Indonesia is exposed to earthquakes, volcanic activities, and associated tsunamis. This is partic... more Indonesia is exposed to earthquakes, volcanic activities, and associated tsunamis. This is particularly the case for Lombok and Sumbawa Islands in West Nusa Tenggara, where evidence of tsunamis is frequently observed in its coastal sedimentary record. If the 1815 CE Tambora eruption on Sumbawa Island generated a tsunami with well-identified traces on the surrounding islands, little is known about the consequences of the 1257 CE tremendous eruption of Samalas on the neighboring islands, and especially about the possible tsunamis generated in reason of a paucity of research on coastal sedimentary records in this area. However, on Lombok Island, the eruption of the Samalas volcano produced significant volumes of pyroclastic flows that entered the sea in the North and East of the island. These phenomena must have produced a tsunami that left their traces, especially on Sumbawa Island, whose western coastline is only 14 km away from Lombok’s eastern shore. Therefore, the main goal of thi...
This paper discusses the relations between the impacts of volcanic eruptions at multiple-scales a... more This paper discusses the relations between the impacts of volcanic eruptions at multiple-scales and the related-issues of disaster-risk reduction (DRR). The review is structured around local and global impacts of volcanic eruptions, which have not been widely discussed in the literature, in terms of DRR issues. We classify the impacts at local scale on four different geographical features: impacts on the drainage system, on the structural morphology, on the water bodies, and the impact on societies and the environment. It has been demonstrated that information on local impacts can be integrated into four phases of the DRR, i.e., monitoring, mapping, emergency, and recovery. In contrast, information on the global impacts (e.g., global disruption on climate and air traffic) only fits the first DRR phase. We have emphasized the fact that global impacts are almost forgotten in the DRR programs. For this review, we have extracted case studies from Indonesia, and compared them to those of...
<p>... more <p>The duration and timing of a northern ocean is a key issue in understanding the past geological and climatic evolution of Mars. Mars experienced its greatest loss of H<sub>2</sub>O between the Noachian and Late Hesperian (~10 m Global Equivalent Layer, Jakosky et al., 2017) roughly the same amount that is thought to have been added to the global inventory by extrusive volcanism over the same time period (Carr and Head, 2015). Thus, the total inventory of water was probably similar during these two epochs. But, the ocean during the Late Hesperian was smaller in extension than the ocean during the Noachian– with significant implications for the potential origin and survival of life. Here we examine the implications of the existence of a Late Hesperian/ Early Amazonian ocean on the planet’s inventory of water (and especially liquid water) and its variation with time. Our previous work (Rodriguez et al., 2016; Costard et al., 2017) concluded that the most plausible explanation for the origin of the Thumbprint Terrain (TT) lobate deposits, with run-ups, found along the dichotomy boundary, especially in Arabia Terra, was tsunami deposits. This supports the hypothesis that an ocean occupied the northern plains of Mars as recently as ~3 billion years ago. Furthermore, Costard et al (2017) produced a tsunami numerical model showing that the TT deposits exhibit fine-scale textural patterns due to the wave’s interference patterns resulting from interactions with the coastal topography. More recently, we suggested that the unusual characteristics of Lomonosov crater (50.52°N/16.39°E ) in the northern plains are best explained by the presence of a shallow ocean at the time of the impact (Costard et al., 2019). Interestingly, the apparent agreement between the age of the Lomonosov impact and that of the TT unit (~3 Ga), strongly suggests that it was the source of the tsunami (Costard et al., 2019). Our preliminary assessment indicates that this impact-generated tsunami required a mostly liquid ocean and because of the high latitude location of the Lomonosov crater site, our results strongly imply relatively warm paleoclimatic conditions. Our conclusions highlight the need for more sophisticated climate models.</p>
In foie gras production the technological yield after the cooking process is one of the main issu... more In foie gras production the technological yield after the cooking process is one of the main issues of processors as it is closely linked to the cooking melting rate. This rate is subjected to strict laws and regulations since it directly affects the organoleptic and technological qualities of this gourmet product. The objective of the study was to better understand the liver fattening and the technological yield decrease during the overfeeding kinetics. A flock of 210 mule ducks was reared and then overfed during 12 D with 2 overfeeding programs; in the test group the amounts of corn in the first meals were higher than in the control group (+430 g during the whole period). Ducks were slaughtered at the end of the rearing period (D0, n = 15) and every other day (D2 to D12, n = 15 by group). Duck performances, anatomical dissections and physical and biochemical liver characteristics were registered. The performances were equivalent in the groups (P > 0.1). The evolution of the liv...
