Mexico Earthquake Research Articles

ATC Mw7.1 Puebla–Morelos earthquake reconnaissance observations: Seismological, geotechnical, ground motions, site effects, and GIS mapping

This article presents the Applied Technology Council (ATC) team’s observations following the 2017 Mw7.1 Puebla–Morelos, Mexico earthquake. The team was deployed in Mexico City to collect seismological, geotechnical, structural, and overall performance information. The focus was on non-ductile concrete structures, to support implementation of recently published FEMA P-2018 procedures and to identify study buildings for incorporation into NIST-funded ATC-134 ongoing project. This article presents seismological data with 71 strong-motion records processed and ready for use in engineering analysis, geotechnical observations, and characterization of sites visited. Analyses of the response of representative soil profiles are presented in the form of acceleration response spectra and seismic amplification at the ground surface. A comparison of the same analysis using records from the 1985 Michoacán Ms8.1 (approximately Mw8.0) earthquake is also discussed. The ATC team composed GIS maps with structural and geotechnical characteristics of the inspected sites, including color-coded damage of inspected buildings and estimated soil fundamental period to correlate observed behavior with potential soil–structure interaction resonance effects. Recommendations on further detailed studies based on this comprehensive set of case histories are proposed.

The 23 June 2020 Mw 7.4 La Crucecita, Oaxaca, Mexico Earthquake and Tsunami: A Rapid Response Field Survey during COVID-19 Crisis

Abstract The 23 June 2020 La Crucecita earthquake occurred at 10:29 hr on the coast of Oaxaca in an Mw 7.4 megathrust event at 22.6 km depth and triggered a tsunami recorded at tide gauge stations and a Deep-ocean Assessment and Reporting of Tsunamis off the coast of Mexico. Immediately after the earthquake, a rapid response effort was coordinated by members of the Tsunami and Paleoseismology Laboratory, Universidad Nacional Autónoma de México. Despite the challenges posed by the Coronavirus disease 2019 (COVID-19) pandemic crisis, a postearthquake and post-tsunami field survey went ahead two days after the event. We describe here the details of the rapid response survey of the vertical coseismic deformation, tsunami, geologic effects, and lessons from working in the field during the COVID-19 crisis. We surveyed 44 km along the coast of Oaxaca. Because of the COVID-19 pandemic, some local communities enforced rules of confinement. We solved most of the challenges faced during this crisis by rapidly networking with local organizations prior to surveying. We assessed coseismic uplift by means of mortality caused by vertical displacement of intertidal organisms and resurveying of benchmarks, and we measured tsunami runup. Our results show coastal uplift of 0.53 m near the epicenter and decreasing farther away from it; uplift was up to 0.8 m in areas related to exposure of the coast. Of our values of coastal uplift, about 0.53 m fit well with the 0.55 m of uplift reported by tide gauge data at Huatulco. Coastal uplift and low tide at the time of the event limited the tsunami inundation and runup on the Oaxaca coast. Nevertheless, we found tsunami inundation evidence at four confined coastal sites reaching a maximum runup of 1.5 m. The enclosed morphology of these sites determined higher runup and tsunami inundation. Local coastal morphology effects are not detected in tsunami models lacking detailed bathymetry and topography. This issue needs to be addressed during tsunami hazard assessments.

Detecting Thermal Anomalies of Earthquake Process Within Outgoing Longwave Radiation Using Time Series Forecasting Models

