Broadband Seismometers Research Articles

Upgrading a Low-Cost Seismograph for Monitoring Local Seismicity

The use of a dense network of commercial high-cost seismographs for earthquake monitoring is often financially unfeasible. A viable alternative to address this limitation is the development of a network of low-cost seismographs capable of monitoring local seismic events with a precision comparable to that of high-cost instruments within a specified distance from the epicenter. The primary aim of this study is to compare the performance of an advanced, contemporary low-cost seismograph with that of a commercial, high-cost seismograph. The proposed system is enhanced through the integration of a 24-bit analog-to-digital converter board and an optimized architecture for a low-noise signal amplifier employing active components for seismic signal detection. To calibrate and assess the performance of the low-cost seismograph, an installation was deployed in a region of high seismic activity in Evgiros, Lefkada Island, Greece. The low-cost system was co-located with a high-resolution 24-bit commercial digitizer, equipped with a broadband (30 s—50 Hz) seismometer. An uninterrupted dataset was collected from the low-cost system over a period of more than two years, encompassing 60 local events with magnitudes ranging from 0.9 to 3.2, epicentral distances from 5.71 km to 23.45 km, and focal depths from 1.83 km to 19.69 km. Preliminary findings demonstrate a significant improvement in the accuracy of earthquake magnitude estimation compared to the initial configuration of the low-cost seismograph. Specifically, the proposed system achieved a mean error of ±0.087 when benchmarked against the data collected by the high-cost commercial seismograph. These results underscore the potential of low-cost seismographs to serve as an effective and financially accessible solution for local seismic monitoring.

Seismic velocity changes from repetitive seismicity at Mauna Loa prior to and during its 2022 eruption

AbstracMauna Loa’s short-lived eruption from late November to early December 2022 marked the culmination of nearly a decade of elevated seismic activity and geodetic inflation. The volcano has been monitored by a network of permanent, short period and broadband seismometers. I used the continuous waveform data from that network starting in 2012 to generate a catalog of seismicity that enhances the US Geological Survey Hawaiian Volcano Observatory’s public seismic catalog with four times the number of earthquakes, which were then grouped by waveform similarity. Analysis of subtle delays in the timing of arrivals of scattered waves between pairs of earthquakes in this catalog yields a history of small changes in the shallow seismic velocity structure of the volcano. Seismic velocities have been shown at other volcanoes to change during unrest and eruption. My results show a decrease in seismic velocity centered on the summit beginning in September 2022, corresponding to the onset of a vigorous precursory swarm of seismic activity and shallow inflation. During the eruption itself, I observe large changes due likely to dike opening along the northeast rift zone and deflation of the summit reservoir. However, seismic velocity changes associated with non-volcanic sources such as ground shaking from large earthquakes and meteorological influences at seasonal and diurnal time scales are also observed, and these dominate the velocity changes prior to the eruption. Proper accounting of these effects will be a requirement for use in real-time monitoring, and this work serves as a starting point in that endeavor for Mauna Loa.

Mechanisms of Noise Transmission in Velocity Broad-Band Seismometers: Modeling and Analysis

This paper focuses on the noise transmission process, presenting a comprehensive noise transfer model for velocity broad-band seismometers, which elucidate the transmission mechanisms of five distinct noise sources. We analyzed the spectral characteristics of the noise transfer functions across the forward path, feedback path, and data acquisition stages, with a focus on gains, corner frequencies, and the 0 dB point. Numerical simulations and experiments using the CS60 seismometer showed excellent agreement with theoretical predictions, validating the proposed model and associated noise optimization strategies. This study identified effective methods to reduce noise transfer gains, including optimizing the input and feedback mechanical constants and refining gains at various stages.

Monitoring May 2024 solar and geomagnetic storm using broadband seismometers

The abrupt variations in the magnetic field due to the May 2024 geomagnetic storm have been recorded by broadband seismometers distributed around the world for a time interval of more than 55 h. Signals related to magnetic field variations can be identified in seismic data for frequencies below 10 mHz, but are clearer between 1.5 and 5 mHz, the frequency band corresponding to Pc5 magnetic pulsations. The number of seismological stations that detect these signals varies significantly between the various seismic networks analyzed, but in general they do not exceed 50–60%. The origin of these signals appears to be related to the interaction between telluric currents induced by magnetic field disturbances associated with the geomagnetic storm and the detection systems in broadband sensors, which measure the current intensity necessary to keep the mass of the seismometer fixed. Although detailed calibration of each seismometer will be necessary to use the seismic data to model the waveforms and amplitudes of the magnetic pulsations, the analysis of this data provides a significant densification with respect to the magnetic observatory data, as is of interest to analyze the temporal and regional evolution of the magnetics disturbances associated to the May 2024 solar storm.

