Research

Dynamics, radiation and overall energy budget of earthquake rupture with coseismic off‐fault damage

First published: 06 August 2019

This animation shows the propagation of dynamic earthquake rupture on a planar fault with spontaneous activation of secondary fractures in the off-fault medium. The secondary fractures are dynamically activated by the dynamic earthquake rupture on the main fault, and the complicated feedback from the secondary fracture network, which enhance the high-frequency components in near-field ground motion. The color contour indicates particle velocity magnitude, while the white lines indicate the coseismic off-fault fracture network. Since all parameters are non-dimensionalized in this simulation, time is represented by the frame number. The results presented in this animation were obtained using the educational version of the Hybrid Optimization Software Suite (HOSSedu).

Details can be found in Okubo et al. (2019).

SeisIO.jl: Powerful Julia tool for seismic data processing.

First published: 29 April 2020

SeisIO is a powerfull tool of seismic data processesing implemented with Julia language. We take an advantage of fast IO for large computation such as ambient seismic noise monitoring.

Details can be found in Jones et al. (2020).

Earthquake Damage Patterns Resolve Complex Rupture Processes

First published: 12 September 2018

We modeled dynamic earthquake ruptures on the Papatea – Jordan - Kekerengu fault system associated with the 2016 Mw 7.8 Kaikōura earthquake for two hypothetical rupture scenarios with spontaneous activation of coseismic off-fault damage. This work demonstrates that comparison of damage pattern inferred from observations to the models helps identify the earthquake rupture path.

This animation shows the dynamic earthquake ruptures on the Kekerengu-Jordan- Papatea fault system associated with the 2016 Mw 7.8 Kaikōura earthquake, New Zealand. The fault geometry is traced from satellite imagery and field observations. Color contour indicates particle velocity magnitude. Dotted lines indicate pre-existing faults, while yellow lines indicate secondarily activated off-fault fractures. In this case, the rupture is artificially nucleated from the southern end of the Papatea fault. As the rupture propagates and gets close to the Kekerengu fault, it jumps and continues to propagate along the Jordan - Kekerengu fault system. In the animation, the top-right window shows the evolution of the slip velocity on the prescribed faults. It is worth noting that the position along faults is nondimensionalized by their corresponding lengths. The bottom-right window shows the two seismograms associated with the seismic stations indicated by the inverted triangles. The results presented in this animation were obtained using the educational version of the Hybrid Optimization Software Suite (HOSSedu), developed by Los Alamos National Laboratory.

In this case, the rupture is artificially nucleated from the southern end of the Jordan thrust. As the rupture propagates towards the North-East along the Jordan - Kekerengu fault system, it jumps to the Papatea fault. However, the rupture on the Papatea fault is promptly arrested due to the off-fault damage and thus parts of the Papatea fault remain unaltered. These results are compared to high-resolution optical satellite image displacement maps and field observations to determine the most likely rupture scenario.