Chile Earthquake Research Articles

Effects in the Ionosphere after the Chilean Earthquake on February 27, 2010, According to Data of Ground-based Ionosondes

The paper analyzes the measurement data of the critical frequency (foF2) of the regular ionospheric F2-layer at a number of ground based stations of the vertical sounding of the ionosphere in order to detect disturbances in the ionosphere that followed the earthquake with a magnitude of M = 8.8. The earthquake occurred in Chile on February 27, 2010 at 0634 UT at an epicentral distance of 335 km from its capital city of Santiago. It was found that at significant distances (over 5000 km) from the earthquake epicenter under a quiet geomagnetic conditions, wave disturbances are observed in the behavior of foF2, exceeding approximately two standard deviations from the background level for three hours, with the maximum relative deviation of 20%. The analysis shows that the characteristics of disturbances in the ionosphere correspond in time to the arrival of a packet of acoustic-gravity waves excited in the atmosphere at the time of the seismic shock.

Bar buckling in ductile RC walls with different boundary zone detailing: Experimental investigation

The performance of reinforced concrete (RC) structural walls during the past earthquakes in New Zealand (2010–11) and Chile (2010) have highlighted the susceptibility of these critical structural components to several undesirable modes of failure. One such failure mode is premature buckling of the longitudinal reinforcing bars, which has also been observed in experimental tests of flexurally-dominant structural walls. This paper presents the results of an experimental program investigating the effects of transverse reinforcement detailing on buckling resistance of longitudinal reinforcement located in the boundary regions of RC structural walls. Three large-scale rectangular walls with different boundary zone transverse reinforcement detailing were tested under in-plane cyclic loading. The effects of these three types of detailing are reported in terms of drift capacity, buckling length of the longitudinal bars and cumulative energy dissipation capacity of the specimens. The test results confirm that bar buckling modes depend on transverse reinforcement detailing, which consequently also influences the ultimate flexural deformation capacity of ductile walls. By comparing the responses of the tested wall specimens, the inadequacy of code-compliant transverse reinforcement to restrain bar buckling is discussed and the effect of improved transverse reinforcement detailing (designed using a mechanics-based approach) on deformation capacity of slender walls is scrutinised.

Near‐Real‐Time Finite‐Fault Inversions for Large Earthquakes in Chile Using Strong‐Motion Data

ABSTRACTRecent efforts have been made to model the rupture process of large earthquakes in near‐real time (NRT) in Chile. In this study, we propose an automated procedure using strong‐motion data in an integrated system, which can characterize large earthquakes with a finite‐fault model (FFM) in NRT. We developed several heuristic rules using the preliminary W‐phase solutions to automatically set up the search ranges of the finite‐fault inversions. The results show using strong‐motion data and a W‐phase magnitude, it is possible to obtain a rapid kinematic FFM in just a few minutes after the earthquake origin time.

Three-Dimensional Displacement Fields from InSAR through Tikhonov Regularization and Least-Squares Variance Component Estimation

Synthetic aperture radar interferometry (InSAR) measures the projection of three-dimensional (3D) ground displacement in the range direction and in the azimuth direction through image processing. The incapability of InSAR in measuring the 3D displacements restricts its capability for assessing real Earth surface deformation. The near-polar orbiting characteristics of InSAR missions reduce the sensitivity of line-of-sight (LOS) displacements significantly to the north-south components of the real 3D displacement fields and weaken the geometric strength of a given configuration. Applying range measurements from various missions to address 3D displacement leads to an ill-posed inverse problem that needs to be regularized. Moreover, it needs appropriate weighting of the observations to give proper estimates of the parameters. In this study, we propose Tikhonov regularization (TR) and least-squares variance component estimation (LS-VCE) methods for retrieving 3D displacement vectors from range and azimuth displacements. Depending on the functional degree of freedom (DoF) of the inverse problem, the TR and LS-VCE methods are applied in determined and overdetermined equation systems, respectively, to stabilize the ill-conditioned models and estimate the variance components of observations. These methods were evaluated by two synthetic data sets and a real data set from the Sentinel-1 terrain observation by progressive scan (TOPS) and ALOS-2 phased array type L-band synthetic aperture radar (PALSAR-2) missions in 2015 of the MW = 8.3 Illapel earthquake in Chile. Results indicate more than 40% improvement in both the precision and accuracy of retrieving 3D deformation fields when the regularized LS-VCE (RLS-VCE) is adopted instead of the conventional method (CM) that considers primary weighting for observations. Applying the range and azimuth InSAR displacements together with adopting the LS-VCE method reveal a north-south convergent borderline near 31.2° S in the 2015 Illapel earthquake.

