scholarly journals Java and Sumatra segments of the Sunda Trench: Geomorphology and geophysical settings analysed and visualized by GMT

2020 ◽  
Vol 100 (2) ◽  
pp. 1-23
Author(s):  
Polina Lemenkova
Keyword(s):  
Indian Ocean ◽  
Cross Section ◽  
Data Distribution ◽  
Shelf Area ◽  
Indonesian Archipelago ◽  
Geological Processes ◽  
Sumatra Island ◽  
Northern Side ◽  
The Indian Ocean ◽  
Two Peaks

The paper discusses the geomorphology of the Sunda Trench, an oceanic trench located in the eastern Indian Ocean along the Sumatra and Java Islands of the Indonesian archipelago. It analysis difference in depths and variation in slope steepness between the two segments of the trench: southern Java transect (108.8?E 10.10?S - 113.0?E 10.75?S) and northern Sumatra transect (97.5?E 1.1?S - 101.0?E 5.5?S). The maps and geomorphological modelling were plotted using Generic Mapping Tools (GMT). The data include high-resolution grids on topography, geology, geodesy and geophysics: GEBCO, EGM2008 EGM-2008, GlobSed. The results include modelled segments, slope gradients, and cross-section profiles. The geological processes take place in the Indian Ocean at different stages of its evolution and influence the nature of the submarine geomorphology and geomorphology of the trench that differs in two segments. Java segment has a bell-shaped data distribution in contrast to the Sumatra with bimodal pattern. Java segment has the most repetitive depths at -2,500 to -5,200 m. Sumatra transect has two peaks: 1) a classic bell-shaped peak (-4,500 m to -5,500 m); 2) shelf area (0 to -1,750 m). The data at middle depths (-1,750 to -4,500 m) have less than 300 samples. The most frequent bathymetry for the Sumatra segment corresponds to the -4,750 m to -5,000 m. Comparing to the Sumatra segment, the Java segment is deeper. For depths > -6,000 m, there are only 138 samples for Sumatra while 547 samples for Java. Furthermore, Java segment has a more symmetrical geometric shape while Sumatra segment is asymmetric, one-sided. The Sumatra segment has a steepness of 57.86? on its eastern side (facing Sumatra Island) and a contrasting 14.58? on the western part. The Java segment has a steepness of 64.34? on its northern side (facing Java Island) and 24.95? on the southern part (facing the Indian Ocean). The paper contributes to the studies of the submarine geomorphology in Indonesia.

scholarly journals Analysis of the difference in depths and variation in slope steepness of the Sunda Trench, Indonesia, east Indian Ocean

2020 ◽  
Vol 22 (1) ◽  
pp. 21-41
Author(s):  
Polina Lemenkova
Keyword(s):  
Indian Ocean ◽  
Geometric Shape ◽  
Shelf Area ◽  
High Resolution Data ◽  
East Indian ◽  
Slope Steepness ◽  
Indonesian Archipelago ◽  
Geological Processes ◽  
The Pacific ◽  
The Difference

