Project Title
Scenario-based risk assessment in Santiago's Piedmont: rupture of the San Ramon Fault and implications at the local scale
Partner Organisations
Internal ID
1251112
Principal Investigator
Type
basic research
Status
VIGENTE
Start Date
April 1, 2025
End Date
April 1, 2028
Investigators
Jorge Maceo
Stojadinovic, Bozidar
Organisations
Georgia Institute of Technology
Swiss Federal Institute of Technology
Zürich, Department of Civil, Environmental and Geomatic Engineering
Description
The San Ramon Fault (SRF), part of the West Andean Thrust, is a multi-segment fault that runs north-south
along the piedmont in Santiago; it crosses densely populated municipalities with visible scarps as high as
100 m, revealing past earthquake activity. For many years, engineering projects and seismic codes have
overlooked the risk of SRF, mainly due to its low slip rate (<0.5 mm per year) and the lack of an appropriate
local network to conduct observations. However, recent studies show that SRF is an active fault capable of
generating magnitude Mw>6.0 earthquakes and significant damage to the infrastructure near the fault.
Understanding seismic risk is critical to earthquake safety and resilience, as highlighted in the National Policy
for Risk Reduction of Disasters 2020-2030. The risk assessment process, however, faces substantial
uncertainties and relies on broad assumptions, especially in the case of SRF. For example, no significant
earthquakes have occurred in SRF, so the ground motion predictions are poorly constrained. In addition,
local hazard and risk analyses often neglect the co-seismic ground deformations induced by the fault rupture
and typically neglect the spatial correlation of ground shaking intensities, leading to potential underestimation
of risk and inaccurate spatial distribution of damage. Similarly, exposure models for non-residential buildings
are scarce, and their relative contribution to seismic risk remains unknown.
To address these limitations, we propose a 3-year research program to evaluate the risk at the municipal
level due to the hypothetical (yet likely) occurrence of a characteristic earthquake along the San Ramon
Fault. The Municipality of Peñalolén, located in southeast Santiago and home to over 250,000 residents, has
been chosen as the case study. The study consolidates and advances the state of knowledge in ground
motion simulations, ground deformation simulations, and asset exposure; the work will be structured around
four scientific modules with the following specific objectives and expected outcomes:
SM1: Development of ground deformation and ground shaking scenarios at the municipality level:
Develop well-constrained simulations of a magnitude Mw 6.5 thrust earthquake on the San Ramon Fault and
its effects on the municipality. The focus will be evaluating surface deformations resulting from fault slips
using advanced finite element simulations and assessing spatially correlated ground acceleration fields with
a state-of-the-art hazard model.
SM2: Building a unified exposure model: Identify the facilities at and near the fault scarp, the most
vulnerable to surface rupture. Build a unified exposure model for the selected municipality that accounts for
residential, non-residential buildings and critical facilities. Different techniques will be used to aggregate new
and existing data, which include previous surveys, aerial images, virtual surveys, and in situ imaging.
SM 3: Map economic losses and develop an aggregated risk parameter. Map earthquake-induced
losses on the physical assets identified in SM2 and develop an aggregated decision variable that captures
the key effects of a rupture scenario on SRF. Information produced by this module can assist facility owners,
and policymakers in comprehending the risk associated with an earthquake in SRF.
SM 4: Dissemination of scientific results and outreach. The scientific outcomes from this research will
be presented in two public workshops (years 2 and 3) hosting international collaborators. Results will also
be presented at national and international conferences and two scientific journals.
This project contributes to Axis 1 (understanding disaster risk) and Axis 3 (planning and investing in disaster
risk reduction) of the National Policy for Risk Reduction of Disasters 2020-2030 (ONEMI 2020). Similarly, the
project contributes to developing Task 2 and Task 14 of the National Strategy of Research, Development and
Innovation for Disaster Resilience (CREDEN 2016).
along the piedmont in Santiago; it crosses densely populated municipalities with visible scarps as high as
100 m, revealing past earthquake activity. For many years, engineering projects and seismic codes have
overlooked the risk of SRF, mainly due to its low slip rate (<0.5 mm per year) and the lack of an appropriate
local network to conduct observations. However, recent studies show that SRF is an active fault capable of
generating magnitude Mw>6.0 earthquakes and significant damage to the infrastructure near the fault.
Understanding seismic risk is critical to earthquake safety and resilience, as highlighted in the National Policy
for Risk Reduction of Disasters 2020-2030. The risk assessment process, however, faces substantial
uncertainties and relies on broad assumptions, especially in the case of SRF. For example, no significant
earthquakes have occurred in SRF, so the ground motion predictions are poorly constrained. In addition,
local hazard and risk analyses often neglect the co-seismic ground deformations induced by the fault rupture
and typically neglect the spatial correlation of ground shaking intensities, leading to potential underestimation
of risk and inaccurate spatial distribution of damage. Similarly, exposure models for non-residential buildings
are scarce, and their relative contribution to seismic risk remains unknown.
To address these limitations, we propose a 3-year research program to evaluate the risk at the municipal
level due to the hypothetical (yet likely) occurrence of a characteristic earthquake along the San Ramon
Fault. The Municipality of Peñalolén, located in southeast Santiago and home to over 250,000 residents, has
been chosen as the case study. The study consolidates and advances the state of knowledge in ground
motion simulations, ground deformation simulations, and asset exposure; the work will be structured around
four scientific modules with the following specific objectives and expected outcomes:
SM1: Development of ground deformation and ground shaking scenarios at the municipality level:
Develop well-constrained simulations of a magnitude Mw 6.5 thrust earthquake on the San Ramon Fault and
its effects on the municipality. The focus will be evaluating surface deformations resulting from fault slips
using advanced finite element simulations and assessing spatially correlated ground acceleration fields with
a state-of-the-art hazard model.
SM2: Building a unified exposure model: Identify the facilities at and near the fault scarp, the most
vulnerable to surface rupture. Build a unified exposure model for the selected municipality that accounts for
residential, non-residential buildings and critical facilities. Different techniques will be used to aggregate new
and existing data, which include previous surveys, aerial images, virtual surveys, and in situ imaging.
SM 3: Map economic losses and develop an aggregated risk parameter. Map earthquake-induced
losses on the physical assets identified in SM2 and develop an aggregated decision variable that captures
the key effects of a rupture scenario on SRF. Information produced by this module can assist facility owners,
and policymakers in comprehending the risk associated with an earthquake in SRF.
SM 4: Dissemination of scientific results and outreach. The scientific outcomes from this research will
be presented in two public workshops (years 2 and 3) hosting international collaborators. Results will also
be presented at national and international conferences and two scientific journals.
This project contributes to Axis 1 (understanding disaster risk) and Axis 3 (planning and investing in disaster
risk reduction) of the National Policy for Risk Reduction of Disasters 2020-2030 (ONEMI 2020). Similarly, the
project contributes to developing Task 2 and Task 14 of the National Strategy of Research, Development and
Innovation for Disaster Resilience (CREDEN 2016).
Keywords
Fields of Science and Technology (OECD)
Engineering and technology
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