We present one of the first case studies demonstrating use distributed acoustic sensing deployed on regional unlit fiber-optic telecommunication infrastructure (dark fiber) for broadband seismic monitoring both near-surface soil properties and earthquake seismology. recorded 7 months passive data a 27 km section dark fiber stretching from West Sacramento, CA to Woodland, CA, densely sampled at 2 m spacing. This dataset was processed extract surface wave velocity information using ambient...

Distributed acoustic sensing (DAS) is a relatively recent development in the use of fiber-optic cable for measurement ground motion. Discrete sensors, typically using Bragg diffraction grating, have been research and field testing more than 15 years with geophysical applications at least 12 old (Bostick, 2000, summary Keul et al., 2005). However, developments sought to remove need point sensors by fiber itself as sensor (Mestayer 2011; Miller 2012).

Ambient-noise-based seismic monitoring of the near surface often has limited spatiotemporal resolutions because dense arrays are rarely sufficiently affordable for such applications. In recent years, however, distributed acoustic sensing (DAS) techniques have emerged to transform telecommunication fiber-optic cables into that cost effective. With DAS enabling both high sensor counts ("large N") and long-term operations T"), time-lapse imaging shear-wave velocity (V S ) structures is now...

Joint entity and relation extraction is to detect using a single model. In this paper, we present novel unified joint model which directly tags labels according query word position p, i.e., detecting at identifying entities other positions that have relationship with the former. To end, first design tagging scheme generate n tag sequences for an n-word sentence. Then position-attention mechanism introduced produce different sentence representations every these sequences. way, our method can...

Surface waves are advantageous for mapping seismic structures of permafrost, in which irregular velocity gradients common and thus the effectiveness refraction methods limited. Nevertheless, complex that permafrost environments often yield unusual dispersion spectra, higher-order leaky modes dominant. Such spectra were prevalent multichannel surface-wave data acquired from our study site at Barrow, Alaska. Owing to difficulties picking identifying curves these conventional inversion become...

We present preliminary results from an intermediate scale field experiment exploring the seismic response of dynamic permafrost thaw generated by active heating. The focus our project was to evaluate utility surface wave monitoring detect precursors thaw-induced subsidence, a common geotechnical hazard in polar regions. In this study, we timelapse measurements conducted over duration experiment. unique aspect combination semi-permanent orbital vibrator (SOV) source and distributed acoustic...

Abstract Permafrost degradation is rapidly increasing in response to a warming Arctic climate, altering landscapes and damaging critical infrastructure. Solutions for monitoring permafrost thaw dynamics are essential understand biogeochemical feedbacks as well issue warnings hazardous geotechnical conditions. We investigate the feasibility of using permanently installed fiber‐optic seismic networks. conducted 2‐month campaign during controlled experiment permanent surface orbital vibrator...

Cryodamage affects the normal physiological functions and survivability of boar sperm during cryopreservation. Lysine acetylation is thought to be an important regulatory mechanism in functions. However, little known about protein its effects on cryotolerance or cryodamage sperm. In this study, characterization dynamics cryopreservation were determined using liquid chromatography-mass spectrometry (LC-MS). A total 1440 proteins identified out 4705 modified proteins, 2764 quantifiable sites...

Saline permafrost is sensitive to thermal disturbances and prone subsidence, which renders it a major source of geohazard in Arctic coastal environments. Seismic methods could be used map monitor saline at scales geotechnical interests because the ice-content dependencies seismic properties. We have developed comprehensive study ultrasonic P-wave properties (i.e., velocity attenuation) synthetic samples for range salinities temperatures, measurements conducted on fine-grained core obtained...

In the summer of 2015 a shallow trenched distributed acoustic sensing (DAS) array was deployed along road north Fairbanks, Alaska as part an effort to develop low-cost system monitor permafrost thaw under infrastructure. Cars on parallel array's direction are dominant noise source. Source analysis with beamforming confirms most came from cars traveling adjacent road. Cross-correlations show strong apparent copies primary Green's function for all virtual source locations, and simple...

Summary We have deployed a novel permanent monitoring system at the Australian CO2CRC Otway Site that includes surface and borehole distributed acoustic sensing (DAS) network with orbital vibrator (rotary) seismic sources. DAS is an emerging technology for performing acquisition based on optical interferometric techniques, which allows data collection wide spatial aperture high temporal resolution using commercially available telecommunications fibres. sensitivity currently lags behind...

