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Associate Researcher Lu Renqi of the Institute of Geology Paid an Exchange Visit to the Department of Earth and Planetary Sciences, Harvard University

2016/6/7 14:33:19

At the invitation of Prof John Shaw from the Department of Earth and Planetary Sciences, Harvard University, associate researcher Lu Renqi from Key Laboratory of Active Tectonics and Volcano, Institute of Geology went to Harvard University for a 17-day exchange visit from January 11 to January 28, 2016.

During this exchange visit, the two sides carried out discussion and exchange mainly in three aspects. Firstly, research and explore Pengxian blind fault at the piedmont of Longmen Mountain and its tectonic characteristics. From piedmont of the trust belt of Longmen Mountain to Chengdu Plain, there are many blind faults, as well as some unknown suspected faults. The existing researches believe these blind faults were ever active after Late Quaternary period, suggesting they still have certain seismic risk. Pengxian blind fault at the piedmont in the middle section of the thrust belt of Longmen Mountainis covered by thick Quaternary sediments of Western Sichuan depression, the research is difficult. Early research of this fault mainly relies on 2D seismic reflection profiles, but as the resolution of 2D seismic data is low and seismic wave impedance shows disorderly emission in a complex tectonic region, diverse interpretation results and models appear. During the exchange visit, 3D seismic data was adopted to accurately interpret Pengxian blind fault, fault-related fold theory was applied to quantitatively analyze and calculate typical structures, and the tectonic geometry, dynamics, segmentation and other characteristics of Pengxian blind fault were preliminarily disclosed.

Figure 1. Communication and discussion with Prof John Shaw

Figure 2. Learning of 3D tectonic modeling of SKUA-GOCAD software

Next, on the basis of the research of predecessors, they discussed in depth the tectonic modeling of Sichuan Lushan Earthquake occurring in 2013. They also discussed many issues, such as: was Lushan Earthquake caused by a blind active fault; focal mechanism solution and geometry for interpreting seismogenic fault; seismotectonic model interpreting co-seismic deformation (including GPS, level, etc.) and artificial seismic profile; single earthquake event and characteristics of near-surface tectonic deformation; long-term accumulated tectonic deformation. Prof John Shaw and Prof Andreas Plesch gave many valuable suggestions on research approaches and methods, and provided very useful knowledge and information in the aspects of tectonic interpretation and tectonic modeling.

In the end, based on the proprietary software plug-in developed by the Department of Earth and Planetary Sciences, Harvard University, and with the generous help of Prof Andreas Plesch and doctoral candidate Joseph M. Stockmeyer, Lu Renqi learned GOCAD three-dimensional seismotectonic modeling technique and its software. In this period, doctoral candidate Sun Yanpeng of Harvard University showed him around the geology and tectonophysics laboratory, and introduced the sandbox principle of basin-mountain deformation in thrust nappe process, box-tank experiments for sedimentation in a water seepage environment, etc.

During this exchange and study, Lu Renqi benefited a lot in such aspects as analysis of active tectonics and tectonic modeling. These are great help and enlightenment to future relevant research. Meanwhile, they also discussed the field and possibility of further cooperative research.