scholarly journals SUBMARINE LANDSLIDE AND LOCALIZED TSUNAMI POTENTIALITY OF MENTAWAI BASIN, SUMATRA, INDONESIA

2016 ◽  
Vol 23 (1) ◽  
pp. 1
Author(s):  
Haryadi Permana ◽  
C. Singh
Keyword(s):  
Active Faults ◽  
Submarine Landslide ◽  
Great Earthquake ◽  
Seismic Reflection Data ◽  
Seafloor Morphology ◽  
Swath Bathymetry ◽  
Reflection Data ◽  
Different Depths ◽  
Landslide Tsunami ◽  
Mentawai Island

The new bathymetry and seismic data were acquired during the PreTI-Gap marine survey (February 15 to March 6, 2008). The survey was carried out along the NE margin of Mentawai Island using multi-beam swath bathymetry equipment, and 28-channels seismic streamer and four-airgun source. The first target was the Mega Island region near the epicenter of the 2007 great earthquake. The shallow bathymetry is characterized as a flat coral platform suggesting that 200 km elongated plateau is slowly subsiding without any active faults. Further north, from South Pagai to North of Siberut Islands, the seafloor morphology changes significantly. The deep and wide canyons or valleys produce very rough seafloor morphology between 50 and 1100 m water. In general, the submarine topography shows two break slopes at different depths. Between slope breaks, the undulating, hilly and circular features dominate, possibly caused by landslides. A push-up ridge is observed that dams the sediments eroded within a steep slope northeastward side. The seismic reflection data acquired along 14 dip seismic lines at the NE flank of Mentawai Islands, from Siberut to the South of Pagai Islands. We observed a set of southwestward dipping back thrust bounding the NE margin of the Mentawai Island. Keywords: submarine landslide, tsunami, Mentawai basin, Sumatra. Data batimetri dan seismik baru telah dihasilkan selama survey kelautan PreTi-Gap (15 Februari hingga 6 Maret 2008). Survei dilaksanakan sepanjang tepian timurlaut P. Mentawai menggunakan peralatan multibeam, seismic saluran ganda 28 kanal dengan sumber energi airgun. Sasaran pertama adalah memetakan kawasan pulau dekat pusat gempa tahun 2007. Kenampakan batimetri dangkal dicirikan dengan adanya dataran terumbu karang yang secara perlahan mengalami penurunan tanpa aktifitas sesar. Lebih jauh ke Utar, dari Pagai Selatan ke utara P. Siberut, morfologi dasar laut memperlihatkan perubahan secara signifikan, dimana lembah dasar laut memiliki lebar dan beda kedalaman antara 50 hingga 1100 meter. Secara umum, topografi dasar laut memperlihatkan dua kemiringan pada kedalaman yang berbeda dengan dicirikan adanya kenampakan perlipatan, perbukitan dan bentuk yang melingkar diperkirakan sebagai hasil gelinciran. Sebanyak 14 line data seismik refleksi pada sayap bagian timurlaut P. Mentawai, dari Siberut hingga ke selatan P. Pagai memperlihatkan adanya bukti sesar naik yang miring ke arah baratdaya yang masih satu set dengan tepian timurlaut P. Mentawai. Kata kunci: longsoran bawah laut, tsunami, Cekungan Mentawai, Sumatra.

Submarine landslide origin of a tsunami at the Black Sea coast: Evidence based on swath bathymetry and 3D seismic reflection data

2021 ◽  
pp. 1-34
Author(s):  
Ilya Tishchenko ◽  
Gabor Tari ◽  
Mohammad Fallah ◽  
Jonathan Floodpage
Keyword(s):  
Numerical Modeling ◽  
Black Sea ◽  
Water Depth ◽  
Seismic Reflection ◽  
Submarine Landslide ◽  
Data Sets ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
Swath Bathymetry ◽  
Reflection Data