The paper discusses geomorphology of the Sunda Trench, an oceanic trench located in eastern Indian Ocean along the Sumatra and Java Islands of the Indonesian archipelago. In particular, it analysis the difference in depths and variation in slope steepness between the two segments of the trench: the southern Java transect (coordinates 108.8°E 10.10°S to 113.0°E 10.75°S) and the northern Sumatra transect (97.5°E 1.1°S to 101.0°E 5.5°S). The thematic maps and geomorphological modelling were plotted using Generic Mapping Tools (GMT). The materials include high-resolution data on topography, geology and geophysics: GEBCO 15 arc-minute resolution grid, EGM2008 2.5 minute Earth Gravitation Model of 2008, GlobSed global 5‐arc‐minute total sediment thickness and vector geological datasets. In addition to the GEBCO-based bathymetric data, geological, topographic and geophysical maps, the results include enlarged transects for the Java and Sumatra segments, their slope gradients and cross-section profiles, derived from the bathymetric GEBCO dataset. The geomorphology framework of the Sunda Trench is largely controlled by the subduction of the Australian plate underneath the Sunda microplate. The geological processes take place in basin of the Indian Ocean at different stages of its evolution and influence the nature of the submarine geomorphology and geometric shape of the trench. Sunda Trench is seismically active part of the Pacific Ring of Fire. A large number of the catastrophic earthquakes are recorded around the trench. The histograms shows variation in depths along the segments of the Sumatra and Java. The Java segment has a bell-shaped data distribution in contrast to the Sumatra with bimodal pattern. The Java segment has the most repetitive depths at -2,500 to -5,200 m. The Sumatra transect has two peaks: 1) a classic bell-shaped peak at depths -4,500 m to -5,500 m; 2) shelf area with a peak from 0 to -1,750 m. The data at middle depths (-1,750 to -4,500 m) have a frequency <300 samples. The most frequent bathymetry for the Sumatra segment corresponds to the -4,750 m to -5,000 m (2,151 samples). Comparing to the Sumatra segment, the Java segment is deeper. For the depths >-6,000 m, there are only 138 samples for the Sumatra while 547 samples for Java. Furthermore, Java segment has more symmetrical geometric shape while Sumatra segment is asymmetric, one-sided. The Sumatra segment has a steepness of 57.86° on its eastern side (facing Sumatra Island) and a contrasting 14.58° on the western part. The Java segment has a steepness of 64.34° on its northern side (facing Java Island) and 24.95° on the southern part (facing Indian Ocean). The paper contributes to the studies of the submarine geomorphology in Indonesia.

scholarly journals Slave Trade and Slavery in Asia—New Perspectives

2020 ◽  
Vol 54 (1) ◽  
pp. 1-14
Author(s):  
Titas Chakraborty ◽  
Matthias van Rossum
Keyword(s):  
Indian Ocean ◽  
Slave Trade ◽  
Global Perspective ◽  
Special Issue ◽  
Local Character ◽  
Indonesian Archipelago ◽  
Long Time ◽  
History Of ◽  
The Indian Ocean ◽  
Different Parts

Abstract Recent years have witnessed an expanding body of scholarship indicating the importance of slave trade and slavery in different parts of the Indian Ocean and Indonesian archipelago worlds. This work has not only challenged the dominant focus of slavery scholarship on the Atlantic context but has also encouraged scholars to reassess wider perspectives on Asian and global social histories. This special issue brings together contributions that explore these new horizons. Together, they take up the issue of slavery and mobility in different parts of the Indian Ocean and Indonesian archipelago worlds from a comparative perspective, dealing not only with the existence and patterns of slave trade itself but also with its social and sociopolitical implications. These articles require us to rethink some of the dominant perspectives in a historiography that for a long time has emphasized the unique and local character of “Asian” slaveries, positing dichotomies between slavery in the Atlantic and elsewhere, as well as between Western and non-Western slaveries. The contributions to this special issue challenge several of these existing dichotomies and provide new contributions to the understanding of the role and importance of slavery from a global perspective, as well as to the history of the Indian Ocean and Indonesian archipelago worlds. This introduction reflects on this collective contribution and aims to provide an outline for a relevant research agenda.

Sailing Ships, Naval Expeditions and ‘Project Mausam’

2020 ◽  
Vol 76 (3) ◽  
pp. 411-424 ◽  
Author(s):  
Himanshu Prabha Ray
Keyword(s):  
Nineteenth Century ◽  
Indian Ocean ◽  
Interdisciplinary Research ◽  
Underwater Archaeology ◽  
Practical Training ◽  
Indonesian Archipelago ◽  
The World ◽  
The Indian Ocean

In recent years, sailing ships of the Indian Navy have been increasingly involved in diplomatic missions and cultural voyages across the world, in addition to their primary purpose of providing practical training in navigation techniques and seamanship. These three-masted barques built at the Goa Shipyard and used by the Indian Navy are very different from wooden sailing vessels that traversed the Indian Ocean in the premodern period prior to the development of steamship navigation in the nineteenth century. Nonetheless, these distinctions have often been blurred as these modern naval ships have been utilised to recreate historical ‘expeditions’ such as the much-celebrated Chola invasion of Srivijaya in the Indonesian archipelago. Nor is India the only country to be involved in promoting this ‘popular history’ for contemporary geopolitical interests, as is evident from China’s efforts to rebuild ships used in the Voyages of Admiral Zheng He across the Indian Ocean. What gets short shrift in the process is investment in research in underwater archaeology and the discovery and preservation of shipwreck sites. This article highlights the urgent need for interdisciplinary research in premodern shipping and seafaring activity beyond the rhetoric of valorising national heroes.