Segmentation in continental forearcs: Links between large-scale overriding plate structure and seismogenic behavior associated with the 2010 Mw 8.8 Maule, Chile earthquake

Subduction along the active margin of a continental plate occurs in a context where the overriding plate's crust and lithospheric mantle may contain inherited structures significantly predating the present tectonic conditions of the margin. These structures are persistent over very long-term time scales (>105 to >106 years) and are thought to play an important role in both seismogenic processes on the megathrust and development of topography along coastlines. We use receiver functions calculated from broadband seismic data collected along the Chilean forearc between ~33°S and 38.5°S in the vicinity of the 2010 Mw 8.8 Maule earthquake to determine the structure of the overriding South American continental plate and subducting Nazca oceanic plate along and inboard of the seismogenic portion of the megathrust. We show that the Chilean forearc is divided into three structurally distinct zones: a northern zone where the continental crust intersects the subducting plate well inboard of the coast at ~35–40 km depth, a central zone where the continental crust tapers to <20 km thickness at the coast before intersecting the subducting plate at 15–20 km depth, and a southern zone corresponding approximately to the rapidly uplifting Arauco Peninsula where we find that the continental crust forms a wedge-shaped feature ~35–40 km in thickness which intersects the subducting plate well inboard of the coast. The thin crust of the central zone is associated with a dense, high velocity mantle body (the Cobquecura anomaly) that may have played an important role in stabilizing this segment of the Chilean forearc since the late Paleozoic.

New constraints on the 1922 Atacama, Chile, earthquake from Historical seismograms

SUMMARYWe recently found the original Omori seismograms recorded at Hongo, Tokyo, of the 1922 Atacama, Chile, earthquake (MS = 8.3) in the historical seismogram archive of the Earthquake Research Institute (ERI) of the University of Tokyo. These recordings enable a quantitative investigation of long-period seismic radiation from the 1922 earthquake. We document and provide interpretation of these seismograms together with a few other seismograms from Mizusawa, Japan, Uppsala, Sweden, Strasbourg, France, Zi-ka-wei, China and De Bilt, Netherlands. The 1922 event is of significant historical interest concerning the cause of tsunami, discovery of G wave, and study of various seismic phase and first-motion data. Also, because of its spatial proximity to the 1943, 1995 and 2015 great earthquakes in Chile, the 1922 event provides useful information on similarity and variability of great earthquakes on a subduction-zone boundary. The 1922 source region, having previously ruptured in 1796 and 1819, is considered to have significant seismic hazard. The focus of this paper is to document the 1922 seismograms so that they can be used for further seismological studies on global subduction zones. Since the instrument constants of the Omori seismographs were only incompletely documented, we estimate them using the waveforms of the observed records, a calibration pulse recorded on the seismogram and the waveforms of better calibrated Uppsala Wiechert seismograms. Comparison of the Hongo Omori seismograms with those of the 1995 Antofagasta, Chile, earthquake (Mw = 8.0) and the 2015 Illapel, Chile, earthquake (Mw = 8.3) suggests that the 1922 event is similar to the 1995 and 2015 events in mechanism (i.e. on the plate boundary megathrust) and rupture characteristics (i.e. not a tsunami earthquake) with Mw = 8.6 ± 0.25. However, the initial fine scale rupture process varies significantly from event to event. The G1 and G2, and R1 and R2 of the 1922 event are comparable in amplitude, suggesting a bilateral rupture, which is uncommon for large megathrust earthquakes.

