scholarly journals Slope failure repetition in active margin environments: Constraints from submarine landslides in the Hellenic fore arc, eastern Mediterranean

Author(s):  
Frank Strozyk ◽  
Michael Strasser ◽  
Annika Förster ◽  
Achim Kopf ◽  
Katrin Huhn
2018 ◽  
Vol 477 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Oded Katz ◽  
Yariv Hamiel

AbstractWe analysed here, for the first time, 278 small to medium earthquakes that have occurred since 1985 along a 200 km section of the Levant passive continental margins, offshore Israel. The earthquakes are spatially overlapping with numerous submarine landslides and thin-skinned salt-tectonic-related faults scarps, bisecting the continental slope. Thus, we focus on the genetic relationship between the earthquakes, the faults and the landslides.We found that a subgroup of 55 earthquakes is spatially overlapping with the marine extension of the Carmel Fault and thus might be of tectonic origin. A second subgroup, hosting approximately 130 earthquakes, is spatially overlapping with the longshore salt-tectonic-related submarine faults. However, due to the non-shallow focal depth of most of these earthquakes, salt tectonics was ruled out as their possible seismic origin. Thus, the seismic source for theanalysed earthquakes is yet to be revealed.We further found that the observed medium earthquakes (M > 4) have a calculated reoccurrence time of more than 10 years and they are capable of inducing submarine slope failure within the studied area. Hence, they might play a role in submarine mass-wasting processes along the studied continental slope, and must now be considered in future hazard analysis.


2019 ◽  
Vol 500 (1) ◽  
pp. 477-494 ◽  
Author(s):  
S. J. Watson ◽  
J. J. Mountjoy ◽  
G. J. Crutchley

AbstractSubmarine landslides occur on continental margins globally and can have devastating consequences for marine habitats, offshore infrastructure and coastal communities due to potential tsunamigenesis. Therefore, understanding landslide magnitude and distribution is central to marine and coastal hazard planning.We present the first submarine landslide database for the eastern margin of New Zealand comprising >2200 landslides occurring in water depths from c. 300–4000 m. Landslides are more prevalent and, on average, larger on the active margin compared with the passive margin. We attribute higher concentrations of landslides on the active margin to tectonic processes including uplift and oversteepening, faulting and seamount subduction. Submarine landslide scars are concentrated around canyon systems and close to canyon thalwegs. This suggests that not only does mass wasting play a major role in canyon evolution, but also that canyon-forming processes may provide preconditioning factors for slope failure.Results of this study offer unique insights into the spatial distribution, magnitude and morphology of submarine landslides across different geological settings, providing a better understanding of the causative factors for mass wasting in New Zealand and around the world.


2021 ◽  
Author(s):  
Philip Sedore ◽  
Alexandre Normandeau ◽  
Vittorio Maselli

<p>High-latitude fiords are susceptible to hazardous subaerial and submarine slope failures. Recent investigations have shown that past slope failures in fiords of Greenland and Alaska have generated devastating landslide induced tsunamis. Since coastal communities inhabit these high-latitude fiords, it is critical to understand the slope failure recurrence time, their distribution, potential triggers, and ability to generate tsunamis. In this study, we identified > 50 near-surface submarine landslides in Pangnirtung Fiord, eastern Baffin Island, Nunavut, using multibeam bathymetric and sub-bottom profiler data, along with sediment gravity-cores collected in 2019. Morphometric and morphological analyses, along with sedimentological analyses, were carried out on submarine landslide deposits to quantify their spatial and temporal distribution throughout the fiord and to evaluate the factors that may have triggered the slope failures.</p><p>Combining bathymetric with topographic data from unmanned aerial vehicle imagery, we found that most of these landslide deposits are relatively small (~ 0.08 km<sup>2</sup>) and are associated with outwash fans and steep fiord sidewalls. However, since most slope failure head scarps lie between the intertidal zone and ~30 m water depth, they could not be mapped, which makes it challenging to determine the triggers of the submarine slope failures. Radiocarbon dating reveals that most of these surficial landslide deposits are younger than 500 years old and that they were most likely triggered at different times. This finding highlights a high recurrence rate of slope failures within the fiord, suggesting that localised triggers are responsible for slope failures within the fiord, as opposed to widespread, seismically induced triggers which do not occur as frequently in the study area. In addition, the elongated morphology of the landslide deposits and the varying degrees of landslide deposit surface roughness supports localised point-source triggers. Since most landslides are associated with subaerial outwash fans and deltas, we suggest that triggers of these relatively frequent submarine landslides within Pangnirtung Fiord include rapid floodwater input, subaerial debris flows, and sea-ice loading during low tide.</p><p>This research shows that slope failures in a high-latitude fiord are affected by the interaction of numerous subaerial and submarine processes, leading us to speculate that a potential increase in the frequency of subaerial debris flows and river floods due to climate change may increase the recurrence of submarine landslides.<strong> </strong></p>


