Abstract: An object is to provide an optical fiber path search method, an optical fiber path search system, a signal processor, and a program that can be operated free of the effects of walls, supporting members, and the like so that only a signal generated by an acoustic wave propagating through the air can be extracted.

Abstract: A system and method of detecting acoustic waves including directing a continuous-wave source laser beam to an optical resonator that is impinged by acoustic the waves. Optionally, the source laser beam can propagate through the optical resonator, thereby generating a propagated laser beam. Using an interferometer, the acoustic waves can be detected by monitoring transients in an optical phase of the propagated laser beam.

Abstract: A non-blind area real-time monitoring and alarming system for an accident on a freeway is provided, which belongs to the field of photoelectric technology and can solve the existing problems in whole journey information monitoring for freeways, such as failure to cover all freeway sections and lack of all-weather and prompt monitoring, and being subject to severe environments such as rain, fog and snow, or conditions such as poor visibility at night. The system includes a distributed sound wave detection fiber-optic cable, a sound wave signal demodulator, a network switch, a workstation, and a monitoring terminal. A fiber-optic sensing network composed of a series of reflection nodes distributed at equal distances is utilized to monitor sound wave signals from traffic accidents efficiently in real time without blind areas, accurately locate a traffic incident by analyzing frequency components, and transmit alarming information in time.

Abstract: A method for evaluating a target, the target having a surface, includes pulsing a defined, energetic particle beam through the surface and into the target such that particle energy deposition from the particle beam is concentrated in a subsurface target volume within a target medium of the target. The deposited particle energy induces a thermoelastic expansion of the target medium in the target volume that generates a corresponding acoustic wave. The method further includes detecting the acoustic wave from the target medium.

Abstract: Method and apparatuses for acoustic sensing using an optical fiber are provide. An optical fiber sensor for acoustic sensing includes an optical fiber, a laser, a pump laser pulse generator, a probe laser pulse generator, a controller, and a detector. The pump laser pulse generator is configured to receive a laser beam, from the laser, and generate a pump laser pulse. Similarly, the probe laser pulse generator is configured to receive the laser beam and generate a plurality of probe laser pulses. The controller is constructed to control the pump laser pulse generator and the probe laser pulse generator to inject the pump laser pulse and the plurality of probe laser pulses, respectively, into the optical fiber at specific timings so as to generate a plurality of Brillouin gratings at a predetermined spacing. The detector is configured to receive reflected pump laser pulses from the plurality of Brillouin gratings, respectively, and provide the reflected pump laser pulses to the controller.

Abstract: A mount for joining a sensor to a structure includes a housing shell joined to the structure and having an interior volume. First and second fluids are disposed in the housing shell. The sensor can be positioned within the housing shell at the interface between the two fluids. A secondary link can be provided to prevent vibration transmission from the structure to the housing shell. A membrane can be provided to separate the first fluid from the second fluid inside the housing shell. Guy lines can also be used to position the sensor.

Abstract: The application provides a interface light path structure with all polarization-maintaining function. A first polarization-maintaining-transferring device includes a first port, a second port, and a third port, wherein the first port receives a first polarized light output by the polarization beam-splitting device, the second port is connected to the first Faraday rotation mirror, and the third port is connected to a first port of the first polarization-maintaining coupler. A second polarization-maintaining-transferring device includes a first port, a second port, and a third port, wherein the first port receives a second polarized light output by the polarization beam-splitting device, the second port is connected to the second Faraday rotation mirror, and the third port is connected to a second port of the first polarization-maintaining coupler.

Abstract: The invention relates to an acoustic emission sensor (100). The acoustic emission sensor comprises an optical resonator (10) having a sensor region (11) configured for reflective operation; an optical waveguide (20) which is optically coupled to the optical resonator (10); a light source (31) which is optically coupled to the optical waveguide (20) to apply light to the optical waveguide (20); and a detection device (32) which is optically coupled to the optical waveguide (20) to detect light from the optical resonator (10). The sensor region (11) of the optical resonator (10) comprises a coupling device (50) for mechanically coupling to a solid measurement object (200). The coupling device (50) comprises a first coupling element (51) for transmitting an acoustic emission signal between the sensor region (11) and the solid measurement object (200), and at least one second coupling element (52).