Tsunami waves were observed along the Bulgarian Black Sea coastline on May 7, 2007. The maximum rise and fall of the sea-level were 1.2 versus 2.0 m, respectively, with wave oscillations between 4-8 minutes. At first submarine landsliding and then later on atmospheric disturbance were suggested as the cause of the tsunami. Numerical modeling by Gusev et al. (2019), assuming a landslide displacing 30 to 60 million m3 material on the slope with a thickness range of over 20-40 m, could produce similar characteristics of the recorded tsunami. In the recent model the landslide initiated on the shelf at a water depth of 100 m with a runout of about 20 km into 1000 m water depth. Subsequent and recent numerical modeling suggested that the failure may have initiated on the slope, anywhere between 200 to 1500 m seafloor depth. The runout of the transported sediments in these latest model was at 1850 m water depth. Just a few years after the tsunami, OMV and its joint venture partners, TOTAL and Repsol, acquired modern deepwater data sets in the same area where the submarine landsliding was assumed to occur. These data sets included multi-beam swath bathymetry area and acquisition of a 3D reflection seismic data. These data sets offer a possibility to establish the presence of speculative submarine landslide responsible for the tsunami, with its geometry and nature. Our results provide direct evidence for the occurrence of large, non-seismic, catastrophic sediment failures along the Bulgarian coast. In this study we illustrate Quaternary submarine landslides on 3D seismic reflection data immediately below than the one responsible for the 2007 event, besides we also briefly point out the potential interpretation pitfall related to sediment waves and mass transport complexes.

Modelling the 1929 Grand Banks slump and landslide tsunami

2018 ◽  
Vol 477 (1) ◽  
pp. 315-331 ◽  
Author(s):  
Finn Løvholt ◽  
Irena Schulten ◽  
David Mosher ◽  
Carl Harbitz ◽  
Sebastian Krastel
Keyword(s):  
Large Mass ◽  
Seismic Reflection Data ◽  
Tsunami Modelling ◽  
Grand Banks ◽  
Sediment Volume ◽  
Reflection Data ◽  
Translational Landslide ◽  
New Information ◽  
Sediment Mass ◽  
Landslide Tsunami

AbstractOn 18 November 1929, an Mw 7.2 earthquake occurred south of Newfoundland, displacing >100 km3 of sediment volume that evolved into a turbidity current. The resulting tsunami was recorded across the Atlantic and caused fatalities in Newfoundland. This tsunami is attributed to sediment mass failure because no seafloor displacement due to the earthquake has been observed. No major headscarp, single evacuation area nor large mass transport deposit has been observed and it is still unclear how the tsunami was generated. There have been few previous attempts to model the tsunami and none of these match the observations. Recently acquired seismic reflection data suggest that rotational slumping of a thick sediment mass may have occurred, causing seafloor displacements up to 100 m in height. We used this new information to construct a tsunamigenic slump source and also carried out simulations assuming a translational landslide. The slump source produced sufficiently large waves to explain the high tsunami run-ups observed in Newfoundland and the translational landslide was needed to explain the long waves observed in the far field. However, more analysis is needed to derive a coherent model that more closely combines geological and geophysical observations with landslide and tsunami modelling.

scholarly journals Active and recent deformation at the Southern Alps – Ligurian basin junction

2001 ◽  
Vol 80 (3-4) ◽  
pp. 255-272 ◽  
Author(s):  
C. Larroque ◽  
N. Béthoux ◽  
E. Calais ◽  
F. Courboulex ◽  
A. Deschamps ◽  
...  
Keyword(s):  
Western Europe ◽  
Active Faults ◽  
Southern Alps ◽  
Historical Seismicity ◽  
Data Set ◽  
Seismic Reflection Data ◽  
Geological Evidence ◽  
Reflection Data ◽  
Rate Versus ◽  
Ligurian Basin

