Three people have died following a landslide at a quarry operated by Island Quarries at Suva on the southeast coast of the island of Viti Levu, Fiji, on Friday 20 March 2020. The dead men have been identified as David Johnson, the managing director of the quarry, Seci Roko, the quarry manager, and Aporosa Ratu, a mechanic employed at the site. The event happened amid heavy rains and flooding associated with a low-pressure system that swept across the islands. 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 with the remains of a vehicle crushed by a landslide that killed three people at a quarry in Fiji on Friday 20 March 2020. Two of the bodies were found adjacent to the vehicle. Fiji Sun.
Fiji has a tropical climate, with a wet season that runs from November to April, with peak rainfall in March, when over 360 mm of rain is usual, and a dry season that lasts from May to October. However, the dry season is not completely arid, typically still receiving about 150 mm of rain per month, and this year has been exceptionally wet, with some of the heaviest rain ever recorded in the islands falling in the past week, and local authorities are warning there is a danger of further landslips and flooding.
The approximate location of the 20 March 2020 Suva landslide. Google Maps.
Low presure systems 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 weather systems 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.
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