Abstract: An optical fiber distributed monitoring system and method is provided. The system includes a laser device, an acousto-optic modulator, a phase matching interferometer, a photoelectric detector and a phase demodulation module. After entering the phase matching interferometer, the Rayleigh backscattering light containing parameter information output from the sensing optical fiber enters the two arms of the phase matching interferometer respectively, and the light of the two arms of the phase matching interferometer is phase-modulated by the first modulation wave and the second modulation wave, respectively and then interfere with each other to generate interference light. The photoelectric detector converts a light signal into an electric signal, and the phase demodulation module processes the electric signal based on the Hilbert algorithm to obtain the parameter change of the environment under test.

Abstract: A method of propagating a laser signal through an optical waveguide and a waveguide laser system provide a novel way of stabilizing the beam emitted by a fiber laser system above the mode instability threshold wherein the beat length of two or more interfering transverse modes of the laser signal in the optical waveguide is modulated in time.

Abstract: A scanning apparatus for measuring the attenuation of radiation passing from a radiation source along a radiation path to a radiation detector includes a source of radiation; at least one radiation detector capable of detecting radiation emitted by the source a data processor associated with the at least one radiation detector for calculating a property of material present in a linear radiation path between the source and the at least one detector; and a spacer arranged between the source and the at least one detector. The spacer defines a space which is capable of excluding water and having an average density which is less than 1 gcm?3. The provision of a spacer in the radiation path enables more radiation to be passed along the radiation path because water can be replaced with a material which is less attenuating to radiation.

Abstract: A disclosed subsurface electromagnetic field monitoring system includes at least one fiberoptic cable to optically communicate measurements from an array of electromagnetic field sensors in a borehole. The array of electromagnetic field sensors includes a distributed feedback fiber laser strain sensor with electromagnetic field sensitivity.

Abstract: A system that is usable with a well includes a telemetry network; a plurality of receivers that are arranged in groups; and a plurality of concentrators that are associated with the groups of receivers. A given concentrator is adapted to acquire data from an associated group of the receivers, and the concentrators communicate the data to an Earth surface of the well using a plurality of frequencies that are allocated among the concentrators.

Abstract: Apparatus, systems and methods associated with a pressure-balanced seismic sensor package are disclosed. One example of an apparatus can include a plurality of optical components, a sensor box enclosing the plurality of optical components, and a lid for the sensor box. The plurality of optical components, the sensor box, and the lid form a pressure-balanced seismic sensor package.

Abstract: The present application described methods an apparatus for locating and/or monitoring subsea cables (101) having an optical fibre (105) deployed along its length. The optical fibre (105) is connected to a distributed acoustic sensing (DAS) interrogator unit to interrogate the optical fibre to provide a fibre optic DAS sensor. To locate the cable an acoustic stimulus is transmitted into the water from one or more known locations. The time of arrival of an acoustic signal matching the stimulus at the sensing portions of the DAS fibre can be detected and used to determine information about the location of those sensing portions to the known location. The DAS signals returns can also be monitored under ambient conditions to detect any signals indicative of likely damage to the cable.

Abstract: An acousto-optic crystal optical waveguide is applicable to an acoustic wave sensor for sensing acoustic wave, wherein the acousto-optic crystal optical waveguide includes an acousto-optic crystal core and an inner cladding layer covering the acousto-optic crystal core. The acoustic wave is able to change the refraction index of the acousto-optical crystal optical waveguide to make a light beam with specific wavelength refracting to outside of the acousto-optic crystal waveguide when a light beam transmits through the acousto-optic crystal optical waveguide. Objective of acoustic wave sensing is achieved by detecting wavelength and intensity variation of the light beam transmits through the acousto-optic crystal optical waveguide.

Abstract: An interferometric optical fiber sensor system comprises a light source, a first coupler optically connected to the light source, a first optical path for inputting measurement light, a second optical path for inputting reference light, a second coupler for combining the first and second optical paths together, a photodetector for measuring modulation of the measurement light and the reference light, and a coil for modulating with a stress exerted thereon the measurement light and the reference light. The first optical path has an optical length equal to that of the second optical path. The first optical path has a first delay line, while the second optical path has a second delay line. The coil is disposed between the first delay line and the second coupler and between the second delay line and the first coupler.

Abstract: A system and method for an acoustic sensor array of a bundle of N different length optical fiber sensors. A coherent or noncoherent light source is input to each fiber for transmission along the length of the fiber. The light signal is reflected back at the fiber end point, and the resulting reflected light is diverted to an optical receiver so that perturbations of intensity and/or phase may be extracted.