The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the... more The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional magnitude (M e 7, VEI 7) of the Samalas eruption with ≥40 km 3 of dense magma expelled and a plinian column estimated to reach 43 km. However, the climatic response to the Samalas event is debated since climate model simulations generally predict a stronger and more prolonged surface air cooling of Northern Hemisphere (NH) summers than inferred from tree-ring based temperature reconstructions. Here, we draw on historical archives, ice-core data and tree-ring records to reconstruct the spatial and temporal climate response to the Samalas eruption. We find that 1258 and 1259 experienced some of the coldest NH summers of the past millennium. However, cooling across the NH was spatially heterogeneous. Western Europe, Siberia and Japan experienced strong cooling, coinciding with warmer-than-average conditions over Alaska and Northern Canada. We suggest that in North America, volcanic radiative forcing was modulated by a positive phase of the El Niño Southern Oscillation. Contemporary records attest to severe famines in England and Japan, but these began prior to the eruption. We conclude that the Samalas eruption aggravated existing crisis, but did not trigger the famines. Despite the exceptional magnitude of the 1257 Samalas volcanic eruption 1-4 , the apparent lack of strong and widespread cooling in climate proxies, with the exception of Western Europe 5 , has puzzled scientists for almost two decades 6-8. This conundrum is emphasized since for some lesser magnitude events, e.g. the 536 "unknown" 9-11 , 1600 Huaynaputina 12 and 1815 Tambora 13,14 eruptions, abundant Holy
A lahar is a flowing mixture of rock debris and water (other than normal streamflow) from a volca... more A lahar is a flowing mixture of rock debris and water (other than normal streamflow) from a volcano, which encompasses a continuum from debris flows (sediment concentration > or =60% per volume) to hyperconcentrated streamflows (sediment concentration from 20 to 60% per volume). Debris flow deposits are poorly sorted and massive with abundant clasts. Lahars can be either syn-eruptive, post-eruptive or have a non-eruptive origin. Four types of lahars can be generated during an eruption, based on distinct sources of water (i.e. ice, snow, crater lake, river, and rain) that allow the sediments to be removed and incorporated in the lahar (e.g., Mount St.-Helens in 1980, Nevado del Ruiz in 1985). Post-eruptive lahars, which are rain-triggered, occur during several years after an eruption (e.g., still occurring at Pinatubo). Non-eruptive lahars are flows generated on volcanoes without eruptive activity, particularly in the case of a debris avalanche or a lake outburst (e.g., Kelud or R...
-astarte est un programme de recherche qui vise à améliorer la résilience des populations europée... more -astarte est un programme de recherche qui vise à améliorer la résilience des populations européennes aux tsunamis. Une enquête à l' échelle européenne a été conduite en 2014-2015 dans des secteurs littoraux exposés à ce risque. Cet article en présente quelques résultats, en s'interrogeant sur le rôle que la perception récurrente, voire quotidienne, d'un paysage de mer agitée-en l' occurrence l'Océan atlantique, sur la côte portugaise de sines-peut jouer dans l'identification d'un paysage de tsunami et, dans les comportements spontanés adoptés par les usagers. Le rôle du paysage dans la perception sociale du risque a été évalué en interrogeant un échantillon d'individus-directement sur le littoral-, en les mettant en situation à l'aide de photographies de divers contextes littoraux (tsunamis, tempêtes et marée basse). il a été demandé aux populations interrogées d' évaluer le niveau de risque qu'ils percevaient sur chaque photographie. Les principales conclusions révèlent que les tsunamis appréhendés à travers des photos pendant l' enquête ont été perçus comme des situations moins risquées que celles montrant des ondes de tempêtes. ainsi, au Portugal il faudrait sensibiliser davantage les populations à l'importance des signes précur
A detailed study had been conducted on the sediment of Mount Samalas' volcanic eruption in 1257 A... more A detailed study had been conducted on the sediment of Mount Samalas' volcanic eruption in 1257 AD. Using the framework of the reconstruction of the ancient eruption of Mount Samalas, the first step was to map and analyze the deposits of volcanic sediment. Secondly, we analyzed the effect of geomorphology and the distance function to the isopach thickness. The results show that a combination of methods allowed to provide a high resolution map of the distribution of the thickness of the volcanic deposits, both on the slope and in alluvial areas. Geo-electric survey results (both Vertical Electric Sound (VES) and 2D mapping) show consistent changes in the pattern of contrast resistivity layer interface, for all areas. The pattern changes in a row of the top layer, the high resistivity turned into the low. Furthermore, the second and third layer interface changes from low to the high resistivity. High resistivity on the top layer is interpreted as a layer of unconsolidated volcanic sediment. High resistivity values are range from 736 to 2000 Ohm.m on the top layer in the area of the slopes while in the area of alluvial, the resistivity values range from 20 to 958 Ohm.m. Generally, the volcanic deposits in the area of the slopes have a higher value of isopach (>17 m) than in areas of alluvial (<25 m). The geomorphology seemed to have no significant effect on the isopach value, particularly pyroclastic fallout. Such is the case with distance from the source to the site, which is not linear. The value of isopach increases westward from 21 to 31 km, in contrast to the East, which began to occur at a distance of 14 km to 21 km.