The catastrophic damages caused by the Jiuzhaigou earthquake in China of August 8, 2017 and the Mexico earthquake of September 20, 2017 have revealed some important weaknesses of currently operational earthquake-monitoring and forecasting systems. In this work, six time series forecasting models were applied to detect pre-earthquake anomalies within infrared outgoing longwave radiation. After comparing their prediction results using non-seismic time series data, the autoregressive integrated moving average (ARIMA) model was selected as the optimal model, and then a new prediction method based on this ARIMA model was proposed. The results show that the values observed on July 27 and August 5 before the Jiuzhaigou earthquake in China exceed the confidence interval for prediction and reaches the maximum on August 5, 2017. This indicates the infrared outgoing longwave radiation (IR-OLR) anomalies before the Jiuzhaigou earthquake in China. For the Mexico earthquake, pre-earthquake IR-OLR anomalies are detected on September 14, 18, and 19, and reaches the maximum on September 14, 2017. This demonstrates that the proposed time series forecasting model based on ARIMA could be an effective method for earthquake anomalies detection within infrared outgoing longwave radiation.

Detecting Destroyed Communities in Remote Areas with Personal Electronic Device Data: A Case Study of the 2017 Puebla Earthquake

Large-scale humanitarian disasters often disproportionately damage poor communities. This effect is compounded when communities are remote with limited connectivity and response is slow. While humanitarian response organizations are increasingly using a wide range of satellites to detect damaged areas, these images can be delayed days or weeks and may not tell the story of how many or where people are affected. In order to address the need of identifying severely damaged communities due to humanitarian disasters, we present an algorithmic approach to leverage pseudonymization locational data collected from personal cell phones to detect the depopulation of localities severely affected by the 2017 Puebla earthquake in Mexico. This algorithm capitalizes on building a pattern of life for these localities, first establishing which pseudonymous IDs are a resident of the locality and then establishing what percent of those residents leave those localities after the earthquake. Using a study of 15 localities severely damaged and 15 control localities unaffected by the earthquake, this approach successfully identified 73% of severely damaged localities. This individual-focused system provides a promising approach for organizations to understand the size and severity of a humanitarian disaster, detect which localities are most severely damaged, and aid them in prioritizing response and reconstruction efforts.

Schumann Resonance anomalies possibly associated with large earthquakes in Mexico

Using Schumann Resonance (SR) data of a station located in Mexico, we analyzed anomalies in frequency and amplitude of the first three SR harmonics within a window of 21 days, 15 days before and 5 days after, of 12 earthquakes of magnitude M > 5 that occurred in the Mexican Pacific coast. The period of study was from June 2013 to May 2018. In order to avoid SR anomalies likely produced by solar activity, we discarded periods with solar proton events; also, we distinguished three levels of geomagnetic activity (low, medium and high). We found either positive or negative statistically significant anomalies in frequency and amplitude around the day of the seismic event. However, a study of anomalies in periods of earthquakes of magnitude lower than M > 5 and quiet solar activity conditions also shows statistically significant anomalies. Therefore, these results concerning the presence of SR anomalies around the time of earthquakes in Mexico using the Mexican SR station data are not conclusive.

Energetic Rupture and Tsunamigenesis during the 2020 Mw 7.4 La Crucecita, Mexico Earthquake

AbstractThe La Crucecita earthquake ruptured on the megathrust, generating strong shaking and a modest but long-lived tsunami. This is a significant earthquake that illuminates important aspects of the behavior of the megathrust as well as the potential related hazards. The rupture is contained within 15–30 km depth, ground motions are elevated, and the energy to moment ratio is high. We argue that it represents a deep megathrust earthquake, the 30 km depth is the down-dip edge of slip. The inversion is well constrained, ruling out any shallow slip. It is the narrow seismogenic width and the configuration of the coastline that allow for deformation to occur offshore. The minor tsunamigenesis can be accounted for by the deep slip patch. There is a significant uplift at the coast above it, which leads to negative maximum tsunami amplitudes. Finally, tide-gauge recordings show that edge-wave modes were excited and produce larger amplitudes and durations in the Gulf of Tehuantepec.