AbstractThe Southern Alps – Ligurian basin junction is one of the most active seismic areas in Western Europe countries. The topographic and the structural setting of this region is complex because of (i) its position between the high topography of the Southern Alps and the deep, narrow Ligurian oceanic basin, and (ii) the large number of structures inherited from the Alpine orogeny. Historical seismicity reveals about twenty moderate-size earthquakes (up to M=6.0), mostly distributed along the Ligurian coast and the Vésubie valley. A recent geodetic experiment shows a significant strain rate during the last 50 years in the area between the Argentera massif and the Mediterranean coastline. Results of this experiment suggest a N-S shortening of about 2-4 mm/yr over the network, this shortening direction is consistent with the seismological (P-axes of earthquakes) and the microtectonic data. The Pennic front (E-NE of the Argentera massif) and the northern Ligurian margin are the most seismically active areas. In the Nice arc and in the Argentera massif, some seismic lineaments correspond to faults identified in the field (such as theTaggia-Saorge fault or the Monaco-Sospel fault). In the western part of the Alpes Maritimes, no seismic activity is recorded in the Castellane arc. In the field, geological evidence, such as offsets of recent alluvial sediments, recent fault breccia, speleothem deformations, radon anomalies and others indicates recent deformation along these faults. Nevertheless, to this date active fault scarps have not been identified: this probably results from a relatively high erosion rate versus deformation rate and from the lack of Quaternary markers. We also suspect the presence of two hidden active faults, one in the lower Var valley (Nice city area) and the other one at the base of the Argentera crustal thrust-sheet. Offshore, along the northern Ligurian margin, the seismic reflection data shows traces of Quaternary extensional deformation, but the accuracy of the data does not yet allow the construction of a structural map nor does it allow the determination of the continuity between the offshore and onshore structures. From these data set we propose a preliminary map of 11 active faults and we discuss the questions which remain unsolved in the perspective of seismic hazard evaluations.

scholarly journals Review of Submarine Landslides in the Eastern Indonesia Region

2019 ◽  
Vol 34 (2) ◽  
Author(s):  
Hananto Kurnio ◽  
Tommy Naibaho ◽  
Catur Purwanto
Keyword(s):  
Seismic Reflection ◽  
Submarine Landslide ◽  
Submarine Landslides ◽  
Seismic Reflection Data ◽  
Bathymetric Data ◽  
Eastern Indonesia ◽  
Reflection Data ◽  
Common Process ◽  
Historical Times ◽  
Active Volcanoes

his paper reviews submarine landslide potential in the eastern Indonesia by analyzing published and recently acquired bathymetric data and interpreting seismic reflection data. This review aims to study and invent hazards that might affect seafloor infrastructure construction such as optic cables, especially in the eastern Indonesia Region. The hazards were also recognized as source of tsunamis such as Palu Bay 2018 and Babi Island north of Flores Island in 1992. On the other hand, submarine landslide is a common process of basin fill sedimentation in the region. As blessed with many active volcanoes, it has 130 of total the world 400, Indonesia should aware of tsunami induced by volcanoes especially the ones closed to the sea. There are five active volcanoes frequently produce tsunami in historical times: Anak Krakatau, Sunda Strait; Makian, Maluku Province; Sangihe, Sulawesi; Teon and Nila, Banda Sea; and Iliwerung, Lembata Island, east Lesser Sunda Islands.Key words: submarine landslide, volcanic tsunami, seafloor infrastructure, eastern Indonesia Makalah ini menelaah potensi langsoran dasar laut di wilayah Timur Indonesia melalui analisis publikasi dan data batimetri yang baru diambil serta penafsiran data seismic refleksi. Tinjauan longsoran dasar laut dimaksudkan untuk mempelajari dan menginventarisasi bencana yang mungkin bisa mempengaruhi pembangunan infrastruktur dasar laut seperti halnya kabel optic, terutama di wilayah Timur Indonesia. Bencana tersebut telah dikenal sebagai sumber beberapa tsunami seperti Teluk Palu 2018 dan Pulau Babi utara Lombok di tahun 1992. Sebaliknya, longsoran dasar laut merupakan proses sedimentasi pengisian cekungan yang biasa terjadi di wilayah tersebut. Dikarunia akan gunungapi terbanyak di dunia, sebab memiliki 130 dari 400 dunia, Indonesia harus menyadari bahaya tsunami yang ditimbulkan oleh aktivitas gunungapi terutama yang dekat laut. Terdapat lima gunungapi aktif yang sering menghasilkan tsunami dalam sejarah: Anak Krakatau, Selat Sunda; Makian, Provinsi Maluku; Sangihe, Sulawesi; Teon dan Nila, Laut Banda; dan Iliwerung, Pulau Lembata, Nusa Tenggara Timur.Kata kunci: longsoran dasar laut, tsunami gunungapi, infrastruktur dasar laut, Wilayah Indonesia Timur

