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Challenges in Site-Specific Seismic Hazard Analyses for Mine Tailings Storage Facilities in South America

Description: 

The recent increased need for site-specific probabilistic seismic hazard analyses (PSHAs) of mine tailings storage facilities (TSFs) has been driven by recent failures worldwide that resulted in significant loss of life and environmental damage. As a result, the Global Industry Standard on Tailings Management was developed, setting guidelines for both the design of new TSFs and evaluations of existing TSFs, with seismic design criteria for high- to extreme-consequence structures being adopted for return periods of 2,475 to 10,000 years. These long return periods present challenges to mine owners as they often result in high design ground motions in seismically active regions such as those along the South America subduction zone. We have performed site-specific seismic hazard analyses for TSFs throughout South America (e.g., Colombia, Ecuador, Peru, Chile, and Argentina). One of the challenges in performing such analyses in these countries is that prior seismic hazard evaluations have often underestimated the hazard for several reasons. First, there has been an over-reliance on the historical seismicity record due to the belief that the historical record alone would accurately predict future hazard. Second, existing Quaternary fault databases are often incomplete, which commonly results in the discovery of previously unrecognized Quaternary sources or re-characterization of known faults. When local fault sources are incorporated, they commonly include narrow epistemic uncertainties that are poorly supported with available data. Third, hazard analyses in South America have not kept pace with rapidly evolving ground motion models (GMMs). The recently developed NGA-Subduction GMMs have presented major challenges because of the significant increase in hazard over previous models. Finally, there has been a lack of adequate characterization of site effects with GMMs and Vs30 being used when the site conditions would call for site response analyses, e.g., thin soil or weathered rock sites.

Session: Assessing Seismic Hazard for Critical Facilities and Infrastructure – Insights and Challenges - I

Type: Oral

Date: 5/3/2024

Presentation Time: 02:00 PM (local time)

Presenting Author: Ivan

Student Presenter: No

Invited Presentation: Yes

Authors