Dynamic rupture propagation on geometrically complex fault with along-strike variation of fault maturity: insights from the 2014 Northern Nagano earthquake

• Published in: Earth, planets, and space Vol. 69; no. 1; pp. 1 - 13
• Main Authors: Ando, Ryosuke, Imanishi, Kazutoshi, Panayotopoulos, Yannis, Kobayashi, Tomokazu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 18.09.2017; Springer Nature B.V; SpringerOpen
• Subjects: 2014 Northern Nagano earthquake; Bends; Boundary element method; Complexity; Computer simulation; Deformation; Deformation effects; Deformation mechanisms; Dynamic rupture; Earth and Environmental Science; Earth Sciences; Earthquakes; Fast domain partitioning BIEM; Fault geometry; Fault lines; Faults; Geology; Geometry; Geophysics/Geodesy; InSAR; Integral equations; Rheological properties; Rupture; Seismic activity; Seismology; InSAR; Fault geometry; Dynamic rupture; 2014 Northern Nagano earthquake; Fast domain partitioning BIEM
• ISSN: 1880-5981; 1880-5981
• DOI: 10.1186/s40623-017-0715-2

Understanding the effect of the complex fault geometry on the dynamic rupture process and discriminating it from the complexity originating from the rheological properties of faults, is an essential subject in earthquake science. The 2014 Northern Nagano earthquake, which occurred near the end zone of a major active fault system, provided unique observations that enabled us to investigate both the detailed geometrical fault structure and surface deformation patterns as well as the temporal sequence led up from a prominent foreshock activity. We first develop a geometrical fault model with a substantial variation along strike, and a model for the regional stress field, which is well constrained by the observations. This significant along-strike variation in fault geometry probably reflects the difference of fault maturity at the end zone of the complex fault system. We used this model in order to conduct a set of dynamic rupture simulations using the highly efficient spatiotemporal boundary integral equation method. Based on our simulations, we show that the observed surface deformation can be reasonably explained as the effect of the non-planar fault geometry with a number of branch faults and bends. Graphical abstract .