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In recent years the negative effects of tsunamis in the Indian Ocean dramatically increased. Although, this subject became very popular lately, the far-field activities of tsunamis are needed to be evaluated in Indian Ocean. In this thesis, Maldives and Sumatra islands were emphasized to analyze the effects of the transoceanic propagation of tsunamis in Indian Ocean. At first, using GIS Based softwares, the geographical data of the region were extracted and organized for analyzing. Secondly, a worst earthquake scenario was initiated at Sumatra which is located at a long distance from Maldives Islands. Then, corresponding effects of transoceanic tsunami were analyzed and accordingly coastal amplifications near Maldivian Islands were computed by NAMI DANCE. As a final step, an evaluation study was carried out to understand the transoceanic propagation behavior of tsunamis in Indian Ocean and results were discussed.

The 2004 Sumatra-Andaman and the 2011 Tohoku-Oki earthquakes demonstrate the importance of understanding subduction zone earthquakes and the faults that produce them. Faults that produce earthquakes and/or tsunamis in these systems include plate boundary megathrusts, splay faults (out of sequence thrusts), and strike-slip faults from strain partitioning. Offshore Japan, IODP Exp. 314 collected logging while drilling (LWD) data across several seismically-imaged fault splays in the Nankai Trough accretionary prism. I combine LWD resistivity data with a model of fluid invasion to compare the permeabilities of sands. My results indicate that sands within faulted zones are 2-3 orders of magnitude more permeable than similar undisturbed sands. Therefore fault zones are likely to be fluid conduits within the accretionary wedge. Fluids can affect the physical and chemical properties of the faulted material, increasing pore pressures and effectively lubricating the faults. Fluids play an important role in fault slip, but hazard analysis also requires an understanding of fault geometry and slip direction. Both Japan and Sumatra exhibit strain partitioning, where oblique convergence between tectonic plates is partitioned between the megathrust and strike-slip faults proximal to the arc. Offshore Sumatra, I combine profiles from a 2D seismic survey (SUMUT) with previous bathymetry and active seismic surveys to characterize the West Andaman Fault adjacent to the Aceh forearc Basin. Along this fault I interpret transpressional flower structures that cut older thrust faults. These flower structures indicate that the modern West Andaman Fault is a right lateral strike-slip fault and thus helps to accommodate the translational component of strain in this highly oblique subduction zone. Offshore the Kii Peninsula, Japan, I analyze a trench-parallel depression that forms a notch in the seafloor just landward of the megasplay fault system, along the seaward edge of the forearc Kumano Basin. Using a 12 km wide, 3D seismic volume, I observe vertical faults and faults which dip toward the central axis of the depression, forming apparent flower structures. The along-strike geometry of the vertical faults makes predominantly normal or thrust motion unlikely. I conclude, therefore, that this linear depression is the bathymetric expression of a transtensional fault system. While the obliquity of convergence in the Nankai Trough is small (~15 degrees), this Kumano Basin Edge Fault Zone could be due to partitioning of the plate convergent strain. The location of the West Andaman Fault and KBEFZ within the forearc may be controlled by the rheology contrast between active accretionary wedges and the more stable crust beneath forearc basins. / text

This is an ethnographic study of the Orang Rimba ('people of the forest'), a Malay-speaking minority group who traditionally lived throughout the lowland rainforests of Jambi, Sumatra. The Orang Rimba have much in common with surrounding Malay peoples, including a similar local dialect and variants of regional Malay customs and beliefs. They are different from the Malay and other Austronesian peoples in that they have a unique, mobile, flexible economy that traditionally shifts in and out of periods of swidden gardening and a very nomadic life based on digging for wild yams, largely upon death. They have an egalitarian social system based on sharing and reciprocity, which occurs within the context of a system of relationships in which women have great rights over forest resources and extraordinary distribution rights. They are also unique for their traditional non-Islamic religious beliefs, which they believe are crucial towards maintaining their way of life in the forest based on maintaining separation with the outside world. While the Makekal Orang Rimba believe themselves to share common origins with the Malay/Melayu, the downstream world of the villagers is perceived as a source of danger and sickness, which holds the potential to disrupt the delicate relations with their gods and make life in the forest impossible. ¶ Within the history of an unstable and assimilative upstream climate that was often hostile towards animist forest peoples, ethnic boundaries have served as a means to maintain their social identity, safety, and maintain a distinctive way of life in the forest. However, within the context of an egalitarian share society in which groupings of closely related women have a great deal of authority over the management and distribution of resources, including game, and the power of men is diminished through dispersed uxorilocal residence patterns, ethnic boundaries are also closely intertwined with internal power issues. The authority adult men is marked by their duty and obligation to protect and shield the rights of women from a