Lahar has been applied as a general term for rapidly flowing, high-concentration, poorly sorted s... more Lahar has been applied as a general term for rapidly flowing, high-concentration, poorly sorted sediment-laden mixtures of rock debris and water (other than normal streamflow) from a volcano. Lahars are one of the most destructive phenomena associated with composite volcanoes, which are dominant in Java Island. Resulting deposits of lahar are poorly sorted, massive, made up of clasts (chiefly of volcanic composition), that generally include a mud-poor matrix. The aim of this research is threefold: to discuss the initiation of lahars occurrences, their dynamics, to assess the hazard and to analyse the deposition. Lahars are either a direct result of eruptive activity or not temporally related to eruptions. Syn-eruptive lahars may result from the transformation on pyroclastic flows or debris avalanches which transform to aqueous flows (e.g. at Papandayan in November 2002); They may be also generated through lake outburst or breaching (e.g. at Kelut in 1909 or 1966), and through remova...
ABSTRACT We established an extensive database of tsunami field evidence in order to facilitate va... more ABSTRACT We established an extensive database of tsunami field evidence in order to facilitate various numerical models of the 26 December 2004 tsunami in the Banda Aceh district of Sumatra, Indonesia. Inputs provided by 12 weeks of efforts during seven field trips include field measurements of run-up, tsunami heights, flow depths, flow directions, and events’ chronology. We deliver detailed inundation maps of the western and northern coasts of Banda Aceh. About ten waves reached the coast. The maximum tsunami height reached 35 m during the third wave on flat areas and the maximum run-up was 51 m measured on hill slope. This value is the highest run-up ever measured in human history for a co-seismic tsunami event. The main hydrologic characteristic of the 26 December 2004 tsunami is the break of the main wave up to 3 km inland from the shoreline. The data collected, such as the numerous warning signs, could help further prevention actions.
Large explosive eruptions inject volcanic gases and fine ash to stratospheric altitudes, contribu... more Large explosive eruptions inject volcanic gases and fine ash to stratospheric altitudes, contributing to global cooling at the Earth's surface and occasionally to ozone depletion. The modelling of the climate response to these strong injections of volatiles commonly relies on ice-core records of volcanic sulphate aerosols. Here we use an independent geochemical approach which demonstrates that the great 1257 eruption of Samalas (Lombok, Indonesia) released enough sulphur and halogen gases into the stratosphere to produce the reported global cooling during the second half of the 13th century, as well as potential substantial ozone destruction. Major, trace and volatile element compositions of eruptive products recording the magmatic differentiation processes leading to the 1257 eruption indicate that Mt Samalas released 158 ± 12 Tg of sulphur dioxide, 227 ± 18 Tg of chlorine and a maximum of 1.3 ± 0.3 Tg of bromine. These emissions stand as the greatest volcanogenic gas injection...
Bulletin de l'Association de géographes français, 2011
ABSTRACT L’état d’alerte maximale du volcan Kelut (Java-Est, Indonésie) en octobre/novembre 2007 ... more ABSTRACT L’état d’alerte maximale du volcan Kelut (Java-Est, Indonésie) en octobre/novembre 2007 a été déclenché en prévision d’une éruption plinienne dangereuse pour les communautés résidant sur ses flancs. Malgré toute l’organisation de gestion stratégique de la crise, les autorités se sont heurtées à des refus d’évacuer et des résistances diverses de la part des habitants. Bien souvent, les refus d’évacuer proviennent d’un manque de communication entre autorités et populations menacés, qui amènent celles-ci à se mettre en danger en refusant d’écouter les ordres donnés. La vulnérabilité peut ainsi être augmentée de manière paradoxale par une gestion de crise très stratégique, mais trop éloignée des préoccupations des communautés en danger qui ne se sentent pas concernées par les évacuations, ainsi que le montre l’exemple de Kelut en 2007. Cette étude de cas est encore un exemple montrant que la vulnérabilité des populations ne peut être résolue uniquement par une gestion de crise, si stratégique soit-elle.
