Offshore Southern Research Articles

Multivariate Environmental Factors and Seasonal Spatial Dynamics Affecting the Phytoplankton Community in Yazhou Bay, South China Sea

This study investigated phytoplankton and water environmental factors in Yazhou Bay, South China Sea, during the winter, spring, and summer of 2023. It examined phytoplankton community structure, subgroup heterogeneity, and key environmental drivers. Phytoplankton abundance ranged from 0.08 to 14.30 × 10⁴ cells·L−1, with high concentrations in estuary and nearshore zones. In summer, currents carry phytoplankton offshore, with stratification leading to high sedimentation in southern offshore waters. RDA results indicated that in winter and spring, inorganic nitrogen mainly influences phytoplankton distribution, while silicate is the primary factor in summer. Although seasonal differences in total phytoplankton abundance are minimal, significant horizontal and vertical distribution variations exist. Diverse preferences of different phytoplankton species for temperature, salinity, nitrogen, and phosphorus result in high species diversity. The Shannon–Wiener diversity index (H′) averages 3.96 ± 0.09, and the Pielou evenness index (J) averages 0.82 ± 0.01. Dominant species include Pseudo-nitzschia pungens, Skeletonema costatum, and Rhizosolenia sinica. Influenced by external oceanic water masses, estuary input, and islands, phytoplankton subgroups show regional and seasonal variations. Despite recorded harmful algal blooms (HABs) in adjacent waters, Yazhou Bay’s high biodiversity and low cell density suggest a low HAB risk, though future risks due to climate change and human activities remain.

‘’Geological characterization of a potential CO2 storage play in the Gela offshore (southern Sicily) and the role of a gravitational slide’’

In a context where European policies mandating a 55% reduction in CO2 emissions by 2030, Carbon Capture Storage (CCS) presents a viable solution for achieving substantial emissions cuts. Identifying existing and new potential sites for CCS in offshore southern Sicily is crucial to meeting this goal.The Gela offshore region is predominantly characterized by the Gela Thrust System (GTS) and its associated Gela Foredeep (GF), a narrow (less than 20 km) and elongated (approximately 100–120 km) depozone that comprises the thicker Plio-Pleistocene sandy sediments of the offshore Sicilian sector. This area is covered by the Gela Slide, a 1500 km2 gravitational slide.The potential of Plio-Pleistocene clastic deposits in this regionfor CCS implementation has not been previously explored. In this study, we investigated a potential caprock-reservoir system covering around 840 km2 in the Gela offshore area. Our analysis involved interpreting key horizons from a dense grid of 2D seismic reflection profiles, conducting well-to-seismic tie analysis and developing a refined velocity model.The study reveals a promising storage play within the foredeep basin-filling deposits. This potential storage play consists of Lower Pleistocene foredeep turbidite sands of Sabbie di Irene Fm. (reservoir) and of the Middle-Upper Pleistocene pelitic deposits of the Argo Fm. (primary seal). Additionally, the basal shear level of the Gela Slide has been investigated as a potential secondary seal. Analyzing its extent, age, and interaction with the GTS offers valuable insights into the relationships between tectonics and sedimentation, which could lead to the identification of suitable sealing layers for CCS purposes.This study thus provided new data on the thickness, depth, facies and rock volumes of the main reservoir and seals, highlighting their potential suitability for CCS applications.

Characterization of sediment organic matter in the outer Yangtze River Estuary using stable isotopes, optical techniques, and FT-ICR-MS: Implications for the carbon burial mechanism

