A series of nine small tremors rattled Mexico City starting early Thursday morning, worrying residents and rupturing a pipe in the Benito Juárez borough.
Five small earthquakes shook the northwestern portion of the city before dawn Thursday. Officials reported that the “microseisms” — faint earth tremors — caused no damage.
A sixth micro-quake was felt at 10:26 a.m., unnerving residents of the capital who are all too familiar with traumatic September earthquakes. It was followed by smaller tremors at 11:41 a.m. and 11:50 a.m. The newspaper Excelsior reported that the quakes broke a pipe in a building in the Nápoles neighborhood of Benito Juárez borough, flooding the building.
Then at 1:03 p.m., a 5.2-magnitude earthquake with its epicenter in Guerrero set off a national seismic alert. The Mexican Seismic Alert System reported alerts in Chilpancingo and Acapulco, Guerrero, as well as in Cuernavaca, Morelos, and Morelia, Michoacán. No alert was reported for Mexico City, though some CDMX residents reported hearing sirens and receiving phone alerts.
Half an hour later, a 4.4-magnitude quake was reported with an epicenter in southern Veracruz. It did not set off a seismic alert because “the estimated energy in the first seconds did not exceed preestablished levels,” the Mexican Seismic Alert System said in a post on the social media platform X.
Mexico’s National Seismological Service (SSN) reported that the epicenter of Mexico City’s five early morning micro-quakes — ranging from magnitude 1.0 to 2.9 on the Richter scale — was in the borough of Miguel Hidalgo.
SISMO Magnitud 5.2 Loc 40 km al SUR de CD ALTAMIRANO, GRO 26/09/24 13:03:02 Lat 18.01 Lon -100.57 Pf 15 km pic.twitter.com/sbdYbziZw5
— Sismologico Nacional (@SismologicoMX) September 26, 2024
After a morning of micro-quakes, a 5.3-magnitude quake in Guerrero set off alarms in some areas of Mexico City.
The shaking of the fourth and strongest of these tremors at 12:39 a.m. was felt in the neighboring boroughs of Álvaro Obregón, Benito Juárez and Cuauhtémoc, according to Animal Político, an online news site.
The sixth and seventh micro-quakes — measuring magnitude 2.4 and 2.2 — were centered in the Benito Juárez borough, causing some concern about the increasing frequency of these tremors. The eighth micro-quake, magnitude 1.5, was centered in the Álvaro Obregón borough. The Miguel Hidalgo borough was the center of a ninth micro-quake of magnitude 1.4 just after 2:30 p.m.
According to the SSN website, the six tremors in Mexico City were very shallow — roughly 1 kilometer beneath the surface of the earth — a factor explaining the low magnitude of the quakes.
A government bulletin issued in January explained that earthquakes originating less than 10 kilometers below the earth’s surface are typically of short duration, and usually of very low magnitude, rarely exceeding 4.0 and generally not even reaching 3.0. According to the SSN, these tremors are perceived only by the population within a radius of 2 or 3 kilometers.
The Mexico City microseisms are primarily due to friction produced by geological fault lines and the resulting dissipation of energy occurs over a very short and localized period of time, producing a sensation like a jump.
According to Pedro Vera Sánchez, a geologist at the National Polytechnic Institute (IPN), the result is “a very short and intense shake, due to the shallow depth, but also due to the short duration of the event, since in the end, the seismic waves released dissipate in this small space.”
The bulletin was produced after nearly 60 micro-quakes occurred in Mexico City last year, including a Dec. 12, 2023, tremor in Benito Juárez that caused structural damage to several buildings.
According to a December 2023 report published by Monterrey Tech, the size of faults generally governs the length of earthquakes and since the faults in Mexico City are relatively minor, the tremors will be minimal.
This notwithstanding, Thursday’s seismic activity still spooked many residents familiar with Mexico City’s history of destructive earthquakes in September. The magnitude 8.0 earthquake on Sept. 19, 1985 (and a large magnitude 7.5 aftershock the following day) killed an estimated 10,000 people and a 7.1 magnitude quake on Sept. 19, 2017, claimed 370 victims.
Thursday’s phenomena came just one week after those tragic anniversaries, anniversaries that are commemorated annually on Sept. 19 by a national earthquake drill.
With reports from Animal Político, Excelsior and El Universal
