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The 2019 MW6.9 Banten Intraslab earthquake occurred at ∼100 km to the northeast of the Sunda Trench with two nodal plane models estimated by the Global Centroid-Moment-Tensor (GCMT) Project with a strike of 200° and a dip of 65°.Continuous GPS data from 11 GPS sites were used to model the source of the earthquake in three-components. The coseismic displacements and its uncertainties are obtained from the coordinates of these GPS sites from 7 days before to 7 days after the earthquake. The coseismic slip is the inversion result of those displacements based on the best fit in an elastic half-space. The maximum displacement is ∼5 cm with a large uncertainty that is comparable to the amplitude of displacement. A seismic moment of the best model (strike of 65° and dip of 54°) is 2.79 × 1019 Nm or equivalent to MW6.89. The fault model of the earthquake is highly presumed as a continuation of Sumatran Fault Zone.

Nowadays, satellite technology has developed significantly. Geodesy satellites such as Grace and Grace-FO can be used for subsurface mapping. The mapping is in the form of detection of the plate details, faults, and regional geodynamic conditions. This study aims to detect plate and faults from space geodesy using the gravity disturbance and Bouguer gravity anomaly parameter. The study area is in the Sunda Strait. Gravity disturbance is one of the gravity model parameters. Gravity disturbance is the gravitational potential of the topography expressed by the spherical harmonic model and the topographic effect by Barthelmes's calculations. Gravity disturbance can visualize subsurface conditions. Bouguer gravity anomaly is needed to get the condition on subsurface objects. This parameter visualizes subsurface conditions in the form of rocks and non-rocks. These conditions can distinguish oceanic crust and continental crust. Gravity contours are needed to obtain plate and faults predictions. The results obtained are validated patterns and shapes with plate and faults secondary data. The tolerance used in this validation is 80%. The gravity disturbance parameter obtained a value of 83% in verifying the accuracy of assessment in plate and faults detection. The Bouguer gravity disturbance parameter obtained a verification value of accuracy assessment in plate detection but 65% in faults detection. This accuracy assessment uses pattern and texture parameters in detecting the similarity of two or more images. This plate and faults detection results are more detailed and can be used for geophysical, geological, earthquake, and earth dynamics applications.

Raffles Bulletin of Zoology, Supplement 36, 95-100

Raffles Bulletin of Zoology, Supplement 36, 17-22

Raffles Bulletin of Zoology, Supplement 36, 451-468

Lane, David J.W., Vimono, Indra B. (2020): Two new species of sea star (Asteroidea, Echinodermata) from mesopelagic depths in the Sunda Strait, Indonesia. Raffles Bulletin of Zoology 68: 662-669, DOI: 10.26107/RBZ-2020-0081

DOI: 10.17014/ijog.7.2.135-159 Tangkil and Rajabasa Volcanoes are neighbouring subduction-zone volcanoes located on the southeast tip of Sumatra Island (Sunda Strait, Indonesia). Stratigraphic correlation of lavas in Tangkil-Rajabasa volcanic area was established from field observations, morphological analysis, and K-Ar dating analysis. Detailed petrography and geochemical data of two and eleven lava units from Tangkil and Rajabasa, respectively, were then integrated with the stratigraphy to show the temporal variations. Early stage (> 4.3 Ma) effusives of Tangkil Volcano are dacitic to rhyolitic (67-71 wt. % SiO2; Tklf), whereas the later (c. 4.3 Ma) rocks are basalt to basaltic andesite (c. 52 wt. % SiO2; Tklm). Tangkil shows bimodal magmatism, of which the felsic endmember is > 71 wt. % SiO2 and < 0.1 wt. % MgO. Lavas of Rajabasa Volcano are comparatively younger (c. 0.3 to 0.1 Ma) with compositions ranging from basalt to andesite (51-62 wt. % SiO2; Rbs). Chemical variations of Rajabasa accounts for the interactions of at least three endmembers: Mg-rich medium-K basalt magma, low-Mg medium-K basalt magma, and high-K andesitic magma. During the long evolution of Rbs magma system, the temporal chemistry shows rising-falling variation in SiO2 and MgO indicating the three magmas were active. The felsic endmember magma of Rajabasa is fixed in composition (at ~62 wt. % SiO2; ~2.2 wt. % MgO). The rocks from the last Tklf and Rbs indicate open system processes by containing plagioclase and pyroxene phenocrysts that show resorption of evolved core and overgrowth of less evolved mantle. The multiple zones of dissolution-overgrowth in plagioclase crystals and the fluctuating trend in temporal whole-rock variation suggest that the changes of magmatic condition in temperature, H2O, or chemical composition were repetitive.

This research was to analyze the reproduction biology of the goldband goatfish in the Sunda Strait as a reference for appropriate and sustainable management. Sampling was collected from April to August 2015. The samples from Sunda Strait were obtained from the fisherman yielded in the Coastal Fishing Port Labuan, Pandeglang, Banten Province. The sample was analyzed in Fisheries Biology Laboratory, Aquatic Resources Management Department, Fisheries and Marine Science Faculty, Bogor Agricultural University. Fish samples were measured, weighed and dissected, then morphologically observed for the reproductive organs. Samples obtained during the research were 811 specimen with the total length of 82-219 mm. Sex ratio among females and males were 1.5:1. The size at first maturity of females and males were 124 mm and 120 mm, respectively. Females were dominated by gonad maturity stage III and I, while for males dominated by gonad maturity stage I and II. Based on the composition of the TKG and IKG values each month, spawning season of the goldband goatfish in the Sunda Strait occurred in April and August. Fecundity obtained ranged 955-59.356 eggs with partial spawning type.

