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Collection Description

The Department of Geological Sciences has a long-standing Senior Thesis research option for the B.S. Degree which involves a written thesis, and a public oral presentation done under the supervision of a faculty member. These independent research projects typically involve field work and laboratory analyses of samples, but can also include laboratory-based experimental projects, numerical modeling of geologic phenomena and literature reviews. Senior theses are kept in the permanent collection of the Malcolm A. Love Library on the SDSU campus.

Authors hold full copyright ownership of their original works. Please contact the repository manager at digital@sdsu.edu for any further questions.

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Implications of a summery of the findings for SDSC localities 413, 413 Upper, 441 & 442
San Diego State University
Innovative uses of opensha for historical earthquake intensity magnitudes
OpenSHA is a new set of highly flexible programs developed by the Southern California Earthquake Center (SCEC) to estimate seismic shaking hazard. These programs are linked via the internet to a standard database that is constantly being improved and upgraded. A subset of these modules was used to estimate the magnitude of the 1892 Laguna Salada earthquake. This earthquake caused severe shaking over much of Southern California. Because this earthquake was pre-instrumental, the magnitude is uncertain. Previous estimates of the magnitude range from M 7.1 (minimum) to M 7.8, based on either felt reports or field observations of the scarp. Intensity observations (based on Mercalli scale) were compared to estimates of shaking determined by OpenSHA. OpenSHA can test several attenuation relationships and site responses, which is an improvement over previous algorithms. The preferred match of the observed intensities was with a USGS attenuation relationship and site conditions, which yielded a best-fit value of M 7.5 for the Laguna Salada event when compared to a table of 66 observations. An M 7 .1 earthquake is incapable of matching the observed data. By applying standard fault area/magnitude relationships it appears that an M 7.5 likely ruptured the entire length ( ~62 km) of the Laguna Salada fault. OpenSHA holds potential for studies of this type, but is not ideally configured at this point., San Diego State University
Instructional value of the "Earthquake Machine" in a 9th grade high school setting
The purpose of this thesis is to test the effectiveness of a laboratory-bases exercise using the "earthquake machine" to address standards-based student learning outcome for a 9th grade earth sciences curriculum. Research has shown that currently employed instructional methods are ineffective. There is a critical need for quality earth science instructional materials in San Diego City Schools where a pilot program has been initiated to make earth science required for all 9th grade students. The San Diego City Schools 9th grade earth sciences curriculum has been spearheaded by Chris Lawrence and Mark Snow who are currently in the first year (2005/2006) of the pilot program at Mira Mesa High School. From October 2005 through April 2006 I have volunteered as a teaching assistant in support of this program. As part of this effort I conducted a pre- and post-test assessment study to determine the effectiveness of a lab based earthquake investigation. I have gathered and analyzed results from the classroom and see promising results. The results show a general increased learning trend with the application of the "earthquake machine as a laboratory experiment. It is hopeful that further positive studies using this model will allow it to be added to the earth science curriculum., San Diego State University
Intraspecific variation in cranial and mandibular morphology of the extinct river dolphin Parapontoporia sternbergi from the Upper Pliocene San Diego Formation, Southern California, USA
Parapontoporia sternbergi is an extinct species of river dolphin. It has been distinguished from two closely related extinct species, Parapontoporia pacifica and Parapontoporia wilsoni. These differences served as a basis for the establishment of P. sternbergi as a separate species. This study tests the validity of recognizing P. sternbergi as a distinct species based on examination of intraspecific variation in the cranial and mandibular morphology of fossil specimens. This study utilized specimens from collections at the San Diego Natural History Museum and the Natural History Museum of Los Angeles County. Specimens included three complete skulls of P. sternbergi and 13 complete skulls of the closely related river dolphin, Pontoporia blainvillei. The skull characters that define P. sternbergi as a species were identified as regions of focus. Variations of these characters are quantified by the following 15 skull measurements: left and right zygomatic process length, neurocranium width and length, left and right temporal fossa width, left and right temporal fossa height, left and right orbital length, width of rostrum at base, rostrum length, zygomatic width, width of rostrum at midpoint, and total length. Measurements were taken on each of the 16 specimens. For each of the skull measurements, mean measurements were calculated for P. sternbergi (n=3) and P. blainvillei (n=13). Separate t-tests were conducted (1 for each skull measurement), testing for a significant difference between the P. sternbergi and P. blainvillei means. Each P. sternbergi mean measurement was tested against the corresponding mean measurement on P. blainvillei. The 2-sample t-tests revealed that 9 of the 15 skull measurements resulted in p-values less than 0.05. This indicates that more than half of the skull characters of P. sternbergi are significantly different from those of P. blainvillei, suggesting that there are significant morphological differences in both river dolphins, supporting their recognition as separate species., San Diego State University
