A swarm of minor seismic activity has recently caught the attention of researchers examining the tectonic dynamics of Mexico City. Earthquakes with magnitudes ranging from 3 to 5 have been recorded in close succession during both 2019 and 2023, leading to surprisingly significant ground shaking. These occurrences have sparked an urgent inquiry among seismologists on how larger, moderate earthquakes might affect the structural integrity of buildings throughout the metropolitan area, which has a dense architectural landscape often challenged by its unique geological setting.
In an insightful study published in the Bulletin of the Seismological Society of America, a team led by researchers Miguel Jaimes and Gerardo Suárez from Universidad Nacional Autónoma de México undertook a comprehensive analysis to forecast potential damage scenarios arising from ground shaking in three distinct regions within the Mexico City basin. This urban expanse, known for its history of destructive seismic events, demands rigorous examination concerning both its infrastructure’s preparedness and its capacity to endure future seismic threats.
The modeling of potential earthquake impacts was anchored in the significant seismic events of recent years. Jaimes and Suárez incorporated data derived from the 2023 earthquake in La Magdalena Contreras, the 2018 San Juan de Aragón earthquake, together with historical records like the catastrophic 1995 Milpa Alta and the infamous 1985 Juchitepec earthquakes. The researchers emphasized these diverse geographical locations, drawing upon crucial data that allowed them to estimate how moderate earthquakes—up to a magnitude of 5.5—could induce varying degrees of building damage across different geological landscapes.
The results indicated that the underlying geological conditions profoundly influenced the extent of structural damage. For instance, according to their detailed modeling, ground shaking anticipated from a moderate earthquake occurring in the Juan de Aragón lake zone could render approximately 15% of one- to two-story structures vulnerable to damage. This vulnerability arises chiefly from the soft, supersaturated deposits of lakebed sediments that characterize the area, which can amplify seismic waves and magnify their impact on susceptible buildings.
Contrarily, if a similar event were to occur in the La Magdalena transition zone, where the soft lake sediments meet the city’s more solidified highland regions, the projected building damage would drop to about 13%. The Milpa Alta highlands, positioned to the southeast of the city, exhibited the most resilience, with estimates suggesting that only about 5% of one- to two-story buildings would sustain damage from seismic activity in that area. Such disparities underline the necessity for localized earthquake preparedness and response strategies.
Suárez noted the evident geographic effect revealed through their research, stating, “We were somewhat surprised that the geographic effect was very dependent on the type of geotechnical region the earthquake occurred.” This observation highlights how the context of an earthquake’s epicenter can dictate the level of risk that residential and commercial infrastructures face, which may not always align with traditional assumptions about seismic dangers.
Mexico City has historically grappled with seismic dangers, presenting a unique tapestry of risk factors. The metropolis experiences both shallow crustal earthquakes, as evidenced by these recent events, and deeper subduction quakes resulting from the converging tectonic plates beneath it. The escalation in seismic activity has awakened a broader community consciousness about potential risks, which are often indiscernible until they strike.
The data revealed through various improved seismic instruments deployed across the region showcases new insights into local microearthquakes and their subsequent effects on ground accelerations. In an astonishing finding, peak ground accelerations recorded during the recent minor earthquakes have surpassed those documented during the major seismic events of September 19, 1985, and 2017. This revelation signals a pressing need for re-evaluation in our understanding of seismic risks in urban areas, as smaller tremors can produce significant ground forces that may have been previously underestimated.
Jaimes and Suárez engaged in a meticulous process to gauge ground motion intensity for their modeled earthquake scenarios. Their methodology relied heavily on advanced ground motion models sourced from regions similar in tectonic disposition, integrated with localized geological data and an inventory of the building stock in each targeted area. Their predictions shine a light on how varying ground conditions can lead to different levels of damage, particularly emphasizing the heightened risk posed to low-rise structures.
A distinctive characteristic of local earthquakes is their high-frequency seismic waves, which resonate at frequencies that specifically coincide with the vibrational characteristics of one- to two-story buildings. This phenomenon explains why these structures tend to be more susceptible to damage during localized seismic events. Suárez articulated it succinctly, drawing an analogy to a child swinging on a swing—if the push matches the rhythm of the swing, it amplifies the motion, much like how matching frequencies can exacerbate building damage.
In light of these findings, Suárez articulates a stark message for urban planners and engineers alike: “The lesson is clear. Seismic risk in Mexico City stems not only from large and frequent subduction earthquakes but also from local crustal sources that, while more sporadic, may cause substantial damage.” This insight calls for a paradigm shift in how seismic risk assessments are conducted, emphasizing the need for preparedness against both dominant and subtle seismic threats.
As Mexico City continues to develop and densify, invigorating the call for robust construction practices becomes even more vital. The unpredictability of moderate earthquakes, coupled with the city’s geological diversity, necessitates a comprehensive assessment of existing building codes. By amplifying this research, urban decision-makers can better gauge the vulnerabilities within their structural ecosystems, allowing for strategically informed decisions that might mitigate damage during future seismic events.
Through this research, a clearer picture of future risks and necessary interventions emerges, creating avenues for improved engineering tribulations in earthquake-prone regions. Whether through implementing stringent safety measures in construction or fostering resilience through community awareness programs, there are evident pathways forward that could lessen the potential impact of future earthquakes on Mexico City’s vast, historically significant urban landscape.
With the ongoing advancements in seismological understanding and building engineering, the door remains open for continuous improvement. The commitment to addressing these risks will not only safeguard infrastructure but will also protect the communities that depend on them, making Mexico City a more prepared and resilient urban environment in the face of geological uncertainties.
Subject of Research:
Article Title: Estimation of Damage Scenarios in the Mexico City Basin Caused by Local Crustal Earthquakes
News Publication Date: 11-Mar-2025
Web References: DOI Link
References: Not applicable
Image Credits: Not applicable
Keywords
Earthquakes, Structural Engineering, Seismology, Urban Planning, Ground Motion, Tectonic Hazards.
Tags: building structural integrityearthquake damage predictionearthquake modeling techniquesgeological challenges in urban areasground shaking impact assessmenthistorical seismic events in MexicoMexico City earthquake riskmoderate earthquake risk managementseismic activity analysisseismological studies in Mexicotectonic dynamics researchurban seismic preparedness