Bulletin de l'Association de géographes français, 2010
Réduction des risques d'inondation à Jakarta : De la nécessaire intégration d'une approche social... more Réduction des risques d'inondation à Jakarta : De la nécessaire intégration d'une approche sociale et communautaire dans la réduction des risques de catastrophe
With growing concerns regarding future impacts of sea-level in major coastal cities, the most acc... more With growing concerns regarding future impacts of sea-level in major coastal cities, the most accurate information is required regarding local sea-level changes with respect to the coast. Besides global and regional sea-level changes, local coastal vertical ground motions can substantially contribute to local changes in sea-level. In some cases, such ground motions can also limit the usefulness of tide-gauge records, which are a unique source of information to evaluate global sea-level changes before the altimetry era. Using satellite synthetic aperture radar interferometry, this study aims at characterizing vertical coastal ground motion in Dakar (Senegal), where a unique century-long record in Africa has been rediscovered. Given the limited number of available images, we use a stacking procedure to compute ground motion velocities in the line of sight over 1992-2010. Despite a complex geology and a rapid population growth and development, we show that the city as a whole is unaffected by differential ground motions larger than 1 mm year −1. Only the northern part of the harbor displays subsidence patterns after 2000, probably as a consequence of land reclamation works. However, these ground motions do not affect the historical tide gauge. Our results highlight the value of the historical sea-level records of Dakar, which cover a 100 year time-span in a tropical oceanic region of Africa, where little data are available for past sea-level reconstructions.
2.-The arChiTeCTUre of si paMUTUNg: BeTweeN loCal TradiTioNs aNd JavaNese iNflUeNCes Véronique De... more 2.-The arChiTeCTUre of si paMUTUNg: BeTweeN loCal TradiTioNs aNd JavaNese iNflUeNCes Véronique Degroot 3.-gpr sUrvey of si paMUTUNg (NorTh sUMaTra): arChaeologiCal reMaiNs
Indonesia is exposed to earthquakes, volcanic activities, and associated tsunamis. This is partic... more Indonesia is exposed to earthquakes, volcanic activities, and associated tsunamis. This is particularly the case for Lombok and Sumbawa Islands in West Nusa Tenggara, where evidence of tsunamis is frequently observed in its coastal sedimentary record. If the 1815 CE Tambora eruption on Sumbawa Island generated a tsunami with well-identified traces on the surrounding islands, little is known about the consequences of the 1257 CE tremendous eruption of Samalas on the neighboring islands, and especially about the possible tsunamis generated in reason of a paucity of research on coastal sedimentary records in this area. However, on Lombok Island, the eruption of the Samalas volcano produced significant volumes of pyroclastic flows that entered the sea in the North and East of the island. These phenomena must have produced a tsunami that left their traces, especially on Sumbawa Island, whose western coastline is only 14 km away from Lombok’s eastern shore. Therefore, the main goal of thi...
This paper discusses the relations between the impacts of volcanic eruptions at multiple-scales a... more This paper discusses the relations between the impacts of volcanic eruptions at multiple-scales and the related-issues of disaster-risk reduction (DRR). The review is structured around local and global impacts of volcanic eruptions, which have not been widely discussed in the literature, in terms of DRR issues. We classify the impacts at local scale on four different geographical features: impacts on the drainage system, on the structural morphology, on the water bodies, and the impact on societies and the environment. It has been demonstrated that information on local impacts can be integrated into four phases of the DRR, i.e., monitoring, mapping, emergency, and recovery. In contrast, information on the global impacts (e.g., global disruption on climate and air traffic) only fits the first DRR phase. We have emphasized the fact that global impacts are almost forgotten in the DRR programs. For this review, we have extracted case studies from Indonesia, and compared them to those of...