The Seismic Station IO.EVN at Pyramid EvK2cnr (Everest): 10 Yr of Activity

Abstract This article presents an overview of the first 10 yr of activity of the IO.EVN seismographic broadband station, managed by the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS and installed near the Observatory-Laboratory Pyramid, about 6 km from Everest Base Camp (Nepal) at 5000 m above sea level. The IO.EVN station is registered in the International Federation of Digital Seismograph Networks (FDSN; see Data and Resources). It has been in operation since 2014 and played a crucial role during the 2015 crisis following the Gorkha earthquake because it was the closest broadband seismometer to the epicenter. The site is located in a remote area with ideal conditions for noise attenuation and is suitable for recording environmental microtremors and earthquakes in the Himalayas and worldwide. Khumbu Valley (Mount Everest) is one of the Himalayan regions that has not been struck by significant earthquakes (Mw > 7.8) in living memory. Although the analysis of microseismicity deserves further investigation, this article focuses more on the analysis of seismic noise, which was conducted to identify the various weather and climate phenomena affecting the region. In our case, we have found that for the major weather phenomena such as typhoons the main effect is due to the reflection of ocean waves on the coasts, whereas local effects such as rain and wind during the monsoon are more significant as the noise level of waves is probably constant throughout the year. The Pyramid is an important station for weather and climate, and the role of the IO.EVN could prove relevant in understanding climate change in the future.

Assessment of seismic station performance in north Chhattisgarh, India: a comprehensive ambient noise analysis

A new network of 16 broadband seismic stations is operational in the northern Chhattisgarh region to monitor the seismicity arising in the otherwise seismically quiescent zone. Ambient noise is comprehensively analyzed to evaluate station performance and validate the data quality. Power spectral densities are computed for all stations, comparing ambient noise levels against global limits for data from November 2022 to December 2023. Results indicate that noise levels consistently fall within global noise limits. The study emphasizes the pronounced effect of instrumental tilt on the horizontal components of broadband seismometers. Spatial variation of ambient noise levels across various period bands of the noise spectrum highlights the contribution of diverse noise sources such as anthropogenic activities, surface waves, body waves, and barometric effects. Seasonal variations in short-period, microseism, and long-period bands reveal temporal variation of noise levels. Diurnal variation in the short-period band indicates a prominent effect of cultural noise. Furthermore, the proximity of seismic stations to major mining areas induces high noise levels in the very short-period band during blasting activities compared to non-blasting periods. Our study thus explores the variability of the ambient noise environment while validating the robustness and stability of the seismic installation across the study region.

Ultra-low frequency calibration of broadband seismometers using a tilt table

Abstract The calibration of current broadband seismometers with the aim to provide traceability to the International System of Units (SI) is an active topic in the vibration metrology community. As it turns out, this exercise has its specific challenges at very low frequencies. A major problem faced at that end of the applicable frequency range, is the influence of tilt as a disturbance on the measured motion component of the sensor. In the presented work, the roles of the quantities are swapped. Tilt is used as a means of excitation of a seismometer and the rectilinear motion is considered as a disturbance, which is, however, well defined by the facilitated set-up. As it is demonstrated, this approach can be very beneficial for very low frequency calibration, and if applied correctly, it can provide a reliable link to base units of the SI.

Reevaluating soil amplification using multi-spectral HVSR technique in La Chana Neighborhood, Granada, Spain

This work presents a thorough reevaluation of soil amplification in the La Chana neighborhood of Granada through a pioneering application of the horizontal-to-vertical spectral ratio technique on seismic noise data using various spectral approaches. The research recycles old seismic noise data recorded at 34 stations with 2 Hz instruments in the year 2010, supplemented with additional measurements recorded with broadband seismometers at nearby locations in the years 2013 and 2017. Initial traditional processing identifies a narrowband dominant frequency around 1.5 Hz, attributed to artificial or anthropogenic sources. To address this, the Maximum Entropy Algorithm was implemented to smooth the spectral response below 1 Hz, and filter out frequency peaks with very narrow spectral bands, while preserving the narrowband frequency around 1.5 Hz in some records. The Thomson Multitaper method further refined the spectral ratio, emphasizing the detection and suppression of narrow frequency bands that may be related to industrial activity. The results demonstrated the reappearance of the 1.5 Hz frequency, but this time without narrow bandwidths, indicating its possible correlation with the natural ground movement. Fundamental periods, ranging from 0.45 s to 0.88 s, suggest a diverse lithological composition, indicating the presence of layers of sands, clays, conglomerates, and carbonates over a basement that represents the main impedance contrast in the area. The multispectral approach surpasses conventional methods in precision and reliability, providing valuable insights for earthquake risk assessment, urban planning, and engineering decisions in seismically active regions.

