Background and Scope - Tohoku, Japan Earthquake and Tsunami of 2011 - page 24

Table 6. Locally generated tsunamis affecting Japan's coast with reported casualties
in excess of 1000 (Sources: NGDC Database, (*) Minoura 2001, (**) National Police
Agency of Japan 2011)

Source Casualties/Damage

Year Magni-

tude

Name LAT LONG Runup

(m)

Deaths Houses
Destroyed

869(*) 8.3 Jogan Sanriku 38 - 40 143-144 > 8m >1,000 --

1498 8.3 Meio Nankaido 34 138.1 10 31,000 1,000

1605 7.9 Keicho Nankaido 33 134.9 10 5,000 700

1611 8.1 Keicho Sanriku 39 144.5 25 5,000 --

1703 8.2 Gen(r)oku Kanto 34.7 139.8 10.5 5,233 20,162

1707 8.4 Hoei (Pair of

events)

33.2 134.8 25.7 5,000 17,000

1771 7.4 Great Yaeyama 24 124.3 85.4 13,486 3,237

1854 8.4 Ansei (Pair of

events)

33.1 135 28 3,000 15,000

1896 7.6 Meiji Sanriku 39.5 144 38.2 27,122 11,000

1923 7.9 Great Kanto 35.1 139.5 13 2,144 868

1933 8.4 Showa Sanriku 39.1 144.7 29 3,000 6,000

1944 8.1 Tonankai 34 137.1 10 1,223 3,059

1946 8.1 Nankaido 33 135.6 6.6 1,362 1,451

2011 9.0 Great East Japan 38.3 142.4 38 15,550 >100,000

(**)

Notably, the maximum runup from the 2011 Great East Japan tsunami at Ryori
reached about 30 m, a runup comparable to that of 1933 but less than the runup in the
1896 event. While the Great East Japan earthquake far surpassed other modern events
on the Japan Trench, a somewhat comparable event may have occurred in 869.
Minoura (2001) reported sand sheet evidence from the Sendai area that, together with
historic records, indicate a tsunami passing up to 3 km inland in Sendai drowned over
1,000 people. Modeling by Satake (2008) places this occurrence as a magnitude 8.3 -
8.4 event from the sand sheet evidence. While not as large an earthquake as the 2011
Great East Japan event, its discovery was the first evidence that the subduction zone
in the Sanriku area was capable of producing a seismic moment in excess of
magnitude 8.0.

1.5.2PropagationofTsunamiWavesattheJapaneseCoast

As in the case of the GPS measurement of seismic displacement, recent advances in
GPS technology have allowed the deployment of moored ocean buoys that can track
the passage of ocean waves. A variety of such sensors recorded the tsunami generated
by the Great East Japan earthquake as it propagated onto the Sanriku coast. Hayashi
(2011) summarizes the observed water surfaces from offshore wave gauges, GPS
buoys, and cabled ocean-bottom pressure gauges during the tsunami.