Tsunami Generation Due to a Landslide or a Submarine Eruption

Abstract

Tsunamis can be triggered by not only submarine earthquakes, but also by landslides, and submarine volcanic eruptions. First, several characteristics of tsunami generation due to a landslide, or a sector collapse, are studied, with the tsunamis simulated numerically, to represent their generation through an interaction between falling bodies, and seawater, in two vertical dimensions. The falling body is assumed to be a fluid, or a rigid body, which moves down a slope with a constant gradient. Second, the mechanism of tsunami generation caused by a submarine volcanic eruption, is discussed, focusing on a phreatomagmatic explosion, where after exposure to high temperature magma, seawater evaporates instantly, with an explosive increase in its volume. An index for submarine volcanic explosive force, concerning tsunami generation, has been developed, by assuming the relationship between a phreatomagmatic explosion, and the resultant initial tsunami waveform. A numerical simulation was also generated, with a specific value for this index, for the propagation of tsunamis due to a submarine volcanic eruption in Kagoshima Bay, where a submarine explosion, leading to tsunami generation, has been observed.

A Numerical Simulation for Tsunamis Due to a Land Slide

“…The release of objects, stacked on the slope, is the start of a landslide, or a sector collapse, to generate tsunamis, where the vertical gate is located at the initial position of the shoreline. In the cases where the falling body is water, both the wave height and the wave phase of the first wave, obtained using the MPS model, are in harmony with the experimental results (Kakinuma, 2016).…”

The AD1835 eruption at Robinson Crusoe Island discredited: Geological and historical evidence

“…For running this numerical simulation with NEOWAVE model a grid with a resolution of 3 arcsec was used. The analytical solution proposed by Kakinuma (2016) was taken as a modelling approach modifying some input parameters. We set the water depth to 150 m (average value for the Cumberland Bay area; Figure 2) and increased the magma temperature to 1250 K, which would be a lower bound for basalts (e.g.…”

“…The dispersion pattern is, however, concentric and formed by an initial cavity on the sea surface followed by a bulge that propagates outward. Taking advantage of the analytical solutions by Kakinuma (2016), we find that a phreatomagmatic eruption in the reasonable range implies an erupted volume of c . 1–10 x 10 6 m 3 , produces an initial water surface displacement of several metres and a maximum run-up of c .…”

Long-Wave Generation due to Atmospheric-Pressure Variation and Harbor Oscillation in Harbors of Various Shapes and Countermeasures against Meteotsunamis

“…Such atmospheric-pressure waves propagating over the sea surface have often generated significant long ocean waves, through an amplification mechanism, that is, the Proudman resonance [2], especially when the phase velocity of the atmospheric-pressure wave is close to that of the long ocean waves, as examined by, for example, Hibiya and Kajiura [3] and Vilibic et al [4], where they numerically reproduced the large harbor oscillation in Nagasaki Bay, Kyushu, Japan, and that in Ciudadella Harbor, Balearic Islands, Spain, respectively. Once long ocean waves are generated by meteorological disturbance due to the instability of a wintry weather system, as well as a storm, and reach a nearshore zone, the wave height of the secondary undulation increases owing to the decrease of water depth, like a tsunami caused by a submarine earthquake (e.g., [5]), a land slide (e.g., [6]), etc., such that The refloatation operation for the fallen fishing boats around 8:00 (the left-hand side), and eight flooded cars at 8:33 (the right-hand side), on February 25, 2009. These photos were taken by Satsumasendai City Office at Oshima Fishing Port, which is located at one of two heads of Urauchi Bay, as indicated in Figure 1.…”