Fakequakes: Earthquake Rupture Scenarios for California and Cascadia

Christine J. Ruhl, Diego Melgar, Ronni Grapenthin, Mario Aranha, & Richard M. Allen

Published August 15, 2016, SCEC Contribution #6903, 2016 SCEC Annual Meeting Poster #319

Limited geodetic observations of earthquakes greater than M6 make it difficult to test and improve GPS-based earthquake early warning systems, such as G-larmS. Scenario ruptures and ground motion simulations are therefore useful for studying earthquake and tsunami hazards expected during future events. We develop a catalog of scenario earthquakes on 25 large faults (capable of M>6.5) in California, as well as the Cascadia subduction zone, built from realistic 3D geometries. Synthetic long-period 1Hz displacement waveforms are obtained from a new stochastic kinematic slip distribution generation method. Waveforms are validated by direct comparison to peak P-wave displacement scaling laws and to PGD GMPEs obtained from high-rate GPS observations of large events worldwide.
We will also discuss the generation of broadband synthetic ground motions by hybrid deterministic/stochastic methods and argue that they are still preferable, for these purposes, over fully deterministic and computationally intensive forward modeling approaches. Particularly, we will focus on portions of the seismogram typically ignored in broadband synthesis: P-waves and long period displacements that correctly capture static offsets. It is important to adequately model these, in addition to strong shaking, in order to study the response of currently operating early warning systems.

Key Words
Fakequakes, Earthquake Simulation, EEW, G-larmS

Citation
Ruhl, C. J., Melgar, D., Grapenthin, R., Aranha, M., & Allen, R. M. (2016, 08). Fakequakes: Earthquake Rupture Scenarios for California and Cascadia. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Simulators