Abstract: A sensor arrangement using an optical fiber and methodologies for performing an analysis of a subterranean formation, such as a subterranean formation containing a hydrocarbon based fluid. The sensor arrangement may be used to measure one or more physical parameters, such as temperature and/or pressure, at a multiplicity of locations in the subterranean reservoir. The sensor arrangement may comprise a sensor array comprising an elongated outer casing for insertion in the subterranean formation and into a fluid in the subterranean formation. The sensor array may comprise an optical fiber defining an optical path that links one or more temperature sensors and one or more pressure sensors and transports measurement data generated by the temperature and pressure sensors. A data processing system may be connected to the sensor array to receive measurements from the sensor array and to compute one or more values of a property of an extraction installation operating on the subterranean formation.

Abstract: The present invention relates to the field of electrodynamic speakers. Particularly, the present invention relates to an electrodynamic speaker structure having MEMS technology. More particularly, the invention relates to such a structure comprising stator-forming means, diaphragm-forming means, and resiliently shape-changing means for connecting such means.

Abstract: Methods for producing a laser-guided underwater electrical discharge are provided. One or more electrodes defining a desired electrical discharge path are situated in a body of water and are attached to an external electrical power supply. A high-powered, intense laser beam is fired through one or more focusing lenses into the water. The laser beam forms an optical filament in the water, which in turn forms an ionized channel having a much greater conductivity than the surrounding water. An external power supply drives an electrical discharge along the path of the ionized channel due to its greater conductivity.

Abstract: An apparatus and method conducting downhole measurement operations in a borehole penetrating an earth formation. The apparatus may include a module configured to be conveyed in a borehole and to receive at least one device. The module may receive the device internally or in one or more recessed areas. A housing with at least one opening may encompass the exterior of the module. The apparatus may have a first position that allows access to the module through the at least one opening, and a second position that isolates the module from the exterior of the housing. The method may include conducting downhole measurement related operations using the apparatus. The method may include moving the housing and module between the first position and the second position.

Abstract: A switch for a marine seismic sensor. The switch includes a bellows having a closed end, a side portion and an open end, wherein the side portion connects the closed end to the open end, the closed end includes a conductive surface, and the side portion acts as a spring; a base plug that includes first input and first output contacts on a first side and second input and second output contacts on an opposite side; and a plug located in the open end of the bellows and configured to form a chamber, inside which the second input contact and the second output contact are provided. The conductive surface short-circuits the second input contact and the second output contact when a pressure larger than a predetermined pressure (P) acts on the conductive surface.

Abstract: The invention consists of an optical hydrophone, an optical fiber element forming a laser cavity, housed in a mechanical structure which comprises an open cylindrical rigid body, defining the cavity enclosing a fluid and in which the optical fiber element is housed, and closed at its ends by two end caps which keep the optical fiber element permanently under tension, in a longitudinal rectilinear position inside the cavity. The end caps are configured in such a way that when the exterior pressure varies, they undergo a deformation giving rise to a variation in the length of the optical fiber element and that when the temperature varies, they undergo a deformation giving rise to a variation in the length of the optical fiber element which compensates for that induced on this element by the temperature variation. The mechanical structure furthermore exhibits one or more orifices allowing equilibration of the static pressures.

Abstract: The present invention relates to a method for determining an acoustic response attributed to a location of an impact, in particular a touch event, on a surface of an object including at least one transducer comprising the steps of: a) receiving an acoustic signal from at least one transducer, wherein the signal corresponds to a predetermined excitation (E) at at least one location on the surface; b) determining an acoustic response based on the acoustic signal received in step a); and c) determining the acoustic response attributed to at least one location on the surface different to the location of the predetermined excitation based on at least two different acoustic responses determined in step b).

Abstract: A method of providing seismic data (such as marine seismic data). A seismic source is actuated at a plurality of source locations (S2, S4). For each source location, a multicomponent seismic measurement is performed at least one receiver location (S3). A reconstructing method is applied to each multicomponent measurement to obtain additional data corresponding to source locations additional to the source locations at which the source was actuated (S5). The additional data are output and/or used (S6).