Inventory and geochemical evaluation of groundwater springs and streams in San Diego County; Upper Sweetwater Watershed
San Diego’s hydrologic system contains a multitude of watersheds, such as the Peñasquitos, San Diego River, Pueblo, Sweetwater, and Otay. This project includes the inventory and geochemical evaluation of groundwater springs and streams within Cuyamaca Rancho State Park in the upper Sweetwater watershed. The Sweetwater watershed flows southwest for 55 miles and covers 230 sq. miles from Upper Green Valley in the semi-arid Cuyamaca Mountains to Mission Bay, where it enters the Pacific Ocean. The objective is to analyze whether the groundwater springs in the upper region of the Sweetwater watershed show similar patterns of flow and geochemistry due to their respective geology. This study focuses on seven locations: Deer Spring, Cold Spring, Azalea Spring, Japacha Spring, Dyar Spring, Granite Spring, and Green Valley Falls. The geology of these sites encompasses the Cuyamaca Gabbro, Chiquito Monzogranite, Quartz Diorite of East Mesa, the Monzogranite of Pine Valley, and the Gneiss of Harper Creek. Several variables will be analyzed in this study via field and lab work. The analysis of these representative samples will illustrate how water quality functions relative to rock weathering in the carbon cycle in which precipitation interacts with the underlying geology., San Diego State University
Investigating the 2010 Moro Gulf deep earthquake sequence using the continuous back-projection technique
Deep earthquakes make up approximately one-quarter of all earthquakes, yet current understanding of mechanisms for deep (300-700 km) earthquake generation fails to explain why deep range earthquakes occur. Various mechanisms have been proposed, however, there is a lack of observational constraints on the properties of deep earthquakes, which deters our understanding. In order to progress our knowledge of the deep earth, robust constraints on the mechanisms of deep earthquakes are required. The goal of this project is to explore the mechanism(s) behind deep earthquakes through studying the 2010 Moro Gulf deep earthquake sequence using a continuous back-projection technique. The Moro Gulf sequence features a 'triplet' of earthquakes with hypocentral depths between 585 and 640 km. The triplet earthquakes are particularly unusual, because they are large magnitude events (Mw7.3, 7.6, and 7.4) that occurred within an hour and a half of each other, which does not agree with the Gutenberg-Richter relationship. No other triplet sequences of this magnitude have been recorded within such a short time period. Another anomalous characteristic of these earthquakes is the emergent waveforms of the sequence. Typically, deep earthquakes have impulsive waveforms, which are thought to be associated with more rapid stress drop than shallow events, for which the stress drop occurs more gradually. The back-projection technique is an efficient method to constrain earthquake rupture properties, such as rupture direction, rupture speed, location, timing, and relative energy release of an earthquake. It requires high-quality data from a dense network of seismic stations covering a large area, and we use data from the High-Sensitivity Seismograph Network (Hi-net) in Japan and Australian Network (AU). The technique creates a grid of potential source locations around the hypocenter. The seismograms are time-shifted and stacked at each grid point. The data from the three earthquakes are filtered to a frequency range of 0.8-2 Hz in order to maximize the resolution from the back-projection, and to capture the first arriving P-waves in the waveforms. Back-projection analysis of the Moro Gulf sequence is expected to provide a detailed rupture process of these deep events with high depth and spatial resolution., San Diego State University
Kinematic analysis of Quaternary and Neogene faults in the Santa Rosalia Basin along the western margin of the Gulf of California
Late Cenozoic volcanic and sedimentary rocks of Santa Rosalía basin located on the western shore of the Gulf of California in central Baja California Sur, México contain an important kinematic record associated with continental rifting and the transfer of Baja California crust from the North American to Pacific plates. This study identifies fault types and orientations, and differs from previous investigations by taking advantage of excellent new exposures created by Minera Boleo mining operations. Faults cutting volcanic rocks were measured in arroyo outcrops, but most measurements were collected from mine cuts. Fault rocks, including fault gouge and breccia, were sampled and analyzed by petrographic, X-ray diffraction, and scanning electron microscopy methods. Analysis document mineralization of sepiolite, a soft white clay mineral, along shear zones. Orientation data were collected on over 250 faults and slickenlines in multiple unconformity bounded formations in the Santa Rosalía basin. Fault orientation data were processed in QGIS, Microsoft Excel, Stereonet 9, and Fault Kin 7. Most faults are oblique faults with a normal component of slip; very few thrust faults were found. The data from successive formations in the basin reveal temporal changes in fault orientations and slip directions. Middle to Late Miocene volcanic rocks are dominated by steep to moderately dipping NW- to N-striking faults that dip dominantly SW or are very high angle, with moderately-plunging slickenlines. Late Miocene sedimentary rocks (Boleo Formation) are dominated by steeply-dipping, NNW- to NNE-striking oblique-slip faults, with a wide range in plunge of slickenlines. Pliocene sedimentary rocks (Tirabuzón and Infierno Formations) faults are dominated by steeply-dipping, NW- and NE-striking faults with dominant normal displacement determined from stratigraphic offset and steep plunge in striations. Quaternary marine terraces are cut by steeply-dipping, NW to NE-striking faults with no preserved slickenlines found. The changes in fault orientations mark a shift in stress conditions during the complex tectonic process of the rifting in the Gulf of California., San Diego State University
