The CWP/SU: Seismic Un∗x package,

Stockwell, John W.

doi:10.1016/s0098-3004(98)00145-9

Cited by 191 publications

(114 citation statements)

References 4 publications

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“…Overall, our work presents for the first time observational evidence of crustal strain-dependent 410 serpentinisation in the Porcupine Basin Seismic Unix software package [Stockwell, 1999] were used in the preparation this manuscript. Step Iteration* Nrefr † Nrefl † tRMS-refr ‡ tRMS-refl ‡ tRMS-all ‡ χ …”

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confidence: 99%

Crustal strain-dependent serpentinisation in the Porcupine Basin, offshore Ireland

Prada

Watremez

Chen

et al. 2017

Earth and Planetary Science Letters

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15Mantle hydration (serpentinisation) at magma-poor rifted margins is thought to play a key role in 16 controlling the kinematics of low-angle faults and thus, hyperextension and crustal breakup. 17However, because geophysical data principally provide observations of the final structure of a margin, 18 little is known about the evolution of serpentinisation and how this governs tectonics during 19 hyperextension. Here we present new observational evidence on how crustal strain-dependent 20 serpentinisation influences hyperextension from rifting to possible crustal breakup along the axis of 21 the Porcupine Basin, offshore Ireland. We present three new P-wave seismic velocity models that 22show the seismic structure of the uppermost lithosphere and the geometry of the Moho across and 23 along the basin axis. We use neighbouring seismic reflection lines to our tomographic models to 24 estimate crustal stretching (βc) of ~2.5 in the north at 52.5 o N and > 10 in the south at 51.7 o N. These 25 values suggest that no crustal embrittlement occurred in the northernmost region, and that rifting may 26 have progressed to crustal breakup in the southern part of the study area. We observed a decrease in 27 mantle velocities across the basin axis from east to west. These variations occur in a region where βc 28 is within the range at which crustal embrittlement and serpentinisation are possible (βc 3-4). Across 29 the basin axis, the lowest seismic velocity in the mantle spatially coincides with the maximum amount 30 of crustal faulting, indicating fault-controlled mantle hydration. Mantle velocities also suggest that 31 2 the degree of serpentinisation, together with the amount of crustal faulting, increases southwards 32 along the basin axis. Seismic reflection lines show a major detachment fault surface that grows 33 southwards along the basin axis and is only visible where the inferred degree of serpentinisation is > 34 15 %. This observation is consistent with laboratory measurements that show that at this degree of 35 serpentinisation, mantle rocks are sufficiently weak to allow low-angle normal faulting. Based on 36 these results, we propose two alternative formation models for the Porcupine Basin. The first involves 37 a northward propagation of the hyperextension processes, while the second model suggests higher 38 extension rates in the centre of the basin than in the north. Both scenarios postulate that the amount 39 of crustal strain determines the extent and degree of serpentinisation, which eventually controls the 40 development of detachments faults with advanced stretching. 41 42 3

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confidence: 99%

Crustal strain-dependent serpentinisation in the Porcupine Basin, offshore Ireland

Prada

Watremez

Chen

et al. 2017

Earth and Planetary Science Letters

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“…The enveloped two way travel time series of 15 kHz backscatter strength data was exported to the SEG-Y format using the INNOMAR ISE software, and visualized by colour-coded echograms using the SEISMIC UNIX open source software (Stockwell 1999). The non-calibrated echosounder delivers dimensionless backscatter strength amplitude values σ which were corrected with a time varying gain to account for geometrical spreading and acoustic absorption.…”

