Málstofa Umhverfis- og byggingarverkfræðideildar: Kvörðun jarðskjálftalíkans og hermun yfirborðshreyfinga sterkra jarðskjálfta á Íslandi

Þann 11. maí kl 13:00 í stofu 157 í VR-II mun Tim Sonnemann flytja fyrirlestur um rannsóknir sínar við Umhverfis- og byggingarverkfræðideild Háskóla Íslands.

 

Kvörðun jarðskjálftalíkans og hermun yfirborðshreyfinga sterkra jarðskjálfta á Íslandi

(e. Earthquake Source Modelling and Strong-motion Simulation in Iceland for Earthquake Engineering Applications)

 

Tim Sonnemann er doktorsnemandi á 3. ári við umhverfis- og byggingarverkfræðideild Háskóla Íslands. Leiðbeinandi hans er Dr. Benedikt Halldórsson, vísindamaður og forstöðumaður rannsókna hjá Rannsóknarmiðstöð í jarðskjálftaverkfræði við umhverfis- og byggingarverkfræðideild Háskóla Íslands, og sérfræðingur í tæknilegri jarðskjálftafræði á úrvinnslu- og rannsóknasviði Veðurstofu Íslands. Í doktorsnefnd Tim sitja enn fremur Dr. Sigurjón Jónsson prófessor í jarðeðlisfræði við King Abdullah University of Science and Technology í Saudi Arabíu, Dr. Birgir Hrafnkelsson prófessor við Raunvísindadeild Háskóla Íslands og Dr. Apostolos S. Papageorgiou, prófessor við Háskólann í Patras í Grikklandi.

 

 

A seismological model for the hybrid simulation of the three largest recorded earthquakes in the South Iceland Seismic Zone (SISZ) is presented. This addresses the relative lack of a region-specific physical ground motion model applicable over a broad frequency bandwidth relevant for engineering purposes. A part of the issue may be that only three strong earthquakes (M6-6.5) have been well recorded in the region and for which static slip distributions exist, and geotechnical information on the complex subsurface structure is sparse. Therefore, we employ a physical modelling approach to the earthquake source and the corresponding strong-motions by combining long-period deterministic synthetic seismograms with high-frequency stochastic seismograms to simulate broadband (0-20 Hz) ground-motion time series from the three earthquakes. We employ the Specific Barrier Model (SBM) in simulating the high-frequency waves and a deterministic model in a 1D subsurface structure in the context of the kinematic approach for the long-period waves. The deterministic representation of fault rupture is described by spatially heterogeneous slip, rupture speed and rise time using an approximated Yoffe-type source time function. The model is calibrated to strong-ground motion records, aided by the existing finite-fault static slip distribution models, and path and site effects constrained using records of several smaller earthquakes. Most model parameters were constrained jointly through a Bayesian approach using informative prior densities for them. The synthetic strong-motion time histories fit the recorded data well. Moreover, on the basis of insight into the physical earthquake source parameters provided by the SBM, the presented models are expected to be representative of strong earthquakes in South Iceland. That in turn provides the basis for future earthquake scenario modeling of larger earthquakes and has potential implications for seismic hazard estimates.