Subsoil Characteristics of Mexico City, acceleration and hysteretic energy spectra for the Mexico Earthquake of September 19, 2017

The September 19, 2017 intraslab earthquake (Mw7.1), whose epicenter was located near the limits between the states of Puebla and Morelos at approximately 120km from Mexico City, caused severe damage in these regions. In Mexico City more than 40 buildings collapsed, and hundreds had moderate to severe damage; dozens of them are to be demolished. This article analyzes the spectral ratios of accelerometric stations in the lake-bed of Mexico City with respect to the average Fourier spectra at hill zone sites in order to study and compare over time the changes in the behavior of local effects and their relationship with the damage presented during this earthquake; these ratios exhibit also the settlement problem in some places in the city due to over exploiting the aquifer for water supply purposes. Finally, pseudoacceleration and hysteretic energy maps for Mexico City with a discussion with a possible correlation with reported damages are presented.

Examination of seismo-ionospheric anomalies before earthquakes of Mw ≥ 5.1 for the period 2008–2015 in Oaxaca, Mexico using GPS-TEC

Earthquakes are a major danger in a constantly growing society due to their imminent impact and power of destruction. Therefore, the idea of successfully forecasting an earthquake continues to motivate the multidisciplinary study of phenomena proposed as possible earthquake precursors such as ionospheric anomalies. In that sense, total electron content (TEC) has demonstrated to be an efficient parameter for investigating the state of the ionosphere by making use of the Global Positioning System receivers. In the present study, raw vertical TEC data obtained from the standard RINEX files of the GPS constellation are used to examine the state of the ionosphere during the occurrence of light to moderate earthquakes in Mexico from years 2008 to 2015 with the aim of search for possible ionospheric anomalies related to seismic activity. In order to evaluate the impact at the geomagnetic and ionospheric environments, the Geomagnetic Equatorial Dst index, which is considered to have a great influence on TEC during geomagnetic storm period, and solar activity parameters, have been considered. The results indicated that 17 (74%) of the studied events presented not quiet geomagnetic conditions for the days before the earthquake. Thus, the changes in VTEC are most likely related to geomagnetic anomalies which rules out its possible seismic origin. Contrariwise, 3 (13%) of the events presented geomagnetic anomalies the days after the earthquake. For the remaining 3 (13%) events, these presented particular characteristics, such as: not quiet geomagnetic condition for the earthquake day, geomagnetic anomalies throughout the period and the opposite.

The September 19th, 2017 Puebla, Mexico earthquake

This report presents the observations and findings following the 2017 Puebla earthquake that occurred inMexico on September 19th, 2017. The reconnaissance mission was a collaboration between the New ZealandSociety of Earthquake Engineering (NZSEE), the Universidad Autónoma Metropolitana (UAM) Azcapotzalco,the American Concrete Institute (ACI) Disaster Reconnaissance team, and the Colegio de Ingenieros Civilesde Mexico (CICM). During the earthquake, 77 buildings suffered partial or total collapse and more than8,000 buildings experienced damage ranging from slight damage to significant structural damage necessitatingdemolition. As observed in previous earthquakes, the unique soil conditions of Mexico City resulted inextensive damage to the city’s infrastructure, primarily due to local site effects. The earthquake causedrelatively more damage to buildings built on transition and soft soil zones (i.e. between hard and deep softsoils) than those on hard soils.The NZSEE and UAM team focussed on areas with widespread and extensive damage. They also assessedthe performance of repaired and retrofitted buildings after the 1985 Michoacán earthquake. It was found thatthe lessons learnt from the 1985 Michoacán earthquake led to some risk mitigation measures which benefitedseveral buildings in the 2017 earthquake. Retrofitted buildings were found to have performed very well withlittle or no damage when compared to other buildings.

