Field Survey and Geological Effects of the 15 November 2006 Kuril Tsunami in the Middle Kuril Islands

Abstract

Abstract-The near-field expression of the tsunami produced by the 15 November 2006 Kuril earthquake (M w 8.1-8.4) in the middle Kuril Islands, Russia, including runup of up to 20 m, remained unknown until we conducted a post-tsunami survey in the summer of 2007. Because the earthquake occurred between summer field expeditions in 2006 and 2007, we have observations, topographic profiles, and photographs from three months before and nine months after the tsunami. We thoroughly surveyed portions of the islands of Simushir and Matua, and also did surveys on parts of Ketoi, Yankicha, Ryponkicha, and Rasshua. Tsunami runup in the nearfield of the middle Kuril Islands, over a distance of about 200 km, averaged 10 m over 130 locations surveyed and was typically between 5 and 15 m. Local topography strongly affected inundation and somewhat affected runup. Higher runup generally occurred along steep, protruding headlands, whereas longer inundation distances occurred on lower, flatter coastal plains. Sediment transport was ubiquitous where sediment was availabledeposit grain size was typically sand, but ranged from mud to large boulders. Wherever there were sandy beaches, a more or less continuous sand sheet was present on the coastal plain. Erosion was extensive, often more extensive than deposition in both space and volume, especially in areas with runup of more than 10 m. The tsunami eroded the beach landward, stripped vegetation, created scours and trim lines, cut through ridges, and plucked rocks out of the coastal plain.

Propagation of the Storegga tsunami into ice‐free lakes along the southern shores of the Barents Sea

“…2C, D), and fines upwards from very coarse to medium sand. Enclosed in the sand is a disc‐shaped cobble (long axis = 10.5 cm) – probably a so‐called ‘tsunami‐ishi’ (Kato and Kimura, 1983; MacInnes et al ., 2009b), that was moved from the shore and into the lake by the tsunami.…”

“…We suggest that erosion and deposition by a tsunami on frozen terrain in winter would be distinctively different from inundation on unfrozen soil and open lakes in summer (Table 2). Frozen, snow‐covered ground probably reduces the erosional power of the tsunami current, as observed in recent tsunami events in Kamchatka and the Kuril Islands (Minoura et al ., 1996; MacInnes et al ., 2009a,b). We assume that, like snow crust and frozen soil, thick lake ice would be resistant to erosion.…”

An extension of the E/M0 tsunami earthquake discriminant Θ to regional distances

“…The great Kuril Islands interplate earthquake of 2006 November 15 ( M w = 8.3; M 0 = 33.7 × 10 27 dyn cm) ruptured the plate boundary where the Pacific Plate subducts beneath the central Kuril arc. The event generated a tsunami significant in the near field (MacInnes et al 2009) but only modest in the far field (Fujii & Satake 2008). Significant far‐field damage was reported only in the harbour at Crescent City, California, USA, due to a series of late waves reaching a maximum peak‐to‐peak amplitude of ∼1.7 m there (Dengler et al 2009).…”

Tsunami-based evidence for large eastern Aleutian slip during the 1957 earthquake

“…4). These features are interpreted as being formed from tsunami inflow as it accelerated over the beach ridge (as in Kitamura et al, 1961; MacInnes et al, 2009).…”