Rupture Model of a Hikurangi Mw 8.6 Megathrust Earthquake for Strong Motion Simulations

Date: 4/24/2019

Time: 08:45 AM

Room: Pine

For the purpose of strong ground motion simulations, we have developed a multi-segment M8.6 rupture model of a Hikurangi (North Island of New Zealand) megathrust event, including unilateral rupture with propagation towards the northeast, in accordance with Schellart and Rawlinson (2012). We used the Graves and Pitarka hybrid Irikura method (Pitarka et al., 2018; GP-IM) for developing the source model. This method combines the Irikura and Miyake (2011) asperity-based kinematic rupture generator with the Graves and Pitarka (2015) rupture generation methods for stochastic spatial variability and background slip in shallow crustal earthquakes. We adapted these for use with subduction earthquakes using the Skarlatoudis et al. (2016) scaling for the corner wavenumbers in the along strike and down-dip directions for great interface subduction earthquakes. We also modified the perturbations to the rupture times for large earthquakes to make them smoother, and modified the parameters that control the average rupture speed and rise time. Relationships between seismic moment, rupture area, asperity area, and stress parameters were based on work by Murotani et al. (2008), Tajima et al (2013) and Miyake (2018). The maximum slip over the rupture planes was found to be approximately 14 m, and the average slip is approximately 3.5 m. Both of these values are broadly consistent with the scaling relations developed by Tajima et al. (2013) and Skarlatoudis et al. (2016). We are now performing simulations to assess the importance of slip randomness, asperity number and location, and hypocenter location in influencing the simulated ground motions.

Presenting Author: Paul Somerville

Authors