Browsing by Author "Aguirre Aparicio, Paula"

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    A measurement of the millimetre emission and the Sunyaev-Zel'dovich effect associated with low-frequency radio sources
    (2014) Gralla, Megan B.; Crichton, Devin; Marriage, Tobias A.; Mo, Wenli; Aguirre Aparicio, Paula; Addison, Graeme E.; Asboth, V.; Battaglia, Nick; Dünner Planella, Rolando; Morales Morales, Gustavo
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    Comparative qualitative and quantitative analyses of the seismic performance of water networks during the Maule 2010, Christchurch 2010-2011, and Tohoku 2011 earthquakes
    (ASCE-AMER SOC CIVIL ENGINEERS, 2022) Alberto, Yolanda; Llera Martin, Juan Carlos de la; Aguirre Aparicio, Paula; Monsalve M., Mauricio; Molinos Senante, María
    Recovery of damaged water supply systems after severe earthquakes is one of the priorities to return to normal conditions. Water supply systems are intrinsically interdependent with other important lifelines such as transportation, energy, health care, and industrial sectors. These interdependencies need to be better understood by means of empirical data and analytical models. This paper is primarily of archival nature and describes empirical impact data of large earthquakes in Chile (Maule 2010), New Zealand (Christchurch 2010-2011), and Japan (Tohoku 2011) on their respective drinking water systems, and summarizes damage observations, emergency actions, and restoration processes within a resilience framework focused on metrics of robustness and rapidity. The archival nature of this article is justified by the paramount importance of systematic data collection to improve network resilience for future analytical models that aim to predict the response and recovery of water networks. Moreover, based on the collected data, the effectiveness of response actions and implemented countermeasures are evaluated relative to the observed earthquake performance of the system components. Important observations are derived to understand the main factors causing water supply system outages, the effectiveness of strategies used, and their capacity to restore the service.
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    Correlations in the (sub) millimeter background from act x blast
    (2012) Hajian, A.; Aguirre Aparicio, Paula
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    Detection of the Power Spectrum of Cosmic Microwave Background Lensing by the Atacama Cosmology Telescope
    (2011) Das, S.; Aguirre Aparicio, Paula; Dünner Planella, Rolando
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    Earthquake damage assessment for deterministic scenarios in Iquique, Chile
    (2018) Aguirre Aparicio, Paula; Vásquez P., Jorge; Llera Martin, Juan Carlos de la; González, Juan; González, Gabriel
    Risk evaluation and loss analysis is key in foreseeing the impact of disasters caused by natural hazards and may contribute effectively in improving resilience in a community through the pre-evaluation of preparedness and mitigation actions. The pilot study presented herein is for the Chilean city of Iquique, which is located at the core of a seismic gap that extends from south Perú to north Chile, and has strategic geopolitical and economic importance for the country. The region was hit April 1, 2014, by an Mw 8.2 earthquake that caused only moderate damage, but seismological evidence suggests that there is still a potential for a much larger event in the region. Therefore, a careful damage assessment study is fundamental to anticipate the possible physical, social, and economic consequences that Iquique may face in the future. In this work, the HAZUS-MH platform was adapted and used to simulate a set of ten plausible physics-based future seismic scenarios with magnitudes ranging from Mw 8.40 to Mw 8.98, which were proposed based on an analysis of interplate locking and the residual slip potential remaining after the April 1, 2014, earthquake. Successful application of this damage assessment methodology relies on the construction of a comprehensive exposure model that takes into account regional features and a good characterization of the physical vulnerabilities. For Iquique, a large body of public and local data was used to develop a detailed inventory of physical and social assets including an aggregated building count, demographics, and essential facilities. To characterize the response of the built environment to seismic demand, appropriate HAZUS fragility curves were applied, and outcomes were validated against the damage observed in the 2014 earthquake. After satisfactory testing, a deterministic earthquake damage assessment study was carried out for the collection of predictive scenarios aimed to estimate their expected impacts. This analysis provides data for future evaluations of different physical and social mitigation measures for the city.
