Coexisting seismic behavior of transform faults revealed by high-resolution bathymetry

Geology ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 379-384
Author(s):  
G.E. Hilley ◽  
R.M. Sare ◽  
F. Aron ◽  
C.W. Baden ◽  
D.W. Caress ◽  
...  
Keyword(s):  
High Resolution ◽  
Gulf Of California ◽  
Slope Failure ◽  
Autonomous Underwater Vehicle ◽  
Transform Fault ◽  
Zone Structure ◽  
Transform Faults ◽  
Small Magnitude ◽  
Slip History ◽  
High Resolution Bathymetry

Abstract Transform faults have anomalously low rates of seismicity, but it’s not clear whether this reflects persistent earthquake-generating fault patches surrounded by creep, or the presence of creep and earthquakes at different times along the same patch. We use new, autonomous underwater vehicle high-resolution seafloor mapping to image the morphology of and offsets along transform fault segments in the Gulf of California, offshore Mexico. Fault zone structure imaged in this study shows evidence for the initiation and cessation of activity along individual fault splays over geologic time. A series of six identically offset depositional fans evidence 21–23 m of slip along the main transform fault, which could not have been produced by a single earthquake given the length of the transform. Rather, the lack of smaller-magnitude offsets indicates synchronous deposition and an absence of multiple slope failure–inducing earthquakes, which is consistent with the idea that creep and/or small-magnitude events occur asynchronously with large earthquakes in the slip history of a given transform fault segment.

A new Method for Fault-Scarp Detection Using Linear Discriminant Analysis (LDA) in High-Resolution Bathymetry Data From the Alarcón Rise and Pescadero Basin, Gulf of California.

2021 ◽  
Author(s):  
Luis Angel Vega Ramirez ◽  
Ronald Michael Splez Madero ◽  
Juan Contreras Perez ◽  
David Caress ◽  
David A. Clague ◽  
...  
Keyword(s):  
High Resolution ◽  
Gulf Of California ◽  
Autonomous Underwater Vehicle ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Fault Scarp ◽  
Fault Line ◽  
Cross Sectional ◽  
Linear Discriminant ◽  
Automated Method

<p>The mapping of faults and fractures is a problem of high relevance in Earth Sciences. However, their identification in digital elevation models is a time-consuming task given the resulting networks' fractal nature. The effort is especially challenging in submarine environments, given their inaccessibility and difficulty in collecting direct observations. Here, we propose a semi-automated method for detecting faults in high-resolution gridded bathymetry data (~1 m horizontal and ~0.2 m vertical) of the Pescadero Basin in the southern Gulf of California, which were collected by MBARI's D. Allan B autonomous underwater vehicle. This problem is well suited to be explored by machine learning and deep-learning methods. The method learns from a model trained to recognize fault-line scarps based on key morphological attributes in the neighboring Alarcón Rise. We use the product of the mass diffusion coefficient with time, scarp height, and root-mean-square error as training attributes. The method consists of projecting the attributes from a three-dimensional space to a one-dimensional space in which normal probability density functions are generated to classify faults. The LDA implementation results in various cross-sectional profiles along the Pescadero Basin show that the proposed method can detect fault-line scarps of different sizes and degradation stages. Moreover, the method is robust to moderate amounts of noise (i.e., random topography and data collection artifacts) and correctly handles different fault dip angles. Experiments show that both isolated and linkage fault configurations are detected and tracked reliably.</p>

Unraveling the Channel–Lobe Transition Zone With High-Resolution AUV Bathymetry: Navy Fan, Offshore Baja California, Mexico

2017 ◽  
Vol 87 (10) ◽  
pp. 1049-1059 ◽  
Author(s):  
Cristian Carvajal ◽  
Charles K. Paull ◽  
David W. Caress ◽  
Andrea Fildani ◽  
Eve Lundsten ◽  
...  
Keyword(s):  
High Resolution ◽  
Turbulent Flows ◽  
Deep Sea ◽  
Baja California ◽  
Autonomous Underwater Vehicle ◽  
Sediment Waves ◽  
Stratigraphic Architecture ◽  
Area North ◽  
High Resolution Bathymetry ◽  
Flow Stripping

