TY - JOUR A1 - Nexer, Maelle A1 - Authemayou, Christine A1 - Schildgen, Taylor F. A1 - Hantoro, Wahyoe S. A1 - Molliex, Stephane A1 - Delcaillau, Bernard A1 - Pedoja, Kevin A1 - Husson, Laurent A1 - Regard, Vincent T1 - Evaluation of morphometric proxies for uplift on sequences of coral reef terraces: A case study from Sumba Island (Indonesia) JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Sequences of coral reef terraces characterized by staircase morphologies and a homogeneous lithology make them appropriate to isolate the influence of uplift on drainage morphology. Along the northern coast of Sumba Island, Indonesia, we investigated the correlations between landscape morphology and uplift rates, which range from 0.02 to 0.6 mm.yr(-1). We studied eight morphometric indices at two scales: whole island (similar to 11,000 km(2)) and within sequences of reefal terraces (similar to 3000 km(2)). At the latter scale, we extracted morphometric indices for 15 individual catchments draining mostly the reefal terraces and for 30 areas undergoing specific ranges of uplift rates draining only the reefal terraces. Indices extracted from digital elevation models include residual relief, incision, stream gradient indices (SL and k(sn)), the hypsometric integral, drainage area, mean relief, and the shape factor. We find that SL, the hypsometric integral, mean relief and the shape factor of catchments positively correlate with uplift rates, whereas incision, residual relief, and k(sn) do not. More precisely, we find that only the areas that are uplifting at a rate faster than 03 mm.yr(-1) can yield the extreme values for these indices, implying that these extreme values are indicative of fast uplifting areas. However, the relationship is not bivalent because any uplift rate can be associated with low values of the same indices. For all indices, the transient conditions of the drainage influence the correlation with Pleistocene mean uplift rates, illustrating the necessity to extract morphometric indices with an appropriate choice of catchment scale. This type of analysis helps to identify the morphometric indices that are most useful for tectonic analysis in areas of unknown uplift, allowing for easy identification of short spatial variations of uplift rate and detection of areas with relatively fast uplift rates in unstudied coastal zones. (C) 2015 Elsevier B.V. All rights reserved. KW - Drainage morphometry KW - Coral reef terraces KW - Uplift KW - Pleistocene KW - Sumba Island KW - Indonesia Y1 - 2015 U6 - https://doi.org/10.1016/j.geomorph.2015.03.036 SN - 0169-555X SN - 1872-695X VL - 241 SP - 145 EP - 159 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Brune, Sascha T1 - Landslide generated tsunamis : numerical modeling and real-time prediction T1 - Tsunamis, die durch unterseeische Rutschungen angeregt werden : numerische Modellierung und Echtzeit-Vorhersage N2 - Submarine landslides can generate local tsunamis posing a hazard to human lives and coastal facilities. Two major related problems are: (i) quantitative estimation of tsunami hazard and (ii) early detection of the most dangerous landslides. This thesis focuses on both those issues by providing numerical modeling of landslide-induced tsunamis and by suggesting and justifying a new method for fast detection of tsunamigenic landslides by means of tiltmeters. Due to the proximity to the Sunda subduction zone, Indonesian coasts are prone to earthquake, but also landslide tsunamis. The aim of the GITEWS-project (German-Indonesian Tsunami Early Warning System) is to provide fast and reliable tsunami warnings, but also to deepen the knowledge about tsunami hazards. New bathymetric data at the Sunda Arc provide the opportunity to evaluate the hazard potential of landslide tsunamis for the adjacent Indonesian islands. I present nine large mass movements in proximity to Sumatra, Java, Sumbawa and Sumba, whereof the largest event displaced 20 km³ of sediments. Using numerical modeling, I compute the generated tsunami of each event, its propagation and runup at the coast. Moreover, I investigate the age of the largest slope failures by relating them to the