2021 ◽  
Vol 55 (1) ◽  
pp. 5-16
Author(s):  
Yongqiang Ge ◽  
Jiawang Chen ◽  
Chen Cao ◽  
Jiamin He ◽  
Yan Sheng ◽  
...  

AbstractSubmarine landslides in gas hydrate areas are a significant geo-hazard that can cause considerable damage. The processes and mechanism of submarine landslides caused by gas hydrate dissociation are not clearly understood. Therefore, we designed a micro-electro-mechanical systems (MEMS) accelerometer array to study and monitor the deep displacement of submarine landslides. The MEMS accelerometer array consists of several gravity acceleration-sensing units that are protected and positioned using a flexible circuit board and elastic steel tape, such that all the units are connected to an Inter-Integrated Circuit (IIC) communication bus. By sensing the three-axis tilt angles, the direction and magnitude of the displacement for a measurement unit can be calculated; then, the overall displacement of the array is calculated as the difference in the displacements from the initial values. To ensure the accuracy of the tilt angle and displacement calculation, the calibration and verification test of the single MEMS sensor and sensor array is conducted. The MEMS accelerometer array is verified with respect to its principle and arrangement by a laboratory physical model test, and the initial experimentation demonstrated the capacities of the monitoring system for collecting real-time and in-situ information about the dynamic process and propagation of slope failure.


2020 ◽  
Vol 20 (7) ◽  
pp. 2055-2065
Author(s):  
Adrien Poupardin ◽  
Eric Calais ◽  
Philippe Heinrich ◽  
Hélène Hébert ◽  
Mathieu Rodriguez ◽  
...  

Abstract. The devastating Mw 7.1 Haiti earthquake in 2010 was accompanied by local tsunamis that caused fatalities and damage to coastal infrastructure. Some were triggered by slope failures of river deltas in the close vicinity of the epicenter, while others, 30 to 50 km to the north across the Bay of Gonâve, are well explained by the reverse component of coseismic ground motion that accompanied this mostly strike-slip event. However, observations of run-up heights up to 2 m along the southern coast of the island at distances up to 100 km from the epicenter, as well as tide gauge and DART buoy records at distances up to 600 km from the epicenter, have not yet received an explanation. Here we demonstrate that these observations require a secondary source, most likely a submarine landslide. We identify a landslide scar 30 km from the epicenter off the southern coast of Haiti at a depth of 3500 m, where ground acceleration would have been sufficient to trigger slope failure in soft sediments. This candidate source, 2 km3 in volume, matches observations remarkably well assuming that the sediment collapse obeys a viscous flow with an initial apparent viscosity of 2×105 Pa s. Although that particular source cannot be proven to have been activated in 2010, our results add to a line of evidence that earthquake-triggered submarine landslides can cause significant tsunamis in areas of strike-slip tectonic regime.


2018 ◽  
Vol 477 (1) ◽  
pp. 85-106 ◽  
Author(s):  
H. Gary Greene ◽  
J. Vaughn Barrie ◽  
Daniel S. Brothers ◽  
James E. Conrad ◽  
Kim Conway ◽  
...  

AbstractMultibeam echosounder (MBES) images, 3.5 kHz seismic-reflection profiles and piston cores obtained along the southern Queen Charlotte Fault Zone are used to map and date mass-wasting events at this transform margin – a seismically active boundary that separates the Pacific Plate from the North American Plate. Whereas the upper continental slope adjacent to and east (upslope) of the fault zone offshore of the Haida Gwaii is heavily gullied, few large-sized submarine landslides in this area are observed in the MBES images. However, smaller submarine seafloor slides exist locally in areas where fluid flow appears to be occurring and large seafloor slides have recently been detected at the base of the steep continental slope just above its contact with the abyssal plain on the Queen Charlotte Terrace. In addition, along the subtle slope re-entrant area offshore of the Dixon Entrance shelf bathymetric data suggest that extensive mass wasting has occurred in the vicinity of an active mud volcano venting gas. We surmise that the relative lack of submarine slides along the upper slope in close proximity to the Queen Charlotte Fault Zone may be the result of seismic strengthening (compaction and cohesion) of a sediment-starved shelf and slope through multiple seismic events.


