Wednesday 20 July 2022

Three children dead after landslide hits school in Antioquia Province, Colombia.

Three children have died and two more required hospital treatment after a landslide hit the cafeteria of a school in the Medellin area of Antioquia Province, Colombia, on Thursday 14 July 2022. The event happened during a recess when 20 children of preschool and first grade ages were taking a break in the cafeteria, along with a teacher and the mother of one of the children. The incident is reported to have happened following a period of heavy rain. 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.

Rescue workers and local residents search for survivors after a landslide hit a school cafeteria in Antioquia Province, Colombia, on 14 July 2022. Associated Press.

Antioquia is a mountainous province with several distinct climate zones. The Medallin area is considered to gave a monsoon climate, with a to peaks in rainfall in May and October. Two hot wet seasons per year is normal on the equator, where the Sun is highest in the sky around the equinoxes and lowest at the solstices, as opposed to the situation at higher latitudes, where the Sun is highest at one solstice and lowest at the other.

This means that July would normally be a relatively dry time of year, making landslides and other high precipitation related events less likely, However, this year the climate of South America, and other areas around the Pacific Rim, are being hit by a La Niña weather system, bringing high rainfall to areas which would normally be dry.

The La Niña weather system is the opposite of the El Niño weather system, in which unusually cold surface temperatures spread across the equatorial Pacific from the upwelling zone on the South American coast. This traps warm water from the western Pacific, preventing it from spreading east and warming the central Pacific. This leads to lower evaporation over the (cooler) east Pacific during the southern summer, leading to low rainfall on the west coast of South America, and higher evaporation over the (warmer) west Pacific, leading to higher rainfall over East and Southeast Asia and northern Australia. However, during the southern winter the cooler climate over the northern Andes leads to higher rates of precipitation as water condenses out of the air more readily, bringing high rainfall, flooding, and landslides to the area at a time of year usually considered safe from such events. 

The effects of a La Niña weather system in December-February and June-August. NOAA.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.