A seismic shaker for exercising an excitation force on the ground has a base plate and a reaction mass connected to the base plate via a resilient structure and an actuator parallel thereto. A first comparison unit sends a difference signal which is the difference between a displacement measured by a displacement sensor and a set value of the displacement. A control unit calculates a correction value as a function of this difference signal, and sends it to a second comparison unit, which adds the correction value to a value of the excitation force to be exerted set in the second comparison unit. This second comparison unit is connected to a controller unit which controls the actuator. At Low frequency this position control will track the ground force through the position set-point. The position feedback loop will be able to suppress the interfering force of the spring and any hysteresis.

A seismic shaker for exercising an excitation force on the ground has a base plate and a reaction mass connected to the base plate via a resilient structure and an actuator parallel thereto. A first comparison unit sends a difference signal which is the difference between a displacement measured by a displacement sensor and a set value of the displacement. A control unit calculates a correction value as a function of this difference signal, and sends it to a second comparison unit, which adds the correction value to a value of the excitation force to be exerted set in the second comparison unit. This second comparison unit is connected to a controller unit which controls the actuator. At Low frequency this position control will track the ground force through the position set-point. The position feedback loop will be able to suppress the interfering force of the spring and any hysteresis.

An apparatus of confining an earth block to engage with a horizontal vibrator for generating shear dominated seismic source and a method of applying the apparatus are related. An apparatus of confining an earth block to be engaged with at least one vibrator for generating a shear dominated seismic source comprises a plurality of horizontal steels, a plurality of vertical steel sheet piles, a plurality of vertical elongated steel pile sheets, a plurality of horizontal elongated steels, and at least one vibrator.

An apparatus of confining an earth block to engage with a horizontal vibrator for generating shear dominated seismic source and a method of applying the apparatus are related. An apparatus of confining an earth block to be engaged with at least one vibrator for generating a shear dominated seismic source comprises a plurality of horizontal steels, a plurality of vertical steel sheet piles, a plurality of vertical elongated steel pile sheets, a plurality of horizontal elongated steels, and at least one vibrator.

Method, source array and source element that generate seismic waves. The source element includes an enclosure having an opening covered by a piston; a local supply accumulator fluidly communicating with an interior of the enclosure, a pressure of the fluid inside the local supply accumulator being larger than a pressure of the fluid inside the enclosure; a local supply valve located between the local supply accumulator and the enclosure and configured to control a flow of the fluid from the local supply accumulator to the interior of the enclosure; and a controller configured to control the local supply valve such that the pressure inside the enclosure does not fall below a first preset value based upon an ambient pressure of the enclosure while seismic waves are generated.

Method, source array and source element that generate seismic waves. The source element includes an enclosure having an opening covered by a piston; a local supply accumulator fluidly communicating with an interior of the enclosure, a pressure of the fluid inside the local supply accumulator being larger than a pressure of the fluid inside the enclosure; a local supply valve located between the local supply accumulator and the enclosure and configured to control a flow of the fluid from the local supply accumulator to the interior of the enclosure; and a controller configured to control the local supply valve such that the pressure inside the enclosure does not fall below a first preset value based upon an ambient pressure of the enclosure while seismic waves are generated.

Systems and methods for a sea-floor seismic source are provided. The seismic source system includes a housing (102) having an internal cavity (104). The housing is configured to be coupled to a surface by gravity. The system further includes a coupling plate (106) fixed to a base (108) of the internal cavity. The coupling plate is configured to transmit energy through the base of the internal cavity and into the surface. The system also includes an excitation source (110) located in the internal cavity. The excitation source is configured to receive an input signal from a computing system communicatively coupled to the excitation source, and transmit energy to a reactive mass (112) located in the internal cavity and transmit energy to the coupling plate.

Systems and methods for a sea-floor seismic source are provided. The seismic source system includes a housing (102) having an internal cavity (104). The housing is configured to be coupled to a surface by gravity. The system further includes a coupling plate (106) fixed to a base (108) of the internal cavity. The coupling plate is configured to transmit energy through the base of the internal cavity and into the surface. The system also includes an excitation source (110) located in the internal cavity. The excitation source is configured to receive an input signal from a computing system communicatively coupled to the excitation source, and transmit energy to a reactive mass (112) located in the internal cavity and transmit energy to the coupling plate.

Method, source array and source element that generate seismic waves. The source element includes an enclosure having an opening covered by a piston; a local supply accumulator fluidly communicating with an interior of the enclosure, a pressure of the fluid inside the local supply accumulator being larger than a pressure of the fluid inside the enclosure; a local supply valve located between the local supply accumulator and the enclosure and configured to control a flow of the fluid from the local supply accumulator to the interior of the enclosure; and a controller configured to control the local supply valve such that the pressure inside the enclosure does not fall below a first preset value based upon an ambient pressure of the enclosure while seismic waves are generated.

Method, source array and source element that generate seismic waves. The source element includes an enclosure having an opening covered by a piston; a local supply accumulator fluidly communicating with an interior of the enclosure, a pressure of the fluid inside the local supply accumulator being larger than a pressure of the fluid inside the enclosure; a local supply valve located between the local supply accumulator and the enclosure and configured to control a flow of the fluid from the local supply accumulator to the interior of the enclosure; and a controller configured to control the local supply valve such that the pressure inside the enclosure does not fall below a first preset value based upon an ambient pressure of the enclosure while seismic waves are generated.