“…The available seismic data reveals that numerous landslides exist along the 109 °meridian fault area (Pham Nang Vu, 2009). Evidences can also be observed in other seismic profiles in Gwang and Watkins (1998), Fyhn et al (2009b), Tan et al (2014), Vu et al (2017). The 109 °meridian fault located in the western SCS belongs to a giant strike-slip fault system: Red River-Ailao fault system which runs through the west part of the South China Sea.…”
Section: Introductionmentioning
confidence: 66%
“…Although the slope has been subsequently adjusted and modified by sediment deposition, most of the slope gradient still maintains above 10 °. Moreover, the east coast of Vietnam is located in a tropical monsoon zone and has numerous montane rivers that drain the 10,350 km 2 range that extends most of the way down the Vietnam and reaches highest of 2,819 m (Souvignet et al, 2014;Tan et al, 2014). Holocene sedimentation rates on the offshore shelf of the Thu Bon River mouth are very high, ranging between 10.1 and 124.5 cm/ka (Schimanski and Stattegger, 2005).…”
Section: Geological History Of the Western Scsmentioning
The 109 meridian fault is located in the west of the South China Sea (SCS) connecting to the offshore Red River Shear Zone. Seismic data from the central Vietnamese shelf indicates that many submarine landslides were developed along the steep continental slope in this offshore region. Here, we analyze the potential for such landslides to trigger damaging tsunamis based on the local geological background and sedimentary environment. We assess their tsunamigenic potential along the coast of Southern Central Vietnam (SCV). We point out that the evolutionary processes of the 109° meridian fault: striking-subsidence of the adjacent basin, combined with the high sediment input from numerous montane rivers of the hinterland generate conditions that likely favor the development of submarine landslides along the well-defined and steep continental slope near SCV. To estimate the impact of tsunami waves on the SCV coastline, we conducted a pilot study using two numerical models: NHWAVE and FUNWAVE-TVD to model 4 representative landslides with volumes ranging between 1.3 and 14 km3 and water depth of 300–1000 m. The submarine landslides were treated as rigid slump and deformable slide corresponding to two different sedimentary environments. Our results show that the tsunami waves generated by rigid slump can reach up to 20 m height in the landslide source area and ∼5 m when arriving at the closest coastline. Tsunami waves could arrive at the central Vietnam coast within 30 min in eight scenarios. Our initial results also suggest that seafloor topography, i.e., waveguide effects of ocean ridges, shelf resonance and the potential bay resonance cause significant variability in potential run-up. We note that ocean ridges located in the deep basin of the SCS focus the tsunami energy propagating towards the northwest coast of Luzon Island, Philippines where tsunami wave heights of ∼2.3 m wave height are modeled. These findings underscore the importance of tsunami hazard assessments that account for both earthquake generated and earthquake triggered tsunamis. Our work also highlights a continued need to examine tsunami sources in the region as mitigation and preparedness for the socio-economically important and heavily populated coastlines of the SCS is reliant on a detailed understanding of the hazard.
“…The available seismic data reveals that numerous landslides exist along the 109 °meridian fault area (Pham Nang Vu, 2009). Evidences can also be observed in other seismic profiles in Gwang and Watkins (1998), Fyhn et al (2009b), Tan et al (2014), Vu et al (2017). The 109 °meridian fault located in the western SCS belongs to a giant strike-slip fault system: Red River-Ailao fault system which runs through the west part of the South China Sea.…”
Section: Introductionmentioning
confidence: 66%
“…Although the slope has been subsequently adjusted and modified by sediment deposition, most of the slope gradient still maintains above 10 °. Moreover, the east coast of Vietnam is located in a tropical monsoon zone and has numerous montane rivers that drain the 10,350 km 2 range that extends most of the way down the Vietnam and reaches highest of 2,819 m (Souvignet et al, 2014;Tan et al, 2014). Holocene sedimentation rates on the offshore shelf of the Thu Bon River mouth are very high, ranging between 10.1 and 124.5 cm/ka (Schimanski and Stattegger, 2005).…”
Section: Geological History Of the Western Scsmentioning
The 109 meridian fault is located in the west of the South China Sea (SCS) connecting to the offshore Red River Shear Zone. Seismic data from the central Vietnamese shelf indicates that many submarine landslides were developed along the steep continental slope in this offshore region. Here, we analyze the potential for such landslides to trigger damaging tsunamis based on the local geological background and sedimentary environment. We assess their tsunamigenic potential along the coast of Southern Central Vietnam (SCV). We point out that the evolutionary processes of the 109° meridian fault: striking-subsidence of the adjacent basin, combined with the high sediment input from numerous montane rivers of the hinterland generate conditions that likely favor the development of submarine landslides along the well-defined and steep continental slope near SCV. To estimate the impact of tsunami waves on the SCV coastline, we conducted a pilot study using two numerical models: NHWAVE and FUNWAVE-TVD to model 4 representative landslides with volumes ranging between 1.3 and 14 km3 and water depth of 300–1000 m. The submarine landslides were treated as rigid slump and deformable slide corresponding to two different sedimentary environments. Our results show that the tsunami waves generated by rigid slump can reach up to 20 m height in the landslide source area and ∼5 m when arriving at the closest coastline. Tsunami waves could arrive at the central Vietnam coast within 30 min in eight scenarios. Our initial results also suggest that seafloor topography, i.e., waveguide effects of ocean ridges, shelf resonance and the potential bay resonance cause significant variability in potential run-up. We note that ocean ridges located in the deep basin of the SCS focus the tsunami energy propagating towards the northwest coast of Luzon Island, Philippines where tsunami wave heights of ∼2.3 m wave height are modeled. These findings underscore the importance of tsunami hazard assessments that account for both earthquake generated and earthquake triggered tsunamis. Our work also highlights a continued need to examine tsunami sources in the region as mitigation and preparedness for the socio-economically important and heavily populated coastlines of the SCS is reliant on a detailed understanding of the hazard.
