A comparison of earthquake backprojection imaging methods for dense local arrays

Beskardes, G. D.; Hole, J. A.; Wang, K; Michaelides, Michael; Wu, Qimin; Chapman, Martin C.; Davenport, K. K.; Brown, L. D.; Quiros, D. A.

doi:10.1093/gji/ggx520

Cited by 26 publications

(35 citation statements)

References 58 publications

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“…For example, McMechan et al (1985) preprocess the earthquake waveforms to construct a true amplitude section by filtering and extrapolating waveforms with a given velocity model. Beskardes et al (2018) compare three methods (envelope, short-term averaging/ long-term averaging, and kurtosis) to regularize the waveform as an input of waveform-based source imaging.…”

Section: Discussionmentioning

confidence: 99%

Hybrid multiplicative time-reversal imaging reveals the evolution of microseismic events: Theory and field-data tests

et al. 2019

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The generation of microseismic events is often associated with induced fractures/faults during the extraction/injection of fluids. A full characterization of the spatiotemporal distribution of microseismic events provides constraints on fluid migration paths in the formations. We have developed a high-resolution source imaging method — a hybrid multiplicative time-reversal imaging (HyM-TRI) algorithm, for automatically tracking the spatiotemporal distribution of microseismic events. HyM-TRI back propagates the data traces from groups of receivers (in space and time) as receiver wavefields, multiplies receiver wavefields between all groups, and applies a causal integration over time to obtain a source evolution image. Using synthetic and field-data examples, we revealed the capability of the HyM-TRI technique to image the spatiotemporal sequence of asynchronous microseismic events, which poses a challenge to standard TRI methods. Moreover, the HyM-TRI technique is robust enough to produce a high-resolution image of the source in the presence of noise. The aperture of the 2D receiver array (azimuth coverage in 3D) with respect to the microseismic source area plays an important role on the horizontal and vertical resolution of the source image. The HyM-TRI results of the field data with 3D azimuthal coverage further verify our argument by producing a superior resolution of the source than TRI.

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Section: Discussionmentioning

confidence: 99%

Hybrid multiplicative time-reversal imaging reveals the evolution of microseismic events: Theory and field-data tests

et al. 2019

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“…Increasing the array's density by a factor of 10 allows us to recover the location of events as small as M ≈ 0:8. Our method focuses energy envelopes onto the source and is hence relatively robust against small errors in the velocity model (Beskardes et al, 2018). However, scattering from small-scale heterogeneities or at layer interfaces may introduce artifacts to backprojection images.…”

Section: Discussionmentioning

confidence: 99%

On the Feasibility of Using the Dense MyShake Smartphone Array for Earthquake Location

Inbal¹,

Kong²,

Savran

et al. 2019

Seismological Research Letters

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MyShake is a growing smartphone-based network for seismological research applications. We study how dense array analysis of the seismic wavefield recorded by smartphones may enhance microearthquake monitoring in urban environments. In such areas, the microearthquake signal-to-noise ratio on smartphones is not well constrained. We address this issue by compiling a seismic noise model for the Los Angeles (LA) metropolitan area using over 500,000 seismograms recorded by stationary phones running MyShake. We confirm that smartphone noise level is reduced during nighttime, and identify strong noise sources such as major traffic highways, the LA airport, and the Long Beach seaport. The noise analysis shows that stationary smartphones are sensitive to human-induced ground motions, and therefore smartphone-derived seismograms may be used to infer the elastic properties of the shallow subsurface. We employ array backprojection analysis on synthetic data to estimate what fraction of LA's smartphone user population is required to install MyShake to enable the location of events whose induced ground motions are below the smartphone noise level. We find that having 0.5% of LA's population download the MyShake app would be sufficient to accurately locate M > 1 events recorded during nighttime by stationary phones located at epicentral distances < 5 km. Currently, the MyShake user coverage in LA is approaching a value that will allow us to locate events whose magnitude is near the regional catalog's magnitude of completeness.

