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Effects of the Buoyancy of Serpentinized Mantle on Stresses in the Overriding Crust in Subduction Zones
No full textFaculty Advisor: Ikuko WadaThis research was supported by the Undergraduate Research Opportunities Program (UROP).Brink, Trey; Wada, Ikuko. (2019). Effects of the Buoyancy of Serpentinized Mantle on Stresses in the Overriding Crust in Subduction Zones. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/203047
Sharp thermal transition in the forearc mantle wedge as a consequence of nonlinear mantle wedge flow
Get PDFAuthor Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 38 (2011): L13308, doi:10.1029/2011GL047705.In the forearc mantle wedge, the thermal field depends strongly on slab-driven mantle wedge flow. The flow is in turn affected by the thermal field via the temperature dependence of mantle rheology. Using thermal modeling, we show that the nonlinear feedback between the thermal and flow fields always leads to complete stagnation of the mantle wedge over a shallow, weakened part of the slab-mantle interface and an abrupt onset of mantle flow further down-dip. The abrupt increase in flow velocity leads to a sharp thermal transition from a cold stagnant to a hot flowing part of the wedge. This sharp thermal transition is inherent to all subduction zones, explaining a commonly observed sharp arc-ward increase in seismic attenuation.This research was partially supported by
National Science Foundation through a MARGINS postdoctoral fellowship
(NSF OCE‐0840800) and by Natural Environment Research Council
<Articles>Rayskins from São Thomé Traded by the Dutch East India Company: A Valued South Asian Commodity in Early Modern Japan
No full textIn early modern Japan there was a special demand for the skins of ray fish which were used as standard material for sword mountings. The most highly valued skins for Japanese sword hilts were from ray fish living in tropical and semi-tropical waters. A strong demand for rayskins was a unique feature in Japan in early modern times, considering that they had to be imported from overseas. This article explores the trade in rayskins using the records of the Dutch East India Company, which played a significant role in procuring tropical rayskins for the Japanese market in the seventeenth and eighteenth centuries. The article specifically focuses on rayskins from the southern region of South Asia, called São Thomé rayskins in the Japanese and Dutch contemporary sources. South Asia was by far the most important source of rayskins available to Dutch traders. By observing the activities of Japanese merchants and ships in Southeast Asia in the early seventeenth century, Dutch traders realized that this tropical product could be a promising commodity for the Japanese market. At first, the Dutch East India Company tried to buy rayskins from Southeast Asian ports, especially in Siam. By the mid-1600s, however, the Company was heavily dependent on its factories along the Coromandel Coast, and later also in Ceylon, for obtaining rayskins. This trend continued in the following century, becoming stronger. In the context of the importance of the region, this article sheds light on how the Dutch East India Company sought to purchase São Thomé rayskins, taking into account the Company's entangled relations with local rulers, merchants and traders against the fluctuating political situation in South Asia, as well as the impact of Japan's changing trade policies
The Relationship of the Sulṭāns of Golkonda and Maritime Trade and Ports: Focusing on the Reign of Sulṭān 'Abd Allāh Quṭb Shāh (1626-72)
Get PDFThe Sultanate of Golkonda (the Qutb Shahis), 1518-1687, first extended its rule over the coastal areas of Andhra during the latter half of the 16th century. It has been recognized that ships, known as the "king's ships, " sailed from their base at the main port of Masulipatnam after their rule was solidified in this region at the end of the 16th century. The destinations of the king's ships were the ports of the Red Sea. These ships not only transported pilgrims but also played a role in importing gold, silver and horses. We do not know that the sultans visit trading ports during this period, but when incidents arose involving the trading ports and trade, there were cases in which they intervened to settle the matter. Thereafter there was a period of decline in the activities of the king's ships, but when the sea route to the Persia Gulf came into use in the decade of the 1630s, the route began to be employed for pilgrimage of the royal family, and the king's ships began to voyage to the Persian Gulf. It was during the rule of