Geological constraints on the stress state and evolution of seismogenic and creeping faults (2019-2021)

Undergraduates: Sofia Marino (B.S. Geology UCD, 2020), Michael Hernandez (SCEC SOURCES intern summer 2021), Kimberly Bowman (B.S. Geology UCD, 2020).
Sofia, Kimberly, and Michael are mapping surficial fractures from high-resolution lidar and field data from a group of seismogenic and creeping faults. They will use their measurements to automatically analyze fracture density and orientation to understand how dynamic and static stresses affect fault growth and evolution. Sofia's undergrad thesis proposal was awarded a Provost's Undergraduate Fellowship that covered her fieldwork expenses. Michael's work was funded through the SCEC SOURCES internship. 
Presentations: Sofia Marino (2020 UC Davis undergraduate science symposium, SCEC 2020 poster), Michael Hernandez (SCEC 2021 poster).

 Unsupervised cluster analysis of surface rupture attributes (2021-2022)

Undergraduate: Mercedes Quintana (Pasadena City College, SCEC SOURCES intern).
Mercedes is using unsupervised learning cluster analysis to look at patterns in surface deformation using UMAP and HDBSCAN. She is applying this method to legacy surface rupture maps from several earthquakes in the ECSZ. Through her analysis, she explores how fracture density mean and variance, distance to main rupture, crack length, and other parameters affect the organization of the rupture.
Presentations: Mercedes presented a preliminary analysis of a section of the Ridgecrest 2019 surface rupture at the SCEC 2021 meeting and the application of this method to legacy rupture maps from the Landers, Hector Mine, and Ridgecrest earthquakes at the 2022 SSA Annual Meeting. 

 The role of bends and splays in rupture propagation in strike-slip earthquakes (2022)

Undergraduates: Vanessa Herrera (B.S. Geophysics, San Diego State University) and Sophia White (B.S. Geology, UCLA)
Vanessa and Sophia are summer 2022 SCEC SOURCES interns working on measuring step-over sizes from the QFDF and FDHI database, mapping and measuring the angles in single and double bends, and fault splays in multi-fault earthquakes from these standardized datasets. From their measurements, they will explore how bend and splay angle, and bend and splay length, condition the mechanics of rupture propagation through these zones of geometrical complexity. Vanessa is also continuing this research for her undergrad thesis at SDSU, where she is investigating how fault bends are oriented with respect to their regional stress field. 
Presentations: Poster presentations at the SCEC 2022 Annual Meeting by Vanessa Herrera and Sophia White. ​
Poster presentation at the SSA 2023 Annual Meeting by Vanessa Herrera. 
Oral presentation at San Diego State University by Vanessa Herrera for her undergrad thesis. 

Mapping the erasure of coseismic scarps from synthetic DEMs (2023)

Undergraduate: Karen Castañeda (B.S Geology, UC Davis)
For her undergraduate thesis, Karen is mapping synthetic digital elevation models of fault scarps to help understand the effect of surface processes in the information available for quantifying probabilistic fault displacement hazard assessment. This project is part of an ongoing collaboration with Ramon Arrowsmith at ASU.

Near-field kinematics of the 2019 Ridgecrest earthquakes (2021)

Undergraduates: Leslie Garcia (B.S. Geology UCD, 2022), Brian Aguilar, Ruth Prado, Mercedes Quintana, Thomas Shea (SCEC SOURCES interns summer 2021). 
​The 2019 Ridgecrest earthquake ruptured a set of orthogonal faults in the best monitored continental earthquake sequence to date. Our team worked with 2-20 cm resolution drone imagery collected by Pierce et al. (2019) and 5 cm resolution orthophotography collected by NCALM to map portions of the surface rupture with unprecedented detail. These maps enable quantifying subtle patterns, including rupture rotations and trade-offs between localized and distributed deformation. 
Presentations: Leslie Garcia (UCD EPS Science Symposium, oral), SCEC 2021 meeting posters by Brian Aguilar, Ruth Prado, Mercedes Quintana, and Tom Shea.
Publications: 
​Rodriguez Padilla, A. M., Quintana, M. A., Prado, R. M., Aguilar, B. J., Shea, T. A., Oskin, M. E., & Garcia, L. (2022). Near‐Field High‐Resolution Maps of the Ridgecrest Earthquakes from Aerial Imagery. Seismological Society of America, 93(1), 494-499.doi: https://doi.org/10.1785/0220210234

