth and Space Exploration (Contributor)
Created2015-05
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Description
A wide range of types of activity in mid-latitude Martian gullies has been observed over the last decade (Malin et al., 2006; Harrison et al., 2009, 2015; Diniega et al., 2010; Dundas et al., 2010, 2012, 2015, 2017) with some activity constrained temporally to occur in the coldest times of

A wide range of types of activity in mid-latitude Martian gullies has been observed over the last decade (Malin et al., 2006; Harrison et al., 2009, 2015; Diniega et al., 2010; Dundas et al., 2010, 2012, 2015, 2017) with some activity constrained temporally to occur in the coldest times of year (winter and spring; Harrison et al., 2009; Diniega et al., 2010; Dundas et al., 2010, 2012, 2015, 2017), suggesting that surficial frosts that form seasonally and diurnally might play a key role in this present-day activity. Frost formation is highly dependent on two key factors: (1) surface temperature and (2) the atmospheric partial pressure of the condensable gas (Kieffer, 1968). The Martian atmosphere is primarily composed of CO2and CO2 frost formation is not diffusion-limited (unlike H2O). Hence, for temperatures less than the local frost point of CO2, (~ 148 K at a surface pressure of 610 Pa) frost is always present (Piqueux et al., 2016). Typically, these frosts are dominated volumetrically by CO2, although small amounts of H2O frosts are also present, and typically precede CO2 frost deposition (due to water’s higher condensation temperature (Schorghofer and Edgett, 2006)). Here we use the Thermal Emission Imaging System (THEMIS) and the Thermal Emission Spectrometer (TES) onboard Mars Odyssey and Mars Global Surveyor, respectively, to explore the global spatial and temporal variation of temperatures conducive to CO2 and H2O frost formation on Mars, and assess their distribution with gully landforms. CO2 frost temperatures are observed at all latitudes and are strongly correlated with dusty, low thermal inertia regions near the equator. Modeling results suggest that frost formation is restricted to the surface due to near-surface radiative effects. About 49 % of all gullies lie within THEMIS frost framelets. In terms of active gullies, 54 % of active gullies lie within THEMIS framelets, with 14.3% in the north and 54% in the south.
Relatively small amounts of H2O frost (~ 10–100 μm) are also likely to form diurnally and seasonally. The global H2O frost point distribution follows water vapor column abundance closely, with a weak correlation with local surface pressure. There is a strong hemispherical dependence on the frost point temperature—with the northern hemisphere having a higher frost point (in general) than the southern hemisphere—likely due to elevation differences. Unlike the distribution of CO2 frost temperatures, there is little to no correlation with surface thermophysical properties (thermal inertia, albedo, etc.). Modeling suggests H2O frosts can briefly attain melting point temperatures for a few hours if present under thin layers of dust, and can perhaps play a role in present-day equatorial mass-wasting events (eg. McEwen et al., 2018).
Based on seasonal constraints on gully activity timing, preliminary field studies, frost presence from visible imagery, spectral data and thermal data (this work), it is likely that most present-day activity can be explained by frosts (primarily CO2, and possibly H2O). We predict that the conditions necessary for significant present-day activity include formation of sufficient amounts of frost (> ~20 cm/year) within loose, unconsolidated sediments (I < ~ 350) on available slopes. However, whether or not present-day gully activity is representative of gully formation as a whole is still open to debate, and the details on CO2 frost-induced gully formation mechanisms remain unresolved.
ContributorsKhuller, Aditya Rai (Author) / Christensen, Philip (Thesis director) / Harrison, Tanya (Committee member) / Diniega, Serina (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
This research focuses on a geologic controversy regarding the stratigraphic position of the Hermit Formation outside of the Grand Canyon, specifically in Sedona, Arizona. The goal of this research is to provide additional constraints on this dispute by pinpointing the transition to the Hermit Formation in Sedona, if possible. To

This research focuses on a geologic controversy regarding the stratigraphic position of the Hermit Formation outside of the Grand Canyon, specifically in Sedona, Arizona. The goal of this research is to provide additional constraints on this dispute by pinpointing the transition to the Hermit Formation in Sedona, if possible. To accomplish this, we use field observations and detrital zircon dating techniques to compare data we collected in Sedona with data previously published for the Grand Canyon. Fossil evidence in Sedona and near Payson, Arizona is also used to aid correlation. Starting from the Grand Canyon, the Hermit Formation pinches out to the southeast and, hypothetically obstructed by the Sedona Arch, does not reach Sedona. Detrital zircon data show similar age distributions between the Grand Canyon and Sedona rock units, but the results are not strong enough to confidently correlate units between these two localities. The data collected for this study suggest that if the Hermit Formation is present in Sedona, it is limited to higher up in the section as opposed to occupying the middle portion of the section as is currently interpreted. To determine with greater accuracy whether the Hermit Formation does exist higher in the section of Sedona, more detrital zircons should be collected and analyzed from the part of the section that yielded a relative increase in young zircons aged 200-600 Ma.
ContributorsFinger, Mikayla (Co-author) / Spitzer, Patrick (Co-author) / Reynolds, Stephen (Thesis director) / Semken, Steven (Committee member) / DeVecchio, Duane (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
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Description
For the geoscience community to continue to grow, students need to be attracted to the field. Here we examine the Incorporated Research Institutions for Seismology (IRIS) Research Experience for Undergraduates (REU) program to understand how the participants' experiences' affects their interest in geoscience and educational and career goals. Eleven interns

