An optical communication system that enables any deployed fiber-optic cable to function as an earthquake-detection sensor. In an example embodiment, a WDM optical transmitter of one network node operates to transmit a CW optical signal together with legacy data-carrying optical signals. At another network node, a low-complexity, low-latency coherent optical receiver is used to obtain time-resolved measurements of the Stokes parameters of the CW optical signal. The signal-processing chain of the optical receiver employs digital filtering to select frequency components of the measurements streams corresponding to seismic disturbances of the fiber-optical cable connecting the nodes. The selected frequency components are then used to compute values of an earthquake indicator, which are reported to a network controller. Based on such reports from three or more nodes, the network controller can determine the epicenter and magnitude of the earthquake and, if warranted, may generate a tsunami forecast.

A method, including: obtaining Earth models including velocity, anisotropy, and attenuation reconstructing a source wavefield using the Earth models; reconstructing a receiver wavefield using the Earth models, wherein the reconstructing the source wavefield and the receiver wavefield each include applying an attenuation operator that increases an amplitude of down-going wavefields within an attenuation body and that decreases an amplitude of up-going wavefields within the attenuation body; applying an imaging condition to the source wavefield and receiver wavefield for a plurality of shots; and generating a subsurface image by stacking images for the plurality of shots.

A data set comprises data obtained by seismic imaging of a region of interest during an observation period. An intrinsic geological variability of a region is determined from the comparison of reception signals for neighbor bins as a function of a difference in signal geometry for the neighbor bins.

A system for analyzing a plurality of channels of data received from a sensor array. The system includes a data acquisition system that receives and independently processes each channel. A low-level processing section receives each channel of processed data and identifies signals of interest in one channel. Signals of interest are stored in an event database. A high-level processing section analyzes data occurring over a preset duration of time and across multiple channels of data and communicates with an operator machine interface. The operator machine interface provides analysis to an operator. Further aspects of the system characterize the data in order to indicate the data source and alert the operator to signals having certain predefined characteristics.

An earthquake estimation method for more promptly estimating an earthquake on the basis of observation data. The earthquake estimation method includes, by a computer: generating an observation image showing a spatial distribution of seismic wave propagation on a basis of an observation result of seismic waves at a plurality of observation points on a ground; and estimating a parameter of an earthquake with respect to the observation image by using an earthquake estimation model in which a parameter of an earthquake including at least a position of a hypocenter and a magnitude is associated with a simulated observation image showing a spatial distribution of seismic wave propagation on a ground obtained from a result of a numerical simulation of the earthquake, performed with the parameter.

Techniques for low power gunshot detection are disclosed. Infrared information is collected using a gunshot sensor device. The infrared information is collected using mid-infrared band sensing to provide motion detection. Additional infrared information is buffered using the gunshot sensor device. The additional infrared information is collected using near-infrared band sensing. The buffering is enabled by the motion detection. Acoustic information is collected using the gunshot sensor device. The collecting acoustic information is enabled by the motion detection. A gunshot is detected using the gunshot sensor device. The detecting is based on the additional infrared information and the acoustic information. The detecting includes monitoring the acoustic information to identify a high-intensity gunshot sound and correlating the high-intensity gunshot sound to the infrared information that was buffered. The gunshot sensor device uses cable-free communication to a network and notifies the network of a possible gunshot occurrence.

So-called “Popcorn shooting”, and especially continuous Popcorn shooting, combined with simultaneous source shooting allows considerable flexibility in producing high-resolution data and in creating source arrays. Using a combination of simultaneous source de-blending and Popcorn reconstruction it is possible to construct using post acquisition processing arrays of any desired length by constructing a popcorn pattern that takes into account the vessel speed and physical arrangement of guns behind the towing vessel.

A method can include receiving data that includes signal data and coherent noise data where the signal data includes signal data that corresponds to a multidimensional physical structure; generating filtered data by filtering at least a portion of the data to attenuate at least a portion of the coherent noise data by applying a multidimensional geometric coherent noise model defined by at least one geometric parameter; and assessing a portion of the signal data in the generated filtered data to characterize the multidimensional physical structure.

A method to generate a tube wave in a tubular system involves reciprocating a plunger in a chamber system to alternatingly increase and decrease net volume, drawing fluid from and returning the fluid to a tubular system and into and from the chamber system, to generate a tube wave, and guiding the tube wave to the tubular system. Also, a tube wave generator-sensor system has a chamber system, a plunger, a driver to reciprocate the plunger within the chamber system to generate a tube wave, a flow passage to guide the tube wave into a tubular system, and a sensor to receive the tube wave signal and/or response from the tubular system. The method and system can work with or without a firing valve and or accumulator, without adding or subtracting fluid from the tubular system.

A retrofit valve shutoff device is provided that comprises a coupling key for coupling with an actuator of a shutoff valve on a fluid supply line, an inertial measurement unit for generating one or more signals in response to arrival of seismic waves, a motor for rotating the coupling key and the actuator of the shutoff valve, and a processing unit for receiving the one or more signals from the inertial measurement unit, analyzing the received signals to determine whether to close the shutoff valve, and sending a signal to the motor to rotate the coupling key and the actuator of the shutoff valve to close the shutoff valve based on the analysis of the received signals.