scholarly journals Timor Collision Front Segmentation Reveals Potential for Great Earthquakes in the Western Outer Banda Arc, Eastern Indonesia

2021 ◽  
Vol 9 ◽  
Author(s):  
Aurélie Coudurier-Curveur ◽  
Satish C. Singh ◽  
Ian Deighton
Keyword(s):  
Active Faults ◽  
Accretionary Prism ◽  
Historical Seismicity ◽  
Normal Faults ◽  
Seismic Reflection Data ◽  
Spatially Correlated ◽  
Eastern Indonesia ◽  
The North ◽  
Reflection Data ◽  
Banda Arc

In Eastern Indonesia, the western Outer Banda arc accommodates a part of the oblique Australian margin collision with Eurasia along the Timor Trough. Yet, unlike the Wetar and Alor thrusts of the Inner Banda arc in the north and the adjacent Java subduction zone in the west, both recent and historical seismicity along the Timor Trough are extremely low. This long-term seismic quiescence questions whether the Banda Arc collision front along the Timor Trough is actually fully locked or simply aseismic and raises major concerns on the possible occurrence of large magnitude and tsunamigenic earthquakes in this vulnerable and densely populated region. Here, we jointly analyze multibeam bathymetry and 2D seismic reflection data acquired along the Timor Trough to characterize the location, nature, and geometry of active faults. Discontinuous narrow folds forming a young accretionary prism at the base of the Timor wedge and spatially correlated outcropping normal faults on the bending northwest Australian shelf reveal two concurrent contrasting styles of deformation: underthrusting and frontal accretion. We find that those tectonic regimes and their associated seismic behaviors depend on 1) the thickness of the incoming and underthrusting Cenozoic sedimentary sequence, 2) the vergence of inherited normal faults developed within the continental shelf, and 3) the depth of the décollement beneath the Timor wedge. Based on the along-strike, interchanging distinct deformation style, we identify the mechanical and seismic segmentation along the Banda arc collision front and discuss the implications for earthquake and tsunami hazards along the western Outer Banda arc region.

scholarly journals The 2018 Mw7.5 Palu ‘supershear’ earthquake ruptures geological fault's multi-segment separated by large bends: Results from integrating field measurements, LiDAR, swath bathymetry, and seismic-reflection data

2020 ◽  
Author(s):  
Danny Hilman Natawidjaja ◽  
Mudrik R Daryono ◽  
Gegar Prasetya ◽  
Udrekh ◽  
Philip L-F Liu ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Field Measurements ◽  
Normal Faults ◽  
Fault Line ◽  
Seismic Reflection Data ◽  
Geological Fault ◽  
Swath Bathymetry ◽  
Reflection Data ◽  
Earthquake Ruptures ◽  
Surface Ruptures