Researches and measurements of high-sensitive seismometers at experimental base «Obninsk»

One of the main directions of new seismometers development for seismological monitoring systems is decreasing the instrumental noise level and nonlinearity distortions of the instrumental seismic channels. In accordance with modern requirements for high-sensitive seismological stations, the instrumental noise of seismometers should be at least three times less than local seismic background noise. By theoretical estimations modern high-sensitive seismometers have high level features: instrumental noise is lower than the minimal seismic background noise, nonlinearity factor is about 0,01% and less. However, the problem of experimental estimation of these parameters in conditions of ambient seismic backgrounds remains to be under consideration. This problem is especially important during development and production of new seismometers. The article presents some results of studying and measuring the instrumental noise level and nonlinearity factor in channels of broadband and short-period seismometers carried out at the experimental base “Obninsk”. To provide a high precision of measurements, the narrow-band digital filtration and spectrum-correlation data procession technique decreasing influence of the seismic background motion on the results uncertainty were used. Due to stable temperature and insulation in the gallery of 30-meter depth, a 20-30% uncertainty for instrumental noise characteristic measuring, which is 10-30 times lower than local seismic background noise, and 0.0004% uncertainty of nonlinearity factor measuring were achieved. The seismological and environmental conditions at the experimental base “Obninsk” of the Geophysical Survey of RAS provide necessary abilities for researche and measurement of instrumental noise characteristics and non-linear distortion factor of high-sensitive seismometers with satisfactory accuracy.

Follow the Trace: Becoming a Seismo-Detective with a Campus-Based Raspberry Shake Seismometer

Abstract Seismic signals, whether caused by earthquakes, other natural phenomena, or artificial noise sources, have specific characteristics in the time and frequency domains that contain crucial information reflecting their source. The analysis of seismic time series is an essential part of every seismology-oriented study program. Enabling students to work with data collected from their own campus, including signals from both anthropogenic and natural seismic sources, can provide vivid, practical examples to make abstract concepts communicated in classes more concrete and relevant. Data from research-grade broadband seismometers enable us to record time series of vibrations at a broad range of frequencies; however, these sensors are costly and are often deployed in remote places. Participation in the Raspberry Shake citizen science network enables seismology educators to record seismic signals on our own campuses and use these recordings in our classrooms and for public outreach. Yale University installed a Raspberry Shake three-component, low-cost seismometer in the Earth and Planetary Sciences department building in Summer 2022, enabling the detection of local, regional, and teleseismic earthquakes, microseismic noise, and anthropogenic noise sources from building construction, an explosive event in a steam tunnel, and general building use. Here, we discuss and illustrate the use of data from our Raspberry Shake in outreach and education activities at Yale. In particular, we highlight a series of ObsPy-based exercises that will be used in courses taught in our department, including our upper-level Introduction to Seismology course and our undergraduate classes on Natural Disasters and Forensic Geoscience.

Local Detection of Ground Coupled Acoustic Waves with Seismic Arrays and Their Potential Role in the Discrimination of Explosions and Earthquakes