A Note on Portuguese Reactions to the Revival of the Red Sea Spice Trade and the Rise of Atjeh, 1540–1600

1969 ◽  
Vol 10 (3) ◽  
pp. 415-428 ◽  
Author(s):  
C. R. Boxer
Keyword(s):  
Indian Ocean ◽  
Red Sea ◽  
16Th Century ◽  
Indonesian Archipelago ◽  
The Indian Ocean ◽  
The Hague ◽  
Spice Trade ◽  
Straits Of Malacca

No reputable historian nowadays maintains that the Portuguese 16th- century thalassocracy in the Indian Ocean was always and everywhere completely effective. In particular, it is widely accepted that there was a marked if erratic revival in the Red Sea spice-trade shortly after the first Turkish occupation of Aden in 1538, though much work remains to be done on the causes and effects of this development. The Portuguese reactions to the rise of Atjeh have been studied chiefly in connection with the frequent fighting in the Straits of Malacca; and the economic side of the struggle has been less considered. The connection of Atjeh with the revival of the Red Sea spice-trade has been insufficiently stressed; though Mrs. Meilink-Roelofsz and Dr. V. Magalhaes Godinho have some relevant observations on this point in their recent and well documented works (Asian Trade and European Influence in the Indonesian Archipelago, 1500–1630, The Hague, 1962, pp. 142–46; Os Descobrimentos e a Economia Mundial, Vol. II, Lisboa, 1967, pp. 111–171). The purpose of this paper is to amplify the facts and figures which they give there, in the hope that someone with the necessary linguistic qualifications will be incited to make complementary researches in the relevant Indonesian, Arabian, or Turkish sources.

scholarly journals Tsunami risk reduction in the new normal era based on community building in Watulimo, Indonesia

2021 ◽  
Vol 916 (1) ◽  
pp. 012033
Author(s):  
F Shoimah ◽  
F Usman ◽  
S Hariyani
Keyword(s):  
Social Capital ◽  
Indian Ocean ◽  
Natural Capital ◽  
Disaster Risk ◽  
The Other ◽  
New Normal ◽  
Tsunami Disaster ◽  
Geological Processes ◽  
Other Hand ◽  
The Indian Ocean

Abstract The coastal area of Watulimo District is included as a tsunami-prone area that is directly adjacent to the Indian Ocean. The Indian Ocean is the subduction zone of the Indo-Australian Plate and the Eurasian Plate, which results in geological processes and high-intensity seismic activities that can trigger tsunamis. On the other hand, in the new normal era, the coast of Watulimo District includes a high-level COVID-19 zone with 74 cumulative cases, comprising 6 active cases, 54 recovered cases, and 14 deaths. The study aimed to examine the level of capacity of coastal communities in Watulimo District, Trenggalek Regency, based on five livelihood capitals (natural capital, financial, physical, human, and social capital) to reduce tsunami disaster risk in the new normal era. The analytical method used in this research consisted of scoring analysis and pentagon assets analysis. The capacity of the coastal community in Watulimo District shows that the sub-villages with high capacity are Gading, Prigi, and Ketawang Sub-villages. On the other hand, the sub-villages with medium capacity are Gandu, Tirto, Gendingan, Sumber, and Gares Sub-villages. Meanwhile, the sub-village with low capacity is Karanggongso Sub-village, due to the low human capital and social capital. Therefore, in efforts to reduce disaster risk, the area that needs to be prioritized for handling is Karanggongso Sub-village through improvements in social conditions, one of which is by prioritizing education levels, such as training related to the threat of the tsunami disaster and the COVID-19 outbreak.