“…Studies of modern and late Pleistocene to Holocene stratigraphy of the shelf areas of central and southern Vietnam (Dung et al, 2013(Dung et al, , 2014Tan et al, 2014) have identified at least five major seismic units and three bounding surfaces that can be linked to known sealevel adjustments including relict beach-ridge deposits at water depths of about ~130 m below present that are associated with the last glacial lowstand. More importantly, in relation to understanding the processes by which sands became weathered and enriched in heavy minerals, studies (Bui et al, 2013; have noted an absence of falling stage systems tract deposits.…”
Heavy mineral rich sands along the coastal margin of southern Vietnam often contain commercial deposits of ilmenite and zircon but their origin is unknown.A multi-method approach based on petrology, geochemistry and detrital zircon geochronology was used to define the provenance and transport history of these mainly Quaternary sands. A trend of progressive enrichment of ilmenite TiO 2 content, from north to south, was observed. This reflects increased levels of weathering attributed to a wider coastal margin and shelf in the south combined with a succession of erosion and reburial events associated with interstadial and interglacial sea-level changes. Weathering took place during lowstands. Detrital zircon U-Pb age signatures collected from 25 major river outlets along the coast of Vietnam helped to locate potential sand sources. Prominent age groups spanning 90-120 Ma and 220-250 Ma with a minor group at 400-500 Ma are present in all of the detrital zircon U-Pb age distributions of contemporary beach sands and Quaternary coastal dune placer deposits. Proterozoic grains are also present but constitute < 10% of dated grains. The main source terrain for the placer sands is southern Vietnam where there are widespread outcrops of Mesozoic magmatic rocks. Detrital zircon U-Pb age signatures from river sands that drain this area are identical to zircon age distributions in placer sands. River sands from northern Vietnam, the Mekong and its delta contain abundant Paleozoic and Proterozoic zircons, which are largely absent from the placer sands, and so are ruled out as primary sources.
“…Formation of the delta – a part of a regional-scale Red River Pull-apart Basin was linked to the India-Eurasia collision and strike-slip motion along the Ailao Shan-Red River Shear Zone ( Hall, 1998 ; HutChison, 2014 ; S. Zahirovic, M.Seton, 2014 ), which have been started since the Eocene. The Quaternary sediments of the Red River Delta have evolved for ~1.9 million years of development, which have been controlled by 5 cycles of global sea level change, corresponding to 5 cycles of glacial/interglacial events (Gunz/G-M; Mindel/R–W1; Wurm1/W1–W2; Wurm2/W2- Flandrian Transgression) ( Nghi et al., 1991 ; Nghi and Toan, 1991 ; Tan et al., 2014 ). Figure 1 Location of the study area.…”
Section: Introductionmentioning
confidence: 99%
“…Zahirovic, M.Seton, 2014), which have been started since the Eocene. The Quaternary sediments of the Red River Delta have evolved for~1.9 million years of development, which have been controlled by 5 cycles of global sea level change, corresponding to 5 cycles of glacial/interglacial events (Gunz/G-M; Mindel/R-W1; Wurm1/W1-W2; Wurm2/W2-Flandrian Transgression) Tan et al, 2014).…”
The Red River Delta is considered one of the largest megadelta systems in Asia. The formation of this delta has been controlled by the continent-ocean interaction and sea-level fluctuation during the Cenozoic. In this study, we present a new sequence stratigraphic framework of the Red River Delta based on borehole lithofacies analysis and high resolution seismic data. The Late Pleistocene-Holocene sediments in the coastal zone of the Red River Delta were subdivided into three systems tracts: (1) the lowstand systems tract (LST) is characterized by a Late Pleistocene alluvial silty sand facies complex (arLSTQ 1 3b ); (2) the transgressive systems tract (TST) is illustrated by the coastal marsh facies complex and the lagoonal greenish-gray clay facies of Early-Middle Holocene (amt, mtTSTQ 2
1À2); and (3) the highstand systems tract (HST) is composed of the Middle-Late Holocene deltaic clayish silt facies complex (amhHSTQ 2
2À3). The boundaries between these three systems tracts are not isochronous, namely: (1) The LST-HST boundary has been associated with the Würm 2 Glaciation, which occurred at~40-18 Ka.; (2) The TST-LST boundary is identified by a transgressive erosion surface, whose age ranges from~12-5 Ka.; and (3) the HST-TST boundary is an unconformity between the submarine deltaic facies complex and the Middle Holocene marine flooding plain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