dangerous outside world, and all outside males who are not immediate kin, through the manipulation of a convoluted system of law and fines paid in sheets of cloth. While females have great rights in their society, and the complete freedom to bully men through their passions and voice, their social mobility is limited by some of the most rigid gender divisions in all of Southeast Asia. Male authority is also marked within the domain of religion, through their duty to maintain the order and balance of their material and spiritual world (adat) in the forests by observing and enforcing religious prohibitions, which restrict relations with the outside world. This serves to facilitate close relations with their gods in matters ranging from health and subsistence to maintaining the timely occurrence of the seasonal fruits, honey, and migrations of bearded pigs. ¶ This thesis explores how the Orang Rimba maintain their distinct social identity as 'the people of the forest' through an examination of their customs, beliefs and religion (adat), and their belief and ritual surrounding fruits and the annual season of fruits, a primary season in the lowland dipterocarp forests of Sumatra. Throughout the thesis, I explore some of the key concepts, structural categories (forest-village, upstream-downstream, mobility-sedentism, hot-cold, and reason-passion), and metaphor that run through their system of beliefs and religion, and how some of these beliefs influence their social, moral and cosmological orders, relations amongst themselves, and with the outside world. A broader theme examines how religious beliefs are intertwined with social relations, which are largely based on issues of gender, adulthood, relations of affinity and male experience in the realms of law and religion, and how some of their beliefs are interrelated with maintaining ethnic boundaries with outsiders. Some of these topics are explored in their social relations, the structure of their origin stories, gender related food prohibitions, and the management of forest resources. These issues are examined in light of the great change that has taken place over the last 30 years, a result of large-scale logging, plantations and development projects.

The colobine monkey Simias concolor, endemic to the Mentawai Islands, West Sumatra, Indonesia, was studied on two is l ets adjacent to South Pagai. Habitat on these islands was observed and described, and observations were made there from September to November 1987. Group sizes ranged from 2 to >10. Population density may vary with habitat structure. Social groups appear to include one or more females. Contrary to some reports, male and female animals are sexually dimorphic. Inability to identify specific animals or groups prevented mapping of home range areas. Observations are correlated with what has been previously reported about this animal. Future research could be focused on further studies of habitat use and ranging behavior, determination of Simias population densities in possible reserve areas, interspecific interactions, and dietary composition. Without such studies, it is unlikely that adequate management plans can be devised. Prospects for the conservation of this species are reviewed. Suggestions which have been advanced to promote its conservation are also evaluated. The fate of this animal is strongly linked to local, provincial, and national cultural and developmental factors. These include forestry operations, agriculture, hunting, population growth, and transmigration plans.

Sumatran elephant (Elephas maximus sumatranus) populations continue to decline due to habitat loss, poaching and conflict with humans. In Sumatra, elephant populations are fragmented into small isolated populations and increasingly cause conflict with humans. Yet, habitat loss due to the rapid land conversion for development is continuing an alarming situation. Developing effective land conservation strategies for elephants is difficult because there is little information available on foraging ecology, habitat use, movements and home range behaviors. I conducted a study on these topics in Seblat, Bengkulu Province, Sumatra during 2007-2008. The five important families of plants in the elephant diet in Sumatra ar: Moraceae, Arecaceae, Fabaceae, Poaceae,and Euphorbiacea. Elephants in Seblat tend to browse more than graze and elephants tend to browse more during the wet season. The nutritional quality (Crude Protein, Calcium, Phosphorus and Gross Energy) of elephant diet in Seblat is suitable to support population reproduction and growth. Home range size of one telemetered 97.4 km2 for the MCP and 95.0 km2 for the 95% fixed kernel. There was no relation between average monthly elephant home range sizes and rainfall, nor any correlation between monthly elephant movement distances and rainfall. Vegetation productivity, as measured by the Enhanced Vegetation Index (EVI), was probably the factor most affecting elephant movements compared to the distances to rivers and ex-logging roads on the SECC. Resource selection analyzes indicate that elephants in Seblat seem to select medium canopy and open canopy areas more than expected. Similarly, habitat ranking using compositional analysis shows that in 2nd order and 3rd order selection, medium canopy and open canopy were the two habitat types with a greater level of used. Habitat use based on diurnal and nocturnal elephant activities indicates that elephants preferred closed canopy habitat compare to the open canopy habitat during the day. The results of this study suggest wide conservation implications for elephants on Sumatra, helping to guide effective land use conservation programs and provide scientific guideline to restore disturbed habitat and select priority areas for Sumatran elephants.

