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  • 550 - Earth sciences  (85)
  • 914  (48)
  • English  (132)
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  • 2010-2014  (122)
  • 1995-1999  (11)
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  • 1
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 43 S.
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  • 2
    Publication Date: 2021-03-29
    Description: The emphasis between theoretical, global and regional geography, proportion from research to publication has changed several times during the history of Hungarian geography. Certain scholars of Hungarian geography (geo-philosophers, and some theorists) were explicitly attached to theoretical issues of geographic science, yet the majority of geographers advantaged the concrete territorial descriptions and analysis. The regional approach appeared in the Hungarian geography much earlier than the demand on clarification of the theoretic issues of landscape. The first attempt to divide the country into macro landscapes was carried out in the first half of the 1500's. From this time on the geographic science formulated a demand to analyse the internal structure of the country within the frameworks of public administration or in the framework of some other way delimited geographic macro-regions. The administrative space enjoyed for centuries a favoured role, yet the demand for analyses based on the macro regional delimitation was always represented too. On general level the issues of landscape have already been present in Hungarian geographic science (the formulation of concepts, categories, border marking theories etc.), but Hungarian geographic science concerning the territorial research of Hungary has achieved the greatest results mostly in the fields of analytical landscape research, and evaluation ...
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 51 S.
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  • 3
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 102 S.
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  • 4
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 126 S.
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  • 5
    Publication Date: 2021-03-29
    Description: The paper is concerned with the development stages and the spatial transformation of the Hungarian banking system in the economic transition & post-transition periods. It gives an overview of the development tendencies of the financial re-integration into the global market and particularly concentrates on the spatial polarisation factors (concentration de-concentration; centralisation decentralisation) which affect banking. The paper explores the arguments behind the extremely high centralisation of headquarter functions in Budapest and the factors that have impact on the establishment of locally-regionally based banks. This is followed by an introduction of the different organisational (institutional) and territorial (location strategies) level of the Hungarian banking system, dealing with either the domestic or the international financial central-function of Budapest and the reorganisation of the bank network and with its social consequences (financial exclusion) in the regions. The paper argues that EU membership is not a dramatic event in the integration process of the Hungarian banking sector, partly due to its particular ownership structure, the integration of the banking sector has already taken place. The paper concludes that the EMU integration could have been affected more adversely the Hungarian regions already characterised by the endogenous disparities, which are to a large extent rooted in the deficiency of their financial base.
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 68 S.
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  • 6
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 46 S.
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  • 7
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 130 ; Angewandte Geographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 40 S.
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  • 8
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 194 ; Budapest {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 54 S.
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  • 9
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 33 S.
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  • 10
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 020 ; Kulturgeographie von Südosteuropa
    Language: English
    Type: article , publishedVersion
    Format: 58 S.
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  • 11
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QEN 520 ; Sowjetisch geprägte sozialistische Stadt {Siedlungsgeographie}
    Language: English
    Type: article , publishedVersion
    Format: 51 S.
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  • 12
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGG 420 ; Kulturgeographie der ehemaligen UDSSR
    Language: English
    Type: article , publishedVersion
    Format: 63 S.
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  • 13
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 150 ; Teilräume von Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 68 S.
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  • 14
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 44 S.
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  • 15
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; QEI 000 ; Kulturgeographie Ungarns ; Politische Geographie, Geopolitik
    Language: English
    Type: article , publishedVersion
    Format: 90 S.
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  • 16
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 137 S.
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  • 17
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGD 425 ; Einzelne Orte von England {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 60 S.
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  • 18
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 65 S.
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  • 19
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 130 ; Angewandte Geographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 54 S.
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  • 20
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 194 ; Budapest {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 75 S.
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  • 21
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 76 S.
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  • 22
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: This paper is introducing a method for analysing the differences and dynamics of the social utilisation of space. The essence of this method lies in the registration of changes in the spatial structure of settlements through analysing the spatial shifts of settlements within settlement network hierarchy with the identification of coherent spatial units. The analysis of spatial relations, i.e. microregional planning is a very useful method as it helps in mapping the interrelationship of settlements, and their major linking points, as well as in identifying their positions in the settlement hierarchy and through the analysis of the directions of gravitational force may localise their gravitational zones as well. Hereinafter, this method will be named as spatial relationship analysis. The startup phase for the workout of this method was funded by the Hungarian Scientific Research Fund's Programme titled 'The Integration Ability of Rural Spaces in Hungary's Socio-economic Process' (registration no. T 7236).
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 92 S.
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  • 23
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 101 S.
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  • 24
    Publication Date: 2021-03-29
    Description: The main purposes of the academic research commissioned by the Rural Development Department of the Ministry of Agriculture and Rural Development were: to examine the interrelation between long-term unemployment and individual as well as family life strategies, the regional characteristics of the labour market and the territorial development of rural areas, as well as explore governmental and local ambitions to alleviate long-term unemployment and evaluate their efficiency. The basic issues of the research were as follows: 1) Which are the regions where the concentrations of long-term unemployment can be found and what are the reasons for it? 2) What kind of interrelation can be observed between long-term unemployment and the potential of the social and economic development of the regions? 3) What central and local attempts have there been to alleviate long-term unemployment? 4) What results did these initiatives have and what were the reasons for their success or failure? 5) What foreign models can be followed when trying to alleviate long-term unemployment? 6) Which are the economic sectors, in which employment of those long-term unemployed is the most possible? The research was carried out by the horizontal work-team of rural development of the Centre for Studies Research of the Hungarian Academy of Sciences.
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 85 S.
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  • 25
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 94 S.
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  • 26
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 39 S.
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  • 27
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 92 S.
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  • 28
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 140 ; Teilfragen zu Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 30 S.
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  • 29
    Publication Date: 2021-03-29
    Description: This paper examines the impact of the Hungarian banking system on regional and urban development in the early 20th century, when local banks were important territorial elements of the financial space developing close links to regional economic structures. The basic concept of the study is that there is closer connection not only between the banking sector and the economy as a whole, but between the banking sector and urban development as well. This is coincided with the argument of the American Historical Geographical school (Conzen, 1977) says that the features of the urban network are in strong correlation with the spatial structure of banking system and the diffusion of financial innovations. We considered the spatial breakdown of capital flows are one of the most important indicators of the regional and urban transformation (Gál, 2005). The Hungarian banking system looks back to a history of more than 160 years. Examining the impact of the banking system on regional and urban development is reasonable in the second half of the 19th century, since in Hungary developed an extensive financial system with a well researchable statistical database (Vargha, 1913). The Hungarian banking system was well developed in comparison to international standards by the first decade of the 20th century (Kövér, 1991; Tomka, 1996). Moreover, it became one of the most rapidly growing sectors of the domestic economy of that time ...
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 73 S.
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  • 30
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 130 ; Angewandte Geographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 55 S.
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  • 31
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 194 ; Budapest {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 73 S.
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  • 32
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: Our study analyses changes undergoing in the relation system of metropolitan areas2 and the issues of social and economic relations arising from the restructuring of spatial and regional disparity systems. Global-scale economic, social and political integration, the processes of global urbanisation, globalising urban networks and the transformation of their subsystems are increasing the importance of large cities and their metropolitan areas. They are squeezing out the earlier systems of spatial relations having shaped up behind nation-state boundaries in the past. All these trends are also manifested by the vigorously increasing importance of cities (Barta, 1998; Cséfalvay, 1999; Enyedi, 2001, 2003, 2006; Knox, 2002). The spatial structuring force of cities and metropolitan areas is leaving its marks on the relation system of cities and their urban areas as well. The earlier hierarchical, mono-centric and core-periphery3 based spatial disparity model of urban areas is now in transition (Ascher, 1995; Baron et al., 2005; Barta - Beluszky, 1999; Enyedi, 2003; Merlin, 2003; Mirloup, 2002; Szirmai et al. 2007). The social, economic and environmental impacts of the newly structured and urbanised regions (Enyedi, 2001, 2003) will reconfigure the system of earlier spatial disparities (Beckouche et al. 1997; Marcuse, 1989; Szirmai, 2004). Besides (and partly instead of) monocentric and hierarchical schemed relations, horizontal cooperation models based on the functional division of labour and networked organisational systems will operate as the driving engines of spatial organisation ...
    Description: report
    Keywords: 910 ; 914 ; QGF 100 ; Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 53 S.
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  • 33
    Publication Date: 2021-03-29
    Description: Territory as we know it is in constant change; distances shorten, new synergies are established, and new challenges make mankind search for answers and ways to develop in a sustainable and environment-friendly way. New contacts with people having different experiences are important because they give the opportunity to learn from others. The European Union is a great example of what is described above. Borders are open, people can freely move within the Schengen Area, territorial harmonisation is an objective of this community in order to provide better living conditions for all citizens, strengthen the economy and equilibrate disparities among regions in each country and all European members. The present study is a result of a European programme called Leonardo da Vinci, which offers work experience for post-graduates. In this case the synergy is between Letters Faculty of Lisbon University and Centre for Regional Studies of the Hungarian Academy of Sciences (Transdanubian Research Institute). The objective of the report is to provide a comparative work on the Portuguese and Hungarian territorial planning system. It is divided into three parts: first, the explanation and comprehension of the Portuguese territorial management system, its instruments and institutions are presented, which is followed by the discussion of the same issues for the Hungarian territory we identify instruments and institutions responsible for territorial organisation in connection with planning; and finally, a comparison of the two systems is given.