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    Earthquake damage assessment for Iquique: case study for implementation of Hazus-MH in Chile
    (National Information Centre of Earthquake Engineering, 2017) Aguirre Aparicio, Paula; Vásquez P., Jorge; Llera Martin, Juan Carlos de la; González López, Gabriel; González, Juan; Shrivastava, Mahesh
    Risk evaluation and loss analysis is key in foreseeing the impact of disasters caused by natural hazards, and may contribute effectively in improving resilience in a community through the pre-evaluation of preparedness and mitigation actions. The pilot study considered herein is the city of Iquique, located in north Chile where a large megathrust earthquake and tsunami is expected to eventually cover the south of Peru and north of Chile. Although the region was recently hit by an Mw 8.2 earthquake April 1st 2014, damage caused was only moderate. Geophysical evidence suggests that there is still a potential for a much larger event in the region. Therefore, a thorough risk assessment is key to anticipate its possible physical, social, and economic consequences. Consequently, HAZUS-MH was used to simulate a set of earthquake hazard scenarios generated from estimates of plate interlocking and the residual slip potential remaining from the April 1st 2014 rupture fault mechanism. Successful application of the HAZUS-MH methodology relies on the construction of a comprehensive exposure model that takes into account regional features and a good characterization of the physical vulnerabilities. For Iquique we have used a large body of public and local data to develop a detailed inventory of physical and social assets including an aggregated building count, demographics, essential facilities, infrastructure, and lifelines. To characterize the response of the built environment to seismic demand, HAZUS fragility curves and downtime models were applied, and outputs were calibrated using the observed damage after the April 1st 2014 earthquake. Using such calibration, a deterministic seismic risk assessment for the collection of generated scenarios and their expected impacts on all physical assets, population, and essential facilities were estimated. This analysis sets a basis for the simulation and evaluation of different physical and social mitigation measures for the city in the future.
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    Empirical site classification of seismological stations in Chile using horizontal-to-vertical spectral ratios determined from recordings of large subduction-zone earthquakes
    (2019) Yang, Shuo; Mavroeidis, G. P.; Llera Martin, Juan Carlos de la; Poulos Campbell, Alan John; Aguirre Aparicio, Paula; Rahpeyma, Sahar; Sonnemann, Tim; Halldorsson, Benedikt
    Despite the significant upgrade and expansion of the seismic monitoring network in Chile over the past several years, precise site characterization of a large number of seismological stations is still lacking, thus hindering a robust development of tools that could improve prediction of regional seismic hazard. To enhance our understanding of site effects in Chilean seismological data, this study classifies 136 stations using the horizontal-to-vertical spectral ratio (HVSR) method based on a database of 283 triaxial ground-motion records from 22 subduction interface earthquakes with moment magnitudes ranging from 6.8 to 8.8 that occurred between 1985 and 2015. This classification, which is based on the SESAME guidelines, divides recording stations into four types according to the shape of the station-average HVSR curve (single-peak, double-peak, broad/multiple-peak, and flat). Furthermore, the variability of the mean HVSRs with different source, path and site parameters is investigated. The derived HVSR results are also compared with those presented in previous HVSR studies for Chile. Finally, representative shear-wave velocity profiles along with parametric uncertainties are estimated for stations with a single-peak HVSR curve using a Bayesian statistical inversion framework.
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    Reconnaissance observations by CIGIDEN after the 2015 Illapel, Chile earthquake and tsunami
    (National Information Centre of Earthquake Engineering, 2017) Rivera Jofré, Felipe Andrés; Jünemann Ureta, Rosita; Candia, Gabriel A.; Favier, Philomène; Fernández Soto, Claudio; Chacón de la Cruz, Matías Fernando Nicolás; Hube Ginestar, Matías Andrés; Chamorro Giné, Marcela Alondra; Aguirre Aparicio, Paula; Llera Martin, Juan Carlos de la; Poulos Campbell, Alan John; Illapel earthquake; Critical infrastructure
    This paper describes the reconnaissance work conducted by researchers from the National Research Center for Integrated Natural Disaster Management (CIGIDEN) between September 23rd and October 2nd in the area affected by the Mw 8.3 Illapel megathrust earthquake, which struck offshore the coast of the Coquimbo Region in central Chile on September 16th, 2015. A first team focused on the seismic performance and effects of the tsunami on public hospitals and on reinforced concrete (RC) buildings. A second team focused on the road network infrastructure. Field work included: (i) a survey on the physical and functional damages of the public hospitals in the Region; (ii) a visual inspection and preliminary damage assessment of 20 RC buildings in the largest cities of the region and an aftershock instrumentation of the Coquimbo hospital; and (iii) the inspection of bridges, pedestrian bridges, and rockfall along overstepped cut slopes of the road network. The overall limited impact of this megathrust earthquake may be explained in part by the long-term efforts made by the country to prepare for such events. Learnings from the 2010 Maule earthquake were evidenced in the successful evacuation along the coast of the country, and the overall good performance of engineered masonry structures, and of RC buildings designed after 2010.
