scholarly journals An earthquake catalogue for seismic events in the Norman Wells region of the central Mackenzie Valley, Northwest Territories, using waveform data from local seismic stations

2021 ◽  
Author(s):  
A M Farahbod ◽  
H Kao ◽  
D Snyder
Keyword(s):  
Northwest Territories ◽  
Seismic Data ◽  
Source Parameters ◽  
Energy Industry ◽  
Dense Array ◽  
Waveform Data ◽  
Seismicity Distribution ◽  
Multi Stage ◽  
Test Operations ◽  
Seismograph Network

The development of unconventional hydrocarbon resources in the Norman Wells region of the Central Mackenzie Valley, Northwest Territories, has been explored by the energy industry. In early 2014, Conoco-Philips Canada conducted two multi-stage test operations of hydraulic fracturing (HF) in the region. In this study, we combine seismic data from the Canadian National Seismograph Network, four new stations established by the Northwest Territories Geoscience Office in collaboration with Natural Resources Canada in the Norman Wells region, and a local dense array installed by Conoco-Philips Canada to study the seismicity distribution during the pre-HF, HF and post-HF periods. We have identified and located 130 earthquakes within 100 km of the geographic centre of the local seismic network near Norman Wells for the pre-HF period (11 September 2013 - 7 February 2014). In comparison, 231 events are located during the HF period (8 February 2014 - 10 March 2014), and for the two post-HF periods, 11 March 2014 - 31 July 2014 and 27 February 2015 - 31 December 2015, we have catalogued 255 and 138 events, respectively. Source parameters and detailed phase pickings of each earthquake are given in the Appendices.

Capturing, Preserving, and Digitizing Legacy Seismic Data from the Montserrat Volcano Observatory Analog Seismic Network, July 1995–December 2004

2020 ◽  
Vol 91 (4) ◽  
pp. 2127-2140 ◽  
Author(s):  
Glenn Thompson ◽  
John A. Power ◽  
Jochen Braunmiller ◽  
Andrew B. Lockhart ◽  
Lloyd Lynch ◽  
...  
Keyword(s):  
Real Time ◽  
Seismic Data ◽  
Original Data ◽  
South Florida ◽  
Seismic Network ◽  
Quality Data ◽  
Spectral Amplitude ◽  
Assistance Program ◽  
Waveform Data ◽  
Amplitude Measurement

Abstract An eruption of the Soufrière Hills Volcano (SHV) on the eastern Caribbean island of Montserrat began on 18 July 1995 and continued until February 2010. Within nine days of the eruption onset, an existing four-station analog seismic network (ASN) was expanded to 10 sites. Telemetered data from this network were recorded, processed, and archived locally using a system developed by scientists from the U.S. Geological Survey (USGS) Volcano Disaster Assistance Program (VDAP). In October 1996, a digital seismic network (DSN) was deployed with the ability to capture larger amplitude signals across a broader frequency range. These two networks operated in parallel until December 2004, with separate telemetry and acquisition systems (analysis systems were merged in March 2001). Although the DSN provided better quality data for research, the ASN featured superior real-time monitoring tools and captured valuable data including the only seismic data from the first 15 months of the eruption. These successes of the ASN have been rather overlooked. This article documents the evolution of the ASN, the VDAP system, the original data captured, and the recovery and conversion of more than 230,000 seismic events from legacy SUDS, Hypo71, and Seislog formats into Seisan database with waveform data in miniSEED format. No digital catalog existed for these events, but students at the University of South Florida have classified two-thirds of the 40,000 events that were captured between July 1995 and October 1996. Locations and magnitudes were recovered for ∼10,000 of these events. Real-time seismic amplitude measurement, seismic spectral amplitude measurement, and tiltmeter data were also captured. The result is that the ASN seismic dataset is now more discoverable, accessible, and reusable, in accordance with FAIR data principles. These efforts could catalyze new research on the 1995–2010 SHV eruption. Furthermore, many observatories have data in these same legacy data formats and might benefit from procedures and codes documented here.

