Behavior of seaquakes in deep ocean is investigated. A three-dimensional seaquake potential function is utilized for evaluating the hydrodynamic pressure. Earthquake rupture (source area is discretized into a number of small source areas. The result shows that the hydrodynamic pressure is not significant outside the source patch if the earthquake wave source area is considered localized. An improved model of the source is suggested from the consideration of earthquake fault theory. The proposed source model establishes that seaquakes travel a great distance before dying out Numerical studies examine the distribution of hydrodynamic pressure for a parametric variation of the source area strength and the location of the point of observation.
Seaquakes generally occur due to oceanic earthquakes. Release of crustal stresses, built up during tectonic processes in the earth's lithosphere, involves the fracturing of the rock along a plane (fault plane) which passes through the origin (focus) of the earthquake event. Energy from earthquakes propagate through rock and soil in the form of compressional and shear waves. Inside the ocean, only compressional waves can exist since water has no shear resistance. The effect of earthquake at the water surface can be felt by any floating structure through strong vibrations primarily due to arrival of P-waves. These waves upon entering the sea water above the ocean floor get refracted and travel upward to the sea surface at the velocity of sound in water. Several cases of seaquakes have been reported worldwide which describe the damaging effect of seaquakes on ships and submarines. These include the failure of communication and navigational equipments, breaking of piping, loosening of pumps and machinery foundations, buckling of frames and girders, cracking in welds and the feeling of a very strong sudden shock to give the impression of hitting an underwater rock.
