We have detected a continuous seismic signal near 2.08 Hz using data from a portable seismic array, 1280 km long, deployed in Siberia and Mongolia. The signal can be observed on almost all the stations along the profile. The amplitude and the frequency of the signal show a clear daily cycle, and their temporal variations are similar at different stations, suggesting that the signals observed at...

We propose a formulation of full-wavefield inversion (FWI) as a constrained optimization problem, and describe a computationally efficient technique for solving constrained full-wavefield inversion (CFWI). The technique is based on using a total-variation regularization method, with the regularization weighted in favor of constraining deeper subsurface model sections. The method helps to promot...

This is the second paper in a two-part series that describes a massively parallel code that performs 2D full-waveform inversion of wide-aperture seismic data for imaging complex structures. We present several numerical validation of the full-waveform inversion code with both canonical and realistic synthetic examples. We illustrate how different multiscale strategies can be applied by either su...

[1] The magnetotelluric dataset collected on the San Andreas Fault at Parkfield has been re-analyzed using superior inversion algorithms that have been developed in recent years. A combination of constrained inversion, forward modeling and synthetic inversion studies are used, and show that at the SAFOD site, the low resistivity fault zone extends to a depth of 2–3 km. An extended zone of low r...

S U M M A R Y We discuss two types of physical constraints derived from thermodynamics that can be applied during seismic inversions. The first constraint involves assimilating heat-flow measurements in seismic inversions. This can improve seismic models beneath continents, particularly beneath cratons and continental platforms where uncertainties in crustal radioactive heat production and the ...

Dynamic imaging provides an effective way to integrate previous time-lapse data with current data in order to estimate a current model. We present two methods useful for continuous dynamic reservoir and subsurface monitoring. The first method is a stochastic method for the inversion of geophysical data. It uses the ensemble Kalman filter (EnKF) that we demonstrate using time-lapse surface seism...

A common problem in seismic tomography is the inadequate amount of data required for accurate traveltime inversion. The inherent nature in which data is acquired and the subsurface velocities of the survey area can result in a nonuniform distribution of raypaths. In such instances the statistical nature of tomographic inversion biases the solution to reflect the acquisition instead of the geolo...

Continuity along reflectors in seismic images is used via Curvelet representation to stabilize the convolution operator inversion. The Curvelet transform is a new multiscale transform that provides sparse representations for images that comprise smooth objects separated by piece-wise smooth discontinuities (e.g. seismic images). Our iterative Curvelet-regularized deconvolution algorithm combine...

Time-lapse seismic data are widely used for monitoring subsurface changes. A quantitative assessment of how reservoir properties have changed allows for better interpretation of fluid substitution and migration during processes like oil and gas production, and carbon sequestration. Full waveform inversion has been proposed as a way to retrieve quantitative estimates of subsurface properties thr...

Missing trace reconstruction is a challenge in seismic processing due to incomplete and irregular acquisition. Noise is a concern, due to the many sources of noise that occur during seismic acquisition. Most of the recent research on denoising and interpolation focuses on transform domain approaches using L1 norm minimization. A specific kind of constraint, called the synthesis approach, is wid...