scholarly journals Seismic velocity structure and depth-dependence of anisotropy in the Red Sea and Arabian shield from surface wave analysis

2008 ◽  
Vol 113 (B10) ◽  
Author(s):  
Samantha E. Hansen ◽  
James B. Gaherty ◽  
Susan Y. Schwartz ◽  
Arthur J. Rodgers ◽  
Abdullah M. S. Al-Amri
Keyword(s):  
Surface Wave ◽  
Red Sea ◽  
Velocity Structure ◽  
Seismic Velocity ◽  
Arabian Shield ◽  
Wave Analysis ◽  
Seismic Velocity Structure ◽  
Depth Dependence

Using seismic noise derived from fluid injection well for continuous reservoir monitoring

2016 ◽  
Vol 4 (4) ◽  
pp. SQ1-SQ11 ◽  
Author(s):  
Takeshi Tsuji ◽  
Tatsunori Ikeda ◽  
Tor Arne Johansen ◽  
Bent Ole Ruud
Keyword(s):  
Surface Wave ◽  
Seismic Noise ◽  
Velocity Structure ◽  
Seismic Velocity ◽  
Carbon Capture And Storage ◽  
Injection Well ◽  
Seismic Interferometry ◽  
Fluid Injection ◽  
Frequency Noise ◽  
Wave Analysis

To construct a reliable and cost-effective monitoring system for injected [Formula: see text] in carbon capture and storage projects, we have considered a seismic monitoring approach using seismic noise from a fluid injection well. The passive seismic interferometry continuously monitors injected [Formula: see text], enabling the detection of associated accidental incidents (e.g., [Formula: see text] leakage). We have applied three approaches: (1) crosscorrelation, (2) crosscoherence, and (3) deconvolution, to the passive seismometer data acquired during a fluid-injection experiment in Svalbard in the Norwegian Arctic. The crosscoherence approach enabled the construction of shot gathers similar to active-source data. Reflectors from the reservoir could be identified on common-midpoint (CMP) gathers constructed via seismic interferometry, and seismic velocity could be estimated from the time-lapse CMP gathers. High-frequency noise from fluid injection operations and low-amplitude background ambient noise were suitable for reconstructing virtual seismic data. However, we clearly found that the time variation characteristics of the noise influenced monitoring results, and thus the stable part of the noise should be used for monitoring. We further applied surface-wave analysis to the virtual shot gathers derived from seismic interferometry and investigated variations in S-wave velocity structure in a shallow formation. We observed clear time variations in seismic velocity in the shallow part of permafrost regions. The information derived from the surface-wave analysis is useful in evaluating the influence of shallow formations on monitoring results of deep reservoirs.

scholarly journals Seismic velocity structure at the southern termination of the 2016 Kumamoto Earthquake rupture, Japan

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Yasuhira Aoyagi ◽  
Haruo Kimura ◽  
Kazuo Mizoguchi
Keyword(s):  
Fault Zone ◽  
Velocity Structure ◽  
Seismic Velocity ◽  
Earthquake Rupture ◽  
2016 Kumamoto Earthquake ◽  
Seismic Velocity Structure ◽  
Kumamoto Earthquake ◽  
Seismogenic Layer ◽  
The 2016 Kumamoto Earthquake ◽  
Tectonic Line

Abstract The earthquake rupture termination mechanism and size of the ruptured area are crucial parameters for earthquake magnitude estimations and seismic hazard assessments. The 2016 Mw 7.0 Kumamoto Earthquake, central Kyushu, Japan, ruptured a 34-km-long area along previously recognized active faults, eastern part of the Futagawa fault zone and northernmost part of the Hinagu fault zone. Many researchers have suggested that a magma chamber under Aso Volcano terminated the eastward rupture. However, the termination mechanism of the southward rupture has remained unclear. Here, we conduct a local seismic tomographic inversion using a dense temporary seismic network to detail the seismic velocity structure around the southern termination of the rupture. The compressional-wave velocity (Vp) results and compressional- to shear-wave velocity (Vp/Vs) structure indicate several E–W- and ENE–WSW-trending zonal anomalies in the upper to middle crust. These zonal anomalies may reflect regional geological structures that follow the same trends as the Oita–Kumamoto Tectonic Line and Usuki–Yatsushiro Tectonic Line. While the 2016 Kumamoto Earthquake rupture mainly propagated through a low-Vp/Vs area (1.62–1.74) along the Hinagu fault zone, the southern termination of the earthquake at the focal depth of the mainshock is adjacent to a 3-km-diameter high-Vp/Vs body. There is a rapid 5-km step in the depth of the seismogenic layer across the E–W-trending velocity boundary between the low- and high-Vp/Vs areas that corresponds well with the Rokkoku Tectonic Line; this geological boundary is the likely cause of the dislocation of the seismogenic layer because it is intruded by serpentinite veins. A possible factor in the southern rupture termination of the 2016 Kumamoto Earthquake is the existence of a high-Vp/Vs body in the direction of southern rupture propagation. The provided details of this inhomogeneous barrier, which are inferred from the seismic velocity structures, may improve future seismic hazard assessments for a complex fault system composed of multiple segments.

Thermal Imaging of the Lithosphere beneath Arabian Shield and Implications for "Harrats" Volcanic Field

2021 ◽  
Author(s):  
Mohamed Sobh ◽  
Khaled Zahran ◽  
Nils Holzrichter ◽  
Christian Gerhards
Keyword(s):  
Red Sea ◽  
Seismic Velocity ◽  
Volcanic Field ◽  
Arabian Plate ◽  
Thickness Variation ◽  
Arabian Shield ◽  
Lithospheric Thickness ◽  
Lithospheric Thinning ◽  
Red Sea Rift ◽  
Seismic Swarms

<p><span>Widespread Cenozoic volcanisms in the Arabian shield including “Harrats” have been referring to lithospheric thinning and/or mantle plume activity as a result of Red Sea rift-related extension.</span></p><p><span>A fundamental key in understanding the deriving mechanism of these volcanic activities and its relationship to 2007-2009 seismic swarms required a reliable model of the present-day lithospheric thermo-chemical structure.</span></p><p><span>In this work, we modeled crustal and lithospheric thickness variation as well as the variations in thermal, composition, seismic velocity, and density of the lithosphere beneath the Arabian shield within a thermodynamically self - consistent framework.</span></p><p><span>The resulting thermal and density structures show large variations, revealing strong asymmetry between the Arabian shield and Arabian platform within the Arabian Plate.</span></p><p><span>We model negative density anomalies associated with the hot mantle beneath Harrats, which coincides with the modelled lithosphere thinned (~ 65 km) as a result of the second stage of lithospheric thinning following the initial Red Sea extension.</span></p>

Seismic velocity structure and gravity anomalies: a comparison

1987 ◽  
Vol 140 (1) ◽  
pp. 115-120
Author(s):  
Yoshibumi Tomoda ◽  
Hiromi Fujimoto
Keyword(s):  
Velocity Structure ◽  
Seismic Velocity ◽  
Gravity Anomalies ◽  
Seismic Velocity Structure
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