Abstract Acoustic waves are widely used to characterize explosive sources such as volcanoes, meteorites, and controlled explosions. This study examines the potential role of ground coupled airwaves (GCA), which effectively propagate at acoustic speeds (∼0.34 km/s) before coupling to the ground near seismometers, in aiding local discrimination between low-yield explosions in shallow boreholes and earthquakes. GCA generated by shallow borehole explosions from the 2014 imaging magma under St. Helens experiment (ML 0.9–2.3) and earthquakes (ML 2–3.4) from 2014 to 2016, were recorded by various seismometers at <150 km source–receiver distance. Potential GCA are analyzed using arrays of broadband seismometers (number of seismometers, n = 85), nodal seismometers with 10-Hz geophones atop the surface (n = 904), and Texan dataloggers with shallowly buried 4.5-Hz geophones (n = 2535). Array-based detections are defined using the distributions of short-time average over long-time average functions in time windows during and adjacent to the predicted GCA arrival for direct source–receiver transmission. GCA are detected for 14 of 23 borehole explosions and 0 of 34 earthquakes. All detections occurred during times of low-mean wind speed (<0.5 m/s) at ground-based weather stations. GCA amplitudes exhibit strong spatial variability, and the number of spatially distributed receivers appears more important for GCA detection than the type of seismometer installation. GCA detections were compared with seismic P/S amplitude ratios, which are a common source discriminant, and field logs of whether the borehole explosions ejected any mass or deformed the surface. No clear correlation was found with either type of source information, suggesting that heterogeneous propagation and near-receiver effects like wind noise are more influential than variations in source processes among the 23 explosions. Our results indicate that local seismic detection of GCA may valuably complement discrimination metrics like P/S ratios, with a low tendency for false-positive indications of explosions but a high tendency for false negatives.

Earthquake Relocations Delineate a Discrete Fault Network and Deformation Corridor Throughout Southeast Alaska and Southwest Yukon

AbstractDeformation in southeastern Alaska and southwest Yukon is governed by the subduction and translation of the Pacific‐Yakutat plates relative to the North American plate in the St. Elias region. Despite notable historical seismicity and major regional faults, studies of the region between the Fairweather and Denali faults are complicated by glacial coverage and the remote setting. In the last decade, significant improvements have been made to the density of regional broadband seismometer networks. We relocate more than 5,000 earthquakes between 2010 and 2021 in the region of southeastern Alaska and southwestern Yukon utilizing these improved seismic networks. With reductions in catalog uncertainty, particularly in depth, we quantify the thickness of the seismogenic layer in the crust throughout the region and locate seismicity on a shallow network of upper‐crustal faults. Relocated earthquakes, combined with an updated focal‐mechanism catalog, permit estimating and classifying motion of active faults. This includes mapping the Totschunda‐Fairweather “Connector” fault, which plays an important role in explaining regional deformation, and identifying new faults like the Kathleen Lake fault. We draw similarities between our seismic observations and simplified conceptual models of regional tectonics, which describe a dominant transpressional regime and localized slip partitioning. Our results support a hypothesis where current deformation is taking place on a well‐defined and evolved network of shallow faults in the corridor between the Totschunda‐Fairweather “Connector” and Denali faults.

Development of improved short-period geophone: Implementation of low-frequency compensation

Short-period geophones are widely used instruments in dense seismic array investigations. However, inherent limitations in capturing low-frequency signals restrict their versatility. This study implements a low-frequency compensation algorithm via a state-variable filtering circuit to enhance the frequency response of a traditional short-period geophone. Through simulation experiments and vibration testing, we validated the performance of the proposed bandwidth-extension (BE) system. Additionally, time–frequency earthquake signal analysis compared outcomes between our BE seismometers, benchmark short-period seismometers, and high-fidelity broadband seismometers across three seismic events with epicentral distances up to 5,186 km. Results demonstrate the BE system successfully extends the natural frequency cutoff from 4.5 Hz to below 0.2 Hz while maintaining strong consistency with broadband counterparts. Moreover, negligible power demands (10 mW) facilitate embedding the BE circuit directly within acquisition hardware. Given these advantages, the BE method shows promise for upgrading future sensors of seismic networks to record low-frequency content with minimal costs.

Multilayer anisotropy along the Alaska-Aleutians Subduction zone

SUMMARY Increasing evidence from seismic methods shows that anisotropy within subduction zones should consist of multiple layers. To test this, we calculate and model shear wave splitting across the Alaska-Aleutians Subduction Zone (AASZ), where previous studies have argued for separate layers of anisotropy in the subslab, slab and mantle wedge. We present an updated teleseismic splitting catalogue along the span of the AASZ, which has many broad-band seismometers recently upgraded to three components. Splitting observations are sparse in the Western Aleutians, and fast directions are oriented generally trench parallel. There are significantly more splitting measurements further east along the AASZ. We identify six regions in the Central and Eastern Aleutians, Alaskan Peninsula and Cook Inlet with a high density of splits suitable for multilayered anisotropy analyses. These regions were tested for multilayer anisotropy, and for five of the six regions we favour multiple layers over a single layer of anisotropy. We find that the optimal setup for our models is one with a dipping middle layer oriented parallel to palaeospreading. A prominent feature of our modelling is that fast directions above and below the dipping layer are generally oriented parallel to the strike of the slab. Additionally, we lay out a framework for robust and statistically reliable multilayer shear wave splitting modelling.