Abstract: There is provided a solid seismic streamer cable for use in seismic surveying in marine environments. The streamer is characterized by a buffer layer 2 which is provided with a cut-out 50 and a sensor element arranged in the cut-out 50. There is also provided an associated hydrophone for integration into the seismic streamer cable. The hydrophone is characteristic in a split-element sensor base 10, 11 being suited for efficient mounting into the cut-outs 50 of the seismic cable. There is also provided an associated accelerometer for integration into the seismic streamer cable. The accelerometer is characteristic by a split-element sensor base 30, 35 for being efficiently arranged into the cut-outs 50 of the seismic cable. A method of producing a seismic streamer cable according to the invention incorporating a hydrophone or accelerometer according to the invention is also provided.

Abstract: A device and system is provided for amplifying vibrations resulting from underwater acoustic signals. In operation, a laser interrogation beam is directed along an axis at the retro-reflector device and is responsive to reflections directed along the axis of the interrogation beam. The retro-reflector device reflects a signal back to a source and a tracking signal superimposed on an interrogation beam enables continuous sensing of the reflected signal to reduce signal dropout. A glint tracker is provided for steering the tracking beam on the surface. A tracker system superimposes the tracking and interrogation beams and is responsive to reflected glints in order to establish a directional location. An interferometer responsive to the reflected interrogation beam produces an interference signal for enabling continuous measurement of surface vibrations.

Abstract: In various embodiments, a multilayer jacket for a seismic streamer is disclosed. The multilayer jacket comprises an outer layer comprising a water-resistant and wear-resistant material. The multilayer jacket further comprises an inner layer comprising a hydrocarbon impermeable material.

Abstract: A method, system and a marine node for recording seismic waves underwater. The node includes a first module configured to house a seismic sensor; bottom and top plates attached to the first module; a second module removably attached to the first module and configured to slide between the bottom and top plates, the second module including a first battery and a data storage device; and a third module removably attached to the first module and configured to slide between the bottom and top plates, the third module including a second battery.

Abstract: The invention provides a method for acoustically and optically characterizing an immersed object of interest by generating a serial plurality of acoustic and optical illumination pulses through a liquid. In addition to the spectral analysis/imaging of objects/environment made possible by the white-light illumination, a target material can be ablated, generating an ionized plume to spectrally identify the target's constituent atoms.

Abstract: The present invention concerns a hydrophone signal limiting shunt switch, electrically associated and physically conjoined with a conventional hydrophone, for limiting hydrophone signal operability to water depths less than a predetermined, proscribed depth. The primary components of the shunt switch are a protected plunging bolt, at least one disk spring and an electrically conducting foot, none of which are ever in direct contact with the ocean environment. Flexure of the disk spring is the sole determinant of switch actuation. Upon sensing a predetermined, proscribed operating depth, the protected plunging bolt forces the electrically conducting foot to shunt the electrical connection between the associated hydrophone and the hydrophone transmission cable, consequently, quenching the hydrophone signal at the proscribed depth.

Abstract: A submarine homing system includes an acoustic emitter configured to emit an acoustic signal comprising at least two narrow-band tones, each narrow-band tone having a respective predetermined center frequency. An acoustic receiver is configured to receive the acoustic signal from the acoustic emitter, and produce one or more receiver signals. A processor is operatively connected to the acoustic receiver. The processor is configured to process the receiver signals to calculate a direction between the acoustic receiver and the acoustic emitter.

Abstract: A sensor system is provided comprising a Laser Doppler Vibrometer (LDV) that senses underwater sound via vibrations on an ice surface. In operation, a beam of the LDV measures a surface velocity and therefore an associated pressure signal from the ice surface due to an impinging underwater sound. The beam reflected from the surface carries the acoustic information back to the LDV. Using interferometry to derive the acoustic signal carried on the reflected beam; the LDV provides acoustic signal data in the form of a voltage signal. A computer processes the voltage signal as data that estimates a sound pressure level of the underwater source.

Abstract: Improved laser sensors (10) employing doped laser crystals (24) for transducing output proportional to forces impinging upon the sensors. The disclosed sensors are compact, low powered and may be constructed relatively inexpensively from readily available materials. The disclosed sensors eliminate the need for costly, optical power-sapping fiber connections at the laser crystals. According to certain embodiments, the disclosed sensors are configured for local recovery of output signals using conventional digital telemetry. According to other embodiments, the sensors generate output through a dense wavelength division multiplexing (DWDM) laser (28), thereby allowing remote recovery without the need for frequency division multiplexing and issues involved with preloading the sensors to produce beat frequencies in unique bands.