Abstract:Ultra-high-resolution (1 m * 1 m * 0.25 m) bathymetry was acquired with an autonomous underwater vehicle (AUV) over a sector of the Navy Fan offshore Baja California. The survey specifically targeted an area where the former interpretation of the fan showed a channel–lobe transition; however, the lobe and the transition were not recognized. Instead, the newly acquired bathymetry shows that the previously identified channel continues basinward changing its overall morphology and stratigraphic architecture, becoming gradually but significantly wider (650–1000 m) and of lower relief (3–4 m). Cores from the channel thalweg recovered mud-poor (< 5%) well-sorted sands, interpreted as deposited by fully turbulent flows. The cores also show several mud-rich (9–18%) poorly sorted sands, probably indicating deposition from more cohesive flows.The high-resolution bathymetry shows large sectors of the seafloor sculpted by elaborate bedforms and scours. The overbank area north of the channel exhibits the most numerous and prominent scours, interpreted to have been largely generated by flow stripping at a bend in the channel. Along high-gradient sectors (more than approximately 1¯) of this area, the scours are largest and deepest. Some of these scours show an erosional headwall and a distal upflow-dipping depositional bulge, forming repetitive bedforms interpreted as erosional cyclic steps associated with locked-in-place trains of hydraulic jumps. The scours seem to coalesce to form an incipient channel, which would likely drive the avulsion of the main channel. Further basinward, average gradients decrease (< 0.6¯ ) and scours become smaller and less deep suggesting a gradient control on erosion. The southern channel margin and adjacent overbank area exhibit a trend of scours that are elongated transverse to flow, that successively repeat themselves basinwards, and that at times merge with sediment waves. Probably these scours are genetically linked to sediment waves, and they may have been formed by cyclic-step-like processes as well. The acquired bathymetry represents a breakthrough in the imaging of the proximal sectors of deep-sea fans, which provides the basis for an accurate morphometric characterization and the understanding of sedimentary processes and morphodynamics associated with the delivery of sediment into the deep sea.

scholarly journals e-Navigating in highly-constrained waters: a case study of the Vistula Lagoon

2021 ◽  
pp. 1-10
Author(s):  
Adam Weintrit ◽  
Jacek Pietraszkiewicz ◽  
Wiesław Piotrzkowski ◽  
Wojciech Tycholiz
Keyword(s):  
High Resolution ◽  
Global Solution ◽  
Transition Process ◽  
Practical Implementation ◽  
Vistula Lagoon ◽  
Digital Era ◽  
High Resolution Bathymetry ◽  
Marine Navigation ◽  
The Vistula Lagoon

Abstract In recent years the transition of marine navigation to the digital era has been gaining momentum. Implementation of e-Navigation solutions varies from country to country in terms of their priorities, goals, levels and effects. Maritime authorities in Poland have been setting the pace in this transition process, not only in Poland but also in general as a global solution. The most recent example is the planned deployment of a variety of e-Navigation tools in the Vistula Lagoon: from GNSS-RTK Ground-Based Augmentation System, to virtual and synthetic aids to navigation, high-resolution bathymetry and advanced navigational software for piloting. The major objectives of this paper are, first, to summarise recent dynamics in the e-Navigation field, and second, to present a practical implementation of the e-Navigation concept in the Vistula Lagoon area.

scholarly journals Development of a High-Resolution Underwater Gravity Measurement System Installed on an Autonomous Underwater Vehicle

2018 ◽  
Vol 15 (12) ◽  
pp. 1937-1941 ◽  
Author(s):  
Masanao Shinohara ◽  
Toshihiko Kanazawa ◽  
Hiromi Fujimoto ◽  
Takemi Ishihara ◽  
Tomoaki Yamada ◽  
...  
Keyword(s):  
High Resolution ◽  
Measurement System ◽  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Gravity Measurement
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