The burial of sediment organic matter (SOM) in the estuary and shelf plays an important role in the global carbon cycle. However, it is challenging to determine the source, composition, and burial of SOM in the coastal sea, especially at the molecular level. This was explored in the coastal area outside the largest Yangtze River of China with multiple techniques including elemental and stable isotopic analysis, absorption spectroscopy, fluorescence excitation-emission matrices coupled with parallel factor analysis (EEMs-PARAFAC), and ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The end-member mixing analysis based on δ13C and δ15N showed a dominance of marine contribution (up to 70%) at most stations while the terrestrial contribution increased to >55% nearshore in summer at a high fluvial sediment flux. This was consistent with the offshore decreasing humic-like C1 and C2, humification index (HIX), %lignin-like compounds, and %CHO but increasing tryptophan-like C3, biological index (BIX), %protein-like compounds, and %CHOS from EEMs-PARAFAC and FT-ICR-MS analysis. The %clay correlated positively with SOM content, HIX, %lignin-like compounds, O/C, and modified aromaticity index (AImod) but correlated negatively with %C3, H/C, and the relative abundance of labile formulas (MLBL), while %silt showed contrasting correlations. These results indicated the fine clay sediments adsorbed more humified, aromatic, oxygenated, and terrestrial compounds that were probably more resistant to biodegradation and thus had a higher burial efficiency than those on the silty sediments. Principal component analysis based on SOM indices further revealed different characteristics of SOM in the nearshore, northern offshore, and southern offshore regions, which were probably dependent on the delivery by local current systems. Overall, these findings contributed to unraveling the source and molecular composition of SOM associated with different grain size sediments and local current delivery, which are fundamental for understanding the factors underlying carbon burial in the complex coastal environment.

Surface carbonate dynamics in a temperate coastal system in the Northern Yellow Sea, China

The carbon sink/source in estuaries and coastal seas may have significant implications for regional climate change. This study investigated seawater carbon dioxide partial pressure (pCO2), aragonite saturation state (Ωarag), and related carbonate parameters in the Yalu River estuary and the adjacent Northern Yellow Sea, China, in September 2023. The results indicate that seawater pCO2 ranged from 261 to 1121 μatm, while Ωarag ranged from 0.49 to 3.34 in the study area. High pCO2 were observed in the estuarine and northwestern areas, whereas low pCO2 were found in the southern offshore area. In the estuarine area, high pCO2 levels were attributed to the input of diluted water from the Yalu River. In the southern areas, low pCO2 were a result of primary production, while community respiration played an important role in increasing seawater pCO2 in the northwestern area. On the other hand, seawater Ωarag was extremely low in the estuarine area, and greater than 1.5 in the southern offshore area. Ωarag in the study area was mainly controlled by water mixing and temperature. The study area acted as a source of atmospheric CO2 with an average air-sea CO2 flux of 6.2 mmol m−2d−1 in autumn, which was relatively high compared with other marginal seas. The high pCO2 and low Ωarag associated with diluted water inputs and community respiration could weaken the ability of coastal oceans to uptake CO2. Therefore, it is crucial to explore ways to reduce CO2 levels in riverine and adjacent coastal seas.

Cretaceous deposits of the northern part of the southern offshore Tanzania: depositional system, seismic manifestation, well data expressions and their implications on petroleum system elements

Cretaceous deposits of the northern part of the southern offshore Tanzania: depositional system, seismic manifestation, well data expressions and their implications on petroleum system elements

Salient Changes of Earth's Magnetic Field Toward the End of Cretaceous Normal Superchron (CNS)

AbstractChanges in Earth's magnetic field during the Cretaceous Normal Superchron (CNS) spanning ∼121 Ma to ∼84 Ma hold important clues about the geodynamo evolution. Canonical models predict a persistently strong geomagnetic field with low variability during CNS, which, however, has not been observed in the available absolute paleointensity data and seafloor marine magnetic anomaly (MMA) records. The lack of relative paleointensity (RPI) data across CNS further impedes tests of model predictions. Here, we present a ∼9‐Myr (∼94–∼85 Ma) RPI record from a Turonian to Santonian hemipelagic succession from IODP Site U1512 offshore southern Australia. Detailed paleomagnetic and rock magnetic analyses demonstrate that the ratio of natural remanent magnetization (NRM) demagnetized at 20 mT over magnetic susceptibility (MS), that is, NRM20mT/MS, as a reliable proxy for the RPI of the Upper Cretaceous succession. The new RPI record shows marked changes in both intensity and variability at ∼90.8 Ma. Also, the 6 Myr‐long (∼94–∼88 Ma), near‐continuous, ∼1.2 kyr‐resolution RPI record exhibits a strong positive correlation between field intensity and variability. Assuming this correlation holds for the entire CNS, an extrapolated RPI curve for the entire CNS is obtained by integrating the positive correlation with field variability estimates from the MMA data. The extrapolated RPI curve shows a strong and highly variable field in the middle CNS but a weak and stable field at its beginning and ending. These features imply a much more dynamic geodynamo than previously thought, and provide crucial benchmarks for unraveling the geodynamo evolution during CNS.

