Various implementations described herein are directed to methods for processing seismic data, including estimating a spectral noise power of multi-measurement seismic data received from a multi-dimensional seismic sensor array having multiple seismic sensors. The methods may include receiving a shot record of multi-measurement seismic data in time-domain, partitioning the shot record into overlapping time-space windows, and computing a frequency-domain spectrum for each time-space window. The methods may include computing a signal presence probability for each time-space window using the frequency-domain spectrum and prior probabilities of signal presence and absence for each time-space window. The methods may include iteratively updating a collective spectral noise power by recursively estimating the spectral noise power of a current time-space window based on the frequency spectrum for the current time-space window, the signal presence probability computed for the current time-space window, and a previously estimated spectral noise power of a previous time-space window.

Embodiments relate to noncontact determination of nonlinearities. Initially, a first and second primary signal are preconditioned to produce a first and second tone capable of reaching a target granular media. Using a sound source, the first and second primary signals are emitted such that the first and second primary signals combine in a nonlinear fashion in the target granular media to produce low frequency acoustic tone that is a difference between the first and primary signals. An acoustic pulse is received by an acoustic receiver, and a quadratic nonlinearity coefficient and an acoustic pressure field are determined based on the acoustic pulse. At this stage, a sediment shear strength of the granular media is correlated to the quadratic nonlinearity coefficient to generate a shear strength lookup table.

A marine seismic acquisition system includes a frame that includes a central longitudinal axis and members that define orthogonal planes that intersect along the central longitudinal axis; a data interface operatively coupled to the frame; hydrophones operatively coupled to the frame; a buoyancy engine operatively coupled to the frame where the buoyancy engine includes at least one mechanism that controls buoyancy of at least the frame, the hydrophones and the buoyancy engine; and at least one inertial motion sensor operatively coupled to the frame that generates frame orientation data, where the hydrophones, the buoyancy engine and the at least one inertial motion sensor are operatively coupled to the data interface.

In some embodiments, an immersion cooling system comprises a spring damper, a crumple block, a frictional layer, and/or preloaded spring-based mounts to mitigate the effects of seismic events. In other embodiments, the combined mass of liquids in the immersion tank and a compensation tank is kept constant to maintain the system's response to seismic events. In still other embodiments, an immersion cooling system comprises a tunable mass to provide an active response to seismic events. In yet other embodiments, an immersion tank is located within a housing pallet and is moveable within the palette. Spring dampers dampen tank movement within the pallet and shutoff switches housed in the pallet cause power to components in the tank to be shut off in response to tank movement. Cooling liquid can be transferred from the tank to a secondary reservoir to avoid cooling liquid loss and protect the tank.

The method comprises providing at least one seismic source in a seismic source area and providing a plurality of seismic receivers in said seismic source area, said method comprising measuring a first type of ground vibrations induced in a subsurface of the area of interest by the at least one seismic source with the plurality of seismic receivers. The method further comprises measuring with the plurality of seismic receivers at least one second type of ground vibrations induced by a mechanical source different from the or from each seismic source and analyzing the second type of ground vibrations to determine at least one information among: a physical parameter of the subsurface and/or, a presence of human and/or an animal and/or a vehicle.

A marine seismic acquisition system includes a frame that includes a central longitudinal axis and members that define orthogonal planes that intersect along the central longitudinal axis; a data interface operatively coupled to the frame; hydrophones operatively coupled to the frame; a buoyancy engine operatively coupled to the frame where the buoyancy engine includes at least one mechanism that controls buoyancy of at least the frame, the hydrophones and the buoyancy engine; and at least one inertial motion sensor operatively coupled to the frame that generates frame orientation data, where the hydrophones, the buoyancy engine and the at least one inertial motion sensor are operatively coupled to the data interface.

Embodiments herein describe techniques for performing acoustic imaging when collocated pressure and three-directional pressure gradient measurements are available. Such measurements become available through the use of a hydrophone and a 3-component geophone or accelerometer when the containing node is neutrally buoyant, or nearly neutrally buoyant, and is coupled to the water column, rather than grounded and thus coupled to the ocean bottom sediments.

A method for seismic surveying includes deploying a group of vertically sensitive seismic particle motion responsive sensors at each of a plurality of geodetic survey positions. The groups each include at least two sensors spaced apart by a first selected horizontal distance. The groups are separated from each other by a second selected distance larger than the first distance. Signals detected by each of the sensors resulting from actuation of a seismic energy source are recorded. At least one of an in-line and a cross-line component of a gradient of the vertical component of the seismic wavefield is determined at each group location by determining a difference between the signals detected by each sensor in a respective group.

A method can include receiving information associated with an interface between a first medium and a second medium where the information includes sensor data; based on at least a portion of the information, estimating wave properties that include elastic properties, depth-dependent properties and horizontal slowness; and, based on the estimated wave properties, calculating an orientation of a sensor utilized to acquire at least a portion of the sensor data.

Methods and apparatus are described for reducing noise in measurements made by one or more pressure sensors disposed in a cable having a generally longitudinal axis. Estimated axial vibration noise at a location along the cable is determined based at least in part on measurements from one or more motion sensors disposed along the cable. The estimated axial vibration noise is subtracted from pressure sensor measurements corresponding to the location. The result is noise-attenuated pressure sensor measurements corresponding to the location.