A man has died after the house he was in was crushed by a landslide in the village of Sibaguan in Camarines Sur Province on Luzon Island in the Philippines on Thursday 2 November 2017. The incident happened slightly before 1.00 pm local time, following several hours 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. The man has been identified as Ryan Lasmariñas, 32. A second man who was in the house escaped unharmed.
The scene of a landslide that killed a man in Camarines Sur Province, the Philippines, on 2 November 2017. GMA News.
The rains which triggered the landslide are associated with Tropical Depression Ramil, a storm system which has passed over the Philippines this week, bringing heavy rains to Luzon and neighbouring islands.
The passage of Tropical Depression Ramil till 8.00 pm local time on 2 November 2017, grey area to the left is the projected future track of the storm. Philippine Atmospheric Geophysical and Astronomical Services Administration.
A Tropical Depression is a Tropical Storm not powerful enough to be formally named (though they are often given names locally). 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 in rushing 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.
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, which are are a common problem during these storms.
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