Laminations of salton sea sediments
The Salton Sea is an enclosed lake in southeastern California that formed accidentally when the Colorado River was detoured into the Imperial Valley. Since that time it has been fed by agricultural and municipal waste waters, which are loaded with nutrients. Since there is no outlet to the Salton Sea, salinity has been increasing to the point that it now exceeds that of seawater. Recent studies have shown that stratification of the Salton Sea results when summer temperatures are high and wind flow is reduced. As a consequence of stratification and high productivity in the surface waters, hydrogen sulfide builds up in the bottom waters of the lake. Near the end of summer, wind flow resumes, resulting in overturn and mixing of the water column. The hydrogen sulfide becomes oxidized by the high oxygen contents in the surface waters, resulting in gypsum precipitation. It is believed that this imparts a green hue to the water in the northern and southern basins of the lake. The color change was first believed to be caused by an algal bloom, but is now believed to be from the precipitation of gypsum in the water column. Associated with the upwelling are large biological die-offs. This thesis looks at this proposed scenario by examining the mineralogy and composition of the bottom sediments from two sites in the Salton Sea: one near shore and the other from the north central basin. Gypsum, calcium carbonate, organic material, diatoms and detrital contents were determined in the laminated sediments. Six samples with high gypsum concentrations were found in the bottom sediments reflecting the overturn event. Overlying these, are laminations containing increased amounts of calcite and residue high in silica tests. Many restoration projects for lowering water salinity have been proposed for the Salton Sea (Salton Sea Authority, 1997). But, any remediation technique must take into account that lowering the salinity of the incoming water will cause salts such as gypsum (averaging 24 percent in the bottom sediments) to go back into solution and diffuse into the overlying waters., San Diego State University
Landslide hazard analysis and mitigation for Sepanjang Village, Central Java Indonesia
This study is based on 8 weeks of field work and study in Indonesia during summer 2013 participating in a student-based community service program run by Universitas Gadjah Mada. The study was focused on the village of Sepanjang in Central Java which is located on the southwestern flank of Mount Lau, a dormant stratovolcano. The project was a landslide mitigation effort focused on the improvement of landslide education for the village by creating an up to date field map that provided the village with locations and descriptions of landslides, potentially dangerous areas, evacuation routes, and general meeting areas during emergencies. Indonesia is a massive archipelago that contains 18,000 islands and is located on the southern lobe of the Eurasian plate. Subduction of the Australian plate underneath the Eurasian plate bounds Indonesia to the west and south, and subduction of the Pacific plate underneath the Eurasian plate takes place to the east. These tectonically active zones are characterized by intense volcanism and seismicity that have a continuous effect on the topography. Annual rainfall for Java is 69.1 inches per year, which is almost seven times that of San Diego, CA. These factors contribute heavily to the susceptibility of landslides and result in the imminent danger to people and infrastructure. These susceptibilities were produced by measuring the physical properties of the landslides, including slope, thickness of soil, amount of vegetation, land use, and existing signs of recent movement. Assistance from other Gadjah Mada students allowed for both dispersal of the susceptibility map to local leaders and rescue teams, as well as providing villagers with landslide education and ways to notice and respond to signs of land movement. Active landsliding is widespread in the area of the village and presents hazards to people and property. The impact of human development on the landscape plays a significant role in producing landslide hazards in the area that include road construction, agricultural terracing, and quarrying for building materials. This study brought to light the lack of landslide understanding in rural Java and the need for educational services to help local villagers see, prepare for, mitigate, and respond to landslide disasters., San Diego State University
Landslides along the Mount Soledad fault, La Jolla, California
The structural uplift of Mount Soledad between mid-Pleistocene and Late Pleistocene time has resulted in steep hillsides and canyon walls, faults, bedding plane faults, and joints that contribute to slope instability. These conditions combined with heavy rainfall during the Late Pleistocene (15,000 to 20,000 years before present) resulted in numerous landslides in the La Jolla district of San Diego, California. Nineteen ancient landslides have been recognized along a four kilometer segment of the Mount Soledad fault. They have been recognized primarily by geomorphology, including topographic maps, aerial photos and field observations. Some borehole data have been used, but subsurface study is generally beyond the scope of this report. Most of the landslides that occurred on southerly facing slopes were translational, moving down dip slopes in the Ardath Shale. The slides that occurred on northerly facing slopes were either rotational or composite landslides, which are translational slides with the head region rotated backward. Many of the landslides originally failed on the remolded clay seams of bedding plane faults. Panoramic views of the Pacific Ocean and surrounding areas have led to residential development on the steep hillsides of Mount Soledad, making the ancient landslides a significant geologic condition, with potential economic loss. The effects of residential development on hillsides , coupled with a wet season or an earthquake could reactivate an ancient landslide and destroy expensive La Jolla homes., San Diego State University