2020 ◽  
Author(s):  
Sally Watson ◽  
Joshu Mountjoy ◽  
Gareth Crutchley

<p>Submarine landslides occur on continental margins globally and can have devastating consequences for marine habitats, offshore infrastructure and coastal communities due to potential tsunamigenic consequences. Evaluation of the magnitude and distribution of submarine landslides is central to marine and coastal hazard planning. Despite this, there are few studies that comprehensively quantify the occurrence of submarine landslides on a margin-wide scale.</p><p> </p><p>We present the first margin-wide submarine landslide database along the eastern margin of New Zealand comprising >2200 landslide scars and associated mass-transport deposits. Analysis of submarine landslide distribution reveals 1) locations prone to mass-failure, 2) spatial patterns of landslide scale and occurrence, and 3) the potential preconditioning factors and triggers of mass wasting across different geologic settings.</p><p> </p><p>Submarine landslides are widespread on the eastern margin of New Zealand, occurring in water depths from ~300 m to ~4,000 m. Landslide scars and mass transport deposits are more prevalent, and on average larger, on the active margin, compared the passive margin. We attribute higher concentrations of landslides on the active margin to the prevalence of deforming thrust ridges, related to active margin processes including oversteepening, faulting and seamount subduction. Higher sediment supply on the northernmost active margin is also likely to be a key preconditioning factor resulting in the concentration of large landslides in this region.</p><p> </p><p>In general, submarine landslide scars are concentrated around canyon systems and close to canyon thalwegs. This suggests that not only does mass wasting play a major role in canyon evolution, but also that slope undercutting in canyons may be a fundamental preconditioning factor for slope failure.</p><p> </p><p>Results of this study offer unique insights into the spatial distribution, magnitude and morphology of submarine landslides across different geologic settings, providing a better understanding of the causative factors for mass wasting in New Zealand and around the world.</p><p> </p>


2021 ◽  
Author(s):  
Alexey Portnov ◽  
Kehua You ◽  
Peter Flemings ◽  
Ann Cook ◽  
Mahdi Heidari ◽  
...  

Abstract Submarine landslides are prevalent on the modern-day seafloor, yet an elusive problem is constraining the timing of slope failure. Herein, we present a novel technique for constraining the age of submarine landslides without sediment core dating. Underneath a submarine landslide in the Orca Basin, Gulf of Mexico, in 3D seismic data we map an irregular bottom simulating reflection (BSR), which mimics the geometry of the pre-slide seafloor rather than the modern bathymetry. Based on the observed BSR, we suggest that the gas hydrate stability zone (GHSZ) is currently adjusting to the post-slide sediment temperature perturbations. We apply transient conductive heat flow modeling to constrain the response of the GHSZ to the slope failure, which yields a most likely age of ~8 ka demonstrating that gas hydrate systems can respond to slope failures even on the millennia timescales. We also provide an analytical approach to rapidly determine the age of submarine slides at any location.


Author(s):  
Yongqiang Ge ◽  
Jiawang Chen ◽  
Chen Cao ◽  
Qiaoling Gao ◽  
Peihao Zhang ◽  
...  

Abstract Submarine landslides in gas hydrate areas are a significant geo-hazard that can cause considerable damage to offshore infrastructures, dramatically change the marine environment and seriously threaten human lives and property. Gas and gas hydrate disassociation was considered to be a main factor inducing submarine landslide. However, the processes and mechanism of submarine landslides caused by gas and gas hydrate dissociation are not clearly understood. Therefore, we design a Micro-Electro-Mechanical Systems (MEMS) accelerometer array to study and monitor the deep displacement of submarine landslides. The MEMS accelerometer array consists of several gravity acceleration-sensing units that are connected to an I2C-communication bus. By sensing the three-axis tilt angles, the direction and magnitude of the displacement for a measurement unit can be calculated. In the end, the laboratory model test was designed to verify the operation of the device in landslide monitoring, which demonstrated the capacities of the monitoring system for collecting real-time and in-situ information during the slope failure.


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