Anomalously low aftershock productivity of the 2019 MW 8.0 energetic intermediate-depth faulting beneath Peru

The 26 May 2019 Peru (MW 8.0) earthquake struck within the nearly-horizontal underthrust Nazca plate at depths from ∼110 to 150 km below the upper Amazon, near a steep bend in the plate where it plunges down to a deep earthquake zone. Little prior seismicity occurred in this region, but large intraslab events with similar normal-faulting mechanisms have occurred to the west. The event is situated in a similar slab position to the 2017 Puebla-Morelos, Mexico earthquake, but the remote location resulted in limited loss of life and damage. Back-projection imaging and finite-fault inversion based on teleseismic data suggest a brittle and energetic rupture process with unilateral expansion northward over a 170-km-long zone at a rupture speed, Vr ∼3 km/s, with three normal-faulting patches of up to ∼4.5 m slip. Despite the mainshock size, it produced only three M4.0+ aftershocks within 300 km (one nearby); the aftershock productivity of the 2019 Peru earthquake is very low even among all large intermediate-depth earthquakes, but similar to that for other large Peruvian intraslab events. Comparison of aftershock productivity of the Peru event with that of global large earthquakes in various tectonic settings suggests that the low aftershock productivity can largely be attributed to regionally homogeneous faulting systems and relatively uniform stress state in the flat Peru slab.

Classifying informative and non-informative tweets from the twitter by adapting image features during disaster

During the crisis, people post a large number of informative and non-informative tweets on Twitter. Informative tweets provide helpful information such as affected individuals, infrastructure damage, availability and resource requirements, etc. In contrast, non-informative tweets do not provide helpful information related to either humanitarian organizations or victims. Identifying informative tweets is a challenging task during the disaster. People often post images along with text on Twitter during the disaster. In addition to tweet text features, image features are also crucial for identifying informative tweets. However, existing methods use only text features but do not use image features to identify crisis-related tweets during the disaster. This paper proposes a novel approach by considering the image features along with the text features. It includes a text-based classification model, an image-based classification model and a late fusion. The text-based classification model uses the Convolutional Neural Network (CNN) and the Artificial Neural Network (ANN). CNN is used to extract text features from a tweet and the ANN is used to classify tweets based on extracted text features of CNN. The image-based classification model uses the fine-tuned VGG-16 architecture to extract the image features from the image and classify the image in a tweet. The output of the text-based classification model and the image-based classification model are combined using the late fusion technique to predict the tweet label. Extensive experiments are carried out on Twitter datasets of various crises, such as the Mexico earthquake, California Wildfires, etc., to demonstrate the effectiveness of the proposed method. The proposed method outperforms the state-of-the-art methods on various parameters to identify informative tweets during the disaster.

Barriers and enablers of breast-feeding protection and support after the 2017 earthquakes in Mexico.

To study the barriers and enablers of breast-feeding protection and support after the 2017 earthquakes in Mexico. A qualitative study using a phenomenological approach to analyse data collected from in-depth interviews, virtual ethnography and documentary analysis of newspapers. Data were collected after the September 2017 earthquakes in Mexico (from 8 September 2017 to 15 May 2018). The participants included key informants (n 13) from different sectors. Postings retrieved from forty-two Facebook and forty-seven Twitter accounts and a WhatsApp group informed the virtual ethnography analysis. Newspaper material covering the 2017 earthquakes in Mexico (seven newspapers) was retrieved for the documentary analysis. Interviews with key informants revealed a lack of knowledge, unclear institutional protocols during emergencies and lack of enforcement of existing international frameworks. The virtual ethnography uncovered a strong call for donations in the immediate aftermath of the earthquakes, and generalized donations of formula revealed a tense relationship between actions taken by breast-feeding experts and the negative reactions from the government and citizens. This analysis highlights the relevance of pre-existing networks of experts in protecting and supporting breast-feeding. From the newspaper documentary analysis, similar themes emerged. This study identified key barriers and enablers in the protection and support of breast-feeding during the 2017 earthquakes in Mexico. Relevant actors should embrace the lessons highlighted in this study because countries such as Mexico are likely to experience other emergencies in the near future.