Great 1977 Sumba earthquake. Continental slopes off northwest Europe are well known for their history of huge underwater landslides. The current geological situation west of Spitsbergen is comparable to the continental margin off Norway after the last glaciation, when the large tsunamigenic Storegga slide took place. The influence of Arctic warming on the stability of the Svalbard glacial margin is discussed. Based on new geophysical data, I present four possible landslide scenarios and compute the generated tsunamis. Waves of 6 m height would be capable of reaching northwest Europe threatening coastal areas. I present a novel technique to detect large submarine landslides using an array of tiltmeters, as a possible tool in future tsunami early warning systems. The dislocation of a large amount of sediment during a landslide produces a permanent elastic response of the earth. I analyze this response with a mathematical model and calculate the theoretical tilt signal. Applications to the hypothetical Spitsbergen event and the historical Storegga slide show tilt signals exceeding 1000 nrad. The amplitude of landslide tsunamis is controlled by the product of slide volume and maximal velocity (slide tsunamigenic potential). I introduce an inversion routine that provides slide location and tsunamigenic potential, based on tiltmeter measurements. The accuracy of the inversion and of the estimated tsunami height near the coast depends on the noise level of tiltmeter measurements, the distance of tiltmeters from the slide, and the slide tsunamigenic potential. Finally, I estimate the applicability scope of this method by employing it to known landslide events worldwide. N2 - Submarine Erdrutsche können lokale Tsunamis auslösen und stellen somit eine Gefahr für Siedlungen an der Küste und deren Einwohner dar. Zwei Hauptprobleme sind (i) die quantitative Abschätzung der Gefahr, die von einem Tsunami ausgeht und (ii) das schnelle Erkennen von gefährlichen Rutschungsereignissen. In dieser Doktorarbeit beschäftige ich mich mit beiden Problemen, indem ich Erdrutschtsunamis numerisch modelliere und eine neue Methode vorstelle, in der submarine Erdrutsche mit Hilfe von Tiltmetern detektiert werden. Die Küstengebiete Indonesiens sind wegen der Nähe zur Sunda-Subduktionszone besonders durch Tsunamis gefährdet. Das Ziel des GITEWS-Projektes (Deutsch- Indonesisches Tsunami-Frühwarnsystem) ist es, schnell und verlässlich vor Tsunamis zu warnen, aber auch das Wissen über Tsunamis und ihre Anregung zu vertiefen. Neue bathymetrische Daten am Sundabogen bieten die Möglichkeit, das Gefahrenpotential von Erdrutschtsunamis für die anliegenden indonesischen Inseln zu studieren. Ich präsentiere neun große Rutschungereignisse nahe Sumatra, Java, Sumbawa und Sumba, wobei das größte von ihnen 20 km³ Sediment bewegte. Ich modelliere die Ausbreitung und die Überschwemmung der bei diesen Rutschungen angeregten Tsunamis. Weiterhin untersuche ich das Alter der größten Hanginstabilitäten, indem ich sie zu dem Sumba Erdbeben von 1977 in Beziehung setze. Die Kontinentalhänge im Nordwesten Europa sind für Ihre immensen unterseeischen Rutschungen bekannt. Die gegenwärtige geologische Situation westlich von Spitzbergen ist vergleichbar mit derjenigen des norwegischen Kontinentalhangs nach der letzten Vergletscherung, als der große Tsunamianregende Storegga-Erdrutsch stattfand. Der Einfluss der arktischen Erwärmung auf die Hangstabilität vor Spitzbergen wird untersucht. Basierend auf neuen geophysikalischen Messungen, konstruiere ich vier mögliche Rutschungsszenarien und berechne die entsprechenden Tsunamis. Wellen von 6 Metern Höhe könnten dabei Nordwesteuropa erreichen. Ich stelle eine neue Methode vor, mit der große submarine Erdrutsche mit Hilfe eines Netzes aus Tiltmetern erkannt werden können. Diese Methode könnte in einem Tsunami-Frühwarnsystem angewendet werden. Sie basiert darauf, dass die Bewegung von großen Sedimentmassen während einer Rutschung eine dauerhafte Verformung der Erdoberfläche auslöst. Ich berechne diese Verformung und das einhergehende Tiltsignal. Im Falle der hypothetischen Spitzbergen-Rutschung sowie für das Storegga-Ereignis