Source parameters of the 1908 Messina Straits, Italy, earthquake from geodetic and seismic data

2002 ◽  
Vol 107 (B4) ◽  
pp. ESE 4-1-ESE 4-11 ◽  
Author(s):  
Antonella Amoruso ◽  
Luca Crescentini ◽  
Roberto Scarpa
Keyword(s):  
Seismic Data ◽  
Source Parameters

scholarly journals Batch seismic inversion using the iterative ensemble Kalman smoother

2021 ◽  
Author(s):  
Michael Gineste ◽  
Jo Eidsvik
Keyword(s):  
Seismic Data ◽  
Time Windows ◽  
Seismic Inversion ◽  
Efficient Estimation ◽  
Solution Strategy ◽  
Adaptive Procedure ◽  
Waveform Data ◽  
Kalman Smoother ◽  
Seismic Waveform ◽  
Single Batch

AbstractAn ensemble-based method for seismic inversion to estimate elastic attributes is considered, namely the iterative ensemble Kalman smoother. The main focus of this work is the challenge associated with ensemble-based inversion of seismic waveform data. The amount of seismic data is large and, depending on ensemble size, it cannot be processed in a single batch. Instead a solution strategy of partitioning the data recordings in time windows and processing these sequentially is suggested. This work demonstrates how this partitioning can be done adaptively, with a focus on reliable and efficient estimation. The adaptivity relies on an analysis of the update direction used in the iterative procedure, and an interpretation of contributions from prior and likelihood to this update. The idea is that these must balance; if the prior dominates, the estimation process is inefficient while the estimation is likely to overfit and diverge if data dominates. Two approaches to meet this balance are formulated and evaluated. One is based on an interpretation of eigenvalue distributions and how this enters and affects weighting of prior and likelihood contributions. The other is based on balancing the norm magnitude of prior and likelihood vector components in the update. Only the latter is found to sufficiently regularize the data window. Although no guarantees for avoiding ensemble divergence are provided in the paper, the results of the adaptive procedure indicate that robust estimation performance can be achieved for ensemble-based inversion of seismic waveform data.

scholarly journals Study on the relationship between multi-stage strike-slip mechanism and basin evolution in Fangzheng fault depression

2018 ◽  
Vol 22 (4) ◽  
pp. 335-339
Author(s):  
Jingfeng Wu ◽  
Qi'an Meng ◽  
Xiaofei Fu ◽  
Yuling Ma ◽  
Meifeng Sun ◽  
...  
Keyword(s):  
Seismic Data ◽  
Structural Characteristics ◽  
Stage Structure ◽  
Tectonic Stress ◽  
Strike Slip ◽  
The West ◽  
Lateral Strike Slip ◽  
Slip Mechanism ◽  
Pull Apart Basin ◽  
Multi Stage

Fangzheng fault depression is controlled by the northern of the Tan-Lu fault zone. It undergoes multi-stage strike-slip, extrusion modification, and erosion of the thermal uplift, forming a tectonic pattern of uplifts connected with sags. Through the regional dynamic analysis, the study of the activity law of the western Pacific plate has clarified the formation and transformation of the regional tectonic stress field. Under the background of the multi-stage of the strike-slip mechanism in the northern part of the Tan-lu fault, the Fangzheng fault depression has a characteristic of the “left-lateral strike-slip pull-apart basin, right-lateral strike-slip extrusion transformation.” According to the difference of the strike-slip, the Fangzheng fault depression has divided into two parts: the East fault depression and the West fault depression. The seismic data, seismic attribute analysis, and geological modeling techniques have applied to analyze the two fault depressions, the East fault depression has actively controlled by the strike-slip activity, and the structure is complex. The seismic data quality is poor; the structure of the West Fault Depression is the opposite and structural characteristics of asymmetrical difference strike-slip in the East and West fault depressions. Interpretation of seismic sections through a slippery background, the strike-slip attributes of the whole fault depression from south to north are segmented, and the strike-slip mechanism from east to west is different. Under the control of the multi-stage strike-slip mechanism, the Fangzheng fault depression is divided into six stages of strike-slip evolution, corresponding to the six different stages of the strike-slip control basin, the formation process of the asymmetric difference strike-slip fault basin is clarified, which provides a reference for the study of the strike-slip pull-apart basin with multi-stage structure.