We present an analysis of a field dataset demonstrating the combined use permanent surface orbital vibrator source (SOV) and trenched fiber-optic cable sampled using distributed acoustic sensing (DAS). examine SOV signal characteristics, repeatability, wavefield decomposition for short duration test. show to have excellent spectral repeatability but asymmetric response depending on spin direction. Wavefield tests demonstrate that rotating can effectively be decomposed into equivalent...

To better understand the relationship between P-wave velocities and ice content in saturated, unconsolidated saline permafrost, we constructed an effective-medium model based upon ultrasonic data that were obtained from earlier laboratory studies. The uses a two-end-member mixing approach which ice-filled, fully frozen end member water-filled, unfrozen are mixed together to form effective medium of partially sediments. This has two key advantages: (1) It does not require parameter tuning...

Global climate change has resulted in a warmer Arctic, with projections indicating accelerated modifications to permafrost the near future. The thermal, hydrological, and mechanical physics of thaw have been hypothesized couple complex fashion but data collection efforts study these feedbacks field limited. As result, laboratory numerical models largely outpaced calibration datasets. We present design, execution, initial results from first decameter-scale controlled thawing experiment,...

Abstract Groundwater resources play an increasingly crucial role in providing the water required to sustain environment. However, our understanding of state surficial aquifers and their spatiotemporal dynamics remains poor. In this study, we demonstrate how Rayleigh wave velocity variation can be used as a direct indicator changes level aquifer discontinuous permafrost Distributed acoustic sensing data, collected on trenched fiber‐optic cable Fairbanks, AK, was processed using multichannel...

Summary We present results from an intermediate scale field experiment conducted in December 2014, evaluating the use of Distributed Acoustic Sensing (DAS) for recording ambient noise generated by infrastructure use; future aim our effort is to utilize real-time geotechnical evaluation soils beneath active infrastructure. details installation, comparisons 4 selected DAS cables, and a comparison between classical 3C geophones. conclude showing preliminary examples interferometry using passive...

The effective monitoring of hydraulic fracturing in unconventional oil and gas production requires tools to quantify elastic property variations even the absence microseismic activity. To track subtle time-lapse reservoir properties during such activities, techniques with high repeatability resolution, spatially temporally, are required. Distributed acoustic sensing (DAS) is a rapidly maturing fiber-optic technology for low-cost, permanent, density, in-well monitoring. Surface orbital...

Continuous improvements at X-ray imaging beamlines synchrotron light sources have made dynamic micro-computed tomography (SXR-µCT) experiments more routinely available to users, with a rapid increase in demand given its tremendous potential very diverse areas. In this work survey of five different four-dimensional SXR-µCT is presented, examining parameters linked the evolution investigated system, and tackling problems areas earth sciences. used monitor microstructural sample following...

We introduce surface orbital vibrator (SOV) as a low-cost, fully automatable source suitable for permanent seismic monitoring. With field data acquired with buried geophone array, we examine signal contents and repeatability of 10-ton-force SOV. Crisp reflections are generated by the SOV across entire 1100 m × array; normalized RMS differences (NRMS) time shifts (Δt) obtained from common shot gather good SNR demonstrate that is sufficiently repeatable time-lapse monitoring (the 75th...

Several recent studies have demonstrated that Distributed Acoustic Sensing (DAS) can utilize existing subsurface telecom fiber (i.e. dark fiber) for high quality seismic measurements. Researchers to date shown this sensing combination, coupled ambient noise interferometry techniques, effectively image the shallow (< 30 m) using vehicle and infrastructure (f = 8 - Hz). We present first long-offset surface wave inversion study targeting deeper (⁓ 500 structure DAS fiber. This utilizes a...

Summary We deployed a shallow trenched distributed acoustic sensing (DAS) array consisting of multiple fiber optic cables and casings to assess the suitability DAS recording ambient noise for near-surface characterization. briefly describe acquisition an dataset, our processing workflow, preliminary results interferometry on small data subset. The approximate virtual source responses show reasonable Rayleigh wave velocity estimates compared geophones. several types cable are comparable,...