Seismic Velocity Estimation Using Passive Downhole Distributed Acoustic Sensing Records: Examples From the San Andreas Fault Observatory at Depth

2019 ◽  
Vol 124 (7) ◽  
pp. 6931-6948 ◽  
Author(s):  
A. Lellouch ◽  
S. Yuan ◽  
Z. Spica ◽  
B. Biondi ◽  
W. L. Ellsworth
Keyword(s):  
San Andreas Fault ◽  
Seismic Velocity ◽  
Velocity Estimation ◽  
Acoustic Sensing ◽  
San Andreas ◽  
Distributed Acoustic Sensing

Velocity‐Based Earthquake Detection Using Downhole Distributed Acoustic Sensing—Examples from the San Andreas Fault Observatory at Depth

2019 ◽  
Vol 109 (6) ◽  
pp. 2491-2500 ◽  
Author(s):  
Ariel Lellouch ◽  
Siyuan Yuan ◽  
William L. Ellsworth ◽  
Biondo Biondi
Keyword(s):  
San Andreas Fault ◽  
Seismic Velocity ◽  
Incidence Angle ◽  
Signal To Noise Ratio ◽  
Plane Waves ◽  
Detection Algorithm ◽  
Angle Of Incidence ◽  
Acoustic Sensing ◽  
San Andreas ◽  
Distributed Acoustic Sensing

Abstract Conventional seismographic networks sparsely sample the wavefields excited by earthquakes. Thus, standard event detection is conducted by analyzing separate stations and merging their results. Emerging distributed acoustic sensing recording technologies allow for unbiased spatial sampling of the wavefield and, as a result, array‐based processing of the recorded signals. Using a cemented fiber in the San Andreas Fault Observatory at Depth main hole, 800 virtual receivers are sampled at a 1 m interval from the surface to 800 m depth. Recorded earthquakes are approximated as plane waves reaching the bottom of the array first. Following this assumption, the relative travel times of the recorded event depend on the local velocity at the array location and the angle of incidence at which the planar wavefront reaches it. Given the seismic velocity, a newly proposed detection algorithm amounts to a single‐parameter scan of the incidence angle and measurement of data coherency along the different possible travel‐time curves. Using the entire recording array, a much higher effective signal‐to‐noise ratio can be obtained when compared to individual channel processing. About 20 days of recorded seismic activity from the San Andreas Fault is analyzed. Using a downhole single array, the majority of cataloged events in the area are detected. In addition, a previously unknown event is unveiled. We estimate its magnitude at roughly −0.5.

Distributed acoustic sensing for seismic monitoring in challenging environments

2020 ◽  
Author(s):  
Zack Spica ◽  
Takeshi Akuhara ◽  
Gregory Beroza ◽  
Biondo Biondi ◽  
William Ellsworth ◽  
...  
Keyword(s):  
Seismic Velocity ◽  
Velocity Estimation ◽  
Motion Sensors ◽  
Recording Technology ◽  
Acoustic Sensing ◽  
Seismic Properties ◽  
Seismic Recording ◽  
Distributed Acoustic Sensing ◽  
Geotechnical Information ◽  
Observation Bias

<p>Our understanding of subsurface processes suffers from a profound observation bias: ground-motion sensors are rare, sparse, clustered on continents and not available where they are most needed. A new seismic recording technology called distributed acoustic sensing (DAS), can transform existing telecommunication fiber-optic cables into arrays of thousands of sensors, enabling meter-scale recording over tens of kilometers of linear fiber length. DAS works in high-pressure and high-temperature environments, enabling long-term recordings of seismic signals inside reservoirs, fault zones, near active volcanoes, in deep seas or in highly urbanized areas.</p><p>In this talk, we will introduce this laser-based technology and present three recent cases of study. The first experiment is in the city of Stanford, California, where DAS measurements are used to provide geotechnical information at a scale normally unattainable (i.e., for each building) with traditional geophone instrumentation. In the second study, we will show how downhole DAS passive recordings from the San Andreas Fault Observatory at Depth can be used for seismic velocity estimation. In the third research, we use DAS (in collaboration with Fujitec) to understand the ocean physics and infer seismic properties of the seafloor under a 100 km telecommunication cable.</p>

scholarly journals Damage and seismic velocity structure of pulverized rocks near the San Andreas Fault

2013 ◽  
Vol 118 (6) ◽  
pp. 2813-2831 ◽  
Author(s):  
Marieke Rempe ◽  
Thomas Mitchell ◽  
Jörg Renner ◽  
Stuart Nippress ◽  
Yehuda Ben-Zion ◽  
...  
Keyword(s):  
Velocity Structure ◽  
San Andreas Fault ◽  
Seismic Velocity ◽  
Seismic Velocity Structure ◽  
San Andreas ◽  
Pulverized Rocks

scholarly journals Seismic velocity variations on the San Andreas fault caused by the 2004 M6 Parkfield Earthquake and their implications

