The Array Network Facility Seismic Bulletin: Products and an Unbiased View of United States Seismicity

Astiz, Luciana; Eakins, J. A.; Martynov, V. G.; Cox, T. A.; Tytell, J.; Reyes, Juan Carlos; Newman, R. L.; Karasu, Gulsum H.; Mulder, T. L.; White, Malcolm C. A.; Davis, Geoffrey A.; Busby, Robert; Hafner, K.; Meyer, Jon C.; Vernon, F. L.

doi:10.1785/0220130141

Cited by 25 publications

(18 citation statements)

References 28 publications

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“…We compare our results to linear fits between moment magnitudes (west) respective local magnitudes (east) and Richter magnitudes. These fits are reported in Figures S07 and S06b in the supporting information of Astiz et al []. Our relationship between moment magnitude and Richter magnitude in the west agrees well with the fit to moment magnitudes determined by the Northern California Seismic Network (NCSN).…”

Section: Resultsmentioning

confidence: 99%

“…Differences between the magnitude relationship presented in Figure and the fits from Astiz et al [] might be due to the fact that most of the latter are only calculated for larger events depending on the completeness of the reference catalog. Furthermore, the mean energy site amplification does not equal the assumed value of 1 and it might be different for different frequencies.…”

Section: Comparison With Other Work and Discussionmentioning

confidence: 99%

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Crustal intrinsic and scattering attenuation of high‐frequency shear waves in the contiguous United States

Eulenfeld

Wegler

2017

JGR Solid Earth

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We use 10 years of data of the USArray project to estimate the areal distribution of crustal intrinsic and scattering attenuation of shear waves for frequencies between 1 Hz and 20 Hz in the contiguous United States. Additionally, we report energy site amplification factors and estimate moment magnitudes for small earthquakes (M 1.5 to M 3.5). The Qopen method is used to invert for intrinsic and scattering attenuation for each event and nearby stations. Observations are collected for around 25,000 events, averaged at each station and interpolated between station locations. In a second inversion, energy site amplifications and moment magnitudes are corrected by assuming that site amplifications for one station and frequency are the same for different earthquakes. We observe a west‐east decline of intrinsic attenuation for high frequencies which reflects the west‐east transition from young, hot to old and cold crust. Scattering attenuation for high frequencies is stronger in the east with an extraordinary high attenuation around the southern part of the Appalachian Highlands and the Interior Low Plateaus. Results at low frequencies do not show clear trends. A large site amplification is observed at high frequencies in parts of the eastern United States. Estimated moment magnitudes show a good agreement to moment magnitudes independently derived from moment tensor inversion. Moment magnitudes in the west are higher than in the east for the same Richter magnitudes.

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Section: Resultsmentioning

confidence: 99%

Section: Comparison With Other Work and Discussionmentioning

confidence: 99%

Crustal intrinsic and scattering attenuation of high‐frequency shear waves in the contiguous United States

Eulenfeld

Wegler

2017

JGR Solid Earth

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“…The event trend is a cartoon of the histograms in Astiz et al . [, Figure 16] depicting the observed number of events from 24 h local origin times. This figure shows that nighttime rates remain stationary while daytime trends exhibit significant variation on a daily, weekly, and locational basis.…”

Section: Methodsmentioning

confidence: 99%

“…Within a polygonal area surrounding the TA footprint at the time of the main shock, the event catalog we recover includes 204 events, whereas the Array Network Facility (ANF) event catalog contains 81 events. The 81 ANF events are a subset of our 204 events (i.e., we captured 100% of the cataloged ANF events) and represent the largest magnitude events based on total number of stations exhibiting coherent signal (i.e., the remaining 123 events not in the ANF catalog are generally smaller and thus at or below the magnitude of completeness for that catalog, which varies spatially and temporally and averages~M2.5 [Astiz et al, 2014]). In addition, the supplemental events that our detection algorithm net occur during both daytime (7 A.M. to 7 P.M. local time) and nighttime (7 P.M. to midnight and midnight to 7 A.M.) hours ( Figure 4).…”

Section: Earthquake Detectionmentioning

confidence: 99%

Exploring remote earthquake triggering potential across EarthScopes' Transportable Array through frequency domain array visualization

et al. 2014

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To better understand earthquake source processes involved in dynamically triggering remote aftershocks, we use data from the EarthScope Transportable Array (TA) that provide uniform station sampling, similar recording capabilities, large spatial coverage, and, in many cases, repeat sampling at each site. To avoid spurious detections, which are an inevitable part of automated time domain amplitude threshold detection methods, we develop a frequency domain earthquake detection algorithm that identifies coherent signal patterns through array visualization. This method is tractable for large data sets, ensures robust catalogs, and delivers higher resolution observations than what are available in current catalogs. We explore seismicity rate changes local to the TA stations following 18 global main shocks (M ≥ 7) that generate median peak dynamic stress amplitudes of 0.001-0.028 MPa across the array. From these main shocks, we find no evidence of prolific or widespread remote dynamic triggering in the continental U.S. within the main shock's wave train or following main shock stress transients within 2 days. However, limited evidence for rate increases exist in localized source regions. These results suggest that for these data, prolific, remote earthquake triggering is a rare phenomenon throughout a wide range of observable magnitudes. We further conclude that within the lower range of previously reported triggering thresholds, surface wave amplitude does not correlate well with observed cases of dynamic triggering. We propose that other characteristics of the triggering wavefield, in addition to specific conditions at the site, will drive the occurrence of triggering at these amplitudes.

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“…Discrimination between local tectonic events and mining or quarry blasts is a challenge common to seismic networks and researchers working to build seismicity catalogs in regions where both tectonic seismicity and anthropogenic sources exist (Astiz et al, ) because published seismic catalogs are typically intended to contain only events that pertain to the study of elastic strain partitioning and release in the crust. Within Utah, both earthquakes and quarry blasts occur in abundance, often in close spatial proximity, making event labelling a significant task for analysts.…”

Section: Introductionmentioning

confidence: 99%

Deep Learning Models Augment Analyst Decisions for Event Discrimination

Linville

Pankow

Draelos

2019

Geophysical Research Letters

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Long‐term seismic monitoring networks are well positioned to leverage advances in machine learning because of the abundance of labeled training data that curated event catalogs provide. We explore the use of convolutional and recurrent neural networks to accomplish discrimination of explosive and tectonic sources for local distances. Using a 5‐year event catalog generated by the University of Utah Seismograph Stations, we train models to produce automated event labels using 90‐s event spectrograms from three‐component and single‐channel sensors. Both network architectures are able to replicate analyst labels above 98%. Most commonly, model error is the result of label error (70% of cases). Accounting for mislabeled events (~1% of the catalog) model accuracy for both models increases to above 99%. Classification accuracy remains above 98% for shallow tectonic events, indicating that spectral characteristics controlled by event depth do not play a dominant role in event discrimination.

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The Array Network Facility Seismic Bulletin: Products and an Unbiased View of United States Seismicity

Cited by 25 publications

References 28 publications

Crustal intrinsic and scattering attenuation of high‐frequency shear waves in the contiguous United States

Crustal intrinsic and scattering attenuation of high‐frequency shear waves in the contiguous United States

Exploring remote earthquake triggering potential across EarthScopes' Transportable Array through frequency domain array visualization

Deep Learning Models Augment Analyst Decisions for Event Discrimination

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