A Comprehensive Assessment of Submarine Landslides and Mass Wasting Processes Offshore Southern California

AbstractIt is critical to characterize submarine landslide hazards near dense coastal populations, especially in areas with active faults, which can trigger slope failure, subsequent tsunamis, and damage seabed infrastructure during earthquake shaking. Offshore southern California, numerous marine geophysical surveys have been conducted over the past decade, and high‐resolution bathymetric and subsurface data now cover about 60 percent of the total region between Point Conception and the United States‐Mexico border from the California coast out to the base of Patton Escarpment ∼200 km offshore. In a comprehensive compilation and interpretive mapping effort, we find evidence of seafloor failure throughout offshore southern California with nearly 1,500 submarine landslide‐related features, including 63 discrete slide deposits with debris and >1,400 slide‐related scarps. In our analysis, we highlight new mapping of submarine landslides in Catalina Basin, the Del Mar slide, the San Gabriel slide complex, and the 232 km2 San Nicolas slide, the largest area of any known submarine landslide mass offshore southern California. Analysis of the spatial distribution of submarine landslide features suggests that most mapped slide features are located relatively near coastal sediment sources, particularly during sea‐level lowstand conditions, which underscores the importance of sediment supply and sediment accumulation on low‐gradient slopes as failure preconditioning processes. Tectonically driven uplift at shelf edges and along basin flanks is another key preconditioning factor, and our results also suggest that earthquakes along active faults trigger mass wasting, especially for repeated, small‐scale failures on tectonically steepened slopes.

Tracing hotspot traces in the Andes

Two segments of subduction of the Nazca plate beneath the South American plate occur at low angles based on seismic hypocenter locations, approaching nearly horizontal below ~100 km in depth. In contrast with most of the rest of the subduction zone, the two segments, beneath central Chile, and central and northern Peru, lack active volcanoes along the crest of the Andes and have more subdued topography to the east of the Andean crest. Each low-angle subduction segment occurs to the east of the intersection of inferred mantle hotspot traces on the Nazca plate with the Peru-Chile Trench: the Nazca ridge (at the southern part of the Peruvian segment), and the Juan Fernández island-seamount chain (offshore the Chilean segment). A third inferred trace, the Galápagos-Carnegie ridge, may be correlated with a zone on incipient low-angle subduction beneath Colombia. 
 The importance of such hotspot traces in contributing to low-angle subduction beneath the Andes is strengthened by updated South American-Nazca plate reconstructions, including three oceanic hotspot traces, in comparison with a new isotopic date compilation of igneous rocks from the mountain range. The Juan Fernández hotspot trace, reconstructed from Pacific-hotspot models to the Nazca-Farallon plate, encountered the subduction zone offshore southern Peru ~65 Ma, broadening arc volcanism to the east; the trace-trench intersection migrated gradually and then rapidly southward, widening the arc east to Bolivia and northern Argentina; it then stabilized about 13 Ma offshore central Chile, producing the contemporary low-angle Pampean segment. The Juan Fernández hotspot may also have been responsible for formation of the Manihiki Plateau on the Pacific plate much earlier, ~125 Ma. The Easter-Nazca hotspot trace intersected the subduction zone beneath Colombia before ~50 Ma and migrated southward beneath Ecuador beginning ~15 Ma, with progressive low-angle subduction implied by migrating volcanic cessation along the Andean crest to southern Peru. The Galápagos-Carnegie hotspot trace only recently encountered the subduction zone, apparently inducing a new low-angle segment and cessation of magmatism in Colombia. The reconstructions and magmatic history provided here strongly support a previously proposed genetic relationship of hotspot traces and low-angle subduction. Additionally, the reconstructions suggest remnants of older subducted traces in the asthenosphere may have sourced post-rift magmatism in eastern Brazil and Paraguay, which cannot be explained otherwise by simple hotspot mechanisms.