    Description: report
    Keywords: 910 ; 914 ; QGF 100 ; Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 48 S.
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  • 34
    Publication Date: 2021-03-29
    Description: With the concept generally known as Wider Europe, the European Union has mapped out an ambitious vision of regional Neighbourhood that goes beyond cooperation to involve a significant measure of integration. Furthermore, the EU sees this new quality of regional interaction and partnership as bringing enormous gains to all involved in terms of increased stability, security and well being. The EUDIMENSIONS (Local Dimensions of a Wider European Neighbourhood: Developing Political Community through Practices and Discourses of Cross-Border Co-operation) research project, financed under the European Union 6th Framework Programme, priority 7, chapter 4.2.1 (New Borders, New Visions of Neighbourhood), has sought to map and analyse crossborder cooperation and political contact-building between the European Union and neighbouring states, with a special emphasis on the development of civil society, economic interaction and the specific issue of gender in the crossborder relationship network. Crossborder cooperation in this respect has been understood as subject to changing political constellation and rhetoric, involving considerable tension between inclusion, or Neighbourhood (the European Union's efforts to integrate its wider neighbourhood in various forms of political and economic partnership) and exclusion, or Fortress Europe (the increasing securitisation of Europe's external borders in order to protect the community from unregulated flows of goods and people) ...
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; QGG 530 ; Kulturgeographie Ungarns ; Ukraine {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 65 S.
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  • 35
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 67 S.
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  • 36
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 218 S.
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  • 37
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QER 800 ; Verkehrsgeographie {Wirtschaftsgeographie}
    Language: English
    Type: article , publishedVersion
    Format: 72 S.
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  • 38
    Publication Date: 2021-03-29
    Description: The results of the representative sociological research of Hungarian cities and their centres are showing a Hungarian way in the general development tendencies of the European and East Central-European city centres. The processes of transition, the impacts of European and global economic integration have adjusted the characteristic features of Hungarian big city centres to the inner space character of European big cities. According to the results of research the central areas of Hungarian big cities following the major features of West European big cities re concentrating high social classes: people with high educational level and high professional qualifications and with high incomes. The marketable, younger and more active demographic groups also prefer settling down in the internal zones of urban space10. The presence of low social classes is higher in suburbs and in backwarded urban peripheries. However handicapped social classes are present in city centres as well and the members of high social classes have also emerged in urban peripheries. The controversial situation of European and East Central European city centres can be well illustrated by the fact that Hungarian big city centres are concentrating not only high social classes and advanced economy (with high-tech infrastructure and sophisticated institutional system and services) but the majority of physical and social problems as well. The central zones of Hungarian big cities are facing much more social problems than their suburbs and peripheries. The further we are moving away from city centres the lower severity of social problems we meet ...
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
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  • 39
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; QGG 360 ; Kulturgeographie Ungarns ; Slowakei {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 80 S.
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  • 40
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
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  • 41
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
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  • 42
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 130 ; Angewandte Geographie Ungarns
    Language: English
    Type: article , publishedVersion
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  • 43
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGG 560 ; Europäisches Rußland {Geographie}
    Language: English
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    Format: 57 S.
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  • 44
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 150 ; Teilräume von Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 146 S.
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  • 45
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 120 ; Kulturgeographie Ungarns
    Language: English
    Type: article , publishedVersion
    Format: 127 S.
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  • 46
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 100 ; Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 63 S.
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  • 47
    Publication Date: 2021-03-29
    Description: report
    Keywords: 910 ; 914 ; QGF 140 ; Teilfragen zu Ungarn {Geographie}
    Language: English
    Type: article , publishedVersion
    Format: 51 S.
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  • 48
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    RKK, Pécs
    Publication Date: 2021-03-29
    Description: This short discussion paper is a cross section or a thematic summary of a considerably longer work. The limited scope of the Discussion Papers series does not allow lengthy, detailed explanations or extensive references, only the presentation of mainly summarizing statements. In spite of the ensuing vulnerability, I did not refrain from the publication of my ideas in this form, hoping that they will become accessible to a wider readership in this way and the positive of negative feedback received will help me improve or further elaborate my theory. Hungary abandoned the practice of the former 'socialist' type planning in the early 1990s and even wound up the institutions related to it, but the development of a new planning system seems to take a longer time than expected. I believe that in a situation like this the best thing we can do to assist practice is to offer a sound theoretical foundation. A general theory can not only lead to a better understanding of the gist and possible forms of planning but can also serve as a basis for a continuously developing methodology of learning and rationalization. My purpose is to foster changes in attitudes to planning and to develop a new philosophy of planning with emphasis on teleology. I also intend to raise awareness concerning the limitations we have to face in the exploration of a given situation ...
    Description: report
    Keywords: 910 ; 914 ; QFG 000 ; Raumordnung und Raumplanung {Anthropogeographie}
    Language: English
    Type: article , publishedVersion
    Format: 89 S.
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  • 49
    Publication Date: 2020-02-12
    Description: On 12 September 2007, an Mw 8.4 earthquake occurred within the southern section of the Mentawai segment of the Sumatra subduction zone, where the subduction thrust had previously ruptured in 1833 and 1797. Traveltime data obtained from a temporary local seismic network, deployed between December 2007 and October 2008 to record the aftershocks of the 2007 event, was used to determine two-dimensional (2-D) and three-dimensional (3-D) velocity models of the Mentawai segment. The seismicity distribution reveals significant activity along the subduction interface and within two clusters in the overriding plate either side of the forearc basin. The downgoing slab is clearly distinguished by a dipping region of high Vp (8.0 km/s), which can be a traced to ∼50 km depth, with an increased Vp/Vs ratio (1.75 to 1.90) beneath the islands and the western side of the forearc basin, suggesting hydrated oceanic crust. Above the slab, a shallow continental Moho of less than 30 km depth can be inferred, suggesting that the intersection of the continental mantle with the subducting slab is much shallower than the downdip limit of the seismogenic zone despite localized serpentinization being present at the toe of the mantle wedge. The outer arc islands are characterized by low Vp (4.5–5.8 km/s) and high Vp/Vs (greater than 2.0), suggesting that they consist of fluid saturated sediments. The very low rigidity of the outer forearc contributed to the slow rupture of the Mw 7.7 Mentawai tsunami earthquake on 25 October 2010.
    Keywords: 550 - Earth sciences
    Language: English
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  • 50
    Publication Date: 2020-02-12
    Description: On 2012 May 20 and 29, two damaging earthquakes with magnitudes Mw 6.1 and 5.9, respectively, struck the Emilia-Romagna region in the sedimentary Po Plain, Northern Italy, causing 26 fatalities, significant damage to historical buildings and substantial impact to the economy of the region. The earthquake sequence included four more aftershocks with Mw ≥ 5.0, all at shallow depths (about 7–9 km), with similar WNW–ESE striking reverse mechanism. The timeline of the sequence suggests significant static stress interaction between the largest events. We perform here a detailed source inversion, first adopting a point source approximation and considering pure double couple and full moment tensor source models. We compare different extended source inversion approaches for the two largest events, and find that the rupture occurred in both cases along a subhorizontal plane, dipping towards SSW. Directivity is well detected for the May 20 main shock, indicating that the rupture propagated unilaterally towards SE. Based on the focal mechanism solution, we further estimate the co-seismic static stress change induced by the May 20 event. By using the rate-and-state model and a Poissonian earthquake occurrence, we infer that the second largest event of May 29 was induced with a probability in the range 0.2–0.4. This suggests that the segment of fault was already prone to rupture. Finally, we estimate peak ground accelerations for the two main events as occurred separately or simultaneously. For the scenario involving hypothetical rupture areas of both main events, we estimate Mw = 6.3 and an increase of ground acceleration by 50 per cent. The approach we propose may help to quantify rapidly which regions are invested by a significant increase of the hazard, bearing the potential for large aftershocks or even a second main shock.
    Keywords: 550 - Earth sciences
    Language: English
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  • 51
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    Seismological Press
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Language: Chinese
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  • 52
    Publication Date: 2020-02-12
    Description: In the framework of the Dead Sea Integrated Research project (DESIRE), 59 seismological stations were deployed in the region of the Dead Sea Basin. Twenty of these stations recorded data of sufficiently high quality between May and September 2007 to be used for ambient seismic noise analysis. Empirical Green’s functions are extracted from cross-correlations of long term recordings. These functions are dominated by Rayleigh waves, whose group velocities can be measured in the frequency range from 0.1 to 0.5 Hz. Analysis of positive and negative correlation lags of the Green’s functions makes it possible to identify the direction of the source of the incoming energy. Signals with frequencies higher than 0.2 Hz originate from the Mediterranean Sea, while low frequencies arrive from the direction of the Red Sea. Travel times of the extracted Rayleigh waves were measured between station pairs for different frequencies, and tomographically inverted to provide independent velocity models. Four such 2D models were computed for a set of frequencies, all corresponding to different sampling depths, and thus together giving an indication of the velocity variations in 3D extending to a depth of 10 km. The results show low velocities in the Dead Sea Basin, consistent with previous studies suggesting up to 8 km of recent sedimentary infill in the Basin. The complex structure of the western margin of the Basin is also observed, with sedimentary infill present to depths not exceeding 5 km west of the southern part of the Dead Sea. The high velocities associated with the Lisan salt diapir are also observed down to a depth of ~5 km. The reliability of the results is confirmed by checkerboard recovery tests.