Summary On 28 September 2018, 18:02:44 local time, the Magnitude 7.5 earthquake accompanied by a tsunami and massive liquefaction devastated Palu region in Central Sulawesi, Indonesia. Comprehensive post-disaster surveys have been conducted, including field survey of surface ruptures, LiDAR, multibeam-bathymetry mapping, and seismic-reflection survey. We used these data to map fault ruptures and measure offsets accurately. In contrast to previous remote-sensing studies, suggesting that the earthquake broke an immature, hidden-unknown fault inland, our research shows that it occurred on the mappable, mature geological fault line offshore. The quake ruptured 177-km long multi-fault segments, bypassing two large releasing bends (first offshore and second inland). The rupture onset occurred at a large fault discontinuity underwater in a transition zone from regional extensional to compressional tectonic regimes. Then it propagated southward along the ∼110-km submarine fault line before reaching the west side of Palu City. Hence, its long submarine ruptures might trigger massive underwater landslides and significantly contribute to tsunami generation in Palu Bay. The rupture continued inland for another 67 km, showing predominantly left-lateral strike-slip up to 6-m, accompanied by a 5–10% dip-slip on average. The 7km sizeable releasing bend results in a pull-apart Palu basin. Numerous normal faults occur along the eastern margin. They cut the Quaternary sediments, and some of them ruptured during the 2018 event. Our fault-rupture map on mature straight geological fault lines allows the possible occurrence of early and persistent ‘supershear’, but significant asperities and barriers on segment boundaries may prohibit it.

Neotectonic activity in Lake Sils (Engadine, Switzerland) as trigger of tsunamigenic delta collapses?

2021 ◽  
Author(s):  
Stefano C. Fabbri ◽  
Valentin Nigg ◽  
Benjamin Bellwald ◽  
Katrina Kremer ◽  
Flavio S. Anselmetti
Keyword(s):  
High Resolution ◽  
Driving Mechanism ◽  
Seismic Reflection Data ◽  
Swath Bathymetry ◽  
Bathymetric Data ◽  
Reflection Data ◽  
Tectonic Zones ◽  
Tectonic Element ◽  
Lake Floor ◽  
Run Up

<p>Tsunamigenic delta collapses in lacustrine environments are still poorly understood phenomena in terms of their recurrence rate, driving mechanism and hazard potential. A partial collapse of the Isola Delta in Lake Sils (Engadine, Switzerland) with an estimated depositional volume of at least 6.5 million m<sup>3</sup> is radiocarbon-dated to 548-797 cal CE and may represent a typical tsunamigenic delta collapse in the Alpine environment. Recent studies propose that this basin-wide tsunami with a run-up height of 2–3 m and an inundation distance of 200 m at the lakeshore highlights the importance to better understand these processes and the associated hazards. The collapse was likely triggered by a strong regional earthquake responsible for several simultaneously triggered mass movements in nearby Lake Silvaplana and Lake Como. Increasingly available datasets from Lake Sils (short cores, high-resolution seismic reflection data, numerical tsunami simulations) are now complemented by multibeam swath bathymetry, providing a high-resolution (1 m grid) model of the lake floor that offers new insights into the failed slope masses, and post-failure basin morphology.</p><p>Lake Sils is located in the Upper Engadine in southeastern Switzerland at ~1800 m above sea level and has four major sub-basins (Maloja, Central, Sils & Lagrev Basins). A major tectonic element is the Engadine Fault Line (EFL), an oblique sinistral strike-slip fault that runs along the entire Upper Engadine valley. Its influence on the subaqueous morphology of the Maloja Basin in Lake Sils is expressed in the form of several localized troughs and ridges. It is suspected that the fault also cross-cuts the Isola Delta, possibly causing renewed delta failures in case of reactivation. In fact, recent studies have indicated that there is strong evidence for Quaternary left-lateral transcurrent faulting of the EFL, e.g. offsetting a river gully in the Forno Valley close to Lake Sils.</p><p>New bathymetric data from Lake Sils and their morphologic interpretations indicate subaquaeous slope failures, the extent of the Isola Delta collapse, and several trough-ridge features within the southwestern Maloja Basin. The latter are possibly indicative of ongoing faulting in the region since such features strongly suggest rhomboidal pull-apart basins within the Maloja Basin along the EFL. In general, such localized troughs within a lacustrine system are expected to level-out over time due to higher sedimentation rates in preferentially deeper regions of the lake. This study thus highlights the use of high-resolution bathymetric data in identifying the combined effects of deep-seated tectonic zones with shallow lake-floor processes, providing new insights into lacustrine hazard studies.</p>

scholarly journals Morphology, structure, and kinematics of the San Clemente and Catalina faults based on high-resolution marine geophysical data, southern California Inner Continental Borderland (USA)