For the geoscience community to continue to grow, students need to be attracted to the field. Here we examine the Incorporated Research Institutions for Seismology (IRIS) Research Experience for Undergraduates (REU) program to understand how the participants' experiences' affects their interest in geoscience and educational and career goals. Eleven interns over two years (2013-2014) were interviewed prior to the start of their internship, after their internship, and after presenting their research at the American Geophysical Union annual meeting. This internship program is of particular interest because many of the interns come into the REU with non-geoscience or geophysics backgrounds (e.g., physics, mathematics, chemistry, engineering). Both a priori and emergent codes are used to convert interview transcripts into quantitative data, which is analyzed alongside demographic information to understand how the REU influences their decisions. Increases in self-efficacy and exposure to multiple facets of geoscience research are expressed as primary factors that help shape their future educational and career goals. Other factors such as networking opportunities and connections during the REU also can play a role in their decision. Overall, REU participants who identified as geosciences majors solidified their decisions to pursue a career in geosciences, while participants who identified as non-geosciences majors were inclined to change majors, pursue geosciences in graduate school, or explore other job opportunities in the geosciences.
ContributorsGossard, Trey Marshall (Author) / Semken, Steven (Thesis director) / Garnero, Edward (Committee member) / Reynolds, Stephen (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
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Description
The collision between the Indian and Eurasian tectonic plates marked the onset of the rise of the Himalayan-Tibetan orogen, but also brought about profound changes to the Earth's oceans and climate. The exact sequence of events that occurred during this collision is poorly understood, leading to a wide range of

The collision between the Indian and Eurasian tectonic plates marked the onset of the rise of the Himalayan-Tibetan orogen, but also brought about profound changes to the Earth's oceans and climate. The exact sequence of events that occurred during this collision is poorly understood, leading to a wide range of estimates of its age. The Indus and Yarlung sutures are generally considered to represent the final collision between India and Eurasia, and together form a mostly continuous belt that can be traced over 2000 km along strike. In the western portions of the orogen the Karakoram Fault introduces a key complexity to the study of timing of collision by offsetting the Indus and Yarlung sutures. Recent work has used the complexities introduced by the Karakoram Fault to suggest that the more northerly Shyok suture, not the Indus suture, represents the India-Eurasia collision zone. Estimates for timing of the India-Eurasia collision fall into one of three groups: 40-34 Ma, 55-50 Ma, and 66-60 Ma. Attempts to reconcile these models have thus far been unsuccessful. In order to provide additional data that might further clarify the timing and location of collision, studies have been performed along the Shyok suture in India and along the Yarlung suture in Tibet at Sangsang. A study along the Shyok suture argues that the suture formed between 92-85 Ma. This timing precludes an interpretation that the Shyok suture marks the location of the India-Eurasia collision. A second study demonstrates the utility of two new geochronometers, (U-Th)/Pb joaquinite and 40Ar/39Ar neptunite, that play an important role in unraveling the tectonic history of the Yarlung suture. A third study is an investigation of the structure and geochronology of the Sangsang ophiolite complex. Here, multiple (U-Th)/Pb and 40Ar/39Ar systems record magmatism and metamorphism spanning ca. 125-52 Ma. By tying these chronometers to tectonic process, a history is reconstructed of the southern margin of Tibet that includes Early Cretaceous to Late Cretaceous forearc rifting associated with mid ocean ridge subduction, Paleocene accretionary wedge uplift and erosion, and finally Eocene metasomatism and collision.
ContributorsBorneman, Nathaniel (Author) / Hodges, Kip (Thesis advisor) / Reynolds, Stephen (Committee member) / Whipple, Kelin (Committee member) / Sharp, Thomas (Committee member) / Tyburczy, James (Committee member) / Arizona State University (Publisher)
Created2016
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Description
I investigate the Black Canyon City landslide (BCC landslide), a prominent deep-seated landslide located northeast of Black Canyon City, Arizona. Although the landslide does not appear to pose a significant hazard to structures, its prominent features and high topographic relief make it an excellent site to study the geologic setting

