IGPP is pleased to invite you to join its Fall 2021 Seminar Series presentation featuring Jianhua Gong. Dr. Gong's talk, "Microseismicity indicates atypical small-scale plate rotation at the Quebrada transform fault system, East Pacific Rise" will be available in person, in the Munk Conference Room and on Zoom on Tuesday, November 23, 2021, starting at 12:00pm. Zoom: https://ucsd.zoom.us/j/97144597101?pwd=azZHZDZ3aEdIdE5nRHYzd3VEOCtMQT09. Password: transform
Date: Tuesday, November 23, 2021
Time: 12:00 pm, Pacific Time
Location: Munk Conference Room and Zoom
Note: This meeting will be recorded. Please make sure that you are comfortable with this before registering.
Abstract: Closely-spaced, multi-strand ridge transform faults (RTFs) accommodate relative motions along fast spreading mid-ocean ridges. However, the relatioships between RTFs and plate spreading dynamics are poorly understood. The Quebrada system is one of the most unique RTF systems at the East Pacific Rise, consisting of four transform faults connected by three short intra-transform spreading centers (ITSCs). We use seven-months of ocean bottom seismograph recording to study the Quebrada system, and find abundant earthquakes unevenly distributed among three active faults. We identify two deep, diffuse seismicity clouds at the inside corners of the ITSC-transform fault intersections, and one seismically-active fracture zone. The observations suggest a complex regional plate-motion pattern, including possible heterogeneous rotations within the Quebrada system. Evolution of multi-strand RTFs may have resulted from a strong three-dimensional local thermal and fluid effects, while the RTFs may have also regulated regional tectonics, forming an intricate feedback system.