EXAMPLES OF THE EFFECT OF SOURCE AND RECORDING SITE PARAMETERS ON THE SEISMIC RESPONSE OBSERVED FROM PLOWSHARE PROJECTS, GASBUGGY AND RULISON

Geophysics ◽  
1972 ◽  
Vol 37 (2) ◽  
pp. 288-300 ◽  
Author(s):  
Walter W. Hays
Keyword(s):  
Seismic Data ◽  
Spectral Response ◽  
Source Parameters ◽  
Sedimentary Basins ◽  
Test Site ◽  
Physical Parameters ◽  
Recording Site ◽  
Matrix Formulation ◽  
Surface Particle ◽  
Depth Of Burial

The amplitude and frequency composition of the seismic motions observed over a wide geographic area from Gasbuggy and Rulison, two Plowshare detonations, illustrates the effect which source and recording site parameters have on the resultant ground motion. Gasbuggy (29 kt) and Rulison (40 kt) were detonated, respectively, in the San Juan and Piceance Creek sedimentary basins of New Mexico and Colorado. Because both detonations were emplaced in sedimentary formations to stimulate the flow of natural gas, these detonations were placed at a greater depth of burial than typically required for containment. The effect of source parameters (device depth of burial and energy release) was simulated by seismic scaling theory. This theory (based on an extension of Sharpe’s problem) predicted a smaller elastic radius and, consequently, higher dominant frequency of generation for the elastic waves than would be expected on the basis of Nevada Test Site experience with typically contained events of 29 and 40 kt. Observed effects of the source variables were displayed in the Gasbuggy and Rulison seismic data: (1) a shift of the frequency of maximum spectral response to the high frequency end of the spectrum and (2) enhancement of the peak vector surface particle accelerations and velocities and a decrease in the peak vector surface particle displacements. Some of the Rulison recording sites were located on thin (50 ft thick or less) layers of alluvium which, on the basis of refraction surveys, exhibited a fairly significant contrast in acoustic impedance relative to that of the underlying sedimentary rocks. The effect of the lowvelocity alluvium layers at recording sites of interest was simulated by amplitude amplification modeling (based on the Haskell‐Thompson matrix formulation) using interpreted data from refraction surveys to define the layer physical parameters. These calculations indicated that significant local frequency‐dependent amplification would occur at some locations in the Piceance Creek Basin, a prediction which was verified by the seismic data.

Amplitude and frequency anomalies in regional 3D seismic data surrounding the Mallik 5L-38 research site, Mackenzie Delta, Northwest Territories, Canada

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. B183-B191 ◽  
Author(s):  
M. Riedel ◽  
G. Bellefleur ◽  
S. R. Dallimore ◽  
A. Taylor ◽  
J. F. Wright
Keyword(s):  
Northwest Territories ◽  
Gas Hydrate ◽  
Seismic Data ◽  
Ratio Method ◽  
Unfrozen Water ◽  
3D Seismic ◽  
Mackenzie Delta ◽  
Data Set ◽  
Seismic Amplitude ◽  
3D Seismic Data