&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;The duration and timing of a northern ocean is a key issue in understanding the past geological and climatic evolution of Mars. Mars experienced its greatest loss of H&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;2&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;O between the Noachian and Late Hesperian (~10 m Global Equivalent Layer, Jakosky et al., 2017) roughly the same amount that is thought to have been added to the global inventory by extrusive volcanism over the same time period (Carr and Head, 2015). Thus, the total inventory of water was probably similar during these two epochs. But, the ocean during the Late Hesperian was smaller in extension than the ocean during the Noachian&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#8211; with significant implications for the potential origin and survival of life. Here we examine the implications of the existence of a Late Hesperian/ Early Amazonian ocean on the planet&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#8217;s inventory of water (and especially liquid water) and its variation with time. Our previous work (Rodriguez et al., 2016; Costard et al., 2017) concluded that the most plausible explanation for the origin of the Thumbprint Terrain (TT) lobate deposits, with run-ups, found along the dichotomy boundary, especially in Arabia Terra, was tsunami deposits. This supports the hypothesis that an ocean occupied the northern plains of Mars as recently as ~3 billion years ago. Furthermore, Costard et al (2017) produced a tsunami numerical model showing that the TT deposits exhibit fine-scale textural patterns due to the wave&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#8217;s interference patterns resulting from interactions with the coastal topography. More recently, we suggested that the unusual characteristics of Lomonosov crater (50.52&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;N/16.39&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;E ) in the northern plains are best explained by the presence of a shallow ocean at the time of the impact (Costard et al., 2019). Interestingly, the apparent agreement between the age of the Lomonosov impact and that of the TT unit (~3 Ga), strongly suggests that it was the source of the tsunami (Costard et al., 2019). Our preliminary assessment indicates that this impact-generated tsunami required a mostly liquid ocean and because of the high latitude location of the Lomonosov crater site, our results strongly imply relatively warm paleoclimatic conditions. Our conclusions highlight the need for more sophisticated climate models.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;
In foie gras production the technological yield after the cooking process is one of the main issu... more In foie gras production the technological yield after the cooking process is one of the main issues of processors as it is closely linked to the cooking melting rate. This rate is subjected to strict laws and regulations since it directly affects the organoleptic and technological qualities of this gourmet product. The objective of the study was to better understand the liver fattening and the technological yield decrease during the overfeeding kinetics. A flock of 210 mule ducks was reared and then overfed during 12 D with 2 overfeeding programs; in the test group the amounts of corn in the first meals were higher than in the control group (+430 g during the whole period). Ducks were slaughtered at the end of the rearing period (D0, n = 15) and every other day (D2 to D12, n = 15 by group). Duck performances, anatomical dissections and physical and biochemical liver characteristics were registered. The performances were equivalent in the groups (P > 0.1). The evolution of the liv...
The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the... more The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional magnitude (M e 7, VEI 7) of the Samalas eruption with ≥40 km 3 of dense magma expelled and a plinian column estimated to reach 43 km. However, the climatic response to the Samalas event is debated since climate model simulations generally predict a stronger and more prolonged surface air cooling of Northern Hemisphere (NH) summers than inferred from tree-ring based temperature reconstructions. Here, we draw on historical archives, ice-core data and tree-ring records to reconstruct the spatial and temporal climate response to the Samalas eruption. We find that 1258 and 1259 experienced some of the coldest NH summers of the past millennium. However, cooling across the NH was spatially heterogeneous. Western Europe, Siberia and Japan experienced strong cooling, coinciding with warmer-than-average conditions over Alaska and Northern Canada. We suggest that in North America, volcanic radiative forcing was modulated by a positive phase of the El Niño Southern Oscillation. Contemporary records attest to severe famines in England and Japan, but these began prior to the eruption. We conclude that the Samalas eruption aggravated existing crisis, but did not trigger the famines. Despite the exceptional magnitude of the 1257 Samalas volcanic eruption 1-4 , the apparent lack of strong and widespread cooling in climate proxies, with the exception of Western Europe 5 , has puzzled scientists for almost two decades 6-8. This conundrum is emphasized since for some lesser magnitude events, e.g. the 536 "unknown" 9-11 , 1600 Huaynaputina 12 and 1815 Tambora 13,14 eruptions, abundant Holy
A lahar is a flowing mixture of rock debris and water (other than normal streamflow) from a volca... more A lahar is a flowing mixture of rock debris and water (other than normal streamflow) from a volcano, which encompasses a continuum from debris flows (sediment concentration > or =60% per volume) to hyperconcentrated streamflows (sediment concentration from 20 to 60% per volume). Debris flow deposits are poorly sorted and massive with abundant clasts. Lahars can be either syn-eruptive, post-eruptive or have a non-eruptive origin. Four types of lahars can be generated during an eruption, based on distinct sources of water (i.e. ice, snow, crater lake, river, and rain) that allow the sediments to be removed and incorporated in the lahar (e.g., Mount St.-Helens in 1980, Nevado del Ruiz in 1985). Post-eruptive lahars, which are rain-triggered, occur during several years after an eruption (e.g., still occurring at Pinatubo). Non-eruptive lahars are flows generated on volcanoes without eruptive activity, particularly in the case of a debris avalanche or a lake outburst (e.g., Kelud or R...
