Site Effects and Damage Patterns

Earthquake Spectra, 2016

In this study, we present comparisons between the local soil conditions and the observed damage for the 1 April 2014 Iquique earthquake. Four cases in which site effects may have played a predominant role are analyzed: (1) the ZOFRI area, with damage in numerous structures; (2) the port of Iquique, in which one pier suffered large displacements; (3) the Dunas I building complex, where soil-structure interaction may have caused important structural damage; and (4) the city of Alto Hospicio, disturbed by the effects of saline soils. Geophysical characterization of the soils was in agreement with the observed damage in the first three cases, while in Alto Hospicio the earthquake damage cannot be directly related to geophysical characterization.

Earthquake Spectra, 2016

In this study, we present comparisons between the local soil conditions and the observed damage for the 1 April 2014 Iquique earthquake. Four cases in which site effects may have played a predominant role are analyzed: (1) the ZOFRI area, with damage in numerous structures; (2) the port of Iquique, in which one pier suffered large displacements; (3) the Dunas I building complex, where soil-structure interaction may have caused important structural damage; and (4) the city of Alto Hospicio, disturbed by the effects of saline soils. Geophysical characterization of the soils was in agreement with the observed damage in the first three cases, while in Alto Hospicio the earthquake damage cannot be directly related to geophysical characterization.

Geo-engineering Reconnaissance of the 2010 Maule, Chile Earthquake, 2010

Executive Summary The February 27, 2010 Maule, Chile earthquake (Mw = 8.8) is the fifth largest earthquake to occur since 1900. Its effects were felt along 600 km of the central Chile coast. Initial field observations suggest that tectonic displacement of the hanging wall produced both uplift of over 2 m and subsidence of up to 1 m in coastal regions. The tsunami initiated by the rupture devastated parts of the coast and killed hundreds of people. Strong shaking lasted for over a minute in some areas, and widespread damage occurred in some cities. A large number of significant aftershocks contributed additional damage to an already fragile infrastructure. The earthquake tested numerous modern structures and facilities. Most of these systems performed well, although some did not. Most often, poor performance resulted from construction deficiencies or oversights in the design process related to structural detailing or recognition of geotechnical effects, such as liquefaction. This major earthquake was the subject of several post-earthquake reconnaissance efforts. This report presents the observations of the NSF-sponsored Geo-engineering Extreme Events Reconnaissance (GEER) team. GEER team members included engineers, geologists, and scientists from Chile and the United States. The GEER team worked closely with other reconnaissance teams, including EERI, USGS, NIST, FEMA, TOSG, PEER, and ASCE, amongst others, to document the geotechnical effects of this significant event so that our understanding of earthquakes can be improved and we may turn disasters such as this one into knowledge for advancing societal resilience. In this report, key observations were carefully documented and geo-referenced with the use of GPS and other geospatial tools such as Google Earth. A selected number of critical sites were further characterized using advanced tools, such as LiDAR, SASW, and DCPT. Reconnaissance was performed remotely using satellite imagery, efficiently through aerial reconnaissance, and in detail through coordinated ground-based reconnaissance studies. This report includes a brief summary of engineering seismology and earthquake ground motions for this event, a description of the use of remote sensing to provide insight into damage patterns, and an in-depth discussion of the important role of coastal uplift and subsidence resulting from the underlying tectonic movement. Localized damage patterns observed during the 2010 Chile earthquake and findings from previous earthquake studies indicate that seismic site effects were also important in this earthquake. Soil liquefaction occurred at many sites, and often led to ground failure and lateral spreading. Of special interest are the effects of liquefaction on the built environment. Several buildings were damaged significantly due to foundation movements resulting from liquefaction. Liquefaction-induced ground failure displaced and distorted waterfront structures, which adversely impacted the operation of some of Chile’s key port facilities. Critical lifeline structures, such as bridges, railroads, and road embankments, were damaged by ground shaking and ground failure. The damage to some sections of Ruta 5, the primary North-South highway in Chile, was pervasive, which disrupted the flow of supplies and traffic following the event. Most dams, levees, and mine tailings dams performed well. However, several key earth structures experienced some distress, and in one case a liquefaction-induced tailings dam failure produced a flow slide that killed a family of four. Most earth retention systems, such as retaining walls and basement walls, proved to be inherently robust. Landsliding was not pervasive, which appears to have resulted from native slopes that are generally composed of competent earth materials and the relatively low groundwater levels present at the end of the dry season. All of these consequences impact how society responds to, plans for, and rebuilds after a major earthquake, which will occur again in this region and other regions such as the Pacific Northwest. GEER team urban planners, geologists, and engineers documented the impacts of the geologic and tsunami hazards and identified the challenges and opportunities that will confront Chile as it rebuilds and addresses these hazards in the future. Careful documentation of the geotechnical effects of the 2010 Chile earthquake will enable advancements in the art and science of engineering that will save lives during the next major event. http://www.geerassociation.org/index.php/component/geer_reports/?view=geerreports&layout=build&id=44

Earthquake Spectra, 2017

The 2015 Illapel earthquake sequence in Central Chile, occurred along the subduction zone interface in a known seismic gap, with moment magnitudes of M w 8.3, M w 7.1, and M w 7.6. The main event triggered tsunami waves that damaged structures along the coast, while the surface ground motion induced localized liquefaction, settlement of bridge abutments, rockfall, debris flow, and collapse in several adobe structures. Because of the strict seismic codes in Chile, damage to modern engineered infrastructure was limited, although there was widespread tsunami-induced damage to one-story and two-stories residential homes adjacent to the shoreline. Soon after the earthquake, shear wave measurements were performed at selected potentially liquefiable sites to test recent V S-based liquefaction susceptibility approaches. This paper describes the effects that this earthquake sequence and tsunami had on a number of retaining structures, bridge abutments, and cuts along Chile's main highway...