Amplitude and frequency anomalies associated with lakes and drainage systems were observed in a 3D seismic data set acquired in the Mallik area, Mackenzie Delta, Northwest Territories, Canada. The site is characterized by large gas hydrate deposits inferred from well-log analyses and coring. Regional interpretation of the gas hydrate occurrences is mainly based on seismic amplitude anomalies, such as brightening or blanking of seismic energy. Thus, the scope of this research is to understand the nature of the amplitude behavior in the seismic data. We have therefore analyzed the 3D seismic data to define areas with amplitude reduction due to contamination from lakes and channels and to distinguish them from areas where amplitude blanking may be a geologic signal. We have used the spectral ratio method to define attenuation (Q) over different areas in the 3D volume and subsequently applied Q-compensation to attenuate lateral variations ofdispersive absorption. Underneath larger lakes, seismic amplitude is reduced and the frequency content is reduced to [Formula: see text], which is half the original bandwidth. Traces with source-receiver pairs located inside of lakes show an attenuation factor Q of [Formula: see text], approximately half of that obtained for source-receiver pairs situated on deep, continuous permafrost outside of lakes. Deeper reflections occasionally identified underneath lakes show low-velocity-related pull-down. The vertical extent of the washout zones is enhanced by acquisition with limited offsets and from processing parameters such as harsh mute functions to reduce noise from surface waves. The strong attenuation and seismic pull-down may indicate the presence of unfrozen water in deeper lakes and unfrozen pore water within the sediments underlying the lakes. Thus, the blanking underneath lakes is not necessarily related to gas migration or other in situ changes in physical properties potentially associated with the presence of gas hydrate.

Crustal-scale ramp in a Middle Proterozoic orogen, Northwest Territories, Canada

1992 ◽  
Vol 29 (1) ◽  
pp. 142-157 ◽  
Author(s):  
Elizabeth A. Clark ◽  
Frederick A. Cook
Keyword(s):  
Northwest Territories ◽  
Seismic Data ◽  
Large Scale ◽  
Thrust Faults ◽  
Crustal Structures ◽  
Scale Similarity ◽  
Compressional Deformation ◽  
Middle Proterozoic

Deep crustal seismic data from the Fort Goodhope area, Northwest Territories, Canada, image crustal structures associated with Middle Proterozoic compressional deformation. These include 10–20 km wide antiforms and thrust faults that lie above a west-dipping crustal-scale ramp with at least 10 km of vertical relief. The deformation is interpreted as being associated with structures observed in the subsurface to the east and may be partly coeval with deformation originally detected in outcrop in the Rackla Range of the Wernecke Mountains. These new deep crustal profiles, coupled with data to the east that delineate structures to 15 km depth, reveal large-scale similarity between this Middle Proterozoic orogen and many Phanerozoic compressional orogens.

Source parameters of the Ensenada Bay earthquake swarm, Baja California, Mexico

1985 ◽  
Vol 22 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Cecilio J. Rebollar
Keyword(s):  
Seismic Data ◽  
Strain Energy ◽  
High Strain ◽  
Source Parameters ◽  
Earthquake Swarm ◽  
Ground Displacement ◽  
Source Dimensions ◽  
Fault Type ◽  
Stress Drops ◽  
High Strain Energy

Seismic data collected from the Ensenada Bay earthquake swarm of late 1981 were used to calculate the spectra of ground displacement. Data from the stations of Ensenada (ENX) and Cerro Bola (CBX), at epicentral distances of 14 and 57 km, respectively, were used to evaluate source parameters. The focal depths determined for these events were less than 10 km. The focal mechanism was a strike-slip fault type, with the plane of motion striking N52°W, parallel to the Agua Blanca Fault. Seismic moments ranging from 3.44 × 1019 to 5.99 × 1020 dyn∙cm (3.44 × 1014 to 5.99 × 1015 N∙cm) were estimated for events with local magnitudes in the range 1.7–2.3. The source dimensions were found to be 186 ± 36 m and the stress drops between 3 and 66 bar (0.3 and 6.6 MPa), comparable to results obtained in previous studies of shallow events (depths <10 km). The Ensenada swarm could be attributed to a localized zone of high-strain energy at the intersection of two faults. Ratios of P to S corner frequencies were evident for only five events; they were 1.39 ± 0.38. Magnitude and seismic moment from other studies were compared with the Ensenada data in the range of magnitudes 0–3. All the data can be accommodated by log M0 = 1.5 ML + (16.9 ± 1.1). The Ensenada earthquake swarm and the Victoria earthquake swarm, which occurred in the Mexicali valley in 1978, have similar source radii and corner frequencies for the same range of seismic moments.