Mental health and media links based on five essential elements to promote psychosocial support for victims: the case of the earthquake in Chile in 2010.

This paper reviews the role of news with respect to the mental health of a population exposed to a disaster. It is based on the five essential elements of psychosocial care presented by Stevan E. Hobfoll et al. (2007) that can be introduced after a potentially traumatic event: promoting a sense of safety, calming, self and collective efficacy, connectedness, and hope. This study developed a method to relate these elements to television coverage and applied it to the stories (n=1,169) aired by the main networks in Chile in the 72 hours after an 8.8 magnitude earthquake struck on 27 February 2010. Of the five elements, promoting a sense of safety occurred most often (82.72 per cent), whereas the others were barely present (less than 10 per cent). The study argues that these elements can increase the possibility of framing the news, given that the audience watching can also be affected by a disaster.

Shallow intraplate seismicity related to the Illapel 2015 Mw 8.4 earthquake: Implications from the seismic source

The September 16, 2015, Mw 8.4 Illapel, Chile earthquake is the first large event occurring in north-central Chile after the 1943 earthquake, filling a known seismic gap in the region. The earthquake took place in a complex tectonic region, nearby an area where transition from erosive to accretionary margin occurs due to the collision of Juan Fernandez Ridge (JFR) along the Chilean margin. We inverted the kinematic rupture process of the 2015 Mw 8.4 Illapel earthquake from the joint inversion of teleseismic body waves and near-field data. The relative weighting between datasets and the weighting of spatial/temporal constraints are objectively estimated by applying the Akaike's Bayesian Information Criterion. The coseismic slip model yields a total seismic moment of 4.92 × 1021 Nm occurred over ~120 s. The rupture shows both downdip and updip propagation with slip extending along the thrust interface from ~50 km depth to shallow near-trench depths (<15 km), with maximum slip of ~9 m located at shallow depths, where low average rupture speeds ~1.8–2 km/s are estimated. Outer-rise events, triggered within the oceanic Nazca plate after the mainshock, did not penetrate into the mantle and are related to preexisting faults due to both bending of Nazca plate and JFR uplift, which promotes a tensional stress regime in the surrounding area. This seismicity was triggered by static stress transfer from near-trench slip revealed by our source rupture modelling, suggesting outer-rise seismicity as a proxy for near-trench coseismic slip. Crustal seismicity within continental South American plate is observed prior to, and after, the mainshock, mainly related to extensional faulting within eroded and fractured wedge due to tectonic processes along erosive margins. We also show evidence of shallow seismicity after the mainshock associated with a long-lived crustal fault, which can represent a high seismic hazard for La Serena-Coquimbo conurbation.

Out-of-plane buckling instability limit state for boundary regions of special RC structural walls

The earthquakes in Chile 2010 and New Zealand 2011 demonstrated the significance of the out-of-plane buckling failure of reinforced concrete structural walls. Past studies have demonstrated that when the out-of-plane deformation is enough to cause instability, loss of vertical load carrying capacity occurs. This paper proposes improvements to an existing wall instability model that estimates the onset of buckling instability. In order to accomplish that objective, a fiber-based computational model is developed to capture the experimental response of twelve reinforced concrete prisms representative of the boundary elements of special planar structural walls with two-layers of reinforcement. The computational model is then employed in a parametric study that aims to improve on an existing out-of-plane buckling instability approach. The computational model is capable of relating the tensile strain developed by in-plane loading to the critical out-of-plane deformation as a function of the prism geometry, the longitudinal and transverse steel contents, and the mechanical properties of materials in the potential buckling region. The proposed approach allows engineers a more accurate means of assessing the parameters that impact the onset of buckling instability.