Catalog of Preinstrumental Earthquakes in Central Mexico: Epicentral and Magnitude Estimations Based on Macroseismic Data

ABSTRACTWe present the first parametric catalog of historical earthquakes in Mexico from 1469 to 1912 composed of 323 historical earthquakes. The historical earthquakes were assigned to specific seismotectonic provinces, and attenuation relations of seismic intensity versus distance were calculated using instrumental earthquakes. The intensity data were inverted using a linear regression for the best-fitting magnitude and source location. From the 323 events identified in the historical record, magnitude and source location were determined for 40 earthquakes from 1568 to 1912. The historical subduction earthquakes are distributed uniformly along the coast. There is, however, a conspicuous absence of subduction earthquakes where the great 1985 Michoacán earthquakes took place. The data also show a large number of earthquakes Mw>7 in the presumed Guerrero gap in the past 320 yr. The source parameters of in-slab earthquakes were obtained for 10 earthquakes that took place in the nineteenth and early twentieth centuries. The analysis of completeness of the historical and instrumental International Seismological Centre-Global Earthquake Model catalogs of subduction earthquakes Mw>7.0 show similar values of the slope of the Gutenberg–Richter relation between 1.62 and 1.95. The large b-values appear to reflect the apparently anomalous large number of earthquakes in the magnitude range Mw 7.4–7.7 and an absence of events Mw∼7. This magnitude distribution suggests that the seismicity in the Mexican subduction zone is dominated by characteristic earthquakes in the magnitude range Mw 7.4–7.7, with larger earthquakes Mw>8 showing longer recurrence times. The catalog of historical subduction earthquakes appears to be complete for Mw>7.5. The catalog of crustal earthquakes in the Trans-Mexican volcanic belt is complete since 1568 for events Mw>6.4. Completeness of the catalog of in-slab earthquakes was not estimated due to the short record for this type of event.

Observations of Rayleigh waves in Mexico City Valley during the 19 September 2017 Puebla–Morelos, Mexico earthquake

This article discusses the principal features of Rayleigh surface waves generated by basin-edge effects in Mexico City during the Mw7.1 19 September 2017 Puebla–Morelos, Mexico earthquake. Rayleigh waves were extracted from ground motions recorded at 12 stations in Mexico City. We used a recently proposed method for extracting surface waves, where the earthquake record is filtered based on the normalized inner product of the Stockwell transform of the three-component earthquake recordings. Results of this study reveal that basin-edge effects produced strong Rayleigh waves, particularly at certain stations, with frequencies that are mainly between 0.2 and 0.9 Hz, which is consistent with previous frequency ranges reported in the literature. Evidence of higher-mode Rayleigh waves was found at all stations located on soft soil sites, even at stations that are more than 1 km away from the basin edges. It was also observed that peak acceleration spectral ordinates of the retrograde component of the extracted Rayleigh waves at two stations exceeded the design spectral ordinates of the 1976 and 2004 editions of the Mexico City Seismic Provisions.

110th Anniversary of the Mexican National Seismological Service: An Account of Its Early Contributions

AbstractThe Mexican National Seismological Service (SSN) was founded on 5 September 1910, in response to commitments made by Mexico to the International Association of Seismology in 1903. The first seismic instruments installed in 1904 were a Bosch–Omori seismograph and a Palmieri seismoscope. The SSN was formally inaugurated on 5 September 1910, a few days before the revolution broke out; a political struggle that lasted over two decades. The SSN was inaugurated with a central station in Tacubaya, Mexico City, and two secondary stations. Wiechert seismographs were selected by the SSN for its budding network. Despite the adverse economic and political situation, the SSN managed to grow and install more stations during the turmoil. Besides the installation of new seismic stations and reporting the location and macroseismic data of earthquakes in Mexico, the SSN staff produced remarkable reports of important earthquakes that occurred in those early years. Notable among these are the detailed reports on the 19 November 1912 and 4 January 1920 earthquakes on the Trans-Mexican volcanic belt. These reports have shaped the estimations of seismic hazard in this highly populated region of Mexico. In the first aftershock studies reported, the SSN took Wiechert instruments to the epicentral areas of a large subduction earthquake in 1907 and to the city of Xalapa, in the vicinity of the 1920 crustal earthquake. With foresight in those early years of seismology, the SSN scientists correctly attributed the 1912 earthquake to a local active fault. The seismograms collected in 1920 confirmed that it was a crustal earthquake and not an in-slab event. Lack of funding and official interest did not permit the modernization of the SSN for many decades. National interest in the Service was boosted by the 19 September 1985 destructive earthquake.