Abstract: It is to provide a semiconductor memory device in which high voltage is not needed in writing, a defect is less likely to occur, the writing time is short, and data cannot be rewritten without an increase in cost. The semiconductor memory device includes a memory element which includes a diode-connected first transistor, a second transistor whose gate is connected to one terminal of a source electrode and a drain electrode of the diode-connected first transistor, and a capacitor connected to the one terminal of the source electrode and the drain electrode of the diode-connected first transistor and the gate of the second transistor.

Abstract: A device and system is provided for amplifying vibrations resulting from underwater acoustic signals. In operation, a laser interrogation beam is directed along an axis at the retro-reflector device and is responsive to reflections directed along the axis of the interrogation beam. The retro-reflector device reflects a signal back to a source and a tracking signal superimposed on an interrogation beam enables continuous sensing of the reflected signal to reduce signal dropout. A glint tracker is provided for tracking the tracking beam on the surface. A tracker system superimposes the tracking and interrogation beams and is responsive to reflected glints in order to establish a directional location. An interferometer responsive to the reflected interrogation beam produces an interference signal for enabling continuous measurement of surface vibrations.

Abstract: An ultrasound system that detects a characteristic of an ultrasound wave. The system includes a circuit member defining a sensing portion operable to be exposed to the ultrasound wave. The system also includes a current generating device that generates a current in the sensing portion of the circuit member. Furthermore, the system includes a voltage sensor that detects a voltage across the sensing portion due to the exposure to the ultrasound wave to thereby detect the characteristic of the ultrasound wave.

Abstract: A sensor system includes a pressure sensor portion, and an accelerometer. Outputs from the sensor system are handled by a signal processing system that includes a first beamforming module for inputs from a pressure sensor, a second beamforming module for inputs from an accelerometer, and an adaptive beam interpolation module. A method for signal processing signals from both a pressure sensor and an accelerometer. An array of sensors transfers data wirelessly.

Abstract: A marine seismic exploration method and system comprised of continuous recording, self-contained ocean bottom pods characterized by low profile casings. An external bumper is provided to promote ocean bottom coupling and prevent fishing net entrapment. Pods are tethered together with flexible, non-rigid, non-conducting cable used to control pod deployment. Pods are deployed and retrieved from a boat deck configured to have a storage system and a handling system to attach pods to cable on-the-fly. The storage system is a juke box configuration of slots wherein individual pods are randomly stored in the slots to permit data extraction, charging, testing and synchronizing without opening the pods. A pod may include an inertial navigation system to determine ocean floor location and a rubidium clock for timing. The system includes mathematical gimballing. The cable may include shear couplings designed to automatically shear apart if a certain level of cable tension is reached.

Abstract: The general field of the invention is that of fiber-optic sensors comprising at least one measurement optical fiber having an optically pumped doped amplifying medium, the optical characteristics of which are sensitive to a physical quantity, the fiber having at least one Bragg grating. The fiber is designed so as to generate, in the amplifying medium, two optical waves having different optical frequencies that propagate in the same direction after reflection on the Bragg grating and are emitted by the amplifying medium, the two optical frequencies depending on the physical quantity. The two waves may be generated using either a birefringent polarization-maintaining fiber or a DBR (Distributed Bragg Reflector) laser cavity. Notably, this sensor may be used as a hydrophone.

Abstract: A system and method is provided for using acoustical pulses generated from an airborne laser source to locate objects under water. An array of acoustic sensors, such as passive sonobuoys at the ocean surface, is deployed in known or determinable locations by aircraft. Each area surrounded by acoustic sensors comprises a search cell, within which sonar scattering data can be used to locate objects. Following sonobuoy deployment, the aircraft uses the laser to rapidly generate many laser-acoustic pulse sources within each search cell, which in turn generate spherical acoustic pulses traveling through the water. The acoustic sensors receive the acoustic pulses, either on a direct path or on a scattered path after the pulse strikes an underwater object. The sensors record the acoustic signatures of the received pulses and transmit data of the recorded acoustic pulses to a processor such as processor on a nearby ship.

