According to the drilling situation and previous research, the thick layers of sand are generally located far from the material source areas where palaeo-water depths were greater (Fu et al. 2013).
Some material in the source area has been washed out down the slope since 2009 Fig. 3 a from 2009, b from 2014.
Over the past ∼ 150 years, climate has exerted control on material released from the source area and prevented triggering of class XL events before 1922.
For the larger slope failure types (debris avalanche and landing failure) the 'scar' and the depositional material extending downslope from the source area (termed 'debris tail') were measured separately.
Two basal shear resistances were chosen, according to the landslide dynamics; one rheology material was used for the source area between 226 and 173 m a.s.l., and another was assumed for the channelized area between 173 and 131 m a.s.l.l
The majority of clastic material was supplied from the north source area through rift-trough sediment-transport pathways, and the eastern, southern and northwestern source areas also contributed detritus to the basin.
According to Chigira et al. ([2010]), the investigators also found water-saturated clayey materials and water flow in the source area.
Because damage was very high in August 2003 in the pre-defined food source area, the remaining undamaged material available as a food source was probably relatively unpalatable low-nutrient foliage.
These geochemical characteristics indicate that the Quaternary sediment sources were composed by more felsic and/or recycled old continental crust derived rock materials than the younger source areas, which contributed major arc volcanic materials to the flood plain deposits.
Since very similar raw materials can be found at more than one source, we combine such similar sources into source areas, and test the area of the source area (AOSA) and the total area of sources within the source area (AOSISA), as two additional independent variables.