Is the offshore southern Tanzanian Basin an atypical igneous-sedimentary petroleum system?

Is the offshore southern Tanzanian Basin an atypical igneous-sedimentary petroleum system?

Critical re-assessment of Middle and Late Miocene submarine fans in offshore southern and western Taranaki Basin, New Zealand, to update the paleogeography

The purpose of this paper is (i) to re-assess the presence of submarine fan systems of Middle and Late Miocene age (Moki and Mount Messenger formations) previously mapped on the continental slope in offshore southern and central Taranaki Basin, New Zealand, and (ii), to demonstrate the occurrence of two newly mapped Late Miocene submarine fans in the deep-water part of offshore western Taranaki Basin, based on accepted seismic stratigraphic criteria for submarine fans. In our work we have found that the fans previously mapped amongst canyons and channels in the Moki and Mount Messenger formations on the upper and middle continental slope in southern and central Taranaki Basin do not fulfil established stratal criteria for submarine fan deposits. Moreover, detuning of 3D seismic reflection volumes for the Moki and Mount Messenger formation intervals ahead of amplitude attribute extraction, shows that the strata previously mapped as submarine fans based on amplitude alone, are merely artifacts of bed thickness. The two new fans systems of Late Miocene age that we map here, both attributed to the Mount Messenger Formation, principally comprise mudstone and represent a minor proportion of the Late Miocene succession that accumulated in southern and central parts of the basin. Our remapping of slope canyons and channels in the southern part of the basin and the identification of the two new fan systems in the western part of the basin are embodied in three new paloegeographic maps for the Middle and Late Miocene development of Taranaki Basin. A modern analogue for the two new Late Miocene fans in Taranaki Basin is the Hikurangi Fan at the terminus of the Hikurangi Channel, located outboard of the modern subduction zone of the Hikurangi margin along Eastern North Island. The new Taranaki Basin deep-water fans documented here, may have significance for hydrocarbon exploration in deep water parts of Taranaki Basin, which is largely unexplored.

Tectonics and evolution of the Palmeiras and Xai-Xai Grabens, offshore southern Mozambique

The tectonic evolution of the Mozambique Basin was controlled by the break-up of Gondwana which led to the development of extensional domains along the East African margin. As a result, multiple grabens systems were formed both onshore and offshore southern Mozambique. Two of them are the Palmeiras and Xai-Xai grabens, which are discussed in greater details in this study using an extensive seismic dataset, together with regional gravity and magnetic data. The data show that the Palmeiras Graben evolved from a single extensional phase in the Middle to Late Jurassic (Kimmeridgian?). In contrast, the Xai-Xai Graben records three extensional phases. The first extensional phase occurred in the Late Jurassic (Tithonian?) to Early Cretaceous (Berriasian), the second during the Aptian-Albian and the third in the Late Miocene. The tectonic evolution of these grabens strongly controlled their sedimentary infill during Late Jurassic and Early Cretaceous rifting.Volcanism associated to these tectonic events is documented by onshore and offshore boreholes, as well as by the presence of buried volcanic bodies, lava extruded along fault planes and intrusions of Mesozoic age. Furthermore, a volcano-sedimentary sequence and dome type volcanoes were imaged in seismic data.Differences in tectonic activity impacted the oil and gas potential of both the Palmeiras and Xai-Xai grabens. The sedimentary sequences deposited in the Palmeiras Graben were preserved due to a period of relative tectonic stability predominating from the Aptian to the present day. The burial of the Palmeiras Graben during this period of tectonic stability under a thermal subsidence favoured the generation and preservation of hydrocarbons. In contrast, the Xai-Xai Graben was impacted by intense tectonics, which led to a limited or restricted deposition of strata since the Late Cretaceous to the Paleocene – Early Eocene. As a consequence of a long lasting tectonic activity in the Xai-Xai Graben, uplifting and erosion of potential reservoirs and destruction of existing traps, impacted on the prospectivity for hydrocarbons.