Reliable Earthquake Source Parameters Using Distributed Acoustic Sensing Data Derived from Coda Envelopes

Abstract A challenge in fully using distributed acoustic sensing (DAS) data collected from fiber-optic sensors is correcting the signals to provide quantitative true ground motion. Such corrections require considering coupling and instrument response issues. In this study, we show via comparison with geophone and broadband seismometer data that we can use coda envelope calibration techniques to obtain absolute moment magnitudes and source spectra from DAS data. Here, we use DAS and nodal geophones deployed as part of a geothermal monitoring experiment at Brady Hot Springs, Nevada, and on a 20 km long dark fiber of the ESnet’s Dark Fiber Testbed–a U.S. Department of Energy user facility, in Sacramento, California. Several DAS line segments with colocated geophone stations were used to compare the amplitude variation using narrowband S-wave coda envelopes. The DAS coda envelope decay at each point showed remarkable similarity with coda envelopes from different events in each narrow frequency range examined. The coda envelopes are used to determine Mw magnitudes and source spectra from regional stations without any major scatter. Because coda waves arrive from a range of directions, the azimuthal sensitivity of DAS is somewhat ameliorated. We show that the openly available seismic coda calibration software toolkit can be used for straightforward and faster processing of large DAS datasets for source parameters and subsurface imaging.

State primary special standard of acceleration unit in the field of gravimetry GET 190-2023: reproduction and transmission of the unit under the influence of geophysical factors

The relevance of research on the reproduction and transmission of the acceleration unit in gravimetry is determined by the development of measuring instruments for the absolute value of the acceleration of free fall and its changes. Qualitative and quantitative changes in the instrument base are due to the requirements of applied tasks solved using gravimetric data in such fields as geodesy, navigation, geodynamics, as well as the expansion of the field of practical application of absolute gravimeters. At the same time, in order to solve applied problems, along with accuracy requirements at a level close to the maximum achievable at the current level of technology development, maximum territorial coverage of measurement sites within the entire territory of the Russian Federation is often necessary. The accuracy of the results obtained with the help of measuring instruments is determined by the level of their metrological support, the main stages of which are the reproduction of the corresponding unit by the standard and its transfer to the measuring instrument. An analysis of possible sources of errors in gravimetric equipment has shown that when reproducing and transmitting the acceleration unit in gravimetry, it is necessary to take into account the influence of geophysical factors that manifest themselves as additional accelerations of a gravitational or inertial nature. The distribution of the gravitational field within a gravimetric point can manifest itself as an additional constant acceleration. Seismic processes and lunar and solar tides manifest themselves as variable accelerations. For various stages of metrological support of gravimetric devices, the mechanisms of the effects of such accelerations have been studied, as well as methods for accounting and reducing their influence using additional equipment have been developed. An additional gravimetric point with a cryogenic relative gravimeter and a broadband seismometer, as well as transported absolute ballistic and relative quartz gravimeters, were introduced into the State primary special standard of acceleration units in the field of gravimetry GET 190-2023.

Detectability analysis of very low frequency earthquakes: methods and application in Nankai using F-net and DONET broad-band seismometers

SUMMARY For a more quantitative discussion of slow earthquake activity, we evaluated the detectable limits of very low frequency earthquakes (VLFEs), which are seismic slow earthquakes observed in very low-frequency (< 0.05 Hz) bands in the Nankai subduction zone. We performed numerical simulations using a local 3-D model and used the observed noise level of permanent broad-band seismometers. First, we investigated the effects of the source-time functions on the maximum amplitudes of the VLFE signals at a certain station. The maximum amplitudes of the VLFE signals were controlled by the VLFE moment rate. The detectable limit of VLFEs at each source location can be defined as the lowest moment rate of detectable VLFEs, which radiate signals larger than the noise levels of any component at ≥ 3 stations. For inland seismometers only, the detectable limits of VLFEs at deep (30–40 km) and shallow (≤ 10 km) depths were 1012–1012.3 and 1012.7 N·m s−1, respectively. Due to the geometrical spreading of VLFE signals and large noise levels in horizontal components, offshore seismometers improved the detectability of shallow VLFEs in regions where seismometers were densely deployed. Based on our detectability and published catalogues, shallow slow earthquakes are less active south-southwest off the Kii Peninsula, where geodetic studies expect mechanical coupling.

