Effect of Rupture Directivity on PSHA for New Madrid Seismic Zone

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Ground motions in the near-fault regions contain pulses in the velocity time history of the motion and can place significant demands on the structures. Traditional ground motion equations do not consider this effect of forward directivity on sites close to the ruptured fault. Thus, the probabilistic seismic hazard assessment (PSHA) carried out using these ground motions equations may not accurately represent the seismic hazard in such regions. This study is intended to improve the PSHA by taking near fault directivity effects into account. We use a ground motion model developed by Shahi and Baker (2013) which explicitly include the directivity effects to integrate the directivity parameters within the PSHA. Based on empirical observations, the model statistically predicts the effect of directivity on the ground motion based on the occurrence of a directivity pulse. The model uses Campbell and Bozorgnia (2008) functional forms to predict the non-directivity parameters and a pulse amplification model to predict the amplification due to a directivity pulse.

The study area is the New Madrid seismic zone, which is one of the most seismically active regions in the central and eastern United States. In the year 1811, the region was hit with a magnitude 7.5 earthquake. While the area was sparsely populated at that time, it has now become an important economic hub. Hence, it is critical to accurately determine the seismic hazard and risk in this area. For this study, we consider several sites near the New Madrid Fault lines and develop the response spectra for the selected sites. These results are then utilized to select and scale ground motions for seismic response analysis on these selected sites.

Presenting Author: Melish Kayastha

Authors