The project will foster the integration of 3D ground motion simulation methods and results into engineering applications. We will validate 3D simulation methods and apply them to complex geological structures, with emphasis on urban sedimentary basins. This is a collaboration between the Pacific Earthquake Engineering (PEER) Center and the Southern California Earthquake Center (SCEC).

3D finite element and finite difference simulations of wave propagation, with kinematically described propagating earthquake sources.

Previous work under PEER Lifelines projects 1A01 and 1A02 has documented the mathematical soundness of the simulation codes to be used for the project. Code verification was carried out by exercising the codes on a systematic, collaboratively-defined set of test simulations. In the first stage of these tests (1A01), the codes were validated for simple sources and geometries. The second stage (1A02) tested the codes for simple sources in the SCEC 3D Reference Model, a seismic velocity model that we believe captures many of the types of complexities present in realistic applications. Especially significant is that the model covers a wide range of scale lengths, representing, for example, variations occurring on a scale of tens of meters in the near surface soils and kilometers in the crystalline basement. The SCEC model also incorporates a realistic range of S velocities, from ~100 m/s in some near-surface deposits to thousands of m/s in basement rock. Comparisons show that all codes are accurate for this class of problems.

PEER Lifelines project 1D02 (Utilization of Physical Model Data to Validate Numerical Procedures for Simulating Near-Field Motions) addresses the problem of source representation through the use of a physical model to validate earthquake source representations for use in numerical modeling.
The PEER project “Empirical Characterization of Basin Effects on Site Response” seeks to develop (through formal regression analysis) statistical models of ground motion amplification associated with basin effects. The proposed project will improve and validate the simulation procedures underlying basin response estimates, as well as provide extensive scenario simulations for use in statistical studies.

The project will deliver a report that (1) documents and compares the results of applying multiple modeling techniques to past earthquakes and future earthquake scenarios, (2) estimates statistical biases and uncertainties in ground motion estimates obtained by 3D numerical modeling, and assesses the strengths and weakness of 3D methodologies (in comparison with each other and with simplified methods such as 1D simulations and standard empirical methods), and (3) applies numerical simulations to develop engineering rules to correct for basin effects in empirical estimates of ground motion.