-astarte est un programme de recherche qui vise à améliorer la résilience des populations europée... more -astarte est un programme de recherche qui vise à améliorer la résilience des populations européennes aux tsunamis. Une enquête à l' échelle européenne a été conduite en 2014-2015 dans des secteurs littoraux exposés à ce risque. Cet article en présente quelques résultats, en s'interrogeant sur le rôle que la perception récurrente, voire quotidienne, d'un paysage de mer agitée-en l' occurrence l'Océan atlantique, sur la côte portugaise de sines-peut jouer dans l'identification d'un paysage de tsunami et, dans les comportements spontanés adoptés par les usagers. Le rôle du paysage dans la perception sociale du risque a été évalué en interrogeant un échantillon d'individus-directement sur le littoral-, en les mettant en situation à l'aide de photographies de divers contextes littoraux (tsunamis, tempêtes et marée basse). il a été demandé aux populations interrogées d' évaluer le niveau de risque qu'ils percevaient sur chaque photographie. Les principales conclusions révèlent que les tsunamis appréhendés à travers des photos pendant l' enquête ont été perçus comme des situations moins risquées que celles montrant des ondes de tempêtes. ainsi, au Portugal il faudrait sensibiliser davantage les populations à l'importance des signes précur
A detailed study had been conducted on the sediment of Mount Samalas' volcanic eruption in 1257 A... more A detailed study had been conducted on the sediment of Mount Samalas' volcanic eruption in 1257 AD. Using the framework of the reconstruction of the ancient eruption of Mount Samalas, the first step was to map and analyze the deposits of volcanic sediment. Secondly, we analyzed the effect of geomorphology and the distance function to the isopach thickness. The results show that a combination of methods allowed to provide a high resolution map of the distribution of the thickness of the volcanic deposits, both on the slope and in alluvial areas. Geo-electric survey results (both Vertical Electric Sound (VES) and 2D mapping) show consistent changes in the pattern of contrast resistivity layer interface, for all areas. The pattern changes in a row of the top layer, the high resistivity turned into the low. Furthermore, the second and third layer interface changes from low to the high resistivity. High resistivity on the top layer is interpreted as a layer of unconsolidated volcanic sediment. High resistivity values are range from 736 to 2000 Ohm.m on the top layer in the area of the slopes while in the area of alluvial, the resistivity values range from 20 to 958 Ohm.m. Generally, the volcanic deposits in the area of the slopes have a higher value of isopach (>17 m) than in areas of alluvial (<25 m). The geomorphology seemed to have no significant effect on the isopach value, particularly pyroclastic fallout. Such is the case with distance from the source to the site, which is not linear. The value of isopach increases westward from 21 to 31 km, in contrast to the East, which began to occur at a distance of 14 km to 21 km.
Lahar has been applied as a general term for rapidly flowing, high-concentration, poorly sorted s... more Lahar has been applied as a general term for rapidly flowing, high-concentration, poorly sorted sediment-laden mixtures of rock debris and water (other than normal streamflow) from a volcano. Lahars are one of the most destructive phenomena associated with composite volcanoes, which are dominant in Java Island. Resulting deposits of lahar are poorly sorted, massive, made up of clasts (chiefly of volcanic composition), that generally include a mud-poor matrix. The aim of this research is threefold: to discuss the initiation of lahars occurrences, their dynamics, to assess the hazard and to analyse the deposition. Lahars are either a direct result of eruptive activity or not temporally related to eruptions. Syn-eruptive lahars may result from the transformation on pyroclastic flows or debris avalanches which transform to aqueous flows (e.g. at Papandayan in November 2002); They may be also generated through lake outburst or breaching (e.g. at Kelut in 1909 or 1966), and through remova...
