Development of a seismic hazard and liquefaction hazard map using a nonlinear site amplification model derived from strong motion records: A case of Metro Manila

• Main Author: Montejo, Mariamae Francia G.
• Format: text
• Language: English
• Published: Animo Repository 2021
• Subjects: Earthquake hazard analysis > Philippines > Metro Manila; Soil liquefaction > Philippines > Metro Manila; Civil Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etdm_civ/5; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1001&context=etdm_civ
• Institution: De La Salle University

Due to the susceptibility of Metro Manila to seismic hazards such as earthquakes and liquefaction, it is necessary to consider the possible factors which could intensify the damages caused by these hazards. Aside from the magnitude or strength of shaking of an earthquake, the properties of the soil in the area also affects the intensity of the seismic hazards. With this, a seismic hazard and liquefaction hazard assessment was conducted considering the local soil conditions in Metro Manila. Probabilistic seismic hazard assessment was performed to obtain the peak accelerations at bedrock at 10%, 5%, and 2% probabilities of exceedance. Average shear wave velocities were also computed from various borehole data within Metro Manila. Using these two parameters, the site amplification factors were computed and used to amplify the ground motion intensities. A total of six amplified peak ground acceleration values were computed for each probability of exceedance and period of amplification. For short-period amplification, the average PGAs are 0.538 g, 0.570 g, 0.659 g for 10%, 5%, and 2% probability of exceedance, respectively. For mid-period amplification, the average PGAs are 0.589 g, 0.649 g, 0.830 g for 10%, 5%, and 2% probability of exceedance. Using the amplified PGAs and the SPT-N data from soil reports, the probability of liquefaction and liquefaction severity index in Metro Manila was obtained. Maps of liquefaction severity index values show that liquefaction is most severe in the western and eastern parts of Metro Manila.