Tsunami hazards were greatly underestimated along the coasts of countries bordering the northeastern Indian Ocean until the occurrence of the 26 December 2004, Mw 9.2 earthquake and its ensuing tsunami. Sourced off the coast of northern Sumatra, on the plate boundary between the Indo-Australian and Eurasian plates, the rupture of the 2004 earthquake propagated ~1300 km northward. The magnitude of this earthquake and the reach of its tsunami exceeded all known precedents, based on instrumental and historic records. The coseismic deformational and post-tsunami depositional features facilitated opportunities to conduct tsunami geology studies along the coasts of countries bordering the Indian Ocean. Several questions are being posed, the answers of which have implications for tsunami hazard assessment. How did this plate boundary behave prior to and after the great earthquake? Was the 2004 earthquake the first of its kind on the Sumatra-Andaman plate boundary? If it had a predecessor, when did it occur and was it a true predecessor in terms of its rupture dimensions and tsunamigenic potential? What types of depositional evidence are preserved and how can we use them to develop the history of past tsunamigenic earthquakes? Researchers are exploring the affected regions and using the imprints left by the 2004 event, to address these questions. There are two components to this study: one, a seismotectonic analysis of the region from the perspective of plate driving forces and their relative roles in the interseismic and post-seismic phases. This study uses global data catalogs like the NEIC PDE (National Earthquake Information Centre Preliminary Determination of Epicenters) and the Global Centroid Moment Tensor (CMT) solutions for earthquake source parameters to understand the along-strike variations in seismicity patterns before and after the 2004 earthquake. The 2004 experience was unprecedented in South Asia. Unaffected by tsunami hazards in the past, tsunami geology is a nascent field for most South Asian researchers. Very little background field data is available on the deformational features of great earthquakes along this plate boundary and the depositional characteristics of extreme coastal surges, such as tsunamis and storms. Where do we begin our search for evidence of past tsunamigenic earthquakes? How best can we use the 2004 tsunami and its deposits as a proxy? What problems are encountered in the interpretations? This thesis addresses these questions in part and presents observations from the Andaman Islands (the ~400 km, northern segment of the Sumatra-Andaman subduction zone) and the southeast coast of India, towards developing a reliable database of tsunami geology for 2004-type events. The premise is that regions affected by the 2004 earthquake are more likely to conserve signatures from older events. Based on the stratigraphic context of the proxy and quality of age estimates, this work presents evidence for past earthquake related deformation and tsunami deposition. In this work we use deformational and depositional features from the Andaman Islands, falling within the 2004 rupture zone and from one location on the Tamil Nadu coast of India (Kaveripattinam). From a perceptive understanding of the features related to tectonic deformation of the Sumatra-Andaman subduction zone, we have selected the Andaman segment that demonstrates explicit evidence for deformation and tsunami deposition through geomorphological and stratigraphic features, which are key to our exploration. A gist of each chapter is given below. The introduction (chapter 1) presents the background, motivation and scope of this work and the organization of this thesis, also summarizing the contents of each chapter. Chapter 2 provides a review of literature on subduction zone earthquakes and updates on tsunami geology, to place this study in the global context. The next two chapters discuss the seismotectonics of the Sumatra-Andaman plate boundary, the important earthquakes and their source processes. In chapter 3 we discuss the Andaman segment (from 10–15° N), characterized by relatively lower level seismicity, but distinctive, as it falls within the northern limit of the 2004 rupture. The deformational and depositional features here are better exposed due to availability of land straddling the hinge line separating the areas of 2004 uplift and subsidence. Here, the pre-2004 earthquakes used to occur along a gently dipping subducting slab, up to a depth of about 40 km. Post-2004, the earthquakes moved up-dip, extending also to the outer-rise and outer-ridge regions, expressing post-earthquake relaxation [Andrade and Rajendran, 2011]. The southern Nicobar segment (5–10° N) differs from the Andaman segment in its style of deformation and seismic productivity. The decreasing obliquity of convergence, the likely influence of a subducting ocean ridge on the subducting plate and the character of the subducting oceanic plate make this segment distinctly different. In chapter 4 we present an analysis of its seismotectonic environment based on the well-constrained focal mechanisms of historic and recent