Sultan 'Abd Allah, when the first visit to Masulipatnam by the sultan of Golkonda was made. He visited the trading port at the close of 1639, met with foreign and domestic merchants and had the opportunity to witness its actual operation. It was probably through this experience that the sultan's interest in trading ports and trade was strengthened, and it is thought that this had great influence on later voyages and trade activities. It has been confirmed that after about year 1650 the king's ships voyaged toward Southeast Asia, and their sphere of activities was extended to both the east and western shores of the Indian Ocean. The sultans would fund the activities of these ships, build up diplomatic and trade relations with the rulers of Southeast Asian lands, and place their representatives in these ports. Although they were rulers of territory within the interior, their direct and indirect involvement with trading ports and trading activities can be seen in this fashion
<Articles>Forts, Town Walls and a 'Steen logie' : Changing Port Towns on the Coromandel Coast, 1606-1707 (Special Issue : CITY)
No full textそもそもヨーロッパ諸勢力が進出するまで、コロマンデル海岸の港町には要塞も市警も存在しなかった。しかし、一七世紀初頭、オランダ東インド会社がプリカットに要塞を築いたことにより、本格的な要塞を擁する港町が登場する。そして約一〇〇年掛の一八世紀初頭には、イギリス東インド会社が租借権を得た一六三九年当時は一漁村に過ぎなかったマドラスが、要塞と市壁を併せ持つ港町として台頭し始めるのである。本稿は、要塞や市壁という新しい建造物が同海岸の港町に造られようとする過程に注目する。特に、一七世紀後半、防備強化の必要に迫られ、市壁や石造りの商館の建設を望みながらも、既存の港町の秩序や現地権力者とのしがらみに阻まれ、思うに任せなかったオランダの事例を分析することによって、同時期にいち早く堅固な防備施設の獲得に成功し、台頭への足がかりを掴んだマドラスの特徴を浮き彫りにしようとするものである。Port towns on the Coromandel Coast generally had no strong defensive structures like fortresses or town walls before the establishment of the European traders and trading companies were formed. At the beginning of the seventeenth century, however, the Dutch East India Company (VOC) built a European style fort named Geldria at Pulicat, once the most prosperous port town on the Coast. The purpose of this study is to examine the changes observed at the Coromandel port towns for a century thereafter. Here, I mainly focus on the process of constructing forts, town walls and a factory built of stone at Pulicat, Madras and Masulipatnam, the three port towns where the English East India Company (EIC) and/or the VOC had their factories in the seventeenth and eighteenth centuries. The first part of this study surveys the existing studies on the patterns and categories of the towns or urban centres in the pre-modern South India. Then it demonstrates the characteristics of the Coromandel port towns in particular. Port towns on the Coast developed mainly due to the significant role of maritime trade. As there were no natural harbours with conditions suited to form a great port town, getting support from a political authority, for example, could help develop a coastal village into a new centre of maritime trade. Pulicat emerged as an important port connected with Vijayanagar rule in the fourteenth century, while Masulipatnam flourished as the Sultanate of Golkonda governed the coastal region more stably in the late sixteenth century. In the second part I discuss how the VOC factories were built and situated at Pulicat and Masulipatnam. Fort Geldria, completed in 1613 with the approval of the local ruling elites, was built, actually not within, but next to the existing town. It is said that there were still wide open spaces left between the town and the fort in the mid-seventeenth century. By the end of the century, however, a wall was built surrounding the town and fort, which distinguished them from neighbouring region. In the case of Masulipatnam, the factory was not the property of the VOC but a lease from the local landowners. It was, therefore, a part of the existing town. Both of the factories were established without forcing any significant changes on the existing port towns, at least when the factories were first opened. The third part deals with the English and Dutch attempts to construct defensive structures around their factories. Madras had been only a small fishing village when the EIC decided to open a factory there in 1639. In the course of seventy years, however, it was transformed into a flourishing port town. As for the process of development of Madras, it was characterized by an expansion of the town that accompanied its fortification. Fort St. George was completed in 1653, while a wall surrounding the town had been already being built in the years from 1644 to 1648. Whereas the inside of the outer fort, whose construction had begun in 1657, came to be called the White Town, the outside of the fort developed into the Black Town, around which a brick wall was completed in 1707. Meanwhile, the VOC had difficulties in building