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“…Trojanowski and Eisner () tested the performance of several CFs with diffraction stacking and cross‐correlation stacking operators, showed the semblance and cross‐correlation stacking have better enhancement of the quality of the stacking profiles, and demonstrated that accounting for the source mechanism by polarization correction improves most efficiently the capability of noise suppression and retrieving weak microseismic events. Beskardes et al () compared the performance of envelope, STA/LTA, and kurtosis with raw waveforms for local earthquakes detection and location. The comparative study showed for an aftershock sequence that stacking of kurtosis waveforms produced the most robust results for detecting the weak events, while stacking of raw waveforms had the best spatial resolution and retrieved magnitude.…”

Section: Methodologiesmentioning

confidence: 99%

“…The comparative study showed for an aftershock sequence that stacking of kurtosis waveforms produced the most robust results for detecting the weak events, while stacking of raw waveforms had the best spatial resolution and retrieved magnitude. Therefore, a two‐phase backprojection imaging process is suggested (Beskardes et al, ): backprojection of kurtosis waveforms for event detection and location within large data volumes, followed by backprojection of raw seismograms of the previously detected events to improve the location accuracy and obtain more reliable magnitudes. A sketch of the principle for PWS methods is shown in Figure .…”

Section: Methodologiesmentioning

confidence: 99%

“…As an alternative of the conventional traveltime‐based methods, modern waveform‐based seismic source location methods do not require phase identification nor phase picking and can detect and locate events with low signal‐to‐noise ratio (SNR) by exploiting migration and stacking techniques commonly used in exploration seismology (e.g., Beskardes et al, ; Cesca & Grigoli, ; Gajewski et al, ; Pesicek et al, ; Zhebel & Eisner, ). The basic principle of waveform‐based methods is locating the source by focusing or reconstructing the source energy into discrete grid of points with a certain migration or imaging operator, which uses traveltime information.…”

Section: Introductionmentioning

confidence: 99%

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Recent Advances and Challenges of Waveform‐Based Seismic Location Methods at Multiple Scales

Tan

Schwarz

et al. 2020

Reviews of Geophysics

132

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Source locations provide fundamental information on earthquakes and lay the foundation for seismic monitoring at all scales. Seismic source location as a classical inverse problem has experienced significant methodological progress during the past century. Unlike the conventional traveltime‐based location methods that mainly utilize kinematic information, a new category of waveform‐based methods, including partial waveform stacking, time reverse imaging, wavefront tomography, and full waveform inversion, adapted from migration or stacking techniques in exploration seismology has emerged. Waveform‐based methods have shown promising results in characterizing weak seismic events at multiple scales, especially for abundant microearthquakes induced by hydraulic fracturing in unconventional and geothermal reservoirs or foreshock and aftershock activity potentially preceding tectonic earthquakes. This review presents a comprehensive summary of the current status of waveform‐based location methods, through elaboration of the methodological principles, categorization, and connections, as well as illustration of the applications to natural and induced/triggered seismicity, ranging from laboratory acoustic emission to field hydraulic fracturing‐induced seismicity, regional tectonic, and volcanic earthquakes. Taking into account recent developments in instrumentation and the increasing availability of more powerful computational resources, we highlight recent accomplishments and prevailing challenges of different waveform‐based location methods and what they promise to offer in the near future.

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A comparison of earthquake backprojection imaging methods for dense local arrays

Cited by 26 publications

References 58 publications

Hybrid multiplicative time-reversal imaging reveals the evolution of microseismic events: Theory and field-data tests

Hybrid multiplicative time-reversal imaging reveals the evolution of microseismic events: Theory and field-data tests

On the Feasibility of Using the Dense MyShake Smartphone Array for Earthquake Location

Recent Advances and Challenges of Waveform‐Based Seismic Location Methods at Multiple Scales

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