Abstract: Improvement in electro-fluid vibrator means used for generating seismic waves in the earth in which the flow of pressurized fluid to the vibrator is controlled in accordance with the resultant holddown pressure on the baseplate in contact with the earth, so that there is always a positive pressure on the baseplate, preventing it from being lifted off the surface of the earth. Force measuring means are provided in the holddown means. So long as this force is large and positive (in the direction to hold the baseplate to the earth) no control is required. When this positive force becomes less than a preselected value, the pressure fluid system is controlled to reduce the maximum pressure of, or rate of flow of, pressure fluid to the vibrator. The force measuring system can conveniently utilize the compliances in the holddown system as the force measuring elements.

Abstract: A seismic signal source apparatus is mounted on the bed of a vehicle by means of a support structure. The apparatus includes a base plate coupled to ground surface beneath the vehicle as well as a seismic signal transducer to inject sweep signals into the ground through the base plate. A restraining means is connected between the upper end of the transducer support structure and the vehicle bed to prevent rocking motion of the seismic signal source. The restraining means includes a double-acting hydraulic piston. The piston is provided with at least two spring-loaded, oppositely-directed check valves. The spring loaded valves open to allow the transducer base plate to adjust itself to the local ground contours when the transducer base plate is pressed to the ground by the weight of the vehicle. The valves remain closed during a sweep cycle to provide a rigid restraining link which prevents destructive rocking movements of the transducer and base plate during a sweep cycle.

Abstract: A seismic energy source which incorporates multiple augers and a rotary mechanism therefor mounted on a vehicle, the auger incorporating an internally situated seismic shock wave source which creates shock waves passing through a window in the auger into the soil. The shock wave source incorporates a chamber which stores compressed air and a valve mechanism which releases the air sharply for a short interval to create a shock wave in the soil.

Abstract: Device for generating shear waves in the earth for seismic prospecting, comprising means for striking with a mass a target-member coupled to the earth, said means including means for lifting and shifting said mass with respect to the target member, an electromagnet for intermittently locking it in an upper position and releasing it abruptly and means for adjusting the stroke of the mass from its upper position to its lower position where it impinges the target member.

Abstract: This invention is a control system for a hydraulic vibrator that permits the injection into the ground of seismic signals having pseudo-random code patterns or other broad band signals. Feedback for controlling vibrator operation is taken from the coupling plate. At low frequencies, the feedback is proportional to coupling plate position and at higher frequencies, the feedback is proportional to the coupling plate velocity.

Abstract: In a variable frequency seismic vibrator including an earth coupling plate, means for generating a reaction impedance, and an energy source for generating reciprocating movement of the coupling plate relative to the reaction impedance, the reaction impedance is generated by a reaction mass and a spring of variable stiffness which couples the reaction mass to the vibrator. As the frequency of vibration changes, the stiffness of the spring is automatically adjusted so that the impedance of the spring resonates with the impedance of the mass to maximize the reaction impedance, thereby increasing the operating efficiency of the vibrator.

Abstract: A device for generating sound waves for use in shallow terristrial seismology incorporates a percussion mass, a motor for driving the percussion mass to strike the ground for intermittent contact and adjustable to vary the frequency of impact, and a sensing element to provide a signal indicative of at least the instant of impact and preferably also the deceleration amplitude of impact.

Abstract: A mobile seismic energy source is formed by an automotive vehicle equipped with a vibrator type seismic energy source, a lifting mechanism, means for generating fluid pressure, and control means. Frame means pivotably linked to the vehicle chassis are provided for supporting the vibrator which is lowered into operational position and raised therefrom by the lifting mechanism acting between the vehicle chassis and linking arms of the frame means.

Abstract: A seismic signal source adaptable for use with various types of seismic exploration vehicles which move over land. A signal means forms a seismic signal, and a transfer means transfers the signal to a fluid-filled tire of the vehicle for improved and more efficient coupling of the signal to the ground surface. Whether the vehicle with which the source is mounted is stationary or moving, signals may be sent from the source into the ground.

Abstract: Apparatus for conducting seismic reflection surveys from oil tankers or other bulk liquid carriers in the course of their normal journeys. Seismic sources and detector apparatus are mounted in the ballast tanks. Pulse compression techniques may be used, and may take the form of a mechanical flail acting on the hull of the ship.

Abstract: Arms extending laterally from an upwardly moving weight, such as a rebounding seismic gas exploder, terminate in guide assemblies adapted to engage a plurality of parallel semi-rigid, resilient ropes connected between the top and the bottom of a supporting frame so that the weight must follow their path. Each guide assembly contacts its respective rope at several vertically spaced positions so as to distribute side loads along the rope resulting from eccentric exploder movement. The construction prevents the exploder from tilting sufficiently to catch or lock on the one or more ropes, thus avoiding pendulum movement of the exploder and abrasion of the ropes.

Abstract: A seismic generator for communicating from either above or below the surface of the earth is disclosed. The generator includes a system of eccentrically weighted masses such as, for example, unbalanced flywheels, which can be rotated to produce a seismic signal capable of being detected at great distances either on the surface or underground.