erhalte ich Amplituden von mehr als 1000 nrad. Die Wellenhöhe von Erdrutschtsunamis wird in erster Linie von dem Produkt aus Volumen und maximaler Rutschungsgeschwindigkeit (dem Tsunamipotential einer Rutschung) bestimmt. Ich führe eine Inversionsroutine vor, die unter Verwendung von Tiltdaten den Ort und das Tsunamipotential einer Rutschung bestimmt. Die Genauigkeit dieser Inversion und damit der vorhergesagten Wellenhöhe an der Küste hängt von dem Fehler der Tiltdaten, der Entfernung zwischen Tiltmeter und Rutschung sowie vom Tsunamipotential ab. Letztlich bestimme ich die Anwendbarkeitsreichweite dieser Methode, indem ich sie auf bekannte Rutschungsereignisse weltweit beziehe. KW - Tsunami KW - Erdrutsch KW - Indonesien KW - Spitzbergen KW - Tiltmeter KW - Tsunami KW - Landslide KW - Indonesia KW - Spitsbergen KW - Tiltmeter Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-32986 ER - TY - GEN A1 - Rößler, Dirk A1 - Krüger, Frank A1 - Ohrnberger, Matthias T1 - Rupture propagation of recent large TsE off-coast Sumatra and Java N2 - The spatio-temporal evolution of the three recent tsunamogenic earthquakes (TsE) off-coast N-Sumatra (Mw9.3), 28/03/2005 (Mw8.5) off-coast Nias, on 17/07/2006 (Mw7.7) off-coast Java. Start time, duration, and propagation of the rupture are retrieved. All parameters can be obtained rapidly after recording of the first-arrival phases in near-real time processing. We exploit semblance analysis, backpropagation and broad-band seismograms within 30°-95° distance. Image enhancement is reached by stacking the semblance of arrays within different directions. For the three events, the rupture extends over about 1150, 150, and 200km, respectively. The events in 2004, 2005, and 2006 had source durations of at least 480s, 120s, and 180s, respectively. We observe unilateral rupture propagation for all events except for the rupture onset and the Nias event, where there is evidence for a bilateral start of the rupture. Whereas average rupture speed of the events in 2004 and 2005 is in the order of the S-wave speed (≈2.5-3km/s), unusually slow rupturing (≈1.5 km/s) is indicated for the July 2006 event. For the July 2006 event we find rupturing of a 200 x 100 km wide area in at least 2 phases with propagation from NW to SE. The event has some characteristics of a circular rupture followed by unilateral faulting with change in slip rate. Fault area and aftershock distribution coincide. Spatial and temporal resolution are frequency dependent. Studies of a Mw6.0 earthquake on 2006/09/21 and one synthetic source show a ≈1° limit in resolution. Retrieved source area, source duration as well as peak values for semblance and beam power generally increase with the size of the earthquake making possible an automatic detection and classification of large and small earthquakes. KW - Tsunami KW - Erdbeben KW - Indischer Ozean KW - Bruchausbreitung KW - Seismologie KW - Tsunami KW - Earthquake KW - Indonesia KW - Indian Ocean KW - Rupture Propagation KW - Seismology Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13039 ER - TY - GEN A1 - Schuck, Christoph T1 - Der Bürgerkrieg in Aceh : Konsequenzen für den Weg Indonesiens zur Demokratie N2 - Indonesia’s arduous path to democracy is threatened by several domestic conflicts. Although the civil war in Aceh – a region in the north of Sumatra – has claimed thousands of victims, the incidents have not yet been adequately dealt with – neither in the public domain nor within the scientific community. In May 2003, the Indonesian president, Megawati Sukarnoputri, imposed material law on the Aceh region in order to crack down on the separatist movement Gerakan Aceh Merdeka (GAM). This step does not seem to be in line with serious concepts of democracy and is threatening the consolidation of the transformation process. The author seeks to shed light on the roots of the conflict, the motivation of leading politicians in Jakarta to deploy military means instead of continuing negotiations, and its consequences for the Indonesian process of democratisation. KW - Indonesia KW - civil war KW - democratisation Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9647 ER -