    Keywords: 550 - Earth sciences
    Language: English
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  • 53
    Publication Date: 2020-02-12
    Description: The Sumatra-Andaman earthquake with a magnitude of 9.3, and the subsequent destructive tsunami which caused more than 225 000 fatalities in the region of the Indian Ocean, happened on 26 December 2004. Less than one month later, the United Nations (UN) World Conference on Disaster Reduction took place in Kobe, Japan to commemorate the 1995 Kobe earthquake. The importance of preparedness and awareness on regional, national and community levels with respect to natural disasters was discussed during this meeting, and resulted in the approval of the Hyogo Declaration on Disaster Reduction. Based on this declaration the UN mandated the Intergovernmental Oceanographic Commission (IOC) of UNESCO (United Nations Education, Science and Cultural Organization), taking note of its over 40 years of successful coordination of the Pacific Tsunami Warning System (PTWC), to take on the international coordination of national early-warning efforts for the Indian Ocean and to guide the process of setting up a Regional Tsunami Early Warning System for the Indian Ocean.
    Keywords: 550 - Earth sciences
    Language: English
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  • 54
    Publication Date: 2020-02-12
    Description: Results obtained from S and P receiver functions produced a clear image of the top and bottom of the subducting Nazca lithosphere beneath northern Chile. Using data from the teleseismic events recorded at 15 permanent Integrated Plate Boundary Observatory Chile (IPOC) stations, we obtained new constraints on the geometry and thickness of the descending Nazca lithosphere. We observed the subducted crust of the Nazca plate at depths ranging from 50 km beneath the Coastal Cordillera down to 110 km beneath the Western Cordillera. We found significant along‐strike variations in the geometry of the Nazca plate beneath northern Chile. On closer inspection, it appears that the oceanic Nazca plate is divided into two distinct segments as it descends beneath the continental South American plate. The transition from the relatively steeper (∼23°) and deeper slab to the north of 21°S to the flatter southern segment (∼19°) is shown reasonably clearly by our data. This feature could well be associated with variations in the curvature of the plate margin and the geometry of the Chile trench, which is mainly curved to the north of 21°S. We have also mapped the continental Moho of the South American plate at depths ranging between 60 and 70 km to the east of the Longitudinal Valley. Beneath the Coastal Cordillera, this boundary becomes invisible, probably due to the serpentinization of the forearc mantle wedge that reduces the velocity in the uppermost mantle. The base of the subducted Nazca plate was clearly identified as a sharp boundary in the results obtained from the P and S receiver functions. The thickness of the subducted oceanic Nazca plate, which has an age of ∼50 My, is estimated to be ∼50 km. Although this thickness is consistent with that predicted by thermal gradients, the explanation of the sharpness of the lithosphere‐asthenosphere boundary may require another mechanism such as hydration or melting.
    Keywords: 550 - Earth sciences
    Language: English
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  • 55
    facet.materialart.
    Unknown
    In:  Journal of Seismology
    Publication Date: 2020-02-12
    Description: An early detection of the presence of rupture directivity plays a major role in the correct estimation of ground motions and risks associated to the earthquake occurrence. We present here a simple method for a fast detection of rupture directivity, which may be additionally used to discriminate fault and auxiliary planes and have first estimations of important kinematic source parameters, such as rupture length and rupture time. Our method is based on the inversion of amplitude spectra from P-wave seismograms to derive the apparent duration at each station and on the successive modelling of its azimuthal behaviour. Synthetic waveforms are built assuming a spatial point source approximation, and the finite apparent duration of the spatial point source is interpreted in terms of rupture directivity. Since synthetic seismograms for a point source are calculated very quickly, the presence of directivity may be detected within few seconds, once a focal mechanism has been derived. The method is here first tested using synthetic datasets, both for linear and planar sources, and then successfully applied to recent Mw 6.2–6.8 shallow earthquakes in Peloponnese, Greece. The method is suitable for automated application and may be used to improve kinematic waveform modelling approaches.
    Keywords: 550 - Earth sciences
    Language: English
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  • 56
    Publication Date: 2020-02-12
    Description: Multibeam bathymetry revealed the occurrence of numerous craterlike depressions, so-called pockmarks, on the sea floor of the Hammerfest Basin and the Loppa High, south-western Barents Sea. To investigate whether these pockmarks are related to ongoing gas seepage, microbial processes associated with methane metabolism were analyzed using geochemical, biogeochemical and microbiological techniques. Gravity cores were collected along transects crossing individual pockmarks, allowing a direct comparison between different locations inside (assumed activity center), on the rim, and outside of a pockmark (reference sites). Concentrations of hydrocarbons in the sediment, particularly methane, were measured as headspace (free) gas, and in the occluded and adsorbed gas fraction. Down to a depth of 2.6 m below sea floor (mbsf) sulfate reduction rates were quantified by radiotracer incubations. Concentrations of dissolved sulfate in the porewater were determined as well. Neither the sulfate profiles nor the gas measurements show any evidence of microbial activity or active fluid venting. Methane concentrations and sulfate reduction rates were extremely low or even below the detection limit. The results show that the observed sediment structures are most likely paleo-pockmarks, their formation probably occurred during the last deglaciation.
    Keywords: 550 - Earth sciences
    Language: English
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  • 57
    Publication Date: 2020-02-12
    Description: On 2001 May 7, following unintentional water injection, a moderate size induced earthquake struck the Ekofisk oil field, North Sea. Despite of its relatively moderate magnitude, clear low-frequency waveforms could be recorded up to more than 2000 km epicentral distance, suggesting a slow rupture at very shallow depth and wave propagation through low-velocity shallow structures. The event poses a rare opportunity to constrain rupture velocity, duration and rise time of a superficial M 〉 4 event occurring on a horizontal plane in soft, water-saturated sediments. Two previous studies discussed the earthquake point source finding vertical dip-slip focal mechanisms with opposite senses of P and T axes. A further investigation was thus required to provide a basis for a deeper discussion of the failure dynamics. We significantly improve the used data set, test different earth models and derive a point source as well as a kinematic rupture model. We carefully discuss parameter uncertainties and effects related to shallow sources and wave propagation through different crustal structures to resolve the previous controversy. We additionally provide a kinematic rupture model, based on apparent source times derived from Rayleigh and Love waves. The waveforms resolve a predominant unilateral rupture along a horizontal plane at about 2 km depth. We derive an unusually slow rupture, consequence of a slow rupture velocity of about 500 m s –1 and a long rise time of about 7 s. An independent modelling of GPS- based static displacements allows to confirm the focal mechanism polarity and to locate the centroid at the eastern side of the field, resulting in a much larger seismic moment in comparison with dynamic seismic moment. The rupture directivity is confirmed by the relative location of the centroid with respect to the epicentre, which is set at the site of water injection.
    Keywords: 550 - Earth sciences
    Language: English
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  • 58
    Publication Date: 2020-02-12
    Description: The Dead Sea Transform (DST) is a major left-lateral strike-slip fault that accommodates the relative motion between the African and Arabian plates, connecting a region of extension in the Red Sea to the Taurus collision zone in Turkey over a length of about 1100 km. The Dead Sea Basin (DSB) is one of the largest basins along the DST. The DSB is a morphotectonic depression along the DST, divided into a northern and a southern sub-basin, separated by the Lisan salt diapir. We report on a receiver function study of the crust within the multidisciplinary geophysical project, DEad Sea Integrated REsearch (DESIRE), to study the crustal structure of the DSB. A temporary seismic network was operated on both sides of the DSB between 2006 October and 2008 April. The aperture of the network is approximately 60 km in the E—W direction crossing the DSB on the Lisan peninsula and about 100 km in the N—S direction. Analysis of receiver functions from the DESIRE temporary network indicates that Moho depths vary between 30 and 38 km beneath the area. These Moho depth estimates are consistent with results of near-vertical incidence and wide-angle controlled-source techniques. Receiver functions reveal an additional discontinuity in the lower crust, but only in the DSB and west of it. This leads to the conclusion that the internal crustal structure east and west of the DSB is different at the present-day. However, if the 107 km left-lateral movement along the DST is taken into account, then the region beneath the DESIRE array where no lower crustal discontinuity is observed would have lain about 18 Ma ago immediately adjacent to the region under the previous DESERT array west of the DST where no lower crustal discontinuity is recognized.