Wind and Solar Energy Generation Potential Features in the Extreme Northern Amazon Using Reanalysis Data

This article examines the potential for wind and solar energy generation in the state of Amapá, Brazil, using ERA5 data from between 1991 and 2020. Key metrics considered include wind power density, capacity factor, photovoltaic potential, and concentrated solar power output. Analyses revealed pronounced wind speeds offshore during summer and in continental regions during spring. Solar irradiance was notably higher in the spring. Differences in wind potential were observed between northern and southern offshore areas. Concentrated solar power efficiency and photovoltaic potential were influenced by location and cloud cover, respectively. Overall, summer presents the best offshore wind energy potential, while spring is optimal for onshore solar energy in Amapá. This study underscores the importance of understanding local climatic patterns when planning energy installations in the region.

CASIE21-OBS: An Open-Access, OBS Controlled-Source Seismic Data Set for Investigating the Structure and Properties of the Cascadia Accretionary Wedge and the Downgoing Explorer-Juan de Fuca-Gorda Plate System

Abstract Geological processes at subduction zones and their associated geohazards (e.g., megathrust earthquakes, submarine landslides, tsunamis, and arc volcanism) are, to a large extent, controlled by the structure, physical properties and fluid content of the subducting plate, the accreted sediments, and the overriding plate. In these settings, modern seismic modeling and imaging techniques based on controlled-source, multicomponent ocean-bottom seismometer (OBS) data are some of the best tools available for determining the subseafloor elastic properties, which can be linked to the aforementioned properties. Here, we present CASIE21-OBS, a controlled-source marine wide-angle OBS data set recently collected across the Cascadia convergent margin as part of the larger CAscadia Seismic Imaging Experiment 2021 (CASIE21). The main component of CASIE21 is a long-offset multichannel seismic (MCS) survey of the Cascadia margin conducted in June–July 2021 onboard R/V M.G. Langseth (cruise MGL2104) aiming to characterize the incoming plate, the plate interface geometry and properties, and the overlying sediment stratigraphy and physical properties. CASIE21-OBS was conducted during R/V M.G. Langseth cruise MGL2103 (May 2021) and R/V Oceanus cruise OC2106A (June–July 2021). It consisted of 63 short-period four-component OBSs deployed at a total 120 stations along 10 across-trench profiles extending from ∼50 km seaward of the deformation front to the continental shelf, and from offshore northern Vancouver Island to offshore southern Oregon. The OBSs recorded the airgun signals of the CASIE21-MCS survey as well as natural seismicity occurring during the deployment period (24 May 2021 19:00 UTC–9 July 2021 09:00 UTC). The OBS data are archived and available at the Incorporated Research Institutions for Seismology Data Management Center under network code YR_2021 for continuous time series (miniSEED) and identifier 21-008 for assembled data set (SEG-Y).

A processing for ocean-bottom multicomponent data with seismic interferometry: a case study of southern offshore in Korea

Marine seismic surveys are widely used to explore oil and gas resources and monitor CO2 storage. In particular, ocean-bottom seismic surveys allow the acquisition of high-quality data without the influence of the water-layer environment. However, ocean-bottom seismic surveys are more expensive than streamer surveys and P-wave survey data exhibit free-surface multiples, which are persistent problems. PZ summation can be applied to process multicomponent ocean-bottom seismic data, which effectively reduces ghosting and water-layer reverberation by combining hydrophone and vertical geophone data. In this study, we processed and analysed ocean-bottom cable data from a shallow gas area offshore from Korea. In our field-survey simulation, PZ summation was applied to the synthetic data to separate up-going and down-going wavefields and attenuate free-surface multiples. In addition, improved image can be obtained compared to conventional stack section by applying seismic interferometry to the acquired up-going wavefield data.