Abstract: A gas exploder for injecting seismic signals into the earth is provided with a high speed hydraulic catching apparatus which allows the exploder to rebound essentially unrestrained after it is fired at the surface and replaces it on the ground in one second or less without generating a significant false signal. The exploder falls freely from its maximum rebound height to within a few inches of the ground and is then lowered slowly to its starting position. Means are provided for automatically adjusting the position of the exploder after each shot so that it rests on the earth ready for the next firing even though compaction of the earth has taken place.

Abstract: A mass positioned above the earth and having downward extensions, which may include wheels, resting on the earth. One or more closed chambers having two parts vertically reciprocable with respect to each other, one part pressing on the earth, the other part fastened to the underside of the mass. Means to inject pressurized fluid into the chamber to expand the chamber and to lift the mass above the earth, and means to modulate the fluid pressure in the chamber to generate seismic waves in the earth, and means alternately to apply a subatmospheric pressure to the chamber, to collapse the chamber and lift said one part above the earth.

Abstract: The underwater gun assembly of this invention has an acceleration barrel and a firing gun. Percussion-initiatable cartridges are carried to the acceleration barrel by a stream of water. Each cartridge has an outside diameter which is nearly equal to the inside diameter of the bore in the barrel whose length is such as to allow the water pressure to optimally accelerate each cartridge in its trajectory through the barrel. The firing gun is detachably coupled to the barrel by a quick-disconnect coupling means. The detachable coupling means preferably includes a non-metallic resilient member which absorbs the shock waves from the ambient charge explosions, thereby preserving the integrity of the coupling means in respect of its detachable characteristics.

Abstract: A gas exploder consisting of a rigid cylindrical lower member and a rigid upper member telescoping therein to form a chamber in which a gas explosion can take place is supported beneath the surface of the water from a float by means of low resilience ropes connected to the bottom of the lower member so as to substantially limit its allowable downward movement. The upper member includes a piston downwardly biased within the lower member by an air spring and a hollow pedestal connected to the piston and extending freely through the float above the surface of the water to accommodate fuel, compressed air and exhaust conduits communicating with the interior of the housing. The energy of an explosion in the combustion chamber is expended primarily through rapid upward movement of the piston, which compresses the air spring and then lifts the lower member. Implosion of the resultant cavitation bubble adjacent the bottom surface of the lower member generates a pressure pulse of large peak amplitude.

Abstract: An apparatus and method for controlling the travel of a vehicle mounted seismic gas exploder adapted to deliver a downwardly directed pulse to the earth and thereafter be driven in an upward direction by the resultant reaction force. The exploder is flexibly coupled by means of a rope and pulley arrangement to the piston rod of a hydraulic cylinder. Compressed coil spring means aligned with the cylinder are released when the exploder jumps upward and apply a force to extend the piston rod and in so doing cause the rope to be retracted with gradually diminishing force. The exploder may be held at the upper limit of its travel, and its subsequent descent is utilized to recompress the spring means.

Abstract: A device for generating acoustic waves in a liquid, comprising two hollow enclosures communicating through a narrow passageway, a valve interposed in said passage way for controlling said communication, means for feeding a first one of said enclosures, in free communication with the ambient liquid, with pressurized fluid and suction means for reducing the pressure in the second enclosure to a level considerably lower than that prevailing in the first one.

Abstract: A firing device is provided for initiation of delay type seismic charge assemblies, which comprises means for conveying and guiding the charge assemblies, in the seismic test zone, into electrical initiation contact with one of any number of available pairs of electrical conductor surfaces, insulated from the other and adapted to connect with opposite poles of an external firing current source; and means for directing the thus initiated assemblies from the initiation zone, during the delay period, for subsequent detonation.Also provided are elongated end-recessed seismic charge assemblies initiated in the above device; and seismic exploration system, and method, utilizing said device.

Abstract: A seismic gas exploder is coupled to the movable piston of a hydraulic catching system so that the piston is constrained to move with the exploder as it rebounds upward from a shot and then falls back to earth. The weight of the gas exploder is applied through the piston to increase the pressure of the hydraulic fluid in the system when the exploder is moving in a downward direction. A two-position diaphragm actuated pressure switch monitors the fluid pressure, the position of the switch contacts being effective to control an exploder firing circuit or provide other indication of the exploder's position.

Abstract: New and improved apparatus and method for seismic exploration on land transports sensing geophones with a flat, lightweight, towing medium or sheet which conforms to the earth's surface. The geophones are mounted on sleds attached to the towing medium by strips or members of resilient material which isolate and decouple the geophone from vibrations and the like induced, sensed, or transmitted by the towing medium. The resilient members enable the geophones and sleds to continually maintain contact with the earth's surface over irregularities in the surface to provide good ground coupling for more accurate seismic exploration results. Plural or multiple towing mediums may be coupled together and towed into place for use in accordance with the desired geophone array to be used.