defences of their factories at Pulicat and Masulipatnam, both of which had already developed as major port towns before its arrival and had been governed by the local authorities. Fearing war and social unrest in the region, the Dutch at Pulicat could and did add some facilities, such as a new cellar for ammunition, to protect Fort Geldria. They also wanted to have a wall around the port town, but the construction work was only started years after it had first been proposed as a necessity because the local authorities did not approve it earlier. At Masulipatnam, the VOC had even fewer options to obtain a more secure factory. Since the mid-seventeenth century, the Dutch had repeatedly asked the Sultanate of Golkonda to build a new factory of stone with high resistance to fire, but never succeeded until the beginning of the next century after the Sultanate was conquered by the Mughals. As to the town wall, it was in 1686 while they occupied Masulipatnam for a few months that the Dutch finally built it. In short, the EIC at Madras could fortify the factory and town from the beginning, while it took years before the VOC at Pulicat and Masulipatnam had a town wall and a factory built of stone. In the early seventeenth century, the VOC had been able to participate in trading activities that were being carried out at the pre-existing port town and could profit thereby. In the mid century, however, there was growing unrest on the Coromandel Coast because of successive wars. Even such unstable circumstances, it was difficult for the Dutch to attempt to start construction of "defensive works" without the approval or agreement of the local authorities governing the town, with whom they had been negotiating in business for years, On the other hand, there were no such established relationships at Madras between the English and the local authorities. We can say that the fortified port town of Madras could be established because it was only a small and insignificant village in local politics
<Note>Two Divided "Towns" of Nagapattinam : Reading Dutch Sources Relating to Seventeenth-Century Southern India
No full text<Article>Mīr Muḥammad Saʿīd Ardistānī and Masulipatnam : On the trade and port administration by Mīr Jumla in the Sultanate of Golkonda
No full text<Articles>Dutch Diamond Trade in the 17th Century
No full text個人情報保護のため削除部分ありオランダ東インド会社によるダイヤモンドの購入は、まずボルネオ島北西岸スカダナを中心に始められ、一六二〇年代にコロマンデル海岸を積み出し港とするインド産のものへと拡大していった。後者は埋蔵量・産出量ともに豊富と見なされ、会社も当初は大きな期待を寄せたが、実際には現地での紛争・政策等に左右された不安定な供給量、購入価格の高騰に悩まされ続けた。そのため、会社はインドでの取引開始後も、互いに供給を補完するような形で双方の産地で取引を行い、これにより継続的に原石を入手し続けようとした。これは本国の研磨技術の発展とも結びつき、今日まで続くオランダのダイヤモンド研磨業の基盤形勢に役立ったと考えられる。また、東南アジア各地の君主へのダイヤモンド売却の例は、当時ヨーロッパにおける研磨業の中心であったオランダの技術がこの地域でも好まれ、取引の要件としても重要であったことを示唆するものである。Diamonds had not been obtained except from India and Borneo before mines were found in Brazil in the 18th century. While in India they have been valued highest of all of the precious stones since ancient times, in Europe, coloured stones like rubies and sapphires were preferred because diamonds could not be cut and polished as beautifully as they can now. As the technique of cutting and polishing developed, especially in the Netherlands, from the latter half of the 15th century, their value rose. In the early 17th century, diamond trade by the Vereenighde Oost Indische Compagnie (V.O.C.) was found both in India and in Borneo. At first, until around 1620, the V.O.C. purchased diamonds mainly from Sukadana on the west coast of Borneo, and then, after the discovery of new mines in Golconda in 1621, the diamond trade was organized in Coromandel on the southeast coast of India. In the 1620's, the diamond trade in both of these areas influenced each other. When the company could obtain only a few diamonds in one area, it ordered the staff of another area to purchase more. The diamond trade was deeply connected with local rulers. In Golconda, all stones which were more than about 8 carats had to be offered to the king. He controlled mines and sometimes closed them. Some rulers in Southeast Asia bought polished diamonds from the V.O.C., sometimes at a higher price than in Europe. They seemed to like the European style cutting by Dutch polishers. Diamonds did not have the greatest volume and were not the most profitable for the V.O.C., but their continuous purchase in the early 17th century was deeply connected with the development of polishing techniques in the Netherlands. Even now the diamond industry in the Netherlands is very developed and famous
<Article>Havāldār of Masulipatnam : A Study of the Port Administration under the Sultanate of Golconda in the Early 17th Century
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