Tsunami Observations in Rivers from a Perspective of Tsunami Interaction with Tide and Riverine Flow

Tsunami Penetration in Tidal Rivers, with Observations of the Chile 2015 Tsunami in Rivers in Japan

“…Our previous thesis -that in tidal rivers, tide modulates tsunami in a certain way common to all rivers (Tolkova et al, 2015), -has been verified with the records containing the 2015 Chilean tsunami at 13 stations in 5 rivers on the Honshu east coast -an area in Japan most susceptible to trans-Pacific tsunamis. The new extensive data set, and a new methodology for data processing allowed to conclude that systematically observed correlation of the tsunami attenuation rate with tidal phase is in fact correlation with the tidally-modified wave-locked slope of the river surface.…”

“…For some reasons, the tsunami damping on ebb was clearly seen during the transition to the lower low water, but not during the second ebb of the mixed tide in the Columbia river estuary. Tolkova et al (2015) brought all the observations together to show that tsunami modulation by tide, in a manner in which receding tide dissipates tsunami the most, and the high tide dissipates it the least, is inherent to rivers in general; and suggested that the observed correlation of the tsunami attenuation rate with tidal phase is in fact correlation with tidally-modified slope of the river surface measured along a space-time trajectory of the tsunami, termed Wave-Locked Slope (WLS).…”

Tsunami Penetration in Tidal Rivers, with Observations of the Chile 2015 Tsunami in Rivers in Japan

“…The records of the 2010 tsunami in Narise/Yoshida and Old Kitakami rivers can be found in (Tolkova et al, 2015), while the records of the 2015 tsunami in these and two other rivers are presented below. The 2015 tsunami, which arrived at the Honshu coast on Sep 18 at about 6:30 Japanese Standard Time (JST), was approximately 3 times lower than that in 2010, and 5 times higher than regular long-wave ocean noise.…”

“…Hence the sampling rate is marginal for the tsunami representation, but still allows to convey useful information; and the records clearly show the tsunami signal. Tolkova et al (2015) suggested that a decrease rate of an instant tsunami amplitude along a river varies with the tidally-modified Wave-Locked Slope (WLS) of the river surface. The instant tsunami amplitude, and WLS were defined as follows.…”

Introduction to “Tsunami Science: Ten Years After the 2004 Indian Ocean Tsunami. Volume I”

“…The unique hydrodynamic response of tsunamis as they propagate up into rivers is examined by TOLKOVA et al (2015). They find that different rivers for different tsunami events modulate the tsunami in very similar ways.…”