The nature of the subduction wedge in an erosive margin: Insights from the analysis of aftershocks of the 2015 Mw 8.3 Illapel earthquake beneath the Chilean Coastal Range

Aftershocks of the 16 September 2015 M8.3 Illapel earthquake in central Chile were recorded for a period of one year by the Chile-Illapel Aftershock Experiment (CHILLAX) seismic network. An initial catalog of about 100,000 events was generated by a novel automated picking algorithm that combines an auto-regressive detection/onset estimation method with some recently developed windowing techniques. We combine arrival times of P and S waves from about 9,000 of the best recorded of these events with relative arrival times of teleseismic P waves and phase delays of Rayleigh waves recovered from ambient noise to generate a three-dimensional image of P and S wavespeeds in that part of the Andean margin located beneath the network. Hypocenters of aftershocks located in the final model appear to be grouped into four distinct zones: two lower parallel zones that dip about 20° to the east, an upper, highly active zone that dips about 30° to the east, and a diffuse zone of smaller events located between this upper zone and the surface. Nearly all of the events with M > 4 are located at the bottom edge of the highly active zone and define a plane dipping about 26° to the east. Most of these events have almost identical thrust mechanisms and are separated from the lower zones by a steep gradient in increasing wavespeeds. The lower end of the upper zone, at about 55 km depth, is marked by another velocity gradient dipping to the west that bounds the diffuse shallow activity and projects to the surface west of the high Andes. We postulate that the triangular region delimited by these two high wavespeed gradients is a subduction wedge, generated by the removal of material from the leading edge of the upper plate by subduction erosion, and subsequently underplated back on to the overriding plate at depth. This model explains many of the features we observe in the seismicity and wavespeeds and is consistent with geologic observations of uplift and extension in this part of the Chilean coastal margin. Characteristics of this wedge, such as its shape and the lack of correlation with the coeval back-arc tectonic setting, suggest that high Andes are not directly coupled with the behavior of the subduction interface.

Assessment of the seismic capacity of tall wall buildings using nonlinear finite element modeling

Two existing RC shear wall buildings of 17 and 26 stories were analyzed using fully nonlinear finite element models, i.e., models that include nonlinear material behavior and geometric nonlinearities. The buildings are located in Santiago, Chile and are representative of Chilean residential buildings in the sense that they have a large number of shear walls. The buildings withstood undamaged the 2010 Chile earthquake even though they were subjected to demands much larger than the code-specified demand. The approach to model the RC shear walls was validated through comparisons with results experimentally obtained from cyclic static tests conducted on isolated wall specimens. Several pushover analyses were performed to assess the global response of the buildings under seismic actions and to evaluate the influence of several modeling issues. Response history analyses were performed considering a ground motion recorded in Santiago during the 2010 Chile earthquake. In general, results (in terms of both global and local response quantities) are consistent with results given by pushover analysis and with the empirically observed lack of damage, a consistency that was not found in a previous study that considered linearly elastic models. The tangential inter-story drift deformation was found to correlate much better with the lack of observable damage than the total inter-story drift deformation typically considered in practice. The analysis also revealed that foundation uplift is possible but does not seem to significantly influence the response. Other modeling issues that were found to deserve further research are the shear stiffness of the walls and the influence of the slabs.

Experimental study of the residual fatigue life of reinforcement bars damaged by an earthquake

Reinforcing bars removed from structural walls that belonged to a damaged building during the 2010 earthquake in Chile are studied under low-cycle fatigue testing. Damage of such walls was characterized by concrete crushing and boundary longitudinal reinforcement buckling. Reinforcement bars are selected from damaged areas, including reinforcement with and without visible buckling. Cyclic load tests are performed with constant strain amplitude in the plastic range (3% and 5%), using an aspect ratio of 20. Fatigue life loss is observed in specimens from reinforcement bars with visible buckling damage with up to 15 cycles less than unaltered bars (3% amplitude tests), and with a fatigue life reduction of at least 40% for bars with and without observed buckling compared to unaltered bars, which indicates a low remaining fatigue capacity. A strain amplitude model also indicates that for a given number of cycles to fatigue failure, the strain amplitude reduces to 36% when comparing bars in buckled zone to unaltered bars. The seismic displacement demand on the building is of about 5 cycles of large amplitude and considering that some longitudinal bars fractured, it indicates that they could have reached 5% strain amplitude.