2010

MAE CENTER TEAM REPORT CONTRIBUTIONS Amr S. Elnashai, planning and initial management, lead on structural engineering field investigations, case study on Cathedral of Talca, executive summary and conclusions. Bora Gencturk, logistical trip and team management, coordinator of data collection, coordinator of complete report, case study on Odontology building, overview, engineering seismology, structural engineering (effects on buildings and historical structures). Oh-Sung Kwon, lead on structural engineering and case study analyses, case study on Paso Cladio Arrau, structural engineering (regional damage description and statistics, effects on bridges). Imad L. Al-Qadi, lead on transportation networks, roads and embankments. Youssef Hashash, lead on geotechnical engineering, engineering seismology. Jefferey R. Roesler, planning and initial management, lead on communications with researchers from Chilean institutions, transportation networks, roads and embankments. Sung-Jig Kim, strong ground motion, case study on Odontology building. Seong-Hoon Jeong, case study on Las Mercedes Bridge. Jazalyn Dukes, seismic fragility analysis of Las Mercedes Bridge, socioeconomic features and impact on communications. Angharad Valdivia, lead on communications during field mission, socioeconomic features and impact on communications. v TABLE OF CONTENTS MAE CENTER TEAM REPORT CONTRIBUTIONS .

A description of the strong 27 February 2010 seismic event occurred in centre and south of Chile is presented. Main geology and geotechnical conditions of selected sites are described. The study focuses mainly, but not only, on the liquefaction phenomenon 27 Description and analysis of geotechnical aspects associated to the large 2010 Chile earthquake Descripción y análisis de aspectos geotécnicos asociados al gran terremoto de Chile del 2010

In order to evaluate the influence of ground condition on damage distribution in Villa de Alvarez town (Colima, Mexico) during the 2003 Colima earthquake (M W =7.8), several geophysical surveys were carried out. The structure of shallow sedimentary materials and the depth of the basement have been estimated applying the Spatial Autocorrelation method (SPAC), using several regular pentagonal arrays with radii up to 25m. Seven Swave velocity (V S) profiles have been inverted in Villa de Alvarez by using Rayleigh wave velocity dispersion curves for depths down to 30m. According to the local shallow structures obtained, we find clear lateral variations in the velocity structure for several urban zones that are correlated with different damage level. Microtremor measurements were recorded at 70 sites with a grid of about 100m x 100m interval across damaged area. The horizontal-to-vertical spectral ratios (HVSR) were determined in order to obtain the predominant period for each site. The predominant period range in the studied zone is about 0.1-0.6sec. Shorter predominant periods (0.1-0.2sec) were found in damaged zone whereas larger periods (greater than 0.4sec) were obtained in urban areas without damage. The site effects and their correlation with damage distribution on masonry structures observed during the 2003 Colima earthquake were very clear and remarkable. One of the main results has been that masonry houses with one or two storeys located on soils with dominant period around 0.15sec in Villa de Alvarez, showed the most serious damages.

This article presents an overview of the different processes of data recollection and the analysis that took place during and after the emergency caused by the M w 8.8 2010 Maule earthquake in central-south Chile. The article is not an exhaustive recollection of all of the processes and methodologies used; it rather points out some of the critical processes that took place with special emphasis in the earthquake characterization and building data. Although there are strong similarities in all of the different data recollection processes after the earthquake, the evidence shows that a rather disaggregate approach was used by the different stakeholders. Moreover, no common standards were implemented or used, and the resulting granularity and accuracy of the data was not comparable even for similar structures, which sometimes led to inadequate decisions. More centralized efforts were observed in resolving the emergency situations and getting the country back to normal operation, but the reconstruction process took different independent routes depending on several external factors and attitudes of individuals and communities. Several conclusions are presented that are lessons derived from this experience in dealing with a large amount of earthquake data. The most important being the true and immediate necessity of making all critical earthquake information available to anyone who seeks to study such data for a better understanding of the earthquake and its consequences. By looking at the information

2016

Following the earthquakes of 27th of 2010 and April 1st of 2014 a good deal of information resulted because of the records obtained from the main shocks and the aftershocks. This data was complemented in some sites with a program of soil exploration and characterization that allowed modeling the subsoil profile. This model was then used to characterize the response of the soil using some records obtained in rock in nearby locations and to compare the absolute acceleration spectra obtained from the original record and from the response of the soil model and with the design spectra of the DF 61 issued by the Ministry of Housing in Chile. The purpose of this research was to find if there are substantial differences between these three spectra to explain them and to discuss their consequences in the analysis and design process.

This article presents an overview of the different processes of data recollection and the analysis done by different stakeholders during and after the emergency caused by the 2010 Maule earthquake in central-south Chile. The article is not an exhaustive recollection of all of the processes and methodologies used; it rather points out some of the critical processes that took place with special emphasis in the earthquake characterization and building data. Although there is strong similarities in all of the different processes for collecting data after the earthquake, the evidence shows that a rather disaggregate or atomized approach was used by the different stakeholders. Moreover, no common standards were implemented or used, and the resulting granularity and accuracy of the data was not comparable even for similar cases, which sometimes led to inadequate decisions. More centralized efforts were observed in resolving the emergency situations and getting the country back to normal in...