13 research outputs found

    Emulation for Digital Preservation in Practice: The Results

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    In recent years a lot of research has been undertaken to ascertain the most suitable preservation approach. For a long time migration was seen as the only viable approach, whereas emulation was looked upon with scepticism due to its technical complexity and initial costs. In 2004, the National Library of the Netherlands (Koninklijke Bibliotheek, [KB]) and the Nationaal Archief of the Netherlands acknowledged the need for emulation, especially for rendering complex digital objects without affecting their authenticity and integrity. A project was started to investigate the feasibility of emulation by developing and testing an emulator designed for digital preservation purposes. In July 2007 this project ended and delivered a durable x86 component-based computer emulator: Dioscuri, the first modular emulator for digital preservation

    Emulation as a Business Solution: the Emulation Framework: Paper - iPRES 2011 - Singapore

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    Emulation is often considered a technically very complex subject. The association with complexity has long prevented it from being considered in an end-to-end business solution for long-term preservation and access to digital collections. The Emulation Framework solves this problem by automating the steps required to render an unknown digital object in its original environment: characterising the object to determine its type; determining the environment required to render that type of object; setting up the required software and emulators providing the hardware; and configuring the environment to properly render the digital object. Automating these steps allows a novice user to easily render a digital object in an environment for accessing it in its original form. Each of the four steps of the emulation workflow are described in detail, providing a simple tool for managing a complex decision making process

    Source parameters of the 2008 Bukavu-Cyangugu earthquake estimated from InSAR and teleseismic data

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    Earthquake source parameter determination is of great importance for hazard assessment, as well as for a variety of scientific studies concerning regional stress and strain release and volcano-tectonic interaction. This is especially true for poorly instrumented, densely populated regions such as encountered in Africa, where even the distribution of seismicity remains poorly documented. In this paper, we combine data from satellite radar interferometry (InSAR) and teleseismic waveforms to determine the source parameters of the Mw 5.9 earthquake that occurred on 2008 February 3 near the cities of Bukavu (DR Congo) and Cyangugu (Rwanda). This was the second largest earthquake ever to be recorded in the Kivu basin, a section of the western branch of the East African Rift (EAR). This earthquake is of particular interest due to its shallow depth and proximity to active volcanoes and Lake Kivu, which contains high concentrations of dissolved carbon dioxide and methane. The shallow depth and possible similarity with dyking events recognized in other parts of EAR suggested the potential association of the earthquake with a magmatic intrusion, emphasizing the necessity of accurate source parameter determination. In general, we find that estimates of fault plane geometry, depth and scalar moment are highly consistent between teleseismic and InSAR studies. Centroid-moment-tensor (CMT) solutions locate the earthquake near the southern part of Lake Kivu, while InSAR studies place it under the lake itself. CMT solutions characterize the event as a nearly pure double-couple, normal faulting earthquake occurring on a fault plane striking 350° and dipping 52° east, with a rake of –101°. This is consistent with locally mapped faults, as well as InSAR data, which place the earthquake on a fault striking 355° and dipping 55° east, with a rake of –98°. The depth of the earthquake was constrained by a joint analysis of teleseismic P and SH waves and the CMT data set, showing that the earthquake occurred in the shallow crust, at approximately 8 km depth. Inversions of ENVISAT (Environment Satellite) and ALOS (Advanced Land Observation Satellite) data place the earthquake at 9 km. A comparison of the scalar moment (9.43 ± 0.06 × 1017 Nm from seismology and 8.99 ± 0.010 × 1017 Nm from the joint InSAR solution) shows good agreement between the two data sets. Such an agreement is in contrast to the large discrepancies observed (up to an order of magnitude) in other places along the EAR where similar earthquake sequences are associated with magmatic intrusion. From this, we infer that the rupture was brittle and occurred with little aseismic deformation as might be expected from magma injection. Our results provide insights into the style of rifting occurring in the South Kivu Volcanic Province and hence will aid future studies on seismic risk in the context of Lake Kivu and underline the importance of systematic monitoring of the EAR area.Peer reviewe
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