Catastrophic landslide induced by Typhoon Morakot, Shiaolin, Taiwan

Abstract

Typhoon Morakot induced the catastrophic and deadly Shiaolin landslide in southern Taiwan on 9 August 2009, resulting in more than 400 casualties. We undertook a geological and geomorphological investigation with the aim of reconstructing the events leading up to this landslide and to clarify factors that contributed to its development. Cumulative rainfall reached up to 1676.5 mm in about three days under the influence of the typhoon, and the Shiaolin landslide, with a volume of 25 x 10(6) m(3), occurred one day after the peak in rainfall intensity. The landslide occurred on a dip slope overlying late Miocene to early Pliocene sedimentary rocks consisting of silty shale, massive mudstone, and sandstone. It started as a rockslide in the upper third of the landslide area and transformed into a rock avalanche that crossed a series of terraces and displaced or buried the village below. It buried the riverbed of the Chishan River and ran up the opposite slope, creating a landslide dam 60 m high, which was breached about I h and 24 min later, flooding the village. The velocity of the landslide is estimated to have been 20.4 to 33.7 m s(-1) and its apparent friction angle was 14 degrees, which indicates its high mobility. The detachments in the source area consist of combinations of bedding planes and joints or faults. The landslide was preceded by gravitational deformation, which appeared as hummocky landforms before the landslide and as buckle folds exposed after the event. The landslide deposits consist of fragments of mudstone, shale, and sandstone, as well as clayey material at its base. This clayey material. consisting of Wire. chlorite, quartz, feldspar, and calcite, is assumed to have strongly influenced the long, rapid runout. (C) 2010 Elsevier B.V. All rights reserved

Formation, failure, and consequences of the Xiaolin landslide dam, triggered by extreme rainfall from Typhoon Morakot, Taiwan

“…The maximum deposited height from the riverbed before the landslide to the SDP and width of the dam are around 107 and 348 m, respectively, on Profile E3. We classified the Xiaolin landslide dam as a rock-avalanche dam and deduced that the dam was formed around 6:16-6:17 on August 9, 2009 (Tsou et al 2011;Feng 2012).…”

Impacts of tropical cyclones on hydrochemistry of a subtropical forest

“…Because the flooding associated with tropical cyclones often causes more property and ecosystem damage than do high winds (Trousdell et al, 1965;Cremer et al, 1977;Foster, 1988;Atallah and Bosart, 2003;Lin, C. W. et al, 2011;Tsou et al, 2011;West et al, 2011), a storm rating system that includes rainfall would be far more useful in preparing for, and understanding, the impacts of tropical cyclones on human and natural systems.…”

“…For example, the 56 deaths and up to $6 billion in property damage caused by the 1999 category 2 hurricane Floyd in the US was due to extensive flooding (Atallah and Bosart, 2003). The more than 400 deaths caused by the 2009 typhoon Morakot in southern Taiwan was a result of landslides and debris flows induced by the nearly 3000 mm of precipitation over three days Tsou et al, 2011). Forest systems also show a strong relationship between the severity of storm induced damage and rainfall quantity (Scatena and Larsen, 1991;West et al, 2011).…”

The seismic signatures of the 2009 Shiaolin landslide in Taiwan

“…The landslide was deep-seated and occurred on a dipping slope of shale, mudstone, and sandstone. The material fell approximately 830 m from the head scarp (Tsou et al, 2011). The landslide was estimated to be 25 million m 3 in volume and traveled approximately 2.83 km (Fig.…”