Earthquakes, Transforms, Mid Ocean Ridge-Understanding the Plate Tectonics beneath the oceans at the Equatorial Mid Atlantic Ridge

Dr Nicholas Harmon, Prof J.M. Kendall (Oxford)
Rationale: 

The oceans make up 70 % of the planet, and yet they are the final frontier in understanding the inner workings of the solid earth with broad implications for climate, hazard and Earth’s evolution and habitability. Due to their harsh and remote environments there are very few ocean bottom seismic measurements of Earth’s interior. Many questions remain about the origin and evolution of the tectonic plates under the oceans, for example, what is the nature of the base of the tectonic plate, and how do the dynamics beneath the plate affect seafloor subsidence and heatflow. The PI-LAB seismic experiment deployed 39 ocean bottom seismometers and 39 ocean bottom magnetotelluric instruments to image and understand the oceanic tectonic plates in the equatorial Mid-Atlantic near the 900 km long Romanche transform fault (https://pilabsoton.wordpress.com/). Ocean transforms represent a rare opportunity to study the factors that influence earthquake rupture and hazard in a relatively simple setting. The experiment recorded a rich dataset including a variety of local, regional and teleseismic events. This is a rare opportunity image and understand the dynamics of ocean lithosphere and directly relate them to tectonic stresses and seismicity for a better understanding of the earthquake cycle.  

Methodology: 

The student will use advanced passive seismic techniques to perform the imaging across the region, building on a substantial amount of work. This will include joint inversions of surface wave, scattered wave and body wave data sets from local and regional seismicity to improve seismic velocity models across the region. The high-resolution velocity models will be used to improve relocation of seismicity, which will then be used understand faulting both near the plate boundary and further off axis in the region, incorporating a rich data set of marine geophysics. The student will make use of techniques in signal processing and software development. In addition, to achieve these goals the student will make use of HPC facilities and advanced machine learning algorithms.    

 

Location: 
University of Southampton
Training: 

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the School of Ocean and Earth Sciences. Specific training will include:

  1. Signal Processing Techniques
  2. Processing and analysis of continuous data recorded by Ocean Bottom Seismometers
  3. Tomographic methods using body and surface waves
  4. Earthquake location
  5. Scientific computational skills in programming, high performance computing, and machine learning that can be transferred easily to a range of fields after graduation;

​The student will also be given the opportunity to gain field experience both on land and at sea through various activities being carried out by the larger research group at the NOC. The student will also be given the opportunity to present their results to the broader scientific community and will receive training in science communication.

 

Eligibility & Funding Details: 

Please check https://inspire-dtp.ac.uk/how-apply for details.  

 

Background Reading: 

Harmon, N., Rychert C. A., Agius, M., Kendall, J. M., Tharimena, S., Bogiatzis, P.  (2020) Evolution of the Oceanic Lithosphere in the equatorial Atlantic, evidence for small-scale convection from the PI-LAB experiment, Geochem. Geophys. Geosys. DOI:10.1029/2020GC009174

Hicks, S. P., Okuwaki, R., Steinberg, A., Rychert, C. A., Harmon, N., Abercrombie, R. E., . . . Sudhaus, H. (2020). Back-propagating supershear rupture in the 2016 Mw 7.1 Romanche transform fault earthquake. Nature Geoscience. doi:10.1038/s41561-020-0619-9

Wang, S, Constable, S., Rychert, C.A., Harmon, N (2020) A lithosphere-asthenosphere boundary and partial melt estimated using marine magnetotelluric data at the central Middle Atlantic Ridge., Geochem. Geophys., Geosys., DOI:10.1029/2020GC009177

 

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