Section: Methodsmentioning

confidence: 99%

Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection

et al. 2015

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This study reports an adaptation of a parametric echosounder system using 15 kHz as secondary frequency to investigate the angular response of sub-bottom backscatter strength of layered mud, providing a new method for enhanced acoustic detection of buried targets. Adaptions to achieve both vertical (0°) and non-vertical inclination (1-15°, 30°, 45°and 60°) comprise mechanical tilting of the acoustic transducer and electronic beam steering. Data were acquired at 18 m water depth at a study site characterized by a flat, muddy seafloor where a 0.1 m diameter power cable lies 1-2 m below the seafloor. Surveying the cable with vertical incidence revealed that the buried cable can hardly be discriminated against the backscatter strength of the layered mud. However, the backscatter strength of layered mud decreases strongly at >3±0.5°incidence and the layered mud echo pattern vanishes beyond 5°. As a consequence, the backscatter pattern of the buried cable is very pronounced in acoustic images gathered at 15°, 30°, 45°and 60°incidence. The size of the cable echo pattern increases linearly with incidence. These effects are attributed to reflection loss from layered mud at larger incidence and to the scattering of the 0.1 m diameter buried cable. Data analyses support the visual impression of superior detection of the cable with an up to 2.6-fold increase of the signal-to-noise ratio at 40°incidence compared to the vertical incidence case.

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“…The bin size of the final data volumes was 25× 25 cm. All processing as demonstrated here was done with Seismic Unix (Stockwell, 1999). Processing modules developed in the project are based on Seismic Unix.…”

Section: The Seamap-3d Seismic Acquisition Systemmentioning

confidence: 99%

Ultra-high-resolution marine 2D–3D seismic investigation of the Liman Tepe/Karantina Island archaeological site (Urla/Turkey)

Müller

Woelz

Ersoy

et al. 2009

Journal of Applied Geophysics

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2D and 3D high-resolution seismic investigations were performed on submerged coastal archaeological sites at Iskele and near to Karantina Island in the Bay of Izmir in western Turkey. Tectonic subsidence of the coastline has submerged a number of archaeological features associated with an important Early Bronze Archaic settlement (Liman Tepe) and the classical Ionian city of Clazomenae. Seismic surveys were focused on imaging of an Archaic harbour structure and other submerged Hellenistic and Roman architectural features. Seismic data were acquired with the SEAMAP-3D ultra-high-resolution 3D marine seismic acquisition system developed for detailed archaeological site investigation. A 2D reconnaissance survey was performed over a 2 km 2 area around Karantina Island to evaluate the seismic penetrability and to locate sites for further 3D investigation. This survey predominantly revealed marine sediment layers covering the local bedrock, which is characterized by scattering of seismic energy showing its rocky nature. Two ultra-high-resolution 3D seismic surveys were performed. The first covered a 350 m × 30 m area in the modern harbour targeting a prominent Archaic harbour structure. The second was acquired across a 120 m × 40 m area on the southeast shore of the Karantina Island close to a Roman architectural feature. The 3D surveys were acquired with nominal line spacings of 1 m, using a 8 × 4 pseudo-rigid hydrophone array and a Boomer source firing at 3 Hz shot frequency. Automated processing of the seismic data using a portable Linux cluster provided stacked 3D seismic volumes with 25 cm × 25 cm bin size on-site. The 3D seismic survey of the harbour clearly imaged the submerged Archaic structure and the underlying sediment sequence. The seismic time slices reveal two seismic anomalies (2-3 m in diameter) in the harbour basin sediments. The 3D surveys southeast of Karantina identified a thicker marine sediment sequence overlying steeply dipping bedrock reflectors. The sediment sequence records the rapid accumulation and progradation of the coastline following the construction the Alexander causeway linking the mainland with the island in 334 B.C.

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The CWP/SU: Seismic Un∗x package,

Cited by 191 publications

References 4 publications

Crustal strain-dependent serpentinisation in the Porcupine Basin, offshore Ireland

Crustal strain-dependent serpentinisation in the Porcupine Basin, offshore Ireland

Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection

Ultra-high-resolution marine 2D–3D seismic investigation of the Liman Tepe/Karantina Island archaeological site (Urla/Turkey)

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