Seismo ionospheric anomalies before the 2007 M7.7 Chile earthquake from GPS TEC and DEMETER

Earthquake (EQ) related variations in the ionosphere may provide some insights to understand the seismo ionospheric coupling and to mitigate the damages of seismic hazards. In this paper, the electromagnetic variations in the ionosphere associated with November 14, 2007, M7.7 Chile EQ are investigated in electron density and electron temperature measurements from ISL (Langmuir Probe) of DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite and TEC (total electron content) estimated from GPS (Global Positioning System). The investigation of temporal and spatial measurements suggests anomalies which are observed within 10 days before the future EQ (i.e. 9 days before on November 5, 2007). The temporal values of daytime DEMETER and diurnal TEC on November 5, 2007 imply abrupt anomalies that are considered to be the fragments of the plasma intensification process in the Southern Hemisphere activated by the rock compression in the quake region. Similarly, spatial maps of TEC and DEMETER (electron density and electron temperature) showed the anomalous configuration of the temporal analysis that may induce by the epicenter. In addition to spatial and temporal analysis, the Index number for the northern and southern sectors of the EQ preparation zone around the epicenter along latitude confirmed the anomalous values of electron density and electron temperature of the DEMETER satellite. Similarly, the comparison of electron density and electron temperature at the epicenter latitude and its conjugate reveals anomalous enhancement over the seismogenic zone on November 5, 2007 (9 days before) prior to the event.

Effects of changes in seismic design criteria in the transverse and vertical response of Chilean highway bridges

Recent earthquakes in Chile have produced extensive damage in highway bridges, such as large transverse residual displacements, yield of shear keys, and unseat of the main girders, showing that bridges are highly vulnerable structures. Many of these damages are attributed to problems in the design codes. After the 2010 Maule earthquake, new structural design criteria were incorporated for the seismic design of bridges in Chile, among which the increase of the strength of the exterior and interior shear keys and the seismic bars, and the mandatory use of diaphragms at the ends of the girders stand out. The present study assesses the effects of the changes in seismic design criteria in the transverse and vertical response of Chilean highway bridges. This assessment is accomplished by comparing fragility curves of a typical bridge designed using the Chilean standards before and after the 2010 Maule earthquake, taking into account the seismic soil types and the different seismic hazard zones. Firstly, the evolution of bridge seismic design codes in Chile is described. Secondly, the performance of bridges and their main failure modes during the 2010 Maule earthquake are summarized. After this, four structural configurations representative of typical bridge typologies were designed using the different design criteria and then they were modeled for the evaluation of their seismic behavior. Finally, fragility curves were generated using Incremental Dynamic Analysis (IDA), nonlinear analytical models and ground motion records from previous earthquakes. The calculated fragility curves show that bridges designed with the current design codes have a seismic performance that depends, to a large extent, on the type of soil in which the bridge is located. The changes in seismic design criteria significantly decrease the probability of collapse of bridges, while the vertical response is unaffected by those changes. Despite those changes in design criteria, the results of the models show that the shear keys behave as sacrificial elements, avoiding damage to the columns and cap beams. Design recommendations that improve the seismic performance of non-skewed bridges are provided.