    Keywords: 550 - Earth sciences
    Language: English
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  • 59
    Publication Date: 2020-02-12
    Description: The Van (Eastern Anatolia, Turkey) earthquake occurred on Sunday, October 23, 2011 with a moment magnitude of 7.2. The tectonics of this region is characterized by strike–slip faulting on the Bitlis Suture Zone, and thrusting in the Zagros fold and thrust belt. Using high-rate (1 second) GPS data from permanent GNSS stations from the CORS-TR network, co-seismic displacements of eleven stations were determined using precise point positioning during this earthquake. We used the time series of coordinate changes for fourteen CORS-TR stations, and calculated the crust movements before and after the earthquake. According to the PPP solutions computed using high frequency GPS data to determine the co-seismic motions of stations, we conclude for the Van earthquake an occurrence time of 10:41:22 (UTC). No pre-seismic horizontal movement of stations at the level more than 5 mm before the earthquake could be observed. That means that no kinematic warning or prediction before the earthquake exists. Along an east–west horizontal line north of the Van Sea with a length of about 100 km, the northern part of this line experienced extension of 0.2–1 ppm in a NW–SE direction. The southern part experienced N–S shortening of 0.5–1.5 ppm. The N–S shortening we estimated geodetically matches well with the N–S shortening and thrust focal mechanism derived independently using seismic data by the USGS. Co-seismic surface displacements derived from the GPS data are consistent with the teleseismic source model given by the USGS. The geodetic source model derived from the GPS data reproduces the same moment magnitude and centroid as the teleseismic model, but shows a higher spatial resolution of the slip distribution. We also analyzed the post-seismic surface displacements derived from the GPS data within the first two weeks after the mainshock. No reasonable slip distribution on the co-seismic fault plane could be found, indicating that the sources for the early post-seismic deformation might come from the widely scattered aftershocks.
    Keywords: 550 - Earth sciences
    Language: English
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  • 60
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Language: English
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  • 61
    Publication Date: 2020-02-12
    Description: Rapid improvements in telemetry technology and the general decrease in communication costs have raised a growing interest in low-cost wireless sensing units. This is especially the case for structural monitoring purposes, where they are becoming a more valuable alternative to conventional wired monitoring system. The main advantages associated with the use of wireless sensing unit include a considerable decrease in installation costs, decentralization of data analysis, and the possibility of broadening the functional capabilities by exploiting the use, at the same time and place, of different sensors. In this work, the design of a low-cost wireless sensing unit able both to collect, analyze, store, and communicate data and estimated parameters is presented. The suitability of a network of these low-cost wireless instruments for monitoring the vibration characteristics and dynamic properties of strategic civil infrastructures is validated during a ambient vibration recording field test on the Fatih Sultan Mehmet Bridge in Istanbul, Turkey.
    Keywords: 550 - Earth sciences
    Language: English
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  • 62
    Publication Date: 2020-02-12
    Description: In 2004 and 2005 a passive seismic experiment was carried out in the northern and northeastern part of the Bohemian Massif (Sudetes) to study the lithospheric structure. We present results from Ps and Sp receiver function analyses. With one exception, Moho depth at stations in the northwestern part of the study area varies between 28 and 32 km. Thicker crust up to 35 km was mapped toward the south (Moldanubian unit) and toward the east (Moravo–Silesian and Brunovistulian units) confirming results from previous active seismic measurements. There exists a relatively sharp step in Moho depth between units of the central Sudetes (~ 30 km) and the Moravo–Silesian unit (~ 35 km). The vp/vs ratios inverted from primary and multiple Moho Ps conversions hint for different crustal compositions of the units. Toward the Carpathian thrust we have no clear indications for any crustal root or slab beneath the western Carpathians. However, our data suggests a deepening of the Moho or at least a complicated crust–mantle transition in this area. Additional Ps phases were observed between 6 and 10 s delay time in the Sudetes. These phases cannot be explained by Moho reverberations, but are most probably caused by low velocity zones in the middle crust or lithospheric mantle as shown by modeling of theoretical receiver functions. The stations showing these abnormal phases are located in the area of Permo-Carboniferous basins on probably Teplá–Barrandian crust. Therefore we assume that the phases hint at a mid-crustal low velocity zone between 16 and 20 km depth, which is interpreted as a felsic solidified magma reservoir of the Permo-Carboniferous volcanism beneath the Sudetic Basins. Sp receiver functions show phases with negative polarity at 9 to 12 s lead time on average, which we interpret as lithosphere–asthenosphere boundary at about 80 to 110 km depth.
    Keywords: 550 - Earth sciences
    Language: English
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  • 63
    Publication Date: 2020-02-12
    Description: We use local earthquake data observed by the amphibious, temporary seismic MERAMEX array to derive spatial variations of seismic attenuation (Qp) in the crust and upper mantle beneath Central Java. The path-averaged attenuation values (t∗) of a high quality subset of 84 local earthquakes were calculated by a spectral inversion technique. These 1929 t∗-values inverted by a least-squares tomographic inversion yield the 3D distribution of the specific attenuation (Qp). Analysis of the model resolution matrix and synthetic recovery tests were used to investigate the confidence of the Qp-model. We notice a prominent zone of increased attenuation beneath and north of the modern volcanic arc at depths down to 15 km. Most of this anomaly seems to be related to the Eocene–Miocene Kendeng Basin (mainly in the eastern part of the study area). Enhanced attenuation is also found in the upper crust in the direct vicinity of recent volcanoes pointing towards zones of partial melts, presence of fluids and increased temperatures in the middle to upper crust. The middle and lower crust seems not to be associated with strong heating and the presence of melts throughout the arc. Enhanced attenuation above the subducting slab beneath the marine forearc seems to be due to the presence of fluids.
    Keywords: 550 - Earth sciences
    Language: English
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  • 64
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    Unknown
    In:  25. Schmucker-Weidelt-Kolloquium für Elektromagnetische Tiefenforschung
    Publication Date: 2020-02-12
    Description: For a long time the root mean square (RMS) error has been used in the EM community: - to characterize data fit for a particular model; - as a criterion to compare several models obtained from inversion. The RMS error appears to be a natural choice since we usually tackle inverse problems in a least-squares sense. Over the years, RMS became a customary criterion and gained ultimate significance. However, on the hunt for low RMS values, one often needs to introduce subjectivity by arbitrarily adjusting error floors or masking “bad” data without referring to the assumptions behind RMS. In this contribution, we revisit basic assumptions behind RMS, demonstrate its deficiency and propose alternative ways, which may provide more insight into our data and allow a more comprehensive assessment of the quality of the modelling result/resistivity model.
    Keywords: 550 - Earth sciences
    Language: English
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  • 65
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Language: English
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  • 66
    Publication Date: 2020-02-12
    Description: We analyse data from seismic stations surrounding the Alboran Sea between Spain and North Africa to constrain variations of the lithosphere–asthenosphere boundary (LAB) in the region. The technique used is the receiver function technique, which uses S-to-P converted teleseismic waves at the LAB below the seismic stations. We confirm previous data suggesting a shallow (60–90 km) LAB beneath the Iberian Peninsula and we observe a similarly shallow LAB beneath the Alboran Sea where the lithosphere becomes progressively thinner towards the east. A deeper LAB (90–100 km) is observed beneath the Betics, the south of Portugal and Morocco. The structure of the LAB in the entire region does not seem to show any indication of subduction related features. We also observe good P receiver function signals from the seismic discontinuities at 410 and 660 km depth which do not indicate any upper-mantle anomaly beneath the entire region. This is in agreement with the sparse seismic activity in the mantle transition zone suggesting the presence of only weak and regionally confined anomalies.
    Keywords: 550 - Earth sciences
    Language: English
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  • 67
    Publication Date: 2020-02-12
    Description: We determined a high-resolution 3-D S-wave velocity model for a 26 km × 12 km area in the northern part of the basin of Santiago de Chile. To reach this goal, we used microtremor recordings at 125 sites for deriving the horizontal-to-vertical (H/V) spectral ratios that we inverted to retrieve local S-wave velocity profiles. In the inversion procedure, we used additional geological and geophysical constraints and values of the thickness of the sedimentary cover already determined by gravimetric measurements, which were found to vary substantially over short distances in the investigated area. The resulting model was derived by interpolation with a kriging technique between the single S-wave velocity profiles and shows locally good agreement with the few existing velocity profile data, but allows the entire area, as well as deeper parts of the basin, to be represented in greater detail. The wealth of available data allowed us to check if any correlation between the S-wave velocity in the uppermost 30 m (v30S) and the slope of topography, a new technique recently proposed by Wald and Allen, exists on a local scale. We observed that while one lithology might provide a greater scatter in the velocity values for the investigated area, almost no correlation between topographic gradient and calculated v30S exists, whereas a better link is found between v30S and the local geology. Finally, we compared the v30S distribution with the MSK intensities for the 1985 Valparaiso event, pointing out that high intensities are found where the expected v30S values are low and over a thick sedimentary cover. Although this evidence cannot be generalized for all possible earthquakes, it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the Santiago basin.