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    Rupture parameter sensitivity of low frequency ground motion response spectra using synthetic scenarios in North Chile
    (SPRINGER, 2021) Fortuño Jara, Catalina Pía; Llera Martin, Juan Carlos de la; Gonzalez, Gabriel; Gonzalez, Juan; Aguirre Aparicio, Paula
    This research performs a sensitivity analysis of response spectrum values for various physical earthquake parameters, which are used to generate synthetic seismograms consistent with the expected seismicity in north Chile. Sensitivity analyses are based on the earthquake scenario and slip distribution model of the 2014, M-w 8.1 Pisagua earthquake, and seven other physically plausible interplate events for north Chile. A finite-fault rupture model, and slip distribution of the Pisagua earthquake, were obtained using inversion of InSAR and GPS data. Three other rupture models based on previous studies of interplate locking for north Chile and capable of generating M-w 8.3-8.6 earthquakes with an estimated maximum slip of 9.2 m, were incorporated in the analyses. Also, four additional scenarios with moment magnitudes in the range M-w 8.6-8.9 were generated by concatenating these physical scenarios into larger rupture areas within the north segment. Using these scenarios, synthetic ground motions were built at four observation sites: Pisagua, Iquique, Tocopilla, and Calama. Response sensitivity was studied for three key rupture parameters: mean rupture velocity, slip rise-time, and rupture directivity. Responses selected were peak ground displacement (PGD), spectral pseudo-velocities, S-v, and spectral displacements, S-d. First and second order variations of PGD, S-v, and S-d relative to the source parameters were computed and used together with a Taylor series expansion to propagate uncertainty into the responses as a function of v(r) and rise-time t(r). To study the effect of rupture directivity, three different foci locations were considered for each scenario: north, south, and at the centroid of the slip model. Response PGD values show no clear trends with rupture velocity, v(r); however, the variability increases as the system period increases. The effect of the slip rise-time is significant, and as t(r) increases, the spectral responses tend to decrease, suggesting that shorter slip rise-times lead to higher seismic demands in long period structures. The results obtained for the directivity analysis suggest that two factors control the expected waveforms and spectral responses: first, the direction of the rupture relative to the location of each site, and the hypocentral distance.
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    Sensitivity of synthetic seismograms for different seismic scenarios in north Chile
    (National Information Centre of Earthquake Engineering, 2017) Fortuño Jara, Catalina Pía; Llera Martin, Juan Carlos de la; González López, Gabriel; González, Juan; Aguirre Aparicio, Paula
    This research studies the sensitivity of spectral response values to various physical earthquake scenario parameters, the latter used to generate synthetic low frequency seismograms in North Chile. Ten earthquake scenarios have been defined using seed information from the slip model of the 2010, Maule earthquake, and different physically plausible interplate locking models in the region. Firstly, the Maule 2010 finite fault rupture model was resituated in the existing seismic gap in north Chile using a curved geometry according to the Slab 1.0 model. From this seed model, one synthetic scenario with constant moment magnitude Mw 8.8 was generated with the same slip distribution as the original 2010 slip model. Three other models with variations in the slip distribution were considered. In addition, three physically plausible fault rupture models based on previous studies of interplate locking were used. Each of these scenarios was capable of generating Mw 8.2 – 8.4 earthquakes with a maximum slip of 7.5 m, approximately. Patches of major slip were located along the coast line approximately in front of the cities of Arica, Iquique, and Tocopilla, respectively. Also, three additional scenarios with moment magnitudes in the range Mw 8.5 – 8.7 were built by connecting these physical scenarios into larger rupture areas. These combined interplate locking models represented the activation of two or more asperities, similar to the experience of the 2010 Maule earthquake. Using these scenarios we built low frequency synthetic seismograms at four control sites: Arica, Iquique, Tocopilla, and Calama. The sensitivity of these results was studied by deterministic analyses on some key rupture parameters, such as mean rupture velocity and slip rise-time. Sensitivity analysis used peak ground displacement (PGD) and acceleration (PGA), pseudo-acceleration spectra, Sa, and displacement spectra, Sd. The range of values considered for mean rupture velocity was vr = 2.2-3.0 km/s. Four points were considered in the vicinity of each specified velocity to compute sensitivities. First and second order derivatives of PGD, PGA, Sd, and Sa relative to the source parameters were then used to build a Taylor series expansion to predict PGD, Sa and Sd as a function of vr. This allows to consider uncertainty in this parameter and propagate such uncertainty into spectral response values. An analogous procedure was considered for rise-time tr in the range from 2 to 10s.