I investigate the Black Canyon City landslide (BCC landslide), a prominent deep-seated landslide located northeast of Black Canyon City, Arizona. Although the landslide does not appear to pose a significant hazard to structures, its prominent features and high topographic relief make it an excellent site to study the geologic setting under which such features develop. This study has the potential to contribute toward understanding the landscape evolution in similar geologic and topographic settings, and for characterizing the underlying structural processes of this deep-seated feature. We use field and remotely-based surface geology and geomorphological mapping to characterize the landslide geometry and its surface displacement. We use the Structure from Motion (SfM) method to generate a 0.2 m resolution digital elevation model and rectified ortho-photo imagery from unmanned aerial vehicle (UAV) - and balloon-based images and used them as the base map for our mapping. The ~0.6 km2 landslide is easily identified through remotely-sensed imagery and in the field because of the prominent east-west trending fractures defining its upper extensional portion. The landslide displaces a series of Early and Middle Miocene volcanic and sedimentary rocks. The main head scarp is ~600 m long and oriented E-W with some NW-SE oriented minor scarps. Numerous fractures varying from millimeters to meters in opening were identified throughout the landslide body (mostly with longitudinal orientation). The occurrence of a distinctive layer of dark reddish basalt presents a key displaced marker to estimate the long-term deformation of the slide mass. Using this marker, the total vertical displacement is estimated to be ~70 m, with maximum movement of ~95 m to the SE. This study indicates that the landslide motion is translational with a slight rotational character. We estimate the rate of the slide motion by resurvey of monuments on and off the slide, and examination of disturbed vegetation located along the fractures. The analysis indicates a slow integrated average landslide velocity of 10-60 mm/yr. The slide motion is probably driven during annual wet periods when increased saturation of the slide mass weakens the basal slip surface and the overall mass of the slide is increased. Results from our study suggest that the slide is stable and does not pose significant hazard for the surrounding area given no extreme changes in the environmental condition. Although the landslide is categorized as very slow (according to Cruden and Varnes, 1996), monitoring the landslide is still necessary.
ContributorsHelmi, Hurien (Author) / Arrowsmith, J Ramon (Thesis advisor) / DeVecchio, Duane (Committee member) / Whipple, Kelin (Committee member) / Arizona State University (Publisher)
Created2016
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Description
Shallow earthquakes in the upper part of the overriding plate of subduction zones can be devastating due to their proximity to population centers despite the smaller rupture extents than commonly occur on subduction megathrusts that produce the largest earthquakes. Damaging effects can be greater in volcanic arcs like Java

Shallow earthquakes in the upper part of the overriding plate of subduction zones can be devastating due to their proximity to population centers despite the smaller rupture extents than commonly occur on subduction megathrusts that produce the largest earthquakes. Damaging effects can be greater in volcanic arcs like Java because ground shaking is amplified by surficial deposits of uncompacted volcaniclastic sediments. Identifying the upper-plate structures and their potential hazards is key for minimizing the dangers they pose. In particular, the knowledge of the regional stress field and deformation pattern in this region will help us to better understand how subduction and collision affects deformation in this part of the overriding plate. The majority of the upper plate deformation studies have been focused on the deformation in the main thrusts of the fore-arc region. Study of deformation within volcanic arc is limited despite the associated earthquake hazards. In this study, I use maps of active upper-plate structures, earthquake moment tensor data and stress orientation deduced from volcano morphology analysis to characterize the strain field of Java arc. In addition, I use sandbox analog modeling to evaluate the mechanical factors that may be important in controlling deformation. My field- and remotely-based mapping of active faults and folds, supplemented by results from my paleoseismic studies and physical models of the system, suggest that Java’s deformation is distributed over broad areas along small-scale structures. Java is segmented into three main zones based on their distinctive structural patterns and stress orientation. East Java is characterized by NW-SE normal and strike-slip faults, Central Java has E-W folds and thrust faults, and NE-SW strike-slip faults dominate West Java. The sandbox analog models indicate that the strain in response to collision is partitioned into thrusting and strike-slip faulting, with the dominance of margin-normal thrust faulting. My models test the effects of convergence obliquity, geometry, preexisting weaknesses, asperities, and lateral strength contrast. The result suggest that slight variations in convergence obliquity do not affect the deformation pattern significantly, while the margin shape, lateral strength contrast, and perturbation of deformation from asperities each have a greater impact on deformation.
ContributorsMarliyani, Gayatri Indah (Author) / Arrowsmith, J Ramon (Thesis advisor) / Clarke, Amanda B (Committee member) / Hartnett, Hilairy (Committee member) / Whipple, Kelin (Committee member) / Garnero, Edward (Committee member) / Arizona State University (Publisher)
Created2016