earthquakes. We report that left-lateral strike-slip faulting on near N-S oriented faults control the deformation and the style of faulting is consistent to ~80 km within the subducting slab [Rajendran, K. et al., 2011]. The 11 April 2012 sequence of earthquakes on the subducting oceanic plate, between the Sumatra Trench and the Ninety East Ridge are the more recent among the oceanic intraplate earthquakes that demonstrate the reactivation of N-S oriented fossil fractures. The limited availability of land and the 2004 coseismic deformation dominated by subsidence, followed by prolonged waterlogging makes exploration difficult in the Nicobar segment. Thus, we focus on the Andaman Islands for deformational and depositional evidence, using observations that can be corroborated through multiple proxies and depositional environments that are not prone to other coastal surges, such as cyclones and storms. The criteria for selection of sites, evaluation of deposits and determination of limiting ages are discussed in chapters 5 through 9. In chapter 5 we discuss different types of coastal environments and their response to high-energy sea surges. We also give a brief review of the comparative analyses of storm and tsunami deposits, a highly debated issue and then discuss important characteristics of these two deposits, using examples from the 2004 tsunami and the 2011 Thane cyclone that affected parts of the Tamil Nadu coast. An important component of tsunami geology is the ability to identify and select datable material from tsunami deposits and chose an appropriate method for dating (chapter 6). The types of material used vary from peat layers, peat-rich soil, gastropod shells, wood, charcoal, organic remains such as bones, coral fragments, pottery sherds and buried soil. Techniques such as AMS Carbon-14 and Thermoluminescence are commonly used with appropriate calibrations and corrections. In addition to the dates generated in this study (based on wood and shell dates) we use some previous dates from the entire stretch of the rupture within the Indian Territory and assign a relative grading to these ages, based on the quality criterion evolved in this study. We believe that this is the first attempt to segregate age data obtained from coastal deposits, and assign them a specific quality grading based on their environment of deposition and the type of material dated. Chapter 7 presents results of our investigations in the Andaman Islands, which cover ~30% of the rupture area. A coseismically subsided mangrove from Rangachanga (Port Blair, east coast of South Andaman) led us to a former subsidence during AD 770–1040, which we believe is the most convincing evidence for a previous tectonic event. Data based on inland deposits of coral and organic debris yielded a younger age in the range of AD 1480–1660. Both these dates fall in the age brackets reported from other regions of this plate boundary (mainly Sumatra) as well as distant shores of Sri Lanka, Thailand and mainland India. To understand the nature of distant deposits, we present observations from Kaveripattinam, an ancient port city on the east coast of India, where a high-energy sea surge deposit, found 1 km inland is attributed to a paleotsunami. The inland location of this archeological site at an elevation of 2 m and characteristics of the deposit that help discriminate it from typical storm deposition provide clinching evidence in favor of a 1000-year old regional tsunami (chapter 8). In chapter 9 we discuss the results of our study. We evaluate the nature of deformation/deposition and the calibrated age data in the context of their environments. Ages based on the organic material associated with coral debris (at Hut Bay and Interview Island) and the remains of mangrove roots, 1 m below the present ground level (at Port Blair) are considered as reliable estimates, due to their sheltered inland location and the in situ root horizon used for dating. Age data from Kaveripattinam is also considered reliable, based on its inland location beyond the reach of storm surges, sediment characteristics typical of tsunami deposition and ages based on multiple methods and samples. The age data based on the sites presented in this thesis are more conclusive about the 800 to 1100 AD and 1250 to 1450 AD tsunamis, and the former is represented from regions closer to the 2004 source as well as distant shores reached by its tsunami. Chapter 10 presents our conclusions and the scope for future studies. We present this as the first study of its kind in the northeastern Bay of Bengal, wherein the coseismic vertical coastal deformation features along an interplate subduction boundary and a variety of tsunami deposits are used to categorize depositional environments and ages of paleoearthquakes and tsunamis. To our knowledge, this is the first study of its kind where the effects of a recent tsunami have been used to evaluate paleodeposits based on their respective environments of occurrence. Our results have implications for tsunami geology studies in coastal regions prone to tsunami hazard.

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