    Keywords: 550 - Earth sciences
    Language: English
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  • 68
    Publication Date: 2020-02-12
    Description: We implement the effects of gravitational self-attraction and loading (SAL) into a global baroclinic ocean circulation model and investigate effects on sea level patterns, ocean circulation, and density distributions. We compute SAL modifications as an additional force on the water masses at every time step by decomposing the field of ocean bottom pressure anomalies into spherical harmonic functions and then applying Love numbers to account for the elastic properties of the solid Earth. Considering SAL in the postprocessing turns out to be insufficient, especially in coastal waters and on subweekly time scales, where SAL modifies local sea level by around 0.6–0.8 cm on average; in the open ocean, changes mostly remain around 0.3 cm. Modifications of water velocities as well as of heat and salt distributions are modeled, yet they are small. Simple parameterizations of SAL effects currently used in a number of ocean circulation models suffer from the process's inhomogeneity in space and time. These parameterizations improve the modeled sea level patterns but fail to reproduce SAL impacts on circulation and density distributions. We therefore suggest to explicitly consider the full SAL effect in ocean circulation models, especially when investigating sea level variations faster than around 4 days.
    Keywords: 550 - Earth sciences
    Language: English
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  • 69
    Publication Date: 2020-02-12
    Description: Frequent landsliding is one of the greatest natural hazards facing the inhabitants of Central Asia's Fergana Basin and the surrounding mountain ranges. Active tectonics in the region is rapidly building the Tien Shan, one of the highest mountain ranges on Earth, and the extreme topographic relief promotes frequent landslide activity, which causes major losses of life and property. In southwestern Kyrgyzstan alone, on average 10 people die and seven houses are destroyed each year in these sudden and rapidly moving landslides.
    Keywords: 550 - Earth sciences
    Language: English
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  • 70
    Publication Date: 2020-02-12
    Description: A series of linked marine and land studies have recently targeted the Sumatra subduction zone, focusing on the 2004 and 2005 plate boundary earthquake ruptures in Indonesia. A collaborative research effort by scientists from the United Kingdom (UK Sumatra Consortium), Indonesia, United States, France, and Germany is focusing on imaging the crustal structure of the margin to examine controls on along-strike and updip earthquake rupture propagation. The fundamental science objective is to examine how margin architecture and properties control earthquake rupture location and propagation.
    Keywords: 550 - Earth sciences
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  • 71
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Language: English
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  • 72
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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  • 73
    Publication Date: 2020-02-12
    Description: Structural features of volcanic and hydrothermal systems can be used to infer the location of magma chambers or productive geothermal areas. The Hengill volcanic triple-junction complex has a well-developed geothermal system, which is being exploited to extract hot fluids that are used for electrical power and heat production. In the framework of the I-GET project, a 4-month temporary seismological network including seven high-dynamic broadband instruments was deployed and 1D transient electromagnetic soundings (TEM) and 3D magnetotelluric (MT) surveys were performed to improve the understanding of the relationships between structural features, seismic activity and fluid production at the Hengill geothermal system. The MT and TEM data set are analysed elsewhere. The analysis of the seismological data set allowed the detection and classification of more than 600 earthquakes, among which long-period (LP) earthquakes were observed for the first time in this area. This work focuses first on a joint inversion for the 3D velocity structure and determination of the locations of the hypocentres from about 250 local volcano-tectonic earthquakes with clear P- and S-wave arrival times. The results confirm those from earlier tomography studies in this area. Integrating the seismic velocity and resistivity models in a semi-quantitative approach by cross-plotting the resistivity model with the velocity ratio VP/VS delineates a structural body with a high seismic velocity ratio and low resistivity that is interpreted as the main heat source of the geothermal system.
    Keywords: 550 - Earth sciences
    Language: English
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  • 74
    Publication Date: 2020-02-12
    Description: Ambient noise tomography is applied to the significant data resources now available across Tibet and surrounding regions to produce Rayleigh wave phase speed maps at periods between 6 and 50 s. Data resources include the permanent Federation of Digital Seismographic Networks, five temporary U.S. Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL) experiments in and around Tibet, and Chinese provincial networks surrounding Tibet from 2003 to 2009, totaling ∼600 stations and ∼150,000 interstation paths. With such a heterogeneous data set, data quality control is of utmost importance. We apply conservative data quality control criteria to accept between ∼5000 and ∼45,000 measurements as a function of period, which produce a lateral resolution between 100 and 200 km across most of the Tibetan Plateau and adjacent regions to the east. Misfits to the accepted measurements among PASSCAL stations and among Chinese stations are similar, with a standard deviation of ∼1.7 s, which indicates that the final dispersion measurements from Chinese and PASSCAL stations are of similar quality. Phase velocities across the Tibetan Plateau are lower, on average, than those in the surrounding nonbasin regions. Phase velocities in northern Tibet are lower than those in southern Tibet, perhaps implying different spatial and temporal variations in the way the high elevations of the plateau are created and maintained. At short periods (〈20 s), very low phase velocities are imaged in the major basins, including the Tarim, Qaidam, Junggar, and Sichuan basins, and in the Ordos Block. At intermediate and long periods (〉20 s), very high velocities are imaged in the Tarim Basin, the Ordos Block, and the Sichuan Basin. These phase velocity dispersion maps provide information needed to construct a 3-D shear velocity model of the crust across the Tibetan Plateau and surrounding regions.
    Keywords: 550 - Earth sciences
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  • 75
    Publication Date: 2020-02-12
    Description: Amplitude ratio of 30 short-period conspicuous P5KP and PKPab phases from five intermediate depth or deep events in Fiji-Tonga recorded at European stations around 150° distance shows a mean value two to three times the ratio of the synthetic amplitudes obtained by the normal-mode theory (and ak135 model) or by full-wave theory (and PREM). There is a large variance in the results, also observed in five amplitude ratios from one event in Argentina observed at temporary stations in China around 156°. Global recordings of three major deep earthquakes in Fiji, Bonin, and Western Brazil observed at ASAR, WRA, and ZRNK arrays, at 59 North America stations and at six South Pole stations displayed conspicuous P4KP and PcP (or ScP) phases. The amplitude ratio values of P4KP vs P(S)cP are sometimes almost one order of magnitude larger than the corresponding values of the synthetics. In both cases, arrival times and slowness values (corrected for ellipticity and station elevation) at the distances up to 23° beyond the A cutoff point predicted by ray theory match both the synthetics, suggesting the observations are the AB branch of PmKP (m = 4, 5) around 1 Hz. In disagreement to ray theory, no reliable BC branch is observed neither on the recordings nor on the normal-mode synthetics. The high amplitude ratio values cannot be explained by realistic perturbations of the velocity or attenuation values of the global models in the proximity of the core-to-mantle boundary (CMB). We speculate that the focusing effects and/or strong scattering most likely associated to some anomalous velocity areas of the lowermost mantle are responsible for that. The results suggest limitations of the previous evaluations of the short-period attenuation in the outer core from PmKP amplitudes (m ≥ 3), irrespective of the fact that they are obtained by using ray theory, normal-mode or full-wave synthetics. Attempts to use PmKP arrival times in order to refine velocity structure in the proximity of CMB should be also regarded with care if the propagation times have been computed with ray theory.
    Keywords: 550 - Earth sciences
    Language: English
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  • 76
    Publication Date: 2020-02-12
    Description: The territory of Lithuania and adjacent areas of the East European Craton have always been considered a region of low seismicity. Two recent earthquakes with magnitudes of more than 5 in the Kaliningrad District (Russian Federation) on 21 September 2004 motivated re-evaluation of the seismic hazard in Lithuania and adjacent territories. A new opportunity to study seismicity in the region is provided by the PASSEQ (Pasive Seismic Experiment) project that aimed to study the lithosphere–asthenosphere structure around the Trans-European Suture Zone. Twenty-six seismic stations of the PASSEQ temporary seismic array were installed in the territory of Lithuania. The stations recorded a number of local and regional seismic events originating from Lithuania and adjacent areas. This data can be used to answer the question of whether there exist seismically active tectonic zones in Lithuania that could be potentially hazardous for critical industrial facilities. Therefore, the aim of this paper is to find any natural tectonic seismic events in Lithuania and to obtain more general view of seismicity in the region. In order to do this, we make a manual review of the continuous data recorded by the PASSEQ seismic stations in Lithuania. From the good quality data, we select and relocate 45 local seismic events using the well-known LocSAT and VELEST location algortithms. In order to discriminate between possible natural events, underwater explosions and on-shore blasts, we analyse spatial distribution of epicenters and temporal distribution of origin times and perform both visual analysis of waveforms and spectral analysis of recordings. We show that the relocated seismic events can be grouped into five clusters (groups) according to their epicenter coordinates and origin and that several seismic events might be of tectonic origin. We also show that several events from the off-shore region in the Baltic Sea (at the coasts of the Kaliningrad District of the Russian Federation) are non-volcanic tremors, although the origin of these tremor-type events is not clear.