Observed damage in public school buildings during the 2017 Mexico earthquakes

In September 2017, two major earthquakes struck south and central Mexico. These earthquakes produced widespread damage in public and private school infrastructure. In Mexico, all school buildings are classified as essential infrastructure and are expected to attain an immediate occupancy performance level after major earthquakes. However, there is a large variation in the quality of the design and construction practices of these buildings due to age of construction, material quality and availability, and great socioeconomic gaps around the country. In this article, an analysis of the observed damage in public school buildings is presented. The results are analyzed depending on the structural system, construction material, and year of construction. The results showed that damage intensity in seismically designed buildings was significantly lower than that observed in the pre-1985 structures. Load bearing and infill masonry walls were the most damaged structural elements.

Simulation of strong ground motions modified by attenuation effects under specific soil conditions: modeling the 2017 Puebla, Mexico (Mw 7.1) earthquake

This research presents an updated scheme of simulation for strong ground motions based on stochastic summation methods and the source-to-site attenuation effects under particular soil conditions different from firm sites. Two approaches are proposed to modify and improve the empirical Green’s functions at different source distances from seismic station records: (1) a spectral shape based on far-field point-source spectra models and (2) through specific ground motion prediction equations (GMPEs) and random vibration theory (RVT). The ground motions simulated were compared with the September 19, 2017 Mexico records (normal-fault-intraslab event, Mw 7.1), finding that for soft soils, it will be possible to reproduce some characteristic of spectral peaks appropriately in high frequency compared with available similar approaches or using one-dimensional wave propagation models. On average, the spectral overestimations from available simulation approaches and for high-frequency bandwidth (i.e., 0.2 s and 0.3 s) can be reduced by a factor between 2 and 5 using proper attenuation corrections; this effect could be especially beneficial for small structures and low-rise buildings where the inertial design forces will be potentially reduced.

Erratum to Analysis of the 2014 Mw 7.3 Papanoa (Mexico) Earthquake: Implications for Seismic Hazard Assessment

Erratum to Analysis of the 2014 Mw 7.3 Papanoa (Mexico) Earthquake: Implications for Seismic Hazard Assessment

Comment on “Do Directionality Effects Influence Expected Damage? A Case Study of the 2017 Central Mexico Earthquake” by Luis A. Pinzón, Luis G. Pujades, Sergio A. Díaz, and Rodrigo E. Alva

Comment on “Do Directionality Effects Influence Expected Damage? A Case Study of the 2017 Central Mexico Earthquake” by Luis A. Pinzón, Luis G. Pujades, Sergio A. Díaz, and Rodrigo E. Alva

Reply to “Comment on ‘Do Directionality Effects Influence Expected Damage? A Case Study of the 2017 Central Mexico Earthquake’ by Luis A. Pinzón, Luis G. Pujades, Sergio A. Diaz, and Rodrigo E. Alva” by Eduardo Reinoso, Pablo Quinde, Danny Arroyo, Mario Ordaz, and Amador Terán-Gilmore

Reply to “Comment on ‘Do Directionality Effects Influence Expected Damage? A Case Study of the 2017 Central Mexico Earthquake’ by Luis A. Pinzón, Luis G. Pujades, Sergio A. Diaz, and Rodrigo E. Alva” by Eduardo Reinoso, Pablo Quinde, Danny Arroyo, Mario Ordaz, and Amador Terán-Gilmore