ABSTRACT We established an extensive database of tsunami field evidence in order to facilitate va... more ABSTRACT We established an extensive database of tsunami field evidence in order to facilitate various numerical models of the 26 December 2004 tsunami in the Banda Aceh district of Sumatra, Indonesia. Inputs provided by 12 weeks of efforts during seven field trips include field measurements of run-up, tsunami heights, flow depths, flow directions, and events’ chronology. We deliver detailed inundation maps of the western and northern coasts of Banda Aceh. About ten waves reached the coast. The maximum tsunami height reached 35 m during the third wave on flat areas and the maximum run-up was 51 m measured on hill slope. This value is the highest run-up ever measured in human history for a co-seismic tsunami event. The main hydrologic characteristic of the 26 December 2004 tsunami is the break of the main wave up to 3 km inland from the shoreline. The data collected, such as the numerous warning signs, could help further prevention actions.
Large explosive eruptions inject volcanic gases and fine ash to stratospheric altitudes, contribu... more Large explosive eruptions inject volcanic gases and fine ash to stratospheric altitudes, contributing to global cooling at the Earth's surface and occasionally to ozone depletion. The modelling of the climate response to these strong injections of volatiles commonly relies on ice-core records of volcanic sulphate aerosols. Here we use an independent geochemical approach which demonstrates that the great 1257 eruption of Samalas (Lombok, Indonesia) released enough sulphur and halogen gases into the stratosphere to produce the reported global cooling during the second half of the 13th century, as well as potential substantial ozone destruction. Major, trace and volatile element compositions of eruptive products recording the magmatic differentiation processes leading to the 1257 eruption indicate that Mt Samalas released 158 ± 12 Tg of sulphur dioxide, 227 ± 18 Tg of chlorine and a maximum of 1.3 ± 0.3 Tg of bromine. These emissions stand as the greatest volcanogenic gas injection...
Bulletin de l'Association de géographes français, 2011
ABSTRACT L’état d’alerte maximale du volcan Kelut (Java-Est, Indonésie) en octobre/novembre 2007 ... more ABSTRACT L’état d’alerte maximale du volcan Kelut (Java-Est, Indonésie) en octobre/novembre 2007 a été déclenché en prévision d’une éruption plinienne dangereuse pour les communautés résidant sur ses flancs. Malgré toute l’organisation de gestion stratégique de la crise, les autorités se sont heurtées à des refus d’évacuer et des résistances diverses de la part des habitants. Bien souvent, les refus d’évacuer proviennent d’un manque de communication entre autorités et populations menacés, qui amènent celles-ci à se mettre en danger en refusant d’écouter les ordres donnés. La vulnérabilité peut ainsi être augmentée de manière paradoxale par une gestion de crise très stratégique, mais trop éloignée des préoccupations des communautés en danger qui ne se sentent pas concernées par les évacuations, ainsi que le montre l’exemple de Kelut en 2007. Cette étude de cas est encore un exemple montrant que la vulnérabilité des populations ne peut être résolue uniquement par une gestion de crise, si stratégique soit-elle.
Bulletin de l'Association de géographes français, 2010
Réduction des risques d'inondation à Jakarta : De la nécessaire intégration d'une approche social... more Réduction des risques d'inondation à Jakarta : De la nécessaire intégration d'une approche sociale et communautaire dans la réduction des risques de catastrophe
With growing concerns regarding future impacts of sea-level in major coastal cities, the most acc... more With growing concerns regarding future impacts of sea-level in major coastal cities, the most accurate information is required regarding local sea-level changes with respect to the coast. Besides global and regional sea-level changes, local coastal vertical ground motions can substantially contribute to local changes in sea-level. In some cases, such ground motions can also limit the usefulness of tide-gauge records, which are a unique source of information to evaluate global sea-level changes before the altimetry era. Using satellite synthetic aperture radar interferometry, this study aims at characterizing vertical coastal ground motion in Dakar (Senegal), where a unique century-long record in Africa has been rediscovered. Given the limited number of available images, we use a stacking procedure to compute ground motion velocities in the line of sight over 1992-2010. Despite a complex geology and a rapid population growth and development, we show that the city as a whole is unaffected by differential ground motions larger than 1 mm year −1. Only the northern part of the harbor displays subsidence patterns after 2000, probably as a consequence of land reclamation works. However, these ground motions do not affect the historical tide gauge. Our results highlight the value of the historical sea-level records of Dakar, which cover a 100 year time-span in a tropical oceanic region of Africa, where little data are available for past sea-level reconstructions.
