Browsing by Author "Urrutia, Alejandro"

Now showing 1 - 7 of 7
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    Analysis of the effects of urban micro-scale vulnerabilities on tsunami evacuation using an agent-based model - case study in the city of Iquique, Chile
    (2024) Cienfuegos, Rodrigo; Alvarez, Gonzalo; Leon, Jorge; Urrutia, Alejandro; Castro, Sebastian
    The occurrence of mega-tsunamis over the last couple of decades has greatly increased the efforts of the research community and practitioners to work hand in hand to reduce risks from these highly destructive threats. Protecting the population through evacuation is the best alternative for avoiding loss of life in the wake of the occurrence of a tsunamigenic earthquake. Therefore, guaranteeing the proper state of evacuation routes is very important to ensuring appropriate movement to the safe zones. This study carries out a detailed analysis of possible evacuation scenarios, considering the actual state of the escape routes of Iquique, a Chilean city prone to tsunamis, with a substantial number of urban micro-scale vulnerabilities, i.e., elements that obstruct or complicate pedestrian flow. The quantification of the delay in evacuation processes resulting from the presence of urban micro-vulnerabilities is carried out through micro-scale agent-based model (ABM) simulations. In addition, these results are integrated with high-resolution tsunami inundation simulations, allowing for an estimation of the potential number of people that the tsunami may reach under different scenarios by emulating the dynamics and behavior of the population and the decision-making regarding the starting time of the evacuation.
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    Effects of earthquake spatial slip correlation on variability of tsunami potential energy and intensities
    (2020) Crempien, Jorge G. F.; Urrutia, Alejandro; Benavente, Roberto; Cienfuegos, Rodrigo
    Variability characterization of tsunami generation is quintessential for proper hazard estimation. For this purpose we isolate the variability which stems solely from earthquake spatial source complexity, by simulating tsunami inundation in the near-field with a simplified digital elevation model, using nonlinear shallow water equations. For earthquake rupture, we prescribe slip to have a log-normal probability distribution function and von Karman correlation between each subfault pair, which we assume decreases with increasing euclidean distance between them. From the generated near-field inundation time-series, emanating from several thousand synthetic slip realizations across a magnitude 9 earthquake, we extract several tsunami intensity measures at the coast. Results show that all considered tsunami intensity measures and potential energy variability increase with increasing spatial slip correlations. Finally, we show that larger spatial slip correlations produce higher tsunami intensity measure exceedance probabilities within the near-field, which highlights the need to quantify the uncertainty of earthquake spatial slip correlation.
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    Ex post analysis of engineered tsunami mitigation measures in the town of Dichato, Chile
    (Springer, 2020) Oportus, Maximiliano; Cienfuegos, Rodrigo; Urrutia, Alejandro; Aránguiz, Rafael; Catalán, Patricio A; Hube, Matías A.; Centro Nacional de Investigación para la Gestión Integrada de Desastres Naturales (CIGIDEN)
    Due to Chile's notorious and frequent seismic activity, earthquake- and tsunami-related studies have become a priority in the interest of developing effective countermeasures to mitigate their impacts and to improve the country's resilience. Mitigation measures are key to accomplish these objectives. Therefore, this investigation adopts a tsunami damage assessment framework to evaluate the direct benefits of tsunami mitigation works implemented by the Chilean government in the town of Dichato in the aftermath of the 2010 tsunami. We perform an ex post analysis of the potential damage reduction produced by these works studying what would have been the consequences on the built environment if they were in place for the tsunami that hit this area after the Maule earthquake in February 27, 2010. We use state-of-the-art tsunami simulation models at high resolution to assess the reduction in tsunami intensity measures, which serve as input to evaluate the benefit from averted damage against the costs of the mitigation measures. The obtained results show a reduction in the flooded area and a delay in the arrival times for the first smaller tsunami waves, but a negligible damage reduction when confronted to the largest waves. In conclusion, the tsunami mitigation measures would not have been effective to reduce the impact of the tsunami generated by the Maule earthquake in the town of Dichato, but could have had a benefit in retarding the inundation of low-land areas for the first smaller tsunami waves. The latter suggests that these works might be useful to mitigate storm waves or tsunamis of much smaller scales than the one that hit central-south Chile in 2010.