scholarly journals Evaluation for hypocenter estimation error in the southwestern Kuril trench using Japan and Russia joint seismic data

2020 ◽  
Author(s):  
Masayoshi Ichiyanagi ◽  
Mikhaylov Valentin ◽  
Dmitry Kostylev ◽  
Yuri Levin ◽  
Hiroaki Takahashi
Keyword(s):  
Real Time ◽  
Seismic Data ◽  
Estimation Error ◽  
Tsunami Warning ◽  
Disaster Mitigation ◽  
Border Zone ◽  
Japan Meteorological Agency ◽  
Estimation Accuracy ◽  
Waveform Data ◽  
Kuril Trench

Abstract The southwestern Kuril trench is seismically active due to the subduction of the Pacific plate. Great earthquakes in this zone have frequently induced fatal disasters. Seismic monitoring and hypocenter catalogues provide fundamental information on earthquake occurrence and disaster mitigation. Real-time hypocenter and magnitude estimates are extremely crucial data for tsunami warning systems. However, this region is located in the international border zone between Japan and Russia. The Japan Meteorological Agency and Russian Academy of Sciences have routinely determined hypocenters and issued earthquake information independently. Waveform data have not yet been exchanged internationally in real time. Here, we evaluated how a hypothetical Japan-Russia joint seismic network could potentially improve the hypocenter estimation accuracy. Experiments using numerical and observed data indicated that the joint network extended the distance over which hypocenters can be accurately determined over 100 km eastward compared to the Japan network only. This fact suggests that joint seismic data have the potential to improve the hypocenter accuracy in this region, which would provide improved performance in gathering disaster information at the moment of a tsunami warning.

Pre-stack Seismic Facies Analysis via Waveform Sparse Representation

Geophysics ◽  
2020 ◽  
pp. 1-77
Author(s):  
Kunhong Li ◽  
Zhining Liu ◽  
Bin She ◽  
Jiandong Liang ◽  
Guangmin Hu
Keyword(s):  
Spatial Structure ◽  
Dictionary Learning ◽  
Seismic Data ◽  
Facies Analysis ◽  
Intensity Variation ◽  
Seismic Facies ◽  
Distance Metric ◽  
Structure Variation ◽  
Waveform Data ◽  
Seismic Facies Analysis

Seismic facies analysis based on pre-stack data is becoming popular. Vertical elastic transitions produce the spatial structure variation of pre-stack waveforms, while lateral elastic transitions produce the amplitude intensity variation. In the stratigraphic seismic facies analysis, more attention should be paid to waveform spatial structure than amplitude intensity. Conventional classification methods based on distance metric are difficult to adapt to stratigraphic seismic facies analysis because a distance metric is a comprehensive measure of waveform structure and amplitude intensity. A dictionary learning method for pre-stack seismic facies analysis is proposed herein. The proposed method first learns several dictionaries from labeled pre-stack waveform data, and these dictionaries consist of several normalization vector bases. The pre-stack waveform spatial structure is therefore embedded in these learned dictionaries, and the amplitude intensity is eliminated by the normalization process. Afterward, these dictionaries are used to sparsely represent pre-stack seismic data. Seismic facies are classified and determined according to representation error. A source error separation method is used to improve the anti-noise performance of dictionary learning by iteratively segmenting the noise out in the training data. The results on synthetic and real seismic data show that the proposed method has a stronger tolerance to noise, and the obtained seismic facies boundary is more accurate and clearer. This demonstrates that the proposed method is an effective seismic facies analysis technique.

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