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Assessment and Results From New Bayesian SPAC Analysis for 1D Velocity Profiles Compared to Traditional MASW in Puerto Rico

Description: 

In March of 2022, a collaborative research initiative between the United States Geological Survey and the University of Puerto Rico at Mayagüez led to the acquisition and processing of average shear wave measurements to a depth of 30 meters (Vs30) at 22 seismic stations across Puerto Rico employing, in part, conventional Multichannel Analysis of Surface Waves (MASW) methodologies. However, estimation of velocity profiles using the MASW technique is a nonlinear process, and rigorous estimation of uncertainty in Vs profiles and Vs30, while crucial for proper physical interpretation, is a challenging problem. The uncertainty in MASW Vs profiles can stem from both theoretical challenges (e.g., higher modes, topography, near and far field effects, insufficient source energy, unknown model parameterization) as well as measurement errors (e.g., noisy geophone recordings). Here, we present a new phase of the investigation wherein select MASW-analyzed sites in Puerto Rico will undergo reevaluation using a Bayesian Spatial Autocorrelation (SPAC) method using microtremor array data collected with temporary small-aperture nodal arrays. Having both MASW and SPAC datasets will provide the opportunity for a comparative analysis between the two methodologies for ocean island environments. The Bayesian SPAC methodology we use provides a rigorous estimation of uncertainty in Vs and Vs30 when compared to the MASW models we developed through a least-squares iterative modeling approach. Based on preliminary SPAC results, the study will be expanded to include new sites not necessarily suitable for traditional active-source multimethod data collection. The additional site selections will be guided by the seismic resilience needs articulated by local communities throughout Puerto Rico. This expansion is conceived as part of a collective impact earthquake science initiative, aligning research endeavors with the practical requirements of the community.

Session: Integrative Assessment of Soil-Structure Interaction and Local Site Effects in Seismic Hazard Analysis [Poster Session]

Type: Poster

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Cherilyn

Student Presenter: Yes

Invited Presentation: 

Authors