Microseisms and a Perceived Earthquake Rock Mexico City and Surrounding Areas
Mexico City residents experienced unsettling tremors on November 20, prompting widespread reports of shaking and raising questions about seismic activity. While initially reported as an earthquake, authorities have clarified that the sensation was primarily caused by a series of microseisms, though a minor earthquake did occur in Naucalpan, State of Mexico. This event has sparked concern and curiosity, particularly regarding why the city’s seismic alert system wasn’t activated.
The initial reports centered around a perceived earthquake felt strongly in various parts of Mexico City (CDMX) and the State of Mexico (Edomex). Residents described a noticeable shaking sensation, leading to anxieties given the country’s history of significant seismic events. However, the National Seismological Network (SSN) quickly identified the primary cause as a series of microseisms – small, localized tremors that are often less damaging but can be distinctly felt, especially in densely populated urban areas. A separate, minor earthquake with a magnitude of 3.8 was registered in Naucalpan, contributing to the overall sensation of movement. Mexico News reported on the initial perceptions of a larger earthquake.
Microseisms, while not typically causing structural damage, can be unsettling. They are often caused by minor geological adjustments or even human activity. The fact that these microseisms were widely felt highlights the sensitivity of the Mexico City basin, which is prone to amplification of seismic waves due to its unique geological composition. López-Dóriga Digital provided details on the microseismic activity affecting both CDMX and Edomex.
Understanding Seismic Activity in the Mexico City Region
Mexico City is situated in a seismically active zone, lying over several fault lines. The city’s location in the Trans-Mexican Volcanic Belt and the subduction of the Cocos Plate beneath the North American Plate contribute to frequent seismic activity. This geological context makes the region particularly vulnerable to earthquakes and even the perception of smaller tremors like microseisms. The soft, clay-rich soil of the former lakebed upon which much of Mexico City is built amplifies seismic waves, increasing the intensity of shaking during an earthquake.
The seismic alert system in Mexico City is designed to provide residents with advance warning of potentially damaging earthquakes. However, the system is calibrated to detect earthquakes of a certain magnitude and intensity. Microseisms, being smaller in scale, often do not trigger the alert. UnoTV addressed the question of why the seismic alert remained silent during today’s events.
Did You Know?: Mexico City’s seismic alert system has undergone significant improvements since the devastating 1985 earthquake, but it remains a complex system with limitations in detecting and responding to all types of seismic events.
The SSN continues to monitor seismic activity in the region, providing real-time data and analysis. Residents are encouraged to familiarize themselves with earthquake safety procedures and to remain vigilant during periods of increased seismic activity. Understanding the difference between a minor tremor and a potentially damaging earthquake is crucial for maintaining calm and ensuring safety. What measures do you take to prepare for an earthquake in your region?
The recent events serve as a reminder of the ever-present seismic risk in Mexico City and the importance of ongoing research and preparedness efforts. The city’s resilience in the face of seismic challenges is a testament to the dedication of scientists, engineers, and emergency responders. How can communities better prepare for and respond to seismic events in the future?
Frequently Asked Questions About Today’s Tremors
What caused the shaking in Mexico City today?
The shaking was primarily caused by a series of microseisms, small tremors that are often felt but rarely cause significant damage. A minor earthquake in Naucalpan also contributed to the sensation.
Why didn’t the seismic alert sound during the microseisms?
The seismic alert system is designed to detect larger earthquakes. Microseisms typically do not reach the magnitude threshold required to trigger the alert.
Are microseisms dangerous?
Microseisms are generally not dangerous and rarely cause structural damage. However, they can be unsettling and may be felt strongly in certain areas.
What is the difference between a microseism and an earthquake?
An earthquake is a sudden release of energy in the Earth’s crust, typically caused by the movement of tectonic plates. Microseisms are smaller, localized tremors that are often caused by minor geological adjustments or human activity.
Where was the epicenter of the earthquake felt in Naucalpan?
The earthquake registered in Naucalpan, State of Mexico, and was felt across parts of Mexico City and surrounding areas. Millennium provided live updates on the situation.
Stay informed about seismic activity in Mexico: National Seismological Network (SSN), United States Geological Survey (USGS).
Share this article with your friends and family to keep them informed. Join the conversation in the comments below – what was your experience during today’s tremors?
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