Eastern little tuna is small pelagic fish that has high economic value. Fishing effort of the eastern little tuna for the last eight years have also exceeded the optimum level. To ensure the sustainability of the pelagic fish resources, it is necessary to perform the management efforts. This study was to observe reproductive Biology of the eastern little tuna, as one of the necessary information in the management of fishery resources. Fish -samples were collected from the catch of local fishermen in April-August 2015. Based on T test (α = 0,05), the eastern little tuna males and females showed positive allometric growth patterns. Average size of the first time caught fish for the female (308,37 mm) and male (280,63 mm) was smaller than that observed in those first time maturity gonads (ranging 407-408 mm for female and 438-440 mm for male). The eastern little tuna spawn gradually or partially (partial spawner), and have high reproductive potential with fecundity ranged 17.814-560.792 eggs (average fecundity: 109.807) in fish of 285-630 mm body length. The gonad maturity level of the eastern Little Tuna is dominated by Gonad maturity level I and II,(immature). The value of gonad maturity for the female level is about 0,0769-0,6879 and the male is 0,1913-0,3000.

The poverty reduction indicator in SDGs also includes small-scale fisheries community groups. Small-scale fisheries’ poverty can be measured by income, expenditure, and income, converted to minimum living consumption and village welfare standards. These research aims to study of fisherman income, and welfare level as an indicator of poverty status. The research was conducted at the fisheries landing port in the Sunda Strait during 2019 to collect fisheries data covering production, operational cost, and household expenditure costs. The results showed that most ship crew fishers and ship captains (74%) were poor. Only 26% of the fishermen lived in no poverty status; however, all fishermen classified as high and medium welfare levels from the welfare indicator. Reducing poverty status (period 2020-2030) to be null (zero poverty) should be gradual with a yearly target. According to SDGs target, it needs comprehensive efforts to reduce poverty within ten years, with an average reduction of 7% per year until 2030. It means the government should implement the fishermen’s poverty reduction as part of the national development target.

The energy from marine environment has not been explored to the fullest, while the needs of energy in Indonesia have increased. Therefore, studying the potential of wind, currents, tides and wave energy might be the solution for building new power plants in Indonesia. This study focused around the area of Sunda Strait and the measurements that are taken from the secondary data of satellite images. From the satellite data processing and references based on energy potential of marine power plants it can be concluded that wave and wind energies are the two energies that are potential to be used.

The coastal and offshore areas around the Sunda Strait will be developed to be a submarine cable corridor connecting between Java and Sumatra Islands. There are some requirements that should be considered before laying the underwater cables. One of these considerations is to understand the seafloor morphology of the Sunda Strait. The study was conducted based on six of track lines with 1 km line spacing and 4 Cross lines. The water depth obtained then was corrected to the depth of water from the Lowest Water Level (LWL). The seabed condition in the near shore area of Sumatra side is very flat and is influenced by 2 km offshore tide activity. The coast line is characterized by mangrove and fine fraction of sediments (mud and clay). At the Java side, the coastal morphology is characterized by the very steep slope and most of the area is occupied by the industrial activities. Keywords: seafloor morphology, under water cables, Sunda Strait Area pantai dan perairan Selat Sunda akan dikembangkan sebagai bagian dalam penempatan kabel bawah laut yang menghubungkan Pulau Jawa dan Pulau Sumatera. Rencana penempatan kabel bawah laut ini membutuhkan beberapa persyaratan teknis yang harus dipertimbangkan. Salah satu pertimbangan untuk peletakan kabel bawah laut adalah memahami morfologi dasar laut selat Sunda. Penelitian dilakukan berdasarkan 6 lintasan pemeruman dengan jarak antar lintasan 1 km, dan 4 lintasan memotong lintasan utama. Kedalaman laut yang diperoleh kemudian dikoreksi dengan muka laut terendah. Kondisi permukaan dasar laut di sisi pantai Sumatra sangat datar serta sejauh 2 km ke arah laut lepas masih dipengaruhi oleh aktifitas pasang surut. Garis pantainya dicirikan oleh tanaman bakau dan fraksi sedimen halus (lumpur dan lempung). Pada sisi Jawa, morfologi pantai dicirikan oleh kemiringan lereng yang curam dan kebanyakan area ditempati oleh aktivitas industri. Kata kunci: morfologi dasar laut, kabel bawah laut, Selat Sunda

Tongkol komo/kawakawa (Euthynnus affinis) and tenggiri (Scomberomerus guttatus) are commonly caught by mini purseiners operated in Sunda Straits and landed in Labuan, West Java. This species inhabits coastal water and has preference staying in relatively warm water. Oceanography parameters commonly influencing the distribution of Euthynnus affinis are temperature, current, and salinity. The oceanography of Sunda Strait is influenced by water masses coming from the north that mainly originated from the Java Sea and water masses from the south mainly originated from Indian Ocean. The internal oceanography of Sunda Strait is also influenced by upwelling and monsoon as regional climate anomaly (ENSO and Indian Ocean Dipole Mode). This paper describes the influence of Dipole Mode (positive and negative event) and ENSO (El- Nino/La-Nina) to the catch dynamics of neritic tuna particularly in Sunda Straits waters. The results shown that regional climate anomaly influenced neritic tuna catch and its composition. The catches Euthynnus affinis in phase negative dipole mode or La-Nina were higher and dominated the catch composition of pelagic fishes of Sunda Strait. Similar situation also is showen by Scomberomorus commerson.