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    Forward energy grade line analysis for tsunami inundation mapping
    (2025) Estrada Carrasco, María Fernanda; Cienfuegos Carrasco, Rodrigo Alberto; Urrutia, Alejandro; Catalán, Patricio A.; Winckler, Patricio
    A simplified model using 1D topobathymetric profiles for generating tsunami inundation maps is implemented and evaluated. The approach is a modification of the ASCE Energy Grade Line Analysis, that allows estimation of the maximum inundation distances using an iterative method. The modified methodology is implemented in three coastal cities in central Chile and compared with a database of 5400 full tsunami simulations obtained from a Nonlinear Shallow Water Equations solver. The key parameter of the model is based on the Froude number, for which three parameterizations and a range of values are tested. Results show that errors in the estimation of the areal extent of the inundation can be as low as 4%, after calibration. However, calibration is site specific and the optimal solution depends on the geographical characteristics of the area of interest. A sensitivity analysis based on the aleatoric sampling of the full tsunami simulation database show that as little as 100 inundation maps are required to perform the calibration of the model. This is a manageable number that offers reduced computational costs when compared with full tsunami simulations, and even those required to train other surrogate models using machine learning.
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    Improving Tsunami Risk Analysis by Integrating Spatial Resolution and the Population’s Evacuation Capacities: A Case Study of Cartagena, Chile
    (Beijing Normal University, 2024-12-09) León, Jorge; Martínez Reyes, Carolina del Pilar; Inzunza General, Simón Ignacio; Ogueda, Alonso; Urrutia, Alejandro
    Intensive human activity in global coastal areas has led to increasing exposure to hazards. Cartagena Bay in Chile, an area with a long history of tsunami disasters, has undergone significant urbanization and experiences heavy tourist activity during the summer. While some studies have examined risk in Cartagena by focusing on hazard and vulnerability characteristics, challenges remain in delivering more spatially accurate studies and incorporating the population’s coping capacities. We undertook a tsunami risk assessment of Cartagena Bay that disaggregates social vulnerability to the census block level and assesses the inhabitants’ pedestrian evacuation potential through an agent-based model. Our findings indicate that urban coastal areas in Cartagena Bay might face substantial tsunami risk in a worst-case scenario, with 31.0% to 54.1% of its territory—depending on the scale of analysis—classified as high-risk areas. Of the examined urban blocks, 31.4% have average evacuation times exceeding 17 min (the critical time required by the tsunami to reach its run-up), and the most disadvantaged census block is 1,971.9 m away from its nearest shelter. We also demonstrated that a more spatially accurate vulnerability analysis is more conservative too. For instance, zones with high-risk levels decreased by 42.8% when the study scale moved from the block to the zone level of analysis. Similarly, areas with low risk increased by 80%. In comparison to previous studies, our findings show that tsunami risk in Cartagena Bay is significantly lower if coping capacities such as evacuation potential are included in the analysis.
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    The 1730 Great Metropolitan Chile Earthquake and Tsunami Commemoration: Joint Efforts to Increase the Country's Awareness
    (2020) Zamora, Natalia; Gubler, Alejandra; Orellana, Victor; Leon, Jorge; Urrutia, Alejandro; Carvajal, Matias; Cisternas, Marco; Catalan, Patricio; Winckler, Patricio; Cienfuegos, Rodrigo; Karich, Cristobal; Vogel, Stefan; Galaz, Jose; Pereira, Sebastian; Bertin, Celeste
    On 8 July 1730, a great earthquake struck metropolitan Chile, causing extensive damage 1000 km along the country and focused in Valparaiso. Due to the date of occurrence of this event, large uncertainties about the earthquake's magnitude have been discussed among the scientific community, and the earthquake and tsunami have remained unknown for most of the population. The purpose of this paper is to describe joint efforts undertaken by organizations, academia, and authorities to rescue the forgotten memory of an event that occurred almost three centuries ago and that may be repeated in the near future. In line with the Sendai Framework, we focus on one of the four priorities for action, which is to understand disaster risk, with the premise that the memory activation and raising awareness can save lives in the future. We designed outreach strategies to communicate this knowledge to the community in a participatory way. The latter involves scientific talks, earthquake simulators, tsunami projection mapping on relief scaled models (mock-up), and a public debate including the participation of academia, politicians, authorities, and the local community. The emulation of such activities and the constant work of regional and national authorities, academia, and non-governmental organizations dealing with risk mitigation encourage involving the community to build safer cities against the tsunami hazard.
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    What Can We Do to Forecast Tsunami Hazards in the Near Field Given Large Epistemic Uncertainty in Rapid Seismic Source Inversions?
    (2018) Cienfuegos Carrasco, Rodrigo Alberto; Catalan, Patricio A.; Urrutia, Alejandro; Benavente, Roberto; Aranguiz, Rafael; Gonzalez, Gabriel