Geosphere ◽  
2020 ◽  
Vol 16 (5) ◽  
pp. 1312-1335
Author(s):  
Maureen A.L. Walton ◽  
Daniel S. Brothers ◽  
James E. Conrad ◽  
Katherine L. Maier ◽  
Emily C. Roland ◽  
...  
Keyword(s):  
High Resolution ◽  
Southern California ◽  
Active Faults ◽  
Plate Boundary ◽  
Vertical Component ◽  
Slip Rates ◽  
Seismic Reflection Data ◽  
The North ◽  
Reflection Data ◽  
Show Evidence

Abstract Catalina Basin, located within the southern California Inner Continental Borderland (ICB), United States, is traversed by two active submerged fault systems that are part of the broader North America–Pacific plate boundary: the San Clemente fault (along with a prominent splay, the Kimki fault) and the Catalina fault. Previous studies have suggested that the San Clemente fault (SCF) may be accommodating up to half of the ∼8 mm/yr right-lateral slip distributed across the ICB between San Clemente Island and the mainland coast, and that the Catalina fault (CF) acts as a significant restraining bend in the larger transform system. Here, we provide new high-resolution geophysical constraints on the seabed morphology, deformation history, and kinematics of the active faults in and on the margins of Catalina Basin. We significantly revise SCF mapping and describe a discrete releasing bend that corresponds with lows in gravity and magnetic anomalies, as well as a connection between the SCF and the Santa Cruz fault to the north. Subsurface seismic-reflection data show evidence for a vertical SCF with significant lateral offsets, while the CF exhibits lesser cumulative deformation with a vertical component indicated by folding adjacent to the CF. Geodetic data are consistent with SCF right-lateral slip rates as high as ∼3.6 mm/yr and transpressional convergence of <1.5 mm/yr accommodated along the CF. The Quaternary strands of the SCF and CF consistently cut across Miocene and Pliocene structures, suggesting generation of basin and ridge morphology in a previous tectonic environment that has been overprinted by Quaternary transpression. Some inherited crustal fabrics, especially thinned crust and localized, relatively hard crustal blocks, appear to have had a strong influence on the geometry of the main trace of the SCF, whereas inherited faults and other structures (e.g., the Catalina Ridge) appear to have minimal influence on the geometry of active faults in the ICB.

scholarly journals New evidence for a major late Quaternary submarine landslide on the external western levee of Laurentian Fan

2018 ◽  
Vol 477 (1) ◽  
pp. 377-387 ◽  
Author(s):  
Alexandre Normandeau ◽  
D. Calvin Campbell ◽  
David J. W. Piper ◽  
Kimberley A. Jenner
Keyword(s):  
Debris Flow ◽  
North Atlantic ◽  
Late Quaternary ◽  
Rare Event ◽  
Horizontal Resolution ◽  
Submarine Landslide ◽  
Seismic Reflection Data ◽  
Submarine Fans ◽  
The North ◽  
Reflection Data

