This quake in Chile occurred at a similar depth, with a similar faulting mechanism, and beneath a highly populated area in a sedimentary basin, similar to the two recent Mexico earthquakes. (a) (b) (c) Figure 3. The M8.0 1985 Michoacan earthquake was an interplate event where the seismic waves traveled more than 350 km before reaching Mexico City. The incident prompted a review of the system. The 2017 Puebla earthquake struck at 13:14 CDT (18:14 UTC) on 19 September 2017 with an estimated magnitude of Mw7.1 and strong shaking for about 20 seconds. The world’s largest recorded earthquake, which struck Chile in 1960, was not the country’s most damaging earthquake. Yet its depth, pinpointed to 70km down, raised eyebrows. A magnitude 8 earthquake that struck the city of Chillán in 1939 contributed to the deaths of nearly 30,000 people. © 2021 Guardian News & Media Limited or its affiliated companies. Nature Geoscience, 2018. Not only do these earthquakes produce dangerous shaking, but if they occur close enough to the point on the seafloor where the two plates meet, they can push up seawater and create a tsunami wave. Beginning just south of Mexico City, the alignment of hills shifted, reflecting a zone where plate subduction flattened. with 25 posters participating, including story author. This warping of the Cocos plate caused a large earthquake to occur close to Mexico city at a relatively shallow depth. Last modified on Thu 5 Oct 2017 11.52 EDT. Tectonic setting. A deadly magnitude-8.2 earthquake struck the southern coast of Mexico on 7 September, killing dozens of people and injuring at least 200. Mexico has had an implementation of an earthquake early warning system for years, developed after the 1985 earthquake that devastated Mexico City. The Gulf of Tehuantepec lies above the convergent boundary where the Cocos Plate is being subducted below the North American Plate at a rate of 6.4 cm/yr (2.5 in/yr).. Background. So, it is difficult to tell where and when these types of ruptures have occurred in the past. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Condé Nast. Let’s not pull on your wrist hard enough to stretch your elbow joint, but doing so would counteract the squeezing on the inside of your elbow as it bends. A magnitude 8.2 on September 8 just offshore the state of Chiapas was followed by a magnitude 7.1 on September 19—this time much closer to Mexico City, causing considerable destruction there. A powerful earthquake struck off the coast of Mexico early this morning and was felt as far away as Mexico City, reports said, the New York Times reports. We have seen such quakes striking Indonesia, Chile and Japan over the past 15 years. - Oct 4, 2018 2:50 pm UTC. The tectonic plate boundary known as a subduction zone, where an oceanic plate dives down beneath another plate. That means that earthquakes along that boundary are typically the result of compressive force that squeezes rock to slide up the plane of the fault. On 6 September, several earthquake alarms in Mexico City were mistakenly activated and this led to the evacuation of buildings. - Mexico City honors earthquake victims in Day of the Dead parade ... "It is not one single sharp plate boundary, but there are numerous fracture zones," Dahm explains. The 8.2 magnitude earthquake that brought devastation and 98 deaths to southern Mexico in September 2017 was even more extreme than initially thought — it split the tectonic plate … The 1985 earthquake was the more typical great earthquake that breaks the boundary between the plates, and caused great devastation in Mexico City despite being more than 100 … This is partly because hotter temperatures at greater depths make the rock less brittle and partly because the inside of the bend in the plate should be feeling squeezing rather than stretching. The 7.1 magnitude earthquake, 19 September. As the Cocos plate plunges deeper into the bowels of our planet, fractures inside the slab bend and pull apart. Tuesday’s earthquake took place on the anniversary of a devastating earthquake that killed thousands in Mexico City in 1985. Mexico City’s potent 2017 earthquake was a rare ‘bending’ quake – and it could happen again March 12, 2018 10.34am EDT • Updated September 19, 2018 3.48pm EDT subduction zone, Mexico City is subjected to both interplate (epicenter at plate boundary) and intraplate (epicenter inside the continental plate) earthquakes. The earthquake caused damage in the Mexican states of Puebla and Morelos and in the Greater Mexico City area, including the collapse of more than 40 buildings. However, as this week’s events have shown, more work is still to be done in retro-fitting older buildings to bring them up to modern standards. The magnitude-8.2 quake damaged buildings in Mexico City. If building structures are improved, early warning systems continue to be implemented and the public is educated about what action to take to protect themselves when the warning sirens sound, then cities located in earthquake-prone areas will be making good progress to better protect their infrastructure and people during future quakes. These systems analyse recordings of the weak and faster-travelling seismic wave arrivals (P-waves) to try to estimate when the slower travelling, but more damaging waves (S-waves) will arrive and how strong they will be. Both September earthquakes were the result of stretching, however, which is almost as much of a head-scratcher as finding that part of your car’s engine was pulled apart during a head-on crash. Mexico City is especially prone to severe damage because of the ground it sits on — an ancient lakebed that quivers like jello, Bellini says. DOI: 10.1038/s41561-018-0229-y (About DOIs). This final kink in the Cocos plate is located right where the 7.1 earthquake happened, and directly beneath the Valley of Mexico, in which Mexico City is located. Mexico’s most recent earthquakes did not directly involve two tectonic plates clashing, as is commonly the case. It occurred only 11 days after the M w 8.2 September 8, 2017 Mexico Earthquake, located further southeast, offshore Chiapas, Mexico. Due to the ongoing subduction of the Cocos plate, earthquakes of this nature in this location are common. The 2017 earthquake likely was the result of “bending stresses occurring at the transition from flat-slab subduction to steeply dipping subduction,” the researchers concluded. The 1985 earthquake was the more typical great earthquake that breaks the boundary between the plates, and caused great devastation in Mexico City despite being more than 100 miles distant. A magnitude 8.2 on September 8 just offshore the state of Chiapas was followed by a magnitude 7.1 on September 19—this time much closer to Mexico City, causing considerable destruction there. Ad Choices. First, seawater percolating down into the cracks that formed as the oceanic plate first bent to head beneath the continent could have cooled the rock and reacted with minerals, making the rock more brittle than it would be otherwise. In this region, the Cocos Plate subducts beneath the North American Plate, creating a seismic and volcanic belt along the Pacific coast of Mexico. In June 1999, a M 7.0 at 70 km depth, just to the southeast of the September 19, 2017 earthquake, caused 14 fatalities, around 200 injuries, and considerable damage in the city … Occasional earthquakes within this bending, sinking plate can reflect that stretching. Mexico lies within two seismically active earthquake zones. In some ways, the region is primed for this activity because its two plates that are actively colliding. In this region, the oceanic Cocos plate dives beneath the North America and Caribbean plates to form the Middle America Trench, a subduction zone with a rich history of very large M>8 earthquakes (Ye et al., 2013). Sign up or login to join the discussions! On Tuesday, a deadly quake reverberated along the boundary between the Cocos and the North American plate as the southern-most plate slid beneath its … The explanation here is that as the oceanic plate disappears beneath the continent, it sinks downward into the mantle. So there is no immediate indication that these two quakes are directly linked. Based on previous scientific studies, the slab begins to behave as normal at shallow depths, but then it suddenly flattens for a distance of around 200 km, before again plunging into the deep Earth. The results show that a 150km-long section of the fault slipped three meters or so. Mexico’s western coast is a tectonic plate boundary, where the oceanic plate collides with and dives beneath the continent. Vertically, the portion of the fault that slipped starts at the top of the oceanic plate—about 15km below the Earth’s surface—and continues all the way down to a depth of about 80km, which is roughly the bottom of the plate. WIRED Media Group Whilst geophysicists continue to try and unravel the factors that drive these deep earthquakes inside tectonic plates, the key for people living in earthquake-prone areas is to prepare. Mexico is adjacent to a plate tectonic boundary. 2017 earthquake off Mexico broke through an entire tectonic plate Magnitude 8.2 in Mexico involved more fault movement than thought possible. The system is widely reported to have detected the impending shaking near the epicenter and provided invaluable seconds to take appropriate actions in areas further afield. © 2021 Condé Nast. The epicentre of the quake was 120 km southeast of Mexico City, 12 km southeast of the city of Axochiapan, Morelos on the boundary between Puebla and Guerrero. Although these types of earthquake are rare, the amount of damage caused by them is not globally unprecedented. Geology. Counter to what we thought possible, the fault seems to have broken clean through the entire tectonic plate. In this case the rupture took place inside a plate itself, not at the locked zone between plates. How Mexico City's 2017 "Bending" Earthquake Could Happen Again. Thu 21 Sep 2017 06.53 EDT Last modified on Thu 5 Oct 2017 11 ... the shallow portion of the tectonic plate boundary. Building code design response spectra in Mexico City for 1976, 1987, and 2004 in the: (a) Firm Mexico, too, lies on the Ring of Fire and is no stranger to such quakes: the 1985 8.0 magnitude earthquake that devastated Mexico City was a fairly typical “thrust” earthquake that ruptured the shallow portion of the tectonic plate boundary. The combination of the earthquake’s location, radiated seismic energy, and the very foundations of Mexico City – thick, loose soils that behave like a bowl of jelly during earthquakes – created the conditions for devastation. Seismologists can model the process backward from the measured surface movement and figure out how the fault moved underground. Mexico has made great strides in improving building codes since the 1985 earthquake. Second, the sinking plate pulls downward as it “hangs” from the part of the plate that is still up at the surface—another stretching force. According to the U.S. Geological Survey, the epicenter of the earthquake took place in Raboso, Mexico—about 75 miles south of the capital city. Within 250 km of the September 19, 2017, earthquake there … While the two earthquakes were not connected, they were the same type of earthquake, which is unusual in the region. All rights reserved. Your California Privacy Rights | Do Not Sell My Personal Information 370 people were killed by the earthquake and related building collapses, including 228 in Mexico City, and more than 6,00… This earthquake comes just 12 days after major M8.1 quake near the coast of Chiapas, Mexico and on the anniversary of the devastating 1985 M8.0 … 2017 earthquake off Mexico broke through an entire tectonic plate September 2017 saw a pair of weird earthquakes in Mexico. Mexico is located on one of Earth's subduction zones, where the ocean floor of the Cocos tectonic plate is forcing its way down ("subducting") beneath the continental edge of the North American plate. parts of Mexico City, resulting in 369 casualties. The Baja California peninsula lies near the boundary of the Pacific Plate and the North American Plate, while southern Mexico lies just north of the boundary between the North American Plate and the Cocos and Rivera tectonic plates. Rescuers work in the rubble after a magnitude 7.1 earthquake struck on September 19, 2017 in Mexico City, Mexico ... of Mexico, and the North American tectonic plate. Mexico City's downtown area is notoriously vulnerable to earthquakes … We know very little about the geometry of these faults within plates, how they behave from one earthquake to another, and the frictional properties of the rocks that fracture. The quake had a magnitude of 8.1 and struck about 60 miles, or 96 kilometers, southwest of Pijijiapan, … Mexico city, the country’s capital, is especially prone to earthquakes because it is situated on top of an ancient lake bed. The reasonably shallow depth suggested that this particular part of the Pacific Ring of Fire does not behave as we expect. Similarly, faults moving because they’re being pulled apart on the outside of the bend should be clamped together on the inside of the bend. Its epicenter was about 55 km (34 mi) south of the city of Puebla. Protecting people during earthquakes is all about minimizing surprises, so while they are always interesting, we want to limit the earthquakes that make you go "Huh.". If the 8.1 tremor raised eyebrows, then Tuesday’s magnitude 7.1 earthquake left everyone stunned. Its depth was puzzling: only 50km down, but the faulting mechanism implied rupture inside a plate. The titanic collision of two tectonic plates, which firmly lock together and accrue strain over tens to hundreds of years, eventually releases this pent-up energy as a large earthquake. CNMN Collection Seismologist Dr Stephen Hicks explains, Dr Hicks is a postdoctoral research fellow in seismology at the University of Southampton. So why did this earthquake break the rules? A major earthquake registered by the USGS as M7.1 hit Puebla, Mexico at 18:14 UTC (13:14 local time) on September 19, 2017. Following its head-on collision with the North American plate (to which Mexico belongs), the Cocos plate (a piece of crust beneath the Pacific Ocean) gradually sinks deeper into the earth under its own weight. Available for everyone, funded by readers. You must login or create an account to comment. Use of and/or registration on any portion of this site constitutes acceptance of our User Agreement (updated 1/1/20) and Privacy Policy and Cookie Statement (updated 1/1/20) and Ars Technica Addendum (effective 8/21/2018). Our detailed earthquake records from instruments only go back a hundred years or so, and these deep quakes do not leave any noticeable imprint in the geological record from surface ruptures or large tsunamis. The equations for the physics of all this tell us that the fault movement should have been restricted to the upper half of the oceanic plate. Since the plates there seem to break rules followed by plate boundaries elsewhere around the world, the local rules need to be better understood. First of all, the bending of the plate downward causes stretching, just as the skin over your elbow has to stretch. Join the Ars Orbital Transmission mailing list to get weekly updates delivered to your inbox. Tuesday’s earthquake occurred near this interface along the tectonic plate boundary known as the Middle American Trench, just offshore at a shallow depth 13.7 miles (22.6 kilometers) according to SSN. This earthquake occurred on the anniversary of the devastating 1985 M 8.0 Michoacan earthquake, which caused extensive damage to Mexico City and the surrounding region. The two earthquakes occurred within just 11 days of each other and both were within the sinking Cocos plate. The M=6.6 earthquake ruptured at 67 km (40 mi) deep along the plate boundary formed offshore of Central America on 1 February 2019. The agency is reporting a depth of 51 km (31.7 miles). Almost nine million people live in Mexico City. The first tremor, a magnitude 8.1 earthquake, had a fairly typical epicentre location – just offshore of the coastline. This process probably caused the magnitude 8.1 earthquake. 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