    Keywords: 550 - Earth sciences
    Language: English
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  • 77
    Publication Date: 2020-02-12
    Description: We examine shear-wave splitting of SKS waveforms collected by a temporary array of 68 stations in the region of the Dead Sea basin. The observed splitting parameters exhibit systematic variations along a dense, EW-trending 60 km profile across the basin. The delay times vary significantly between 1.0 and 2.8 seconds with smaller values in the very center of the profile. The fast polarizations are oriented more-or-less parallel to the strike of the Dead Sea transform fault and vary between −10 and 20 degrees with respect to North. Finite-frequency waveform modeling reveals that the source-region of the small-scale lateral variations is likely located within the crust. The modeling further shows that purely isotropic velocity variations affect shear-wave splitting: To a large degree, the observed variations of splitting parameters can be explained by the sedimentary fill of the basin and its low isotropic seismic velocities, whereas the mantle is uniformly anisotropic. Our study indicates that precaution must be taken when interpreting short-scale lateral variations of shear wave splitting in terms of anisotropic structures in the crust or upper mantle.
    Keywords: 550 - Earth sciences
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  • 78
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    In:  Journal of Structural Chemistry
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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  • 79
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Language: English
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  • 80
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    In:  Global Gravity Field and Its Temporal Variations | International Association of Geodesy Symposia
    Publication Date: 2020-02-12
    Description: In sequence of the GFZ93 high resolution gravity models (Gruber Th., et al, 1993) a new model, named GFZ95A, which is complete to degree and order 360 of a spherical harmonic series was computed. The model is based on new data sets, which were collected during the last months. This new data promises a major step towards a more precise high resolution gravity model. Especially from new available data over CIS (Community of Independent States) major progress can be expected with respect to the former models, which were based on predicted data in this area.
    Keywords: 550 - Earth sciences
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  • 81
    Publication Date: 2020-02-12
    Description: We performed a teleseismic P wave tomography study using seismic events at both teleseismic and regional distances, recorded by a temporary seismic array in the Argentine Puna Plateau and adjacent regions. The tomographic images show the presence of a number of positive and negative anomalies in a depth range of 20–300 km beneath the array. The most prominent of these anomalies corresponds to a low-velocity body, located in the crust, most clearly seen in the center of the array (27°S, 67°W) between the Cerro Peinado volcano, the Cerro Blanco caldera and the Farallon Negro in the east. This anomaly (southern Puna Magmatic Body) extends from the northern most part of the array and follows the line with the highest density of stations towards the south where it becomes smaller. It is flanked by high velocities on the west and the east respectively. On the west, the high velocities might be related to the subducted Nazca plate. On the northeast the high velocity block coincides with the position of the Hombre Muerto basin in the crust and could be indicating an area of lithospheric delamination where we detected a high velocity block at 100 km depth on the eastern border of the Puna plateau, north of Galan. This block might be related to a delamination event in an area with a thick crust of Paleozoic metamorphic rocks at the border between Puna and Eastern Cordillera. In the center of the array the Southern Puna magmatic body is also flanked by high velocities but the most prominent region is located on the east and is interpreted as part of the Sierras Pampeanas lithosphere with high velocities. The position of the Sierras Pampeanas geological province is key in this area as it appears to limit the extension of the plateau towards the south.
    Keywords: 550 - Earth sciences
    Language: English
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  • 82
    Publication Date: 2020-02-12
    Description: The transition between the lithosphere and the asthenosphere is subject to numerous contemporary studies as its nature is still poorly understood. The thickest lithosphere is associated with old cratons and platforms and it has been shown that seismic investigations may fail to image the lithosphere-asthenosphere boundary in these areas. Instead, several recent studies have proposed a mid-lithospheric discontinuity of unknown origin existing under several cratons. In this study we investigate the Tanzania craton in East Africa which is enclosed by the eastern and western branches of the East African Rift System. We present evidence from S receiver functions for two consecutive discontinuities at depths of 50–100 km and 140–200 km, which correspond to significant S wave velocity reductions under the Tanzania craton and the Albert and Edward rift segments. By comparison with synthetic waveforms we show that the lower discontinuity coincides with the LAB exhibiting velocity reductions of 6–9%. The shallower interface reveals a velocity drop that varies from 12% beneath the craton to 24% below the Albert-Edward rift. It is interpreted as an infiltration front marking the upper boundary of altered lithosphere due to ascending asthenospheric melts. This is corroborated by computing S velocity variations based on xenolith samples which exhibit a dense system of crystallized veins acting as pathways of the infiltrating melt. Mineral assemblages in these veins are rich in phlogopite and pyroxenite which can explain the reduced shear wave velocities. Melt infiltration represents a suitable mechanism to form a mid-lithospheric discontinuity within cratonic lithosphere that is underlain by anomalously hot mantle.
    Keywords: 550 - Earth sciences
    Language: English
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  • 83
    Publication Date: 2020-02-12
    Description: Clear S-to-P converted waves from the crust–mantle boundary (Moho) and lithosphere–asthenosphere boundary (LAB) have been observed on the eastern part of the Dead Sea Basin (DSB), and are used for the determination of the depth of the Moho and the LAB. A temporary network consisting of 18 seismic broad-band stations was operated in the DSB region as part of the DEad Sea Integrated REsearch project for 1.5 years beginning in September 2006. The obtained Moho depth (∼35 km) from S-to-P receiver functions agrees well with the results from P-to-S receiver functions and other geophysical data. The thickness of the lithosphere on the eastern part of the DSB is about 75 km. The results obtained here support and confirm previous studies, based on xenolith data, geodynamic modeling, heat flow observations, and S-to-P receiver functions. Therefore, the lithosphere on the eastern part of the DSB and along Wadi Araba has been thinned in the Late Cenozoic, following rifting and spreading of the Red Sea. The thinning of the lithosphere occurred without a concomitant change in the crustal thickness and thus an upwelling of the asthenosphere in the study area is invoked as the cause of the lithosphere thinning.
    Keywords: 550 - Earth sciences
    Language: English
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  • 84
    Publication Date: 2020-02-12
    Description: In the past decade the analysis of seismic noise has become an efficient tool to recover the Green's function between pairs of receivers by cross-correlation of seismic traces. Most studies focus on the investigation of the surface wave component of the ambient noise. Several attempts to recover the body wave part of the Green's function have been documented. In this paper I present the results of cross-correlation of seismic noise and the retrieval of refracted and reflected P-waves along a seismic line in the Karoo region (Republic of South Africa). Body wave refractions (direct phases) and reflections have been observed in the Green's functions derived from ambient noise records of up to 60 hours. The results are compared with shot gathers from a controlled source experiment (borehole explosions), carried out along the same line. The significant potential of ambient noise analysis, especially with respect to P-wave reflections will be shown and discussed.
    Keywords: 550 - Earth sciences
    Language: English
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  • 85
    Publication Date: 2020-02-12
    Description: The magnitude-8.8 Maule (Chile) earthquake of 27 February 2010 ruptured a segment of the Andean subduction zone megathrust that has been suspected to be of high seismic potential1,2,3,4,5,6. It is the largest earthquake to rupture a mature seismic gap in a subduction zone that has been monitored with a dense space-geodetic network before the event. This provides an image of the pre-seismically locked state of the plate interface of unprecedentedly high resolution, allowing for an assessment of the spatial correlation of interseismic locking with coseismic slip. Pre-seismic locking might be used to anticipate future ruptures in many seismic gaps6,7,8,9,10,11,12, given the fundamental assumption that locking and slip are similar. This hypothesis, however, could not be tested without the occurrence of the first gap-filling earthquake. Here we show evidence that the 2010 Maule earthquake slip distribution correlates closely with the patchwork of interseismic locking distribution as derived by inversion of global positioning system (GPS) observations during the previous decade. The earthquake nucleated in a region of high locking gradient and released most of the stresses accumulated in the area since the last major event in 1835. Two regions of high seismic slip (asperities) appeared to be nearly fully locked before the earthquake. Between these asperities, the rupture bridged a zone that was creeping interseismically with consistently low coseismic slip. The rupture stopped in areas that were highly locked before the earthquake but where pre-stress had been significantly reduced by overlapping twentieth-century earthquakes. Our work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future great earthquakes, which thus might be anticipated by geodetic observations.
    Keywords: 550 - Earth sciences
    Language: English
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  • 86
    Publication Date: 2020-02-12
    Description: Local earthquake data from a dense temporary seismological network in the southern Dead Sea area have been analysed within the project DESIRE (Dead Sea Integrated Research Project). Local earthquakes are used for the first precise image of the distribution of the P-wave velocity and the vP/vS ratios. 65 stations registered 655 local events within 18 months of observation time. A subset of 530 well-locatable events with 26 730 P- and S-arrival times was used to calculate a tomographic model for the vP and vP/vS distribution. Since the study area is at first-order 2-D, a gradual approach was chosen, which compromised a 2-D inversion followed by a 3-D inversion. The sedimentary basin fill is clearly imaged through high vP/vS ratios and low vP. The basin fill shows an asymmetric structure with average depth of 7 km at the western boundary and depth between 10 and 14 km at the eastern boundary. This asymmetry is reflected by the vertical strike-slip eastern border fault, and the normal faulting at the western boundary, caused by the transtensional deformation within the last 5 Myr. Within the basin fill the Lisan salt diapir is imaged through low vP/vS ratios, reflecting its low fluid content. The extensions were determined to 12 km in E–W and 17 km in N–S direction while its depth is 5–6 km. The thickness of the pre-basin sediments below the basin fill cannot be derived from the tomography data—it is estimated to less than 3 km from former investigations. Below the basin, down to 18 km depth very low P-wave velocities and low vP/vS ratios are observed—most likely caused by fluids from the surrounding crust or the upper mantle.
