Influence of natural catastrophes on the development of Southern Kuril Island landscapes in the Holocene

Southern Kuril Islands are situated within a geodynamically active zone noteworthy for an exceedingly high concentration of catastrophic events. Besides those arising from tectonic regime of the region, such as volcanism, earthquakes and tsunami, some extreme events of climatic nature occur repeatedly, including typhoons and related floods, and violent storms. Impact of those catastrophic factors on the environmental evolution was conspicuous against the background of long-term climatic changes, often concealing influence of the latter or reversing temporarily the direction of natural development. Those factors are of special importance on relatively small islands. A sequence of various short-term catastrophic events could even exert an irreversible effect on landscape evolution and occasionally trigger cardinal restructuring of environments. Particularly important consequences occur from events that involve a momentary (in terms of geological time) input of huge masses of loose material: they disturb stable trends in the landscape evolution (primarily that of lithogenic base of the landscapes, namely landforms and deposits). Judging from the structure of the loose sediment mantle on the islands, catastrophic events varied over wide ranges of intensity and frequency during the Holocene. On the whole, their occurrence agreed with phases of tectonic and volcanic activity in the volcanic belt of the Northwestern Pacific.