Africans in the Indian Ocean World

2020 ◽  
Author(s):  
Richard B. Allen
Keyword(s):  
Indian Ocean ◽  
South Asia ◽  
Arabian Gulf ◽  
Eastern Africa ◽  
High Morbidity ◽  
Indonesian Archipelago ◽  
The Indian Ocean ◽  
The Persian Gulf ◽  
Indian Ocean World ◽  
The 19Th Century

The African diaspora in the Indian Ocean is inextricably intertwined with slavery and slave trading in an oceanic world that encompasses southern and eastern Africa, the Red Sea, the Persian (or Arabian) Gulf, South Asia, the Indonesian archipelago, and parts of East Asia. A combination of factors, including the cost of free labor, high morbidity and mortality rates from diseases such as malaria and smallpox, and the perceived attributes of different African peoples spurred the exportation by Arab, Muslim, and Swahili merchants of an estimated 2.9–3.65 million men, women, and children from diverse populations in southern and eastern Africa, Madagascar, and the Horn of Africa to Arabia, the Persian Gulf, South Asia, and Southeast Asia between 800 and c.1900. European involvement in this transoceanic slave trade began during the early 16th century and continued well into the 19th century. This diaspora’s legacy includes the presence of communities of African descent in modern Iran, India, Sri Lanka, and Indonesia.

The impact of diurnal precipitation over Sumatra Island, Indonesia, on synoptic disturbances and its relation to the Madden-Julian Oscillation

2021 ◽  
Author(s):  
Ayako Seiki ◽  
Satoru Yokoi ◽  
Masaki Katsumata
Keyword(s):  
Indian Ocean ◽  
Diurnal Cycle ◽  
Lower Troposphere ◽  
Reanalysis Data ◽  
Eastern Indian Ocean ◽  
Sumatra Island ◽  
The Indian Ocean ◽  
Precipitation Area ◽  
High Precipitation ◽  
The Impact

&lt;p&gt;The impact of diurnal precipitation over Sumatra Island, the Indonesian Maritime Continent (MC), on synoptic disturbances over the eastern Indian Ocean is examined using high-resolution rainfall data from the Global Satellite Mapping of Precipitation project and the Japanese 55-year Reanalysis data during the rainy season from September to April for the period 2000&amp;#8211;2014. When the diurnal cycle is strong, the high precipitation area observed over Sumatra in the afternoon migrates offshore during nighttime and reaches 500 km off the coast on average. The strong diurnal events are followed by the development of synoptic disturbances over the eastern Indian Ocean for several days, and apparent twin synoptic disturbances straddling the equator develop only when the convective center of the Madden&amp;#8211;Julian Oscillation (MJO) lies over the Indian Ocean (MJO-IO). Without the MJO, the synoptic disturbances develop mainly south of the equator. The differences in the locations and behaviors of active synoptic disturbances are related to the strength of mean horizontal winds in the lower troposphere. During the MJO-IO, the intensification of mean northeasterly winds in the northern hemisphere blowing into the organized MJO convection in addition to mean southeasterly winds in the southern hemisphere facilitate the formation of the twin disturbances. These results suggest that seed disturbances arising from the diurnal offshore migration of precipitation from Sumatra develop differently depending on the mean states over the eastern Indian Ocean. Furthermore, it is shown that the MJO events with the strong diurnal cycle tend to have longer duration and continuing eastward propagation of active convection across the MC, whereas the convective activities of the other MJO events weaken considerably over the MC and develop again over the western Pacific. These results suggest that the strong diurnal cycle over Sumatra facilitates the smooth eastward propagation of the intraseasonal convection across the MC.&lt;/p&gt;

Middle Jurassic arc reversal, Victoria–Katha Block and Sibumasu Terrane collision, jadeite formation and Western Tin Belt generation, Myanmar

2021 ◽  
pp. 1-17
Author(s):  
Andrew Mitchell ◽  
Myint Thein Htay ◽  
Kyaw Min Htun
Keyword(s):  
Indian Ocean ◽  
Cross Section ◽  
Middle Jurassic ◽  
Western Margin ◽  
Early Oligocene ◽  
Sunda Arc ◽  
The Indian Ocean ◽  
Tin Deposits ◽  
Extensional Faulting ◽  
Tectonic Interpretation