Saltwater intrusion regulates the distribution and partitioning of heavy metals in water in a dynamic estuary, South China

The mixing processes of fresh-salt water in estuarine and coastal regions have a substantial impact on the characteristics of heavy metals. A study was conducted in the Pearl River Estuary (PRE), located in South China, to examine the distribution and partitioning of heavy metals and the factors that influence their presence. Results showed that the hydrodynamic force, caused by the landward intrusion of the salt wedge, was the major contributor to the aggregation of heavy metals in the northern and western PRE. Conversely, metals were diffused seaward at lower concentrations along the plume flow in surface water. The study found that some metals, including Fe, Mn, Zn and Pb, were significantly higher in surface water than in bottom water in eastern waters, but the reverse was true in the southern offshore area, where limited mixing hindered the vertical transfer of metals in the water column. The partitioning coefficients (KD) of metals varied, with Fe exhibiting the highest KD (1038 ± 1093 L/g), followed by Zn (579 ± 482 L/g) and Mn (216 ± 224). The highest KD values of metals in surface water were observed in the west coast, while the highest KD in bottom water was found in eastern areas. Furthermore, re-suspension of sediment and the mixing of seawater and freshwater offshore, caused by seawater intrusion, resulted in the partitioning of Cu, Ni and Zn towards particulate phases in offshore waters. This study provides valuable insights into the migration and transformation of heavy metals in dynamic estuaries influenced by the interaction of freshwater and saltwater and highlights the importance of continued research in this field.

Earthquake Nowcasting: Retrospective Testing in Greece.

Earthquake nowcasting (EN) is a modern method of estimating seismic risk by evaluating the progress of the earthquake (EQ) cycle in fault systems. EN evaluation is based on a new concept of time, termed 'natural time'. EN employs natural time, and uniquely estimates seismic risk by means of the earthquake potential score (EPS), which has been found to have useful applications both regionally and globally. Amongst these applications, here we focused on Greece since 2019, for the estimation of the EPS for the largest-magnitude events, MW(USGS) ≥ 6, that occurred during our study period: for example, the MW= 6.0 WNW-of-Kissamos EQ on 27 November 2019, the MW= 6.5 off-shore Southern Crete EQ on 2 May 2020, the MW= 7.0 Samos EQ on 30 October 2020, the MW= 6.3 Tyrnavos EQ on 3 March 2021, the MW= 6.0 Arkalohorion Crete EQ on 27 September 2021, and the MW= 6.4 Sitia Crete EQ on 12 October 2021. The results are promising, and reveal that the EPS provides useful information on impending seismicity.

Thermal maturity modelling for the source rocks in blocks 10 and 11.1, Nam Con Son basin

Blocks 10 and 11.1 are located at the western boundary of the Nam Con Son basin, offshore southern Vietnam. Hydrocarbon shows have been encountered in many wells as the Gau Chua (GC), Ca Cho (CC), Gau Ngua (GN), Phi Ma (PM), Than Ma (TM), etc. In the CC and GN fields, the oil and gas were discovered in Miocene sandstone reservoirs and in fractured granite basement. The Cau and Dua formations are active source rocks in this area. Oil and gas discovered in wells were generated from coal and coaly claystone sediments which deposited under oxidation conditions to weak reducing in fluvio-delta to estuarine environments, in which land plants develop very abundantly. The 2D modeling results suggested that hydrocarbons discovered in the study area mainly derived from the local source rocks. The large quantity of hydrocarbons yields from source rocks in deeper part of southeastern kitchen migrated both vertically and laterally into the overlaying formations. Hydrocarbon strongly migrated lost through open fault. Prospects located near kitchen can trap hydrocarbons if they have a good seal. Block 10 and western block 11.1 face high risk of hydrocarbon charge due to the distance from the kitchen, weak top seal and fault seal. Of seal scenario, the composition of hydrocarbons accumulated in GC structure contains 87.5% volume of liquid and 12.5% volume of gas that derived from local Oligocene source rock. The composition of hydrocarbons in accumulation in CT (Ca Ty) structure of contains 99% volume of liquid and 92.5% volume of gas that derived from local Oligocene source rock.