Abstract: A system and method is provided for using acoustical pulses generated from an airborne laser source to locate objects under water. An array of acoustic sensors, such as passive sonobuoys at the ocean surface, is deployed in known or determinable locations by aircraft. Each area surrounded by acoustic sensors comprises a search cell, within which sonar scattering data can be used to locate objects. Following sonobuoy deployment, the aircraft uses the laser to rapidly generate many laser-acoustic pulse sources within each search cell, which in turn generate spherical acoustic pulses traveling through the water. The acoustic sensors receive the acoustic pulses, either on a direct path or on a scattered path after the pulse strikes an underwater object. The sensors record the acoustic signatures of the received pulses and transmit data of the recorded acoustic pulses to a processor such as processor on a nearby ship.

Abstract: The invention provides a method for acoustically and optically characterizing an immersed object of interest by generating a serial plurality of acoustic and optical illumination pulses through a liquid. In addition to the spectral analyses/imaging of objects/environment made possible by the white-light illumination, a target material can be ablated, generating an ionized plume to spectrally identify the target's constituent atoms.

Abstract: A hydrophone (10) for immersion in a liquid body defining a depth-dependent static pressure and a dynamic pressure. The hydrophone (10) includes a pressure-bearing element (11) for exposure to the liquid body; a motion sensor (13) spaced apart from the pressure bearing element (11); and a dilatant coupling material (14) disposed intermediate the pressure-bearing element (11) and the motion sensor (13) so as to mechanically transmit movements substantially corresponding to the dynamic pressure from the pressure-bearing element (11) to the motion sensor (13). The dilatant coupling material (14) does not transmit movements to the motion sensor (13) that substantially correspond to the depth-dependent static pressure.

Abstract: A fiber optic hydrophone has a reflective diaphragm having an exposed face and a reflective protected face, at least one transmitting multimode optical fiber having an end spaced apart from the protected face of the diaphragm positioned to emit light toward the diaphragm housing, and a reservoir. A cavity is defined by the diaphragm and the interior surface of the housing. Silicone oil and a compliant elastomeric material with embedded air bubbles are located in the cavity. Ports between the cavity and the reservoir and the reservoir and the exterior of the hydrophone allow static pressure communication between the cavity and the exterior of the hydrophone. The fiber optic probe can have one transmitting multimode optical fiber and six receiving multimode optical fibers, or more or fewer optical fibers. A grating can protect the diaphragm from environmental damage.

Abstract: A fiber optic hydrophone has a reflective diaphragm having an exposed face and a reflective protected face, at least one transmitting multimode optical fiber having an end spaced apart from the protected face of the diaphragm positioned to emit light toward the diaphragm housing, and a reservoir. A cavity is defined by the diaphragm and the interior surface of the housing. Silicone oil and a compliant elastomeric material with embedded air bubbles are located in the cavity. Ports between the cavity and the reservoir and the reservoir and the exterior of the hydrophone allow static pressure communication between the cavity and the exterior of the hydrophone. The fiber optic probe can have one transmitting multimode optical fiber and six receiving multimode optical fibers, or more or fewer optical fibers. A grating can protect the diaphragm from environmental damage.

Abstract: The present application relates to a system and method for real-time monitoring and failure prediction of electrical submersible pumps. The design includes generating a failure prediction value with a management system by calculating a percentage change of the respective first measurement values and the corresponding user-supplied stable operating values, the failure prediction value representing likelihood of failure of the electrical submersible pump.

Abstract: A hydrophone (10) for immersion in a liquid body defining a pressure is disclosed The hydrophone (10) includes a sensor (11) for providing an electrical signal indicative of the pressure; and a transducer (12) electrically connected to the sensor (11). The transducer (12) acts upon a fiber optic cable (15) so as to convert the electrical signal into a corresponding optical output signal for transmission within the fiber optic cable (15). The liquid body defines a depth-dependent static pressure and a dynamic pressure and the sensor (11) provides an electrical signal having a first component indicative of the static pressure and a second component indicative of the dynamic pressure. A filter (16) is electrically connected to the sensor (11) so as to receive (the electrical signal, filter out the first component, and output to the transducer (12) a uttered electrical signal indicative of substantially only the second component.

Abstract: A technique includes obtaining seismic data acquired by at least one seismic sensor. The technique includes processing the seismic data to determine a value that is indicative of a three-dimensional directional propagation attribute of a seismic event based on the seismic data.