Abstract Myanmar is occupied by the N-wards continuation of the Sunda arc and by the Shan Plateau and its continuation through Yunnan into Tibet. Our new tectonic interpretation of the ophiolite–flysch belts, world-famous jadeite and tin deposits in Myanmar west of the Salween adopts previous proposals that, before 450-km post-early Oligocene dextral displacement along the Sagaing Fault, the ophiolite belt in NE Myanmar continued through the topography that is now located west of the fault in the Indo-Burman Ranges. Differences in cross-section through Mogok and the Shan Scarps are reconciled by the recently proposed emplacement, in our view during Permian time, of the Mogok Metamorphic Group onto the Slate Belt to form Sibumasu. We argue that during Early Jurassic time a Neo-Tethys ophiolite nappe was obducted over turbidites on Sibumasu’s passive western margin. Following reversal in tectonic polarity, the remaining Neo-Tethys subducted E-wards generating the 113–128 Ma Mondaung Arc. During ocean closure the Victoria–Katha Block and its Triassic flysch subducted beneath Sibumasu, resulting in jadeite veins in overlying serpentinite that ascended in the subduction zone and were exhumed at Hpakant and Nat Hmaw, bordering the Jade Mines Uplift. Subduction of the Indian Ocean since Albian time generated the Popa–Loimye arc, while extensional faulting led to uplift of the Indo-Burman Ranges and to the formation of the Western Tin Belt granites. Tectonic effects in Myanmar of the India–Asia collision may be confined to the Disang thrust belt in the Naga Hills.

scholarly journals Bomb 14C in the Indian Ocean Measured by Accelerator Mass Spectrometry: Oceanographic Implications

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 510-522 ◽  
Author(s):  
Edouard Bard ◽  
Maurice Arnold ◽  
J R Toggweiler ◽  
Pierre Maurice ◽  
Jean-Claude Duplessy
Keyword(s):  
Mass Spectrometry ◽  
Indian Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Equatorial Indian Ocean ◽  
Equatorial Zone ◽  
Mode Water ◽  
Indonesian Archipelago ◽  
The Pacific ◽  
The Indian Ocean

AMS 14C measurements on samples collected in the tropical-equatorial Indian Ocean during the INDIGO program (leg II, 1986) are presented and compared with β-counting results obtained under both INDIGO program and GEOSECS expedition in the Indian Ocean (1978). The most significant observation is a doubling of the bomb-14C inventory and mean penetration depth in the equatorial zone. Based on hydrologic considerations, two hypotheses can be proposed: 1) direct influx of Pacific mid-latitude waters through the Indonesian archipelago and 2) advection and/or mixing with Mode Water from the southern gyre of the Indian Ocean. Results obtained with a general circulation model of the ocean suggest that the influx from the Pacific is important in the upper 300m and that below 500m the bomb-14C budget is dominated by Mode Water advection.

scholarly journals Phytoplankton blooms induced/sustained by cyclonic eddies during the Indian Ocean Dipole event of 1997 along the southern coasts of Java and Sumatra

2008 ◽  
Vol 5 (5) ◽  
pp. 3905-3918 ◽  
Author(s):  
P. Rahul Chand Reddy ◽  
P. S. Salvekar
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
State Of The Art ◽  
Sea Surface ◽  
Phytoplankton Blooms ◽  
Indian Ocean Dipole Event ◽  
Indonesian Archipelago ◽  
The Indian Ocean ◽  
The Tropics ◽  
Sst Anomalies

Abstract. The Indonesian archipelago is the gateway in the tropics connecting two oceans (Pacific and the Indian Ocean) and two continents (Asia and Australia). During the Indian Ocean Dipole 1997, record anomalous and unanticipated upwelling had occurred along the southern coasts of Java and Sumatra causing massive phytoplankton blooms. But the method/mode/process for such anomalous upwelling was not known. Using monthly SeaWifs chlorophyll-a anomalies, TOPEX Sea Surface Height (SSH) anomalies, Sea Surface Temperatures (SST) and currents from a state-of-the-art OGCM, we report the presence of a series of cyclonic eddies along southern coasts of Sumatra and Java during November, December 1997 and January 1998. Upwelling caused by these cyclonic eddies, as also supported by the SSH and SST anomalies, has been responsible for the phytoplankton blooms to persist and dissipate during the 3 months (November, December 1997 and January 1998).

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