2.-The arChiTeCTUre of si paMUTUNg: BeTweeN loCal TradiTioNs aNd JavaNese iNflUeNCes Véronique De... more 2.-The arChiTeCTUre of si paMUTUNg: BeTweeN loCal TradiTioNs aNd JavaNese iNflUeNCes Véronique Degroot 3.-gpr sUrvey of si paMUTUNg (NorTh sUMaTra): arChaeologiCal reMaiNs
The 17 July 2006, a tsunami struck the southern coast of Java, Indonesia, causing over 730 casual... more The 17 July 2006, a tsunami struck the southern coast of Java, Indonesia, causing over 730 casualties. The triggering earthquake located 225 km off the coast of Pangandaran (9.222 • S, 107.320 • E), occurred at 15:19 LT (UTC +7) with a 7.7 magnitude on the Richter scale (Harward Center and CEA/DAM). In order to calibrate numerical models and understand the phenomenon, we conducted a 6-weeks field survey in July and August 2006 from Cimerak district in West Java to Gunung Kidul district in Central Java. Data collection involved measurements of wave height before its breaking, flow depth, run-up height, inundation depth, flow directions and a detailed chronology of the tsunami.
Previous research on debris-flow deposit structure typically reports little to no visually discer... more Previous research on debris-flow deposit structure typically reports little to no visually discernible stratigraphy. The preliminary findings presented here provide evidence for more complex internal deposit architecture with inverse grading and subunits thought to reflect individual flow surges. Ground-penetrating radar surveys, geospatial data and field observations are used to describe 10 subunits traceable over the 14 lateral radargrams imaging the lower 38 m of the deposit. Additional subunits are depicted further upslope in a longitudinal transect. As well as demonstrating the need for continued investigation of deposit architecture using non-traditional techniques, these results may help improve future interpretations of post-event deposits.
The hazardous and unpredictable nature of lahars makes them challenging to study, yet the in-flow... more The hazardous and unpredictable nature of lahars makes them challenging to study, yet the in-flow processes characterizing these events are important to understand. As a result, much of the previous research on lahar sedimentation and flow processes has been derived from experimental flows or stratigraphic surveys of post-event deposits. By comparison, little is known on the time-dependent sediment and flow dynamics of lahars in natural environments. Using video-footage of seven lahars on the flanks of Semeru Volcano (East Java, Indonesia), the present study offers new insights on the in-flow evolution of sediment in natural lahars. Video analysis revealed several distinctive patterns of sediment entrainment and deposition that varied with time-related fluctuations in flow. These patterns were used to generate a conceptual framework describing possible processes of formation for subsurface architectural features identified in an earlier lateral survey of lahar deposits on Semeru Volcano (Gomez and Lavigne, 2010a). The formation of lateral discontinuities was related to the partial erosion of transitional bank deposits followed by fresh deposition along the erosional contact. This pattern was observed over the course of several lahar events and within individual flows. Observations similarly offer potential explanations for the formation of lenticular features. Depending on flow characteristics, these features appeared to form by preferential erosion or deposition around large stationary blocks, and by deposition along channel banks during episodes of channel migration or channel constriction. Finally, conditions conducive to the deposition of fine laminated beds were observed during periods of attenuating and surging flow. These results emphasize the difficulties associated with identifying process-structure relationships solely from post-event deposit interpretation and illustrate that an improved understanding of the time-dependent sediment dynamics in lahars may be advantageous when interpreting post-event structural features.
Semeru Volcano is the highest mountain of Java (Indonesia), and a vulcanian explosion occurs ever... more Semeru Volcano is the highest mountain of Java (Indonesia), and a vulcanian explosion occurs every 15 minutes on average, since 1967. Thus a constantly renewed stock of material and the heavy monsoon rainfall [3700 mm yr −1 at 1500 m above sea level (a.s.l.)] provide a perfect setting for the study of lahars and their deposits. Hence, we examined the architecture of lahars' terraces 9·5 km from the summit in the Curah Lengkong Valley. We fi rst used ground penetrating radar (GPR) over vertical exposures of the lahars cut-bank terraces. This allowed us to better understand transversal radargrams across terraces, which are not visually accessible in the fi eld.
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Papers by Franck Lavigne