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    Strong ground motion simulation of the 2015 Illapel earthquake using corrected empirical Green’s functions
    (National Information Centre of Earthquake Engineering, 2017) Fernández Soto, Claudio; Aguirre Aparicio, Paula; Llera Martin, Juan Carlos de la; Candia, Gabriel A.; Nozu, A.
    The September 16th 2015 Illapel, Chile, earthquake (Mw 8.4) generated a good set of aftershock data that enabled us to develop and to validate a model for synthetic ground motion generation. This study presents a methodology to generate strong ground motions based on site amplification and phase characteristics of seismic waves, and also based on a source model that was newly developed for the earthquake. The methodology includes the superposition of corrected empirical Green’s functions that consider the three effects: source, path and site. The path effects incorporate the attenuation of seismic waves between the source and the recording stations, and include both geometric spreading and inelastic attenuation. Weak motion data obtained at the strong-motion stations was used to evaluate empirical site amplification factors. For this purpose, aftershocks recorded during the first three months after the main shock were used. Furthermore, the phase characteristics of the Green’s functions were determined based on the weak motion data recorded at the stations. The source model involves two SPGAs (strong-motion pulse generation areas). The locations of the SPGAs were basically determined based on the arrival times of the velocity pulses. The SPGA sizes were chosen according to the pulse duration. The methodology was validated using observed records in terms of velocity waveforms and Fourier spectra. According to the results, the velocity waveforms including pulses were well reproduced in a frequency range of interest to structural engineering (0.2 to 1 Hz). The agreement between the simulated and measured waveforms makes this model a strong platform to assess hazard at specific sites where detailed hazard assessment is required.
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    The Atacama Cosmology Telescope : Data Characterization and Map Making
    (2013) Dunner Planella, Rolando; Hasselfield, M.; Marriage, T.; Sievers, J.; Acquaviva, V.; Addison, G.; Ade, P.; Aguirre Aparicio, Paula; Barrientos, Luis Felipe; Infante Lira, Leopoldo; Quintana, H. et al.
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    The Atacama Cosmology Telescope : the LABOCA/ACT Survey of Clusters at All Redshifts
    (2015) Lindner, Robert; Aguirre Aparicio, Paula; Baker, Andrew J.; Bond, J. Richard; Crichton, Devin; Devlin, Mark J.; Essinger-Hileman, Thomas; Gallardo, Patricio; Gralla, Megan B.; Hilton, Matt
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    The Atacama cosmology telescope: a measurement of the cosmic microwave background power spectrum at 148 and 218 ghz from the 2008 southern survey
    (2011) Das, S.; Aguirre Aparicio, Paula; Barrientos, Luis Felipe; Dünner Planella, Rolando
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    The Atacama cosmology telescope: calibration with the Wilkinson microwave anisotropy probe using cross-correlations
    (2011) Hajian, A.; Aguirre Aparicio, Paula; Barrientos, Luis Felipe; Infante Lira, Leopoldo
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    The Atacama cosmology telescope: cosmological parameters from the 2008 power spectrum
    (2011) Dunkley, J.; Aguirre Aparicio, Paula; Barrientos, Luis Felipe; Dünner Planella, Rolando
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    The Atacama cosmology telescope: cosmology from galaxy clusters detected via the sunyaev-zel'dovich effect
    (2011) Sehgal, N.; Aguirre Aparicio, Paula; Barrientos, Luis Felipe; Dünner Planella, Rolando
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    The Atacama cosmology telescope: extragalactic sources at 148 GHZ in the 2008 survey
    (2011) Marriage, T.; Aguirre Aparicio, Paula; Barrientos, Luis Felipe; Dünner Planella, Rolando
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    The Atacama cosmology telescope: high-resolution sunyaev-zel'dovich array observations of act sze-selected clusters from the equatorial strip
    (2012) Reese, E.; Aguirre Aparicio, Paula; Dünner Planella, Rolando; Rojas Aracena Felipe Alberto