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1.
Mount Pinatubo volcano erupted in June 1991 in the main island of Luzon belonging to the Philippines archipelago. Huge economic
losses and population exodus have followed. This major crisis has been relayed with other crises due to rain-fed lahars which
have been supplied with eruption deposits. These lahars have occurred every year since 1991 during the rainy season. They
will probably last until 2005. After a brief presentation of the Philippine official response system to disasters, this paper
draws up a critical analysis of the different kinds of institutional and social responses deployed to manage