Deformation Anomalies Accompanying Tsunami Origination

Abstract

Basing on the analysis of data on variations of deformations in the Earth’s crust, which were obtained with a laser strainmeter, we found that deformation anomalies (deformation jumps) occurred at the time of tsunami generation. Deformation jumps recorded by the laser strainmeter were apparently caused by bottom displacements, leading to tsunami formation. According to the data for the many recorded tsunamigenic earthquakes, we calculated the damping ratios of the identified deformation anomalies for three regions of the planet. We proved the obtained experimental results by applying the sine-Gordon equation, the one-kink and two-kink solutions of which allowed us to describe the observed deformation anomalies. We also formulated the direction of a theoretical deformation jump occurrence—a kink (bore)—during an underwater landslide causing a tsunami.

Sea Level Fluctuations

“…When considering marine processes that lead to changes in sea level, one cannot disregard tsunamis, which bring significant troubles to humankind. Paper [11] presents a new method for short-term tsunami forecasting. General regularities of distribution of deformation anomalies associated with seafloor motions and leading to tsunamis were established in three seismically active zones of the earth [11].…”

“…Paper [11] presents a new method for short-term tsunami forecasting. General regularities of distribution of deformation anomalies associated with seafloor motions and leading to tsunamis were established in three seismically active zones of the earth [11]. The established regularities, the foremost of which is the general law of divergence, confirm the indisputable fact that these deformation anomalies, the behavior of which is described by the sine-Gordon equation, are related to the tsunami generation process.…”

Deformation Anomalies Accompanying Tsunami Origins near the Japanese Islands

“…The broadband seismograph, like the laser strainmeter, is located in a thermally insulated room at a depth of 3 m from the Earth's surface. It is used to register earthquakes, but due to the limited operating frequency range, it cannot register the observed deformation anomalies described in [16] and further described in this paper. The seismoacoustic and hydrophysical complex is located far from highways and infrastructure facilities, which allows for more accurate and reliable seismic observations without extraneous noise.…”

“…Using this method, we analyzed the records of earthquakes that occurred between 2010 and 2018 in three tsunami-hazardous areas: Indonesia, Chile, and the western coast of North America. For each of these regions, large earthquakes were selected with a magnitude of more than 7.5 and a depth of no more than 50 km, after which a tsunami was registered [16]. The results of the studies described in [16] allow us to determine with great accuracy the value of the seabed displacement, which leads to the generation of a tsunami.…”

“…For each of these regions, large earthquakes were selected with a magnitude of more than 7.5 and a depth of no more than 50 km, after which a tsunami was registered [16]. The results of the studies described in [16] allow us to determine with great accuracy the value of the seabed displacement, which leads to the generation of a tsunami. Based on this important result, it is possible to construct an adequate working model of an emerging tsunami, which is important for its monitoring and assessment of its impact on natural and artificial objects.…”