How Much Should We Pay for Mental Health Deterioration? The Subjective Monetary Value of Mental Health After the 27F Chilean Earthquake

In this article we use the life satisfaction approach to assess the non-pecuniary costs of Mental health impacts after the 2010 Chile earthquake. By linking both subjective well-being valuation literature with studies that describe psychological impacts after natural disasters, we are able to quantify how big a compensation should be to leave individuals as well as they were before the event. Our results suggest that people who experience stress should be compensated by approximately 80–90% of the average monthly income if the shock was strong enough to cause significant damages. These estimates are robust to different empirical specifications, endogeneity, shock intensity measures, and mental health definitions. We estimate that the total costs of mental health deterioration are about 7% of the total reported damages, a significant amount that policymakers should not ignore in post-earthquake reconstruction stages.

Energy Budget of Intermediate‐Depth Earthquakes in Northern Chile: Comparison With Shallow Earthquakes and Implications of Rupture Velocity Models Used

AbstractWe calculate well‐resolved corner frequencies and radiated energies for a set of 96 earthquakes divided into two clusters located in the same tectonic setting but with different depths in northern Chile. Fifty‐three shallow events with a mean depth of 20 km are analyzed, along with 43 intermediate‐depth earthquakes with a mean depth of 110 km. We deduce and compare their static (stress drop Δσ) and dynamic (rupture energy EG and radiation efficiency ηR) source parameters and test the implications of different common assumptions on their depth dependence, such as stress drop invariance, strain drop invariance, or constant rupture velocities. Our data show that, in this zone of Chile, most of these models imply higher rupture velocities at depth than for shallow earthquakes. In these cases, high stress drop, high fracture energy release rate, and higher radiation efficiency are observed for intermediate‐depth earthquakes, suggesting short and impulsive ruptures.

Evidence for a large strike-slip component during the 1960 Chilean earthquake

SUMMARYThe strainmeter record observed at Isabella (ISA), California, for the 1960 Chilean earthquake (Mw = 9.5) is one of the most important historical records in seismology because it was one of the three records that provided the opportunity for the first definitive observations of free oscillations of the Earth. Because of the orientation of the strainmeter rod with respect to the back azimuth to Chile, the ISA strainmeter is relatively insensitive to G (Love) waves and higher order (order ≥ 6) toroidal modes, yet long-period G waves and toroidal modes were recorded with large amplitude on this record. This observation cannot be explained with the conventional low-angle thrust mechanism typical of great subduction-zone earthquakes and requires an oblique mechanism with half strike-slip and half thrust. The strain record at Ogdenburg, New Jersey, the Press–Ewing seismograms at Berkeley, California, and the ultra-long period displacement record at Pasadena, California, also support the oblique mechanism. We tested the performance of the ISA strainmeter using other events including the 1964 Alaskan earthquake and found no instrumental problems. Thus, the ISA observation of large G/R and toroidal/spheroidal ratios most likely reflects the real characteristics of the 1960 Chilean earthquake, rather than an observational artefact. The interpretation of the large strike-slip component is not unique, but it may represent release of the strike-slip strain that has accumulated along the plate boundary as a result of oblique convergence at the Nazca–South American plate boundary. The slip direction of the 2010 Chilean (Maule) earthquake ( Mw = 8.8) is rotated by about 10° clockwise from the plate convergence direction suggesting that right-lateral strain comparable to that of an Mw = 8.3 earthquake remained unreleased and accumulates near the plate boundary. One possible scenario is that the strike-slip strain accumulated over several great earthquakes like the 2010 Maule earthquake was released during the 1960 Chilean earthquake. If this is the case, we cannot always expect a similar behaviour for all the great earthquakes occurring in the same subduction zone and such variability needs to be considered in long-term hazard assessment of subduction-zone earthquakes.