Determination of the seismic structure of the Earth based on joint analysis of gravimetric and seismometric data – a case study

The evolution of the Earth’s surface is driven by external and internal forces, the latter of which can only be studied indirectly. Knowledge about the structure of the Earth’s interior is very important for modeling and predicting the processes occurring at the surface. This study presents a new concept of joint analysis of the gravimetric and seismometric recordings of earthquakes for determining the seismic structure of the Earth down to the depth of 1250 km. The proposed method allows the use of gravimetric data without the known full transfer function of the instrument. Group velocity dispersion curves of the fundamental mode of Rayleigh waves up to the period of 550 s are measured based on the joint analysis of the recordings of superconducting gravimeter and broadband seismometers operating at the same location in five testing sites in Europe, allowing for the exploration of a broader response for incoming seismic waves. Averaged dispersion curves for earthquakes around the world for each site are inverted by the weighted linear inversion and Monte Carlo methods to estimate the distribution of shear-wave seismic velocity in the Earth’s mantle. A comparison of the deterministic and probabilistic inversion methods can excellently demonstrate surface waves’ ability to determine the Earth’s mantle structure. The inversion results are compared with the global ak135 seismic model (Kennett et al. 1995) to verify the proposed method.

Comprehensive data set of in situ hydraulic stimulation experiments for geothermal purposes at the Äspö Hard Rock Laboratory (Sweden)

Abstract. In this article, a high-resolution acoustic emission sensor, accelerometer, and broadband seismometer array data set is made available and described in detail from in situ experiments performed at Äspö Hard Rock Laboratory in May and June 2015. The main goal of the hydraulic stimulation tests in a horizontal borehole at 410 m depth in naturally fractured granitic rock mass is to demonstrate the technical feasibility of generating multi-stage heat exchangers in a controlled way superiorly to former massive stimulations applied in enhanced geothermal projects. A set of six, sub-parallel hydraulic fractures is propagated from an injection borehole drilled parallel to minimum horizontal in situ stress and is monitored by an extensive complementary sensor array implemented in three inclined monitoring boreholes and the nearby tunnel system. Three different fluid injection protocols are tested: constant water injection, progressive cyclic injection, and cyclic injection with a hydraulic hammer operating at 5 Hz frequency to stimulate a crystalline rock volume of size 30 m × 30 m × 30 m at depth. We collected geological data from core and borehole logs, fracture inspection data from an impression packer, and acoustic emission hypocenter tracking and tilt data, as well as quantified the permeability enhancement process. The data and interpretation provided through this publication are important steps in both upscaling laboratory tests and downscaling field tests in granitic rock in the framework of enhanced geothermal system research. Data described in this paper can be accessed at GFZ Data Services under https://doi.org/10.5880/GFZ.2.6.2023.004 (Zang et al., 2023).

Characterization of anisotropy in basin-scale subsurface using teleseismic receiver function analysis

Teleseismic receiver function (RF) analysis offers a passive-source analogue to detect impedance boundaries using the converted body waves generated by earthquakes. While the technique traditionally has targeted deep earth structures such as the Moho and transition zones, there is growing interest in assessing its applicability in basin-scale seismic characterization, ultimately aimed for onshore commercial integration as a cost-effective complement to existing active-source seismic surveys. Specifically, the conventional broadband seismometers used in global observational seismic experiments are not only logistically simple in terms of data acquisition, but they also record ground motions in three mutually orthogonal time series, enabling effective detection of shear waves and directional variations of observed signals. Here, we perform teleseismic RF analysis to detect shear-wave anisotropy and related symmetry axes orientations in a basin setting, using open-source seismic data recorded at 55 closely spaced seismic stations in the LaBarge Passive Seismic Experiment deployed in Wyoming between November 2008 and June 2009. We find that the strengths and geometry of the observed anisotropy are variable along the array. Significantly, not only can anisotropy effectively delineate subsurface fault interfaces, it can also substantiate and reveal additional interpretable signals that are otherwise disregarded. The estimated fast axes orientations compare favorably with the complex fracture systems documented in the region. Finally, we show that P-to-S amplitude variations with P incidence are systematic and modelable using existing computational tools, offering an opportunity to develop an analysis technique similar to amplitude variation with offset with the products of RF analysis.