AbstractThe Laurentian Fan is one of the largest submarine fans on the western margin of the North Atlantic. Recently acquired high-resolution multibeam bathymetric data (60 m horizontal resolution) reveal a major mass-transport deposit (MTD) on the Western Levee of Western Valley (WLWV), covering >14 000 km2 in water depths from 3900 to >5000 m. Typical submarine landslide features are observed such as headscarps that in places reach the crest of the levee, crown cracks, extensional ridges, blocky debris and flow lineations. Multiple headwalls are observed on 3.5 kHz sub-bottom profiles, indicating that the landslide retrogressed upslope. While the upper parts of the MTD consist of intact blocks that were displaced downslope as ridges and troughs, the lower parts exhibit a c. 30 m thick incoherent to transparent acoustic facies, typical of debris flows. Landslide geomorphology therefore suggests that it was generated as a retrogressive spread and that slide blocks disintegrated downslope to become a blocky landslide with a surficial debris flow. The blocky landslide/debris flow extends downslope c. 90 km and partially fills a submarine channel. The superposition of the MTD filling the channel and its location at the top of the stratigraphic succession in the levee suggests that it is late Quaternary in age, possibly Holocene. Deeper seismic reflection data also show that this is a rare event during the Quaternary; it is the largest MTD observed in the upper c. 375 m of the levee succession and among the largest and deepest in the western North Atlantic.

scholarly journals Substrate Entrainment, Depositional Relief, and Sediment Capture: Impact of a Submarine Landslide on Flow Process and Sediment Supply

2021 ◽  
Vol 9 ◽  
Author(s):  
A. Martínez-Doñate ◽  
A. M-L. J. Privat ◽  
D. M. Hodgson ◽  
C. A-L. Jackson ◽  
I. A. Kane ◽  
...  
Keyword(s):  
Large Scale ◽  
Submarine Landslide ◽  
Sediment Supply ◽  
Submarine Landslides ◽  
Dispersal Patterns ◽  
Flow Process ◽  
Seismic Reflection Data ◽  
Growth Strata ◽  
Reflection Data ◽  
Stratal Architecture

Submarine landslides can generate complicated patterns of seafloor relief that influence subsequent flow behaviour and sediment dispersal patterns. In subsurface studies, the term mass transport deposits (MTDs) is commonly used and covers a range of processes and resultant deposits. While the large-scale morphology of submarine landslide deposits can be resolved in seismic reflection data, the nature of their upper surface and its impact on both facies distributions and stratal architecture of overlying deposits is rarely resolvable. However, field-based studies often allow a more detailed characterisation of the deposit. The early post-rift Middle Jurassic deep-water succession of the Los Molles Formation is exceptionally well-exposed along a dip-orientated WSW-ENE outcrop belt in the Chacay Melehue depocentre, Neuquén Basin, Argentina. We correlate 27 sedimentary logs constrained by marker beds to document the sedimentology and architecture of a >47 m thick and at least 9.6 km long debrite, which contains two different types of megaclasts. The debrite overlies ramps and steps, indicating erosion and substrate entrainment. Two distinct sandstone-dominated units overlie the debrite. The lower sandstone unit is characterised by: 1) abrupt thickness changes, wedging and progressive rotation of laminae in sandstone beds associated with growth strata; and 2) detached sandstone load balls within the underlying debrite. The combination of these features suggests syn-sedimentary foundering processes due to density instabilities at the top of the fluid-saturated mud-rich debrite. The debrite relief controlled the spatial distribution of foundered sandstones. The upper sandstone unit is characterised by thin-bedded deposits, locally overlain by medium-to thick-bedded lobe axis/off-axis deposits. The thin-beds show local thinning and onlapping onto the debrite, where it develops its highest relief. Facies distributions and stacking patterns record the progradation of submarine lobes and their complex interaction with long-lived debrite-related topography. The emplacement of a kilometre-scale debrite in an otherwise mud-rich basinal setting and accumulation of overlying sand-rich deposits suggests a genetic link between the mass-wasting event and transient coarse clastic sediment supply to an otherwise sand-starved part of the basin. Therefore, submarine landslides demonstrably impact the routing and behaviour of subsequent sediment gravity flows, which must be considered when predicting facies distributions and palaeoenvironments above MTDs in subsurface datasets.

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