At least 40 peoplehave died in the Mexican states of Puebla and Veracruz after Tropical Storm Earl made landfall on Saturday 6 August 2016, brining heavy rain across the region. The highest number of casualties happened in the township of Huaucinango in northern Puebla State, where a number of mudslides and hillslope collapses occured. Three people also died in the nearby town of Tlaola. 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.
Tropical storms are caused by solar energy heating the air above the oceans,
which causes the air to rise leading to an inrush of air. If this
happens over a large enough area the inrushing air will start to
circulate, as the rotation of the Earth causes the winds closer to the
equator to move eastwards compared to those further away (the Coriolis
Effect). This leads to tropical storms rotating clockwise in the
southern hemisphere and anticlockwise in the northern hemisphere.These
storms tend to grow in strength as they move across the ocean and lose
it as they pass over land (this is not completely true: many tropical
storms peter out without reaching land due to wider atmospheric
patterns), since the land tends to absorb solar energy while the sea
reflects it.
Damaged homes at Huauchinango in northern Puebla after a landslide on 7 August 2016. Reuters.
The
low pressure above tropical storms causes water to rise there by ~1 cm
for every millibar drop in pressure, leading to a storm surge that can
overwhelm low-lying coastal areas, while at the same time the heat leads
to high levels of evaporation from the sea - and subsequently high
levels of rainfall. This can cause additional flooding on land, as well
as landslides.
See also...
Eruption on Mount Popocatépetl The Mexican National Centre for Disaster Prevention reported an eruption on Mount Popocatépetl, a stratovolcano (cone
shaped volcano made up of layers of ash and lava) in the central part of
the country, on Sunday 12 June 2016. This began with the...
Eruption on Mount Popocatépetl. Mount Popocatépetl in southern Mexico underwent a major eruption on
Monday 18 April 2016, producing a column of ash rising 3 km above the
summit and throwing incandescent material (glowing hot rocks...
Hurricane Patricia: The most severe storm ever recorded causes widespread flooding but relatively few casualties. Hurricane Patricia formed as a tropical depression over the eastern
Pacific Basin in mid-October 2015, before increasing rapidly in
intensity on 22 October...
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