2007 ◽  
Vol 59 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Yong-Gang Li ◽  
Po Chen ◽  
Elizabeth S. Cochran ◽  
John E. Vidale
Keyword(s):  
San Andreas Fault ◽  
Seismic Velocity ◽  
San Andreas ◽  
Parkfield Earthquake ◽  
Velocity Variations

Continuous source system and distributed acoustic sensing for reservoir to crust monitoring

2020 ◽  
Author(s):  
Takeshi Tsuji ◽  
Tatsunori Ikeda ◽  
Koshun Yamaoka
Keyword(s):  
Monitoring System ◽  
Field Experiments ◽  
Seismic Velocity ◽  
Seismic Source ◽  
Seismic Signal ◽  
Geothermal Field ◽  
High Temporal Resolution ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing ◽  
Continuous Source

<p><strong>We have developed a permanent seismic monitoring system using a continuous seismic source and distributed acoustic sensing (DAS). </strong><strong>The active seismic source system continuously </strong><strong>generates waveforms </strong><strong>with wide frequency range. By stacking the continuous waveforms, our monitoring system improves signal-to-noise ratio of the seismic signal. Thus, less-energy vibration using</strong><strong> s</strong><strong>mall-size source could be utilized for the exploration of deeper geological targets. Presently, we have deployed the small-size monitoring source system in the Kuju geothermal field in the northeast Kyushu Island, Japan. Although our monitoring source system is small and generates high frequency vibrations (10-20Hz), the signal propagated ></strong><strong>80 </strong><strong>km distance using two-month continuous source data. Our field experiments demonstrate that variation of seismic velocity of the crust could be identified with high accuracy (~0.01 %). </strong><strong>To record the monitoring signal from continuous source system, we need to deploy seismometers. Deployment of many seismometers increase spatial resolution of the monitoring results. Recently, we have deployed the DAS system close to the continuous seismic source system. Using DAS, dense and long seismometer network can be realized, and we succeeded to identify the temporal variation of seismic velocity. By using both continuous source and DAS, we are able to monitor wide area with lower cost. </strong><strong>Our monitoring system could accurately monitor the larger-scale crust and smaller-scale reservoir in high temporal resolution.</strong></p>

scholarly journals Fracture detection and imaging through relative seismic velocity changes using distributed acoustic sensing and ambient seismic noise

2017 ◽  
Vol 36 (12) ◽  
pp. 1009-1017 ◽  
Author(s):  
Stephanie R. James ◽  
Hunter A. Knox ◽  
Leiph Preston ◽  
James M. Knox ◽  
Mark C. Grubelich ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Seismic Velocity ◽  
Ambient Seismic Noise ◽  
Fracture Detection ◽  
Acoustic Sensing ◽  
Seismic Velocity Changes ◽  
Distributed Acoustic Sensing ◽  
Velocity Changes

Time variance of seismic velocity from multiple explosive sources southeast of Hollister, California

1977 ◽  
Vol 67 (5) ◽  
pp. 1339-1354 ◽  
Author(s):  
L. G. Peake ◽  
J. H. Healy ◽  
J. C. Roller
Keyword(s):  
Fault Zone ◽  
San Andreas Fault ◽  
Seismic Velocity ◽  
Temporal Distribution ◽  
Rock Properties ◽  
Arrival Times ◽  
Time Variance ◽  
San Andreas ◽  
Shot Point ◽  
Explosive Charges

abstract As part of an intensive effort to monitor the section of the San Andreas fault south of Hollister, California, for any seismic velocity time variance associated with earthquakes, 17 explosive charges were fired between August 1974 and May 1975, at a point 35 km east of the fault zone and recorded by a special network of 51 seismometers within and west of the San Andreas fault zone. The shot point was selected to minimize differences in rock properties for successive shot locations, and all the data were recorded on a single tape recorder dedicated to the experiment. By cross-correlating the records from successive shots, it was possible to determine differential travel times to an accuracy of 4 msec or better using a 250-kg explosive charge recorded in the distance range between 30 to 50 km. No definitive changes in seismic velocity were detected during the time covered by this experiment. The spatial distribution of stations and the temporal distribution of shots were designed to reveal anomalies that might be associated with a magnitude 4 or greater earthquake. Nine small earthquakes (M = 2.9 to 3.3) did occur during the experiment, but anomalies associated with these earthquakes could have escaped detection. This work demonstrates the feasibility of monitoring large regions with a high density of instruments to detect systematic changes in arrival times from artifical sources with an accuracy approaching 1 msec and a cost commensurate with the task of earthquake prediction.

Shaking in California continues: Magnitude 4.7 strikes the San Andreas Fault south of Hollister

Temblor ◽  
2020 ◽  
Author(s):  
Ross Stein ◽  
◽  
Volkan Sevilgen ◽  
Keyword(s):  
San Andreas Fault ◽  
San Andreas

Detecting Leaks in Abandoned Gas Wells with Fibre-Optic Distributed Acoustic Sensing

2014 ◽  
Author(s):  
K. Boone ◽  
A. Ridge ◽  
R. Crickmore ◽  
D. Onen
Keyword(s):  
Fibre Optic ◽  
Gas Wells ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing
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