​Measuring vertical displacements from post earthquake lidar point clouds (2021-2023)

Undergraduate: Guadalupe (Lupita) Bravo (McNair Scholar, UC Davis) 
​Lupita is working on measuring coseismic vertical displacements over different wavelengths from lidar point clouds, using the 0.5m per pixel resolution dataset collected following the Ridgecrest 2019 earthquakes. Using the lidR package for R and the lidar point cloud, we created a code to assist in selecting cross-sections along the Ridgecrest faults to measure the vertical displacement in 100-meter spaced increments along the surface rupture. We apply a linear fit to the top and the bottom of the scarps. The vertical separation between the best-fit lines is the vertical displacement accommodated by the fault. Our results highlight that, in flat sections along the rupture, it is possible to resolve vertical displacements as low as 10 cm from the post-earthquake point clouds alone (i.e. without requiring differential lidar). Lupita is a 2021-2022 McNair scholar and will be working with Mike Oskin and I through Spring 2023 through her McNair research program and an undergraduate thesis. 
Presentations: Lupita presented her work in a poster at the 2022 Undergraduate Research Symposium in the Earth and Planetary Sciences Department at UC Davis, in a poster at the SCEC 2022 meeting, and in a talk at the McNair research symposium at UCLA in July 2022. 

Semiautomated fault displacement profile extraction from lidar DEMs (2022-2023)

Undergraduate: Mercedes Quintana (Pasadena City College, Computer Science, SCEC SOURCES intern)
Mercedes is working in a semiautomated routine for extracting and analyzing fault displacement profiles for normal faults using a combination of published, simplified fault maps and high-resolution lidar DEMs. We start by training a Support Vector Machine to detect fault scarps in profiles collected perpendicular to the fault at evenly spaced increments along strike. Then we fit each profile and calculate the throw as the vertical separation across the fault. The algorithm outputs the displacement profile for every fault mapped, and the maximum displacement vs length relationship for the network of faults. This approach enables rapid and standardized collection of fault throw and length metrics for large datasets.
Presentations: Mercedes presented this work in a poster presentation at the SCEC 2022 Annual Meeting and the 2023 SSA Annual Meeting.

List and current positions of mentored undergraduate researchers

  1. Sofia Marino (BS Geology 2020 UC Davis, 2020 Provost's Undergraduate Fellowship) co-supervised undergraduate thesis with Mike Oskin (2019-2020). Currently a MSc student at UNC Chapel Hill working with Eric Kirby.
  2. Michael Hernandez (BS Geology 2022 Cal State Bakersfield) SCEC SOURCES intern (summer 2021). Now an Engineering Geologist at the California Department of Conservation.
  3. Kimberly Bowman (BS Geology 2020 UC Davis) summer remote mapping project (2021). Currently an Engineering Geologist at the California Department of Water Resources.
  4. Leslie Garcia (BS Geology 2022 UC Davis) spring mapping and data analysis research project (2021). 
  5. Brian Aguilar (BS Geology 2022 Cal State Bakersfield) SCEC SOURCES intern (summer 2021). Currently a teacher in Kern County.
  6. Tom Shea (BS Geology 2022 USF) SCEC SOURCES intern (summer 2021). Currently a Park Guide for the National Park Service.
  7. Ruth Prado (AS Geology 2021 Glendale College) SCEC SOURCES intern (summer 2021). Now pursuing a ​BS in Environmental Science with a focus on management (expected 2023).
  8. Mercedes Quintana (AS Computer Science 2022 PCC) SCEC SOURCES intern (2021-2023).
  9. Lupita Bravo (BS Geology 2022 UC Davis, 2021-2022 McNair Scholar) McNair project mentor (2021-2022) and senior thesis (2022-2023), co-supervised with Mike Oskin. Incoming PhD student at UC Riverside.
  10. Vanessa Herrera (BS Geophysics 2023 San Diego State University) SCEC SOURCES intern (2022) and undergraduate thesis (2022-2023). Incoming MSc student at San Diego State University.
  11. Sophia White (AS Geology 2022, BS Geology 2024 UCLA) SCEC SOURCES intern (2022). Currently a BS Geology student at UCLA doing research with Seulgi Moon.​
  12. Karen Castañeda (BS Geology 2023, UC Davis) undergraduate thesis in Spring and Summer 2023. ​