Chemo stratigraphic Profile of a Reservoir in Well “X” of Field “Y” Offshore Southern Gabon

In a bid to evaluate the elemental and mineralogical content of reservoir samples from the “X” well in the “Y” oil field offshore Southern Gabon, analyses were performed using XRD and XRF. The log view profile of the result inferred that Na, Mg, and Calcite were absent in the shallower series of the reservoir sandstones studied, this observation implies that they are soluble ions that had eroded and refer to warm and humid paleoclimate and a depositional environment that is arid, which corresponds to the continental crust as their source. The plot of Ti and FeO+Mg discriminate the deeper series of the reservoir sandstone samples from the shallower samples. The lower series showed heavier values which implies their origin from Oceanic Crust. These are also the pre-salt facies while the shallower series were more of continental origin and represent the post-salt facies.

Tsunami scenario triggered by the activity of the Mentawai Fault Zone offshore western Sumatra Island

Subduction zones worldwide pose tsunami risks, mainly linked to megathrust activity near subduction trenches. However, tsunamis can originate from various sources, including marine volcanic eruptions, submarine landslides, and strike-slip earthquakes. In the Sumatra subduction zone, a seismic gap in the Mentawai region heightens the tsunami risk. This region’s tectonics are complex due to the oblique subduction of the India-Australia oceanic plate beneath the Eurasian continental plate, leading to the sliver faults system of Mentawai Fault Zone (MFZ) and Sumatra Fault Zone (SFZ). The SFZ on Sumatra Island has limited tsunami potential, except at its northern and southern offshore extensions. In contrast, the MFZ, situated in the marine Northern Bengkulu basin, holds a higher tsunami-generation potential. This study aims to assess the MFZ activity in generating tsunamis, estimate the maximum wave height, and analyze propagation, and arrival times at several crucial sites in Western Sumatra Province. We utilized the COMCOT tsunami model to simulate scenarios with two fault mechanisms, i.e., strike-slip and back thrust, and two magnitudes (Mw 7.6, and 8.2). The results indicate that the most hazardous tsunami, generated by a strike-slip fault with Mw 8.2, produces a 2-meter tsunami on the east coast of Siberut Island and the west coast of Padang City, West Sumatra. The scenarios reveal that Mentawai Island’s eastern part lacks evacuation time, with an almost instantaneous tsunami arrival. In contrast, western Sumatra, including Pariaman and Padang City, has 13 to 20 minutes for evacuation planning. Thus, disaster risk reduction strategies in these locations should consider these findings.

ASSESSMENT OF WIND ENERGY POTENTIAL IN THE BIEN DONG SEA USING CCMP SATELLITE DATA

This study assessesed the wind energy potential in the Bien Dong Sea by using the Cross-Calibrated Multi-Platform (CCMP) satellite wind data from 1991 to 2020. The results showed that the wind energy potential at 10 m height above ground is not high in the offshore areas with annual mean wind speeds ranging from 5 to 8 m/s. At heights of 100 m, 150 m, and 200 m, the greatest wind energy potential is found in the offshore areas of the North Bien Dong Sea Region, Binh Dinh - Ninh Thuan, Binh Thuan - Ca Mau, and the central part of the Gulf of Tonkin. Especially, the wind energy is quite high in the Sea of Ninh Thuan to Ba Ria - Vung Tau with annual mean wind speeds of 8 to 10 m/s, and the annual mean wind power density of 500 to 700 W/m2 at a height of 100 m. On the seasonal scale, the wind energy potential of January and October is greater than that of April and July for the orthern offshore areas while the wind energy potential of January is the greatest, followed by July and transition months for the southern offshore areas.