Learning patterns of spatial abilities in the perception of geological structures
The spatial ability required to study basic structural geology is a complex skill to learn. It is even more difficult to teach and understand how students learn it. In the mid 1990s Yael Kali and Nir Orion, of the Department of Science Teaching at the Weizmann Institute of Science in Rehovot, Israel, created a Flash based computer program that they named Geo3D. To test this programs' effectiveness they also created a test named GeoSAT, or the Geologic Spatial Ability Test. The environment that they ran their experiment in was a science specialized high school consisting of students with very little diversity of culture and background. Kori Truesdale, Matt Ales, and Dr. Eric Riggs ran an experiment with a slightly modified Geo SAT. The experiment was conducted with students from the Department of Geology at San Diego State University's Geology 101 Lab. The experiment was done to determine if there were any beneficial effects using the Geo3D program as opposed to the traditional teaching methods. It was determined that both teaching methods taught different ideas equally as well., San Diego State University
Linear compositional modeling and the statistical significance of alteration intensity facrots, Clar segment, San Jacinto fault zone, Horse Canyon, California: Implications for the illit/smectite to illite transition and the development of fault zones at
The NE block of the Clark segment of the San Jacinto fault zone within Horse Canyon, NE of Anza, southern California displays a well-defined damage zone, transition zone, and fault core. Previous work by N. Morten and colleagues (2012) showed that through fragmentation and slip grain and fragment size progressively diminishes from the outer damage zone inward toward the fault core where the finest grain size material is found. In addition, the proportion of plagioclase declines while the proportion of quartz increases towards the fault core. When chemical data are plotted on a A-CN-K ternary diagram a linear trend extending from wall rock compositions toward the compositional field of illite is evident. In addition, N. Morten and colleagues showed through evaluation of the <4 micron fraction, that the illite/smectite to illite transition occurred at or near the transition zone/fault core boundary. However, because of the coarseness of <4 micron fraction, XRD data included peaks from quartz, plagioclase, K-feldspar, and amphibole along with those derived from the clay minerals, all making interpretations difficult and at times problematical. We therefore undertook a clay mineralogy study of the <2 micron fraction, and revaluated the chemical alteration trends first recognized by Morten and colleagues utilizing the linear compositional modeling techniques promulgated by H. von Eynatten and colleagues in 2003. From the latter work we determined the translational invariant alteration intensity factors for the damage zone, transitional zone, and fault core of the NE block. The results of our work shows that the <2 micron fraction provides a more concise and cleaner interpretation of the illite/smectite to illite transition within the NE block. In addition, our modeling using non-central component analysis shows that A-CN-K data spread about a compositional linear trend with PC1 explaining 99.7% of the simplicial variability. Through orthogonal projection we calculated the alteration intensity factors for each sample analyzed from the various architectural components of the fault zone. In order to assess whether or not the means of the alteration intensity factors were statistically different at the 95% confidence level, we utilized the one-way ANOVA routine in SPSS. The significance level of the omnibus results was .0001; hence, there is not sufficient statistical evidence to reject the null hypothesis that at least one of the means was different than the other two. We then utilized the post hoc routines in SPSS which revealed that the mean of the alteration intensity factors for the fault core are different from the means of those obtained from the transition and damage zones at the 95% confidence level. In contrast, the means of the transition and damage zones are not different at the 95% confidence level. The above results suggest that for fault zones derived from tonalitic wall rocks at depths of ~0.5 km, the illite/smectite to illite transition will occur when alteration intensity factors exceed 0.20, the average intensity factor calculated for the transition zone. We speculate that under such conditions during repeated rupturing events fluids with elevated temperatures (≥ ~125oC) are flushed through the fault core. In short, over time, the combination of shearing, fragmentation, and relatively elevated temperatures eventually overcomes the kinetic barrier for the illite/smectite to illite transition. Such settings and processes are unique to fault zones, and as a result, fault zones represent an underappreciated setting for the development of illite from illite/smectite., San Diego State University

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