Source Estimate for the 1960 Chile Earthquake From Joint Inversion of Geodetic and Transoceanic Tsunami Data

AbstractThe slip distribution of the 1960 Chile earthquake was estimated using geodetic data, local tsunami data, and newly usable transoceanic tsunami data. The large slips triggered a significant tsunami which was recorded by the tide gauges around the Pacific Ocean. We performed a two‐step inversion to estimate the slip distribution. In the first step, we jointly inverted the tsunami waveforms and local geodetic data to recover the ground and seafloor vertical displacement. The transoceanic tsunami data could not be used for waveform inversions until the wave phase and arrival time discrepancies were recently reconciled by improving the long‐wave theory with the phase correction method. The random arrival time discrepancy due to inaccurate local bathymetry and/or instrumental problems was considered by the optimal time alignment. In the second step, we estimated the slip distribution on the plate interface by inverting the vertical displacement obtained in the first step. Checkerboard tests showed that our method and data can resolve displacement at a spatial resolution of at least ~100 km but cannot estimate the rupture velocity. The result for actual data shows a rupture extended about 800 km with a width of about 150 km and three asperities. The large slips are concentrated in the offshore shallow plate interface. Our results indicate that the central and south patches contribute to the large coastal elevation changes at southern source area and high tsunami waves at far field. The estimated moment ranges 1.3–1.9 × 1023 Nm (Mw 9.3–9.4) for rake angles of 90–140°.

Development and Application of the Real-Time Individual Asset Attribute Collection Tool

Rapid and profound changes in the technology used for data acquisition, computing and information management provides a framework that has the potential to allow communities to consider acquiring, analysing and managing data in new ways. Improving the collection and management of data, immediately in post-disaster reconnaissance and in long-term impact assessments, is central to enabling knowledge of such events to be used and applied to improving community resilience to those disasters. This paper presents the development and applications of an integrated and extensible framework for the capture of attribute data that describes pre-disaster physical characteristics and post-disaster damage of assets within our communities. The framework, referred to as Real-time Individual Asset Attribute Collection Tool (RiACT) and its associated Asset Repository Web Portal, enables data capture by direct field observations of asset attributes. It also includes the real-time transfer of these field observations to the web portal and/or the download of previously acquired history and metadata of any specific asset of interest to the observer whilst they are in the field. The use of this framework enables improved understanding of asset portfolios within the context of risk reduction and readiness, as well as facilitating efficient and rapid capture of damage distribution across the affected region. This in turn supports better decision making for a quicker disaster response and recovery. This paper presents a review of the existing state-of-art data collection methodologies and describe the development of an improved tool and its Information Technology architecture. Experiences and challenges in applying the framework are highlighted through: 1) the capture of community data in Viet Nam for a multi-hazard assessment in 2014 and 2018, the refinement of asset data related to residential buildings in the Greater Wellington region in 2016, and a survey of building types in Tanna, Vanuatu in 2018; 2) facilitating training in field data capture processes in Indonesia in 2015, as well as in Samoa and Vanuatu in 2017; 3) collection of asset damage data following the 2016 Kaikōura earthquake in New Zealand, the 2016 Tropical Cyclone Winston in Fiji and the 2015 Illapel earthquake and tsunami in Chile.

Preliminary Assessment on Seismic Vulnerability of Masonry Churches in Central Chile

ABSTRACTThe 2010 Maule Chile earthquake (Mw 8.8) caused extensive structural damage to the built heritage. In particular, the poor seismic performance of a set of unreinforced masonry (URM) churches highlighted the need to implement protective and safety strategies in order to preserve these buildings which exhibit unique constructive and typological features, as a result of a combination of Chilean and European construction cultures.The peculiarity of this heritage and the high seismic hazard of Chilean territory have motivated the present study which aims to apply systematic procedures to assess the seismic vulnerability of these buildings. This article is of archival nature and presents a complete database generated from the geometrical, constructive, and structural characteristics of a representative stock of 106 churches located in central Chile, with the goal of proposing fragility curves to be used in seismic risk assessment. Considering variables related with geometrical, architectonic, and stylistic features, as well as damage levels for the 2010 Maule earthquake, this church sample is classified into three homogenous groups: colonial, neo-classic, and neo-gothic. Moreover, a preliminary qualitative assessment of the seismic capacity of these structures is provided using a survey and analysis of geometric indices for each of the three selected groups.