    Keywords: 550 - Earth sciences
    Language: English
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  • 87
    Publication Date: 2020-02-12
    Description: For the first time, ambient noise tomography is used to clearly image the magma chamber beneath Lake Toba caldera, one of the largest Quaternary calderas on Earth. Using data from 40 seismic stations deployed between May and October 2008 around Lake Toba, empirical Green's functions are extracted from long term cross-correlations of continuous records. These functions are dominated by Rayleigh waves, whose group velocities can be measured in the period range from 2.5 to 12 seconds. Arrival times of these waves are picked for a given period and inverted using 2-D tomography to calculate lateral variations in velocity for the given period. This was done for six different periods, which all correspond to different sampling depths. Thus the six 2-D models presented together provide information on velocity variations with depth. The results show a low-velocity body coincident with the Lake Toba caldera, representing the magma chamber under the volcano. The chamber is observed to have a complex 3-D geometry, with at least two separate sub-chambers underlying the caldera. Other results include a deep low velocity body, possibly another magma chamber, south west of the lake with an upper limit of ∼7 km depth. The maximum depth to which this body reaches could not be resolved. The Sumatra Fault marks a velocity contrast, but only down to depths not greater than 5 km. The reliability of the results was further confirmed by checkerboard recovery tests.
    Keywords: 550 - Earth sciences
    Language: English
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  • 88
    Publication Date: 2020-02-12
    Description: During the TOR-1 passive seismic experiment in 1996/97, a maximum of 139 temporary seismograph stations were operating over the Sorgenfrei-Tornquist Zone (STZ) in an area extending from northern Germany through Denmark to central Sweden. One of the objectives was to study horizontal anisotropy directions in the subcrustal lithosphere and asthenosphere across the Trans-European Suture Zone. To achieve this goal,broad-band and intermediate-period (5 s) data of the TOR-1 stations and additional stations of permanent networks (GRSN, GEOFON) were analysed for splitting of SKS and SKKS phases. As a result of the relatively dense station spacing, the method offers good lateral resolution of anisotropy.Preliminary results suggest that the directions of the fast horizontal S wave velocity are affected by the STZ. In central Europe and southern Sweden, far away from the STZ, fast S wave directions are approximately E-W while they turn more northerly closer to the STZ where they are approximately parallel to the trend of the STZ. No significant shear wave splitting was observed north of 57 degr. N and east of 14 degr. E. Small delay times between 0.2 and 0.5 s observed at the northernmost TOR-1 station T40S and T60S may be controlled by anisotropy in a thickened crust. The mantle contribution of horizontal anisotropy within the STZ is probably constrained to an approximately 60-km-thick zone in the depth range between 70 and 300 km. The observations are consistent with a model where azimuthally anisotropy is not governed by present-day mantle flow in the asthenosphere, but rather is frozen into the subcrustal lithosphere during the last episode of tectonic activity.
    Keywords: 550 - Earth sciences
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  • 89
    Publication Date: 2020-02-12
    Description: We investigate microseismic activity at the convergent plate boundary of the Hellenic subduction zone on- and offshore south-eastern Crete with unprecedented precision using recordings from an amphibian seismic network. The network configuration consisted of up to eight ocean bottom seismometers as well as five temporary short-period and six permanent broadband stations on Crete and surrounding islands. More than 2,500 local and regional events with magnitudes up to M L = 4.5 were recorded during the time period July 2003–June 2004. The magnitude of completeness varies between 1.5 on Crete and adjacent areas and increases to 2.5 in the vicinity of the Strabo trench 100 km south of Crete. Tests with different localization schemes and velocity models showed that the best results were obtained from a probabilistic earthquake localization using a 1-D velocity model and corresponding station corrections obtained by simultaneous inversion. Most of the seismic activity is located offshore of central and eastern Crete and interpreted to be associated with the intracrustal graben system (Ptolemy and Pliny trenches). Furthermore, a significant portion of events represents interplate seismicity along the NNE-ward dipping plate interface. The concentration of seismicity along the Ptolemy and Pliny trenches extends from shallow depths down to the plate interface and indicates active movement. We propose that both trenches form transtensional structures within the Aegean plate. The Aegean continental crust between these two trenches is interpreted as a forearc sliver as it exhibits only low microseismic activity during the observation period and little or no internal deformation. Interplate seismicity between the Aegean and African plates forms a 100-km wide zone along dip from the Strabo trench in the south to the southern shore-line of Crete in the north. The seismicity at the plate contact is randomly distributed and no indications for locked zones were observed. The plate contact below and north of Crete shows no microseismic activity and seems to be decoupled. The crustal seismicity of the Aegean plate in this area is generally confined to the upper 20 km in agreement with the idea of a ductile deformation of the lower crust caused by a rapid return flow of metamorphic rocks that spread out below the forearc. In the region of the Messara half-graben at the south coast of central Crete, a southward dipping seismogenic structure is found that coalesces with the seismicity of the Ptolemy trench at a depth of about 20 km. The accretionary prism south of Crete indicated by the Mediterranean Ridge showed no seismic activity during the observation period and seems to be deforming aseismically.
    Keywords: 550 - Earth sciences
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  • 90
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    In:  Natural Hazards and Earth System Sciences (NHESS)
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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  • 91
    Publication Date: 2020-02-12
    Description: We present a series of 1-D shear velocity models for the Sumatran Forearc and Arc derived from Rayleigh wave group dispersion in noise correlation functions from vertical and pressure records from an onshore–offshore seismic deployment. The 1-D models represent the crustal structure of the downgoing Indian Plate, the accretionary prism and the arc. There is a progression in shear velocity across the forearc to the arc associated with thickening of the accretionary prism and the development of an arc crust. The velocity structure inferred for the upper 20 km based on path averages between stations on the accretionary prism has velocities consistent with a thick sediment package in agreement with estimates of depth to the plate boundary determined from active source experiments. We also find low Indian Plate shear velocities, 〈4 km s−1 to 25 km depth beneath our station locations on the downgoing plate. These low seismic velocities are consistent with at least 14–24 per cent serpentinization of the oceanic crust and upper mantle of the downgoing plate. This high degree of serpentinization, may weaken the plate interface and explain the segmentation observed in the great Sumatran thrust earthquakes if the serpentinization is localized. The success of this study suggests that future onshore–offshore seismic deployments will be able to utilize this method.
    Keywords: 550 - Earth sciences
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  • 92
    Publication Date: 2020-02-12
    Description: The Mw = 9.3 Sumatra earthquake of 26 December 2004 generated a tsunami that affected the entire Indian Ocean region and caused approximately 230 000 fatalities. In the response to this tragedy the German government funded the German Indonesian Tsunami Early Warning System (GITEWS) Project. The task of the GEOFON group of GFZ Potsdam was to develop and implement the seismological component. In this paper we describe the concept of the GITEWS earthquake monitoring system and report on its present status. The major challenge for earthquake monitoring within a tsunami warning system is to deliver rapid information about location, depth, size and possibly other source parameters. This is particularly true for coast lines adjacent to the potential source areas such as the Sunda trench where these parameters are required within a few minutes after the event in order to be able to warn the population before the potential tsunami hits the neighbouring coastal areas. Therefore, the key for a seismic monitoring system with short warning times adequate for Indonesia is a dense real-time seismic network across Indonesia with densifications close to the Sunda trench. A substantial number of supplementary stations in other Indian Ocean rim countries are added to strengthen the teleseismic monitoring capabilities. The installation of the new GITEWS seismic network – consisting of 31 combined broadband and strong motion stations – out of these 21 stations in Indonesia – is almost completed. The real-time data collection is using a private VSAT communication system with hubs in Jakarta and Vienna. In addition, all available seismic real-time data from the other seismic networks in Indonesia and other Indian Ocean rim countries are acquired also directly by VSAT or by Internet at the Indonesian Tsunami Warning Centre in Jakarta and the resulting "virtual" network of more than 230 stations can jointly be used for seismic data processing. The seismological processing software as part of the GITEWS tsunami control centre is an enhanced version of the widely used SeisComP software and the well established GEOFON earthquake information system operated at GFZ in Potsdam (http://geofon.gfz-potsdam.de/db/eqinfo.php). This recently developed software package (SeisComP3) is reliable, fast and can provide fully automatic earthquake location and magnitude estimates. It uses innovative visualization tools, offers the possibility for manual correction and re-calculation, flexible configuration, support for distributed processing and data and parameter exchange with external monitoring systems. SeisComP3 is not only used for tsunami warning in Indonesia but also in most other Tsunami Warning Centres in the Indian Ocean and Euro-Med regions and in many seismic services worldwide.
