Next-Generation of Liquefaction Assessment (NGL)

NGL is an international research program comprised of top researchers in the field in which a community database for liquefaction case histories is developed, supporting studies on key effects poorly constrained by the database are undertaken, and models are developed by distinct groups of model developers drawing upon these resources.

As a preliminary effort, UCLA team collected liquefaction occurrence information from 2011 Tohoku earthquake and site conditions and performed post-event ground invesitations for Tokyo / Chiba area in Japan, UW team investigated liquefied / non-liquefied sites from historical earthquakes for the entirety of Japan, and UCB team worked for the case of the 2011 Christchurch earthquake in New Zealand.

The detailed project description and preliminary database can be found in NGL project webpage.


Probabilistic Evaluation of Seismic Levee Performance

Funded by California Department of Water Resources, seismic levee fragility was evaluated. The general objective of this project is to begin to fill this knowledge gap using levee performance data from the 2004 and 2007 Niigata, Japan earthquakes. Numerous levees were strongly shaken during this earthquake, and data on the performance of those levees was gathered by the jurisdictional government agencies. Please refer to the project webpage for detailed information.

After gathering all information related to levee performance (geology, hydrology, topography, and ground motion) and correlating to levee damage states, we developed empirical levee fragility functions against peak ground velocities. We found that relative elevation of ground water to levee base is an important factor other than severeness of ground shaking.


Shear-wave Velocity Estimation from Geotechnical and Geomorphic Indices

Shear-wave velocity (Vs) was correlated to Standard Penetration Test (SPT) resistance (N-value) and vertical effective stress considering geomorphology and topography using site condition data from Kyoshin Network (K-NET) in Japan. This correlation proposes better estimate for Vs30, time-averaged Vs up to 30 m depth, than other proxy based Vs30 estimation such as geology, geomorphology, slope, and combination of those. Between-boring residual for this correlation model for the entirety of Japan can be found in this link.