Tsunami height survey was conducted immediately after the 2003 Tokachi-oki earthquake. Results of the survey show that the largest tsunami height was 4 m to the east of Cape Erimo, around Bansei-onsen, and locally at Mabiro. The results also show that the tsunami height distribution of the 2003 Tokachi-oki earthquake is clearly different from that of the 1952 Tokachi-oki earthquake, suggesting the different source areas of the 1952 and 2003 Tokachioki earthquakes. Numerical simulation of tsunami is carried out using the slip distribution estimated by Yamanaka and Kikuchi (2003). The overall pattern of the observed tsunami height distribution along the coast is explained by the computed ones although the observed tsunami heights are slightly smaller. Large later phase observed at the tide gauge in Urakawa is the edge wave propagating from Cape Erimo along the west coast of the Hidaka area.

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On June 3, 1994, an Ms = 7.2 earthquake occured at a depth of 15 km near the east end of the Java trench in the Indian Ocean. The earthquake generated a large tsunami that violently struck southeast Java and extended to southwest Bali (Figures 1 and 2). Approximately 200 people were killed, 400 were injured, and 1000 houses were destroyed. Runup heights (Figure 2) ranged from 0–5 m in west Bali to 1–14 m in southeast Java. This unusual tsunami was generated about 250 km from the hardest hit area. Surprisingly, strong earthquake‐induced ground shaking was not a precursor so local residents had no warning of the impending catastrophe. The long‐period characteristics of the earthquake were incommensurate with the relatively weak high‐frequency magnitude Mb=5.5, and the rate of seismic moment release grew monotonically up to at least 270s. The pattern resembled that of the Nicaragua earthquake of September 2, 1992, in which strong ground shaking did not occur. Most of the damage was concentrated in villages located in pocket beaches, unlike previous tsunami damage in west Nicaragua, Flores, Indonesia [Yeh et al., 1993], and Okushiri, Japan.

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A practical method for estimating maximum superposed force due to simultaneous or near-simultaneous collision of pieces of driftwood accompanying tsunami inundation flow and its probability of occurrence is presented by examining inundation flow velocity (≅ collision velocity), acceleration distance within which the driftwood velocity becomes almost the same as inundation flow velocity, collision force, collision force duration, rise time from start to peak collision force, driftwood collision probability and by systematically integrating examination results.

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