    Keywords: 550 - Earth sciences
    Language: English
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  • 93
    Publication Date: 2020-02-12
    Description: We analyse broad-band SS waveformdata recorded by several networks in Europe with sources mainly in the west Pacific to study the underside reflections of teleseismic SS waves in the lithosphere and the upper mantle beneath eastern Asia and the NW Pacific ocean. SS bounce points sample a corridor from the Aleutian, Kamchatka and Japan subduction zones through the North China Craton and Central Asian Orogenic Belt to the Tibetan plateau. The corridor passes through different tectonic units such as subduction zones, an old continental shield, a fold belt and a high plateau. We investigate the seismic structure of the lithosphere and the mantle transition zone beneath the different geotectonic units along the profile and infer the correlation of geodynamic processes at different depths.We explore the short period frequency content in the SS waveform data and use moveout correction and common midpoint stack to acquire profiles with high lateral and depth resolution from the crust to the mantle transition zone. Clear SS precursors of the 410 and 660 km discontinuities show the effects of the interaction between the subducted oceanic lithosphere and the mantle transition zone beneath the NW Pacific subduction zones. A low-velocity layer has also been detected beneath the 410 km discontinuity and can be traced along the entire profile. Due to the improved resolution acquired by the method presented here we have been able to study the shallower structures such as the Moho and the lithosphere–asthenosphere boundary by SS precursors. The continental Moho can be clearly seen along this corridor. The depth variation agrees well with earlier receiver function results. We also see negative reflectors along the profile at varying depths, which can be interpreted as the lithosphere–asthenosphere boundary.
    Keywords: 550 - Earth sciences
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  • 94
    Publication Date: 2020-02-12
    Description: Earthquake early warning systems should provide reliable warnings as quickly as possible with a minimum number of false and missed alarms. Wireless meshed networks, coupled with low-cost seismometers for monitoring, evaluation, and information about seismic vibrations in space and time are introducing a new generation of warning infrastructures for mega-cities. The use of a cooperative method for signal analysis makes it possible to distinguish earthquakes (with a certain minimal magnitude) from other ground shaking in a city. The paper gives a short overview of our approach for developing decentralized early warning systems and an evaluation based on experiences gained from model investigations, testbeds in Berlin, and prototype installations in Istanbul.
    Keywords: 550 - Earth sciences
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  • 95
    Publication Date: 2020-02-12
    Description: S receiver functions obtained from seismograms of teleseismic events recorded at 78 European permanent broad-band stations are used to estimate the thickness of the European lithosphere. Our results provide new, independent information about the lithospheric thickness beneath the Precambrian platform of Eastern Europe and the Phanerozoic platform of central Europe. Detailed high-resolution images of the lithosphere–asthenosphere boundary (LAB) reveal indications for a typical continental lithosphere of about 100 km thickness beneath a majority of stations within Central Europe, whereas in the vicinity of the Trans-European Suture Zone (TESZ), the lithosphere thickens to about 130 km. A relatively thin lithosphere of 80 km was found beneath the Upper Rhine Graben region suggesting that the Cenozoic extension affects the whole lithosphere. No clear signal from the LAB was detected beneath the Alps and Carpathians. The LAB Sp phase might be disturbed by complicated structure due to ongoing collision/subduction in these regions, or the data are not yet sufficiently dense. A relatively thicker lithosphere of about 120 km was found beneath the SW part of the Bohemian Massif that was formed during the Variscan orogeny.We found an LAB depth of about 190 km near a single station located in the Vrancea area/Eastern Carpathians, which is characterized by the occurrence of intermediate deep earthquakes. Beneath the stations located in the Precambrian platform of Eastern Europe, the LAB deepens to approximately 〉200 km, even though the converted phase from the LAB is not as sharp as found beneath other stations located in Central Europe or even is missing.
    Keywords: 550 - Earth sciences
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  • 96
    Publication Date: 2020-02-12
    Description: We use Global Positioning System (GPS) velocities and kinematic Finite Element models (FE-models) to infer the state of locking between the converging Nazca and South America plates in South-Central Chile (36[degree sign]S - 46[degree sign]S) and to evaluate its spatial and temporal variability. GPS velocities provide information on earthquake-cycle deformation over the last decade in areas affected by the megathrust events of 1960 (Mw= 9.5) and 2010 (Mw= 8.8). Our data confirm that a change in surface velocity patterns of these two seismotectonic segments can be related to their different stages in the seismic cycle: Accordingly, the northern (2010) segment was in a final stage of interseismic loading whereas the southern (1960) segment is still in a postseismic stage and undergoes a prolonged viscoelastic mantle relaxation. After correcting the signals for mantle relaxation, the residual GPS velocity pattern suggests that the plate interface accumulates slip deficit in a spatially and presumably temporally variable way towards the next great event. Though some similarity exist between locking and 1960 coseismic slip, extrapolating the current, decadal scale slip deficit accumulation towards the ~ 300-yr recurrence times of giant events here does neither yield the slip distribution nor the moment magnitude of the 1960 earthquake. This suggests that either the locking pattern is evolving in time (to reconcile a slip deficit distribution similar to the 1960 earthquake) or that some asperities are not persistent over multiple events. The accumulated moment deficit since 1960 suggests that highly locked patches in the 1960 segment are already capable of producing a M ~ 8 event if triggered to fail by stress transfer from the 2010 event.
    Keywords: 550 - Earth sciences
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  • 97
    Publication Date: 2020-02-12
    Description: Determining the relative orientation of the horizontal components of seismic sensors is a common problem that limits data analysis and interpretation for several acquisition setups, including linear arrays of geophones deployed in borehole installations or ocean bottom seismometers deployed at the seafloor. To solve this problem we propose a new inversion method based on a complex linear algebra approach. Relative orientation angles are retrieved by minimizing, in a least-squares sense, the l2-norm between the complex traces (hodograms) of adjacent pairs of sensors. This methodology can be applied without restrictions only if the wavefield recorded by each pair of sensors is very similar. In most cases, it is possible to satisfy this condition by low-pass filtering the recorded waveforms. The main advantage of our methodology is that, in the complex domain, the relative orientations of seismic sensors can be viewed as a linear inverse problem, which ensures that the preferred solution corresponds to the global minimum of a misfit function. It is also possible to use simultaneously more than one independent data set (other seismic events) to better constrain the solution of the inverse problem. Furthermore, by a computational point of view, our method results faster than the relative orientation methods based on waveform cross-correlation. After several tests on synthetic data sets we applied successfully our methodology to different types of real data. These applications include the alignment of borehole sensors relative to a Vertical Seismic Profiling (VSP) acquisition and the orientation of Ocean Bottom Seismometers (OBS) relative to a neighbouring land station of known orientation. Using land stations, the absolute orientation of OBS can be retrieved. Finally, as a last application, we checked the correct orientation for land stations of a seismological array in Germany.
    Keywords: 550 - Earth sciences
    Language: English
    Type: info:eu-repo/semantics/article
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  • 98
    Publication Date: 2020-02-12
    Description: An automatic procedure is presented to retrieve rupture parameters for large earthquakes along the Sunda arc subduction zone. The method is based on standard array analysis and broadband seismograms registered within 30°–100° epicentral distance. No assumptions on source mechanism are required. By means of semblance the coherency of P waveforms is analysed at separate large-aperture arrays. Waveforms are migrated to a 10°×10° wide source region to study the spatio-temporal evolution of earthquakes at each array. The multiplication of the semblance source maps resulting at each array increases resolution. Start, duration, extent, direction, and propagation velocity are obtained and published within 25 min after the onset of the event. First preliminary results can be obtained even within 16 min. Their rapid determination may improve the mitigation of the earthquake and tsunami hazard. Real-time application will provide rupture parameters to the GITEWS project (German Indonesian Tsunami Early Warning System). The method is applied to the two M8.0 Sumatra earthquakes on 12 September 2007, to the M7.4 Java earthquake on 2 September 2009, and to major subduction earthquakes that have occurred along Sumatra and Java since 2000. Obtained rupture parameters are most robust for the largest earthquakes with magnitudes M≥8. The results indicate that almost the entire seismogenic part of the subduction zone off the coast of Sumatra has been ruptured. Only the great Sumatra event in 2004 and the M7.7 Java event on 17 July 2006 could reach to or close to the surface at the trench. Otherwise, the rupturing was apparently confined to depths below 25 km. Major seismic gaps seem to remain off the coast of Padang and the southern tip of Sumatra.
    Keywords: 550 - Earth sciences
    Language: English
    Type: info:eu-repo/semantics/article
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  • 99
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    In:  Handbook of Hydrocarbon and Lipid Microbiology
    Publication Date: 2020-02-12
    Description: In this essay we provide a short introduction to and overview of the basics of stable isotope geochemistry and its common application in petroleum geochemistry. We identify the processes that are responsible for the carbon and hydrogen isotopic compositions of biological and geological organic matter and indicate the utility of stable isotopes in oil-source rock correlations. Stable isotope analyses are also exploited in the investigation of different alteration processes within oils and petroleum reservoirs. State of the art work is presented, and future research needs are identified.
    Keywords: 550 - Earth sciences
    Language: English
    Type: info:eu-repo/semantics/bookPart
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  • 100
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    In:  Bulletin of the Seismological Society of America
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Language: English
    Type: info:eu-repo/semantics/article
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