Two people, including a three-year-old girld, have now been confirmed dead and another two are still missing following a landslide that hit the city of Tlalnepantla in Mexico State, Mexico, on Friday 10 September 2021. The landslide was caused by the collapse of part of the Cerro del Chiquihuite hillside following heavy rain in the area, which dislodges a series of large boulders, estimated to weigh up to 200 tons, onto a residential district.Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. However, in this case the rains are thought to have been only part of the problem, with the area having been shaken by a Magnitude 7.0 Earthquake which occurred near Acapulco on the coast of Guerrero State, 400 km to the south of Tlalnepantla, on Tuesday 7 September.
Boulders lying on top of residential housing in Tlalnepantla, Mexico, following a landslide on 10 September 2021. Eduardo Verdugo/AP.
The 7 September 2021 Acapulco Earthquake was recorded by the United States Geological Survey as occurring at a depth of 20 km, roughly 17.7 km to the north of the city, slightly after 8.45 pm local time (slightly after 1.45 am on Wednesday 8 September GMT). The event was felt over much of southern area, and caused minor damage to many buildings, but no major casualties or destruction.
Mexico is located on the southernmost part of the North American Plate. To the south, along the Middle American Trench, which lies off the southern coast off Mexico, the Cocos Plate is being subducted under the North American Plate, passing under southern Mexico as it sinks into the Earth. Guatemala is located on the southern part of the Caribbean Plate, close to its boundary with the Cocos Plate, which underlies part of the east Pacific. The Cocos Plate is being pushed northwards by expansion of the crust along the East Pacific Rise, and is subducted beneath the Caribbean Plate along the Middle American Trench. This is not a smooth process, and the plates frequently stick together then break apart as the pressure builds up, causing Earthquakes on the process.