Two people have been confirmed dead and twenty five are still missing following a landslide that hit the township of Zhangjiawan in Nayong Couty, Guizhou, on Monday 28 August 2017. The event happened at about 10.40 am local time, destroying 34 homes and damaging about 140 more, after several days of heavy rain in the area associated with Typhoo Hato, which made landfall in Guangdong Province on 23 August, and subsequently slowed and weakened but remained over South China. 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 efforts in Zhangjiawan have been hampered by continuing slope instability, with emergency responders having to repeatedly retreat in the face of further landslides.
Rescue workers at the site of the Zhangjiawan landslide on 28 August 2017. Chinatopix/AP.
Tropical storms (called Typhoons in the West Pacific and Indian Oceans) 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.
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