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Hybrid Broadband Ground motion simulations of Porters Pass fault earthquakes

Mohammad A. Nazer, Hoby N. Razafindrakoto, & Brendon A. Bradley

Published August 12, 2016, SCEC Contribution #6656, 2016 SCEC Annual Meeting Poster #285

We present ground motion simulations of the Porters Pass (PP) fault in the Canterbury region of New Zealand; a major active source near the Christchurch city. The active (slip rate 3.2-4.1 mm/yr) segment of the PP fault has an inferred length of 82 km and a mostly strike-slip sense of movement. This slip makes up approximately 10% of the total 37 mm/yr margin-parallel plate motion whilst also comprising a significant proportion of the total strain budget in regional tectonics. Given that the closest segment of the PP fault is less than 45 km from Christchurch city, the PP fault is crucial for accurate earthquake hazard assessment for this major population center.

We employ the hybrid simulation methodology of Graves and Pitarka (2010, 2015), which combines low (f<1 Hz) and high (f>1 Hz) frequencies into a broadband spectrum. We have used validations from three moderate magnitude events (Mw4.6 Sept 04, 2010; Mw4.6 Nov 06, 2010; Mw4.9 Apr 29, 2011) to build confidence for the Mw > 7 PP simulations. Thus far our simulations include multiple rupture scenarios which test the impacts of hypocenter location and the finite-fault stochastic rupture representation of the source itself. In particular, we have identified the need to use location-specific 1D VS/VP models for the high frequency part of the simulations to better match observations.

Key Words
Earthquake Engineering and seismology.

Nazer, M. A., Razafindrakoto, H. N., & Bradley, B. A. (2016, 08). Hybrid Broadband Ground motion simulations of Porters Pass fault earthquakes. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motion Simulation Validation (GMSV)