Background and Scope - Tohoku, Japan Earthquake and Tsunami of 2011 - page 29

The chart at the right of Figure 14 (Tsuji 2011) summarizes some of the observed
water levels during the 1896 Meiji Sanriku and the 1933 Showa Sanriku tsunamis. In
general, water levels from the 1896 Meiji tsunami exceeded those of 1933 with two
sites — Northern Iwate and at Ryori Bay — experiencing local maxima levels above
20 meters. At Ryori Bay, the wave overtopped Mizuai Pass at a height of 38.2 meters
above tide level. In 1933, the water reached 29.2 meters. In 2011, the water reached
23.3 meters at this same pass, one of the few locations where the historical water
heights exceeded the water levels of the Great East Japan tsunami. Taken together,
the most damaging effects of the Meiji and Showa Sanriku tsunamis occurred in a
narrower and more northerly area than the 2011 Great East Japan event and were
mostly smaller in magnitude than the those in 2011. Figure 15 shows the port of Taro
in Iwate prefecture in May of 2011. Visible on the north side of the bay, white
markers record the levels of the 1896 and 1933 tsunamis. In this location, the runup
reached about 20 meters in the 2011 event, as seen by the deforested band on the cliff
face.
Figure 15. Damage from 2011 Great East Japan earthquake at Taro, Iwate
prefecture. The white markers on the south-facing cliff memorialize water levels from
1896 and 1993 tsunamis.
1.5.4GlobalTsunamiPropagation
The Great East Japan earthquake generated a tsunami of such magnitude that
communities throughout the Pacific Basin felt its effects. Figure 16 shows the
offshore water surface elevations of the tsunami. NOAA's Pacific Marine
Environmental Laboratory (PMEL) Center for Tsunami Research used the MOST
forecast model to calculate amplitudes. Filled colors show the maximum computed
tsunami amplitude during 24 hours of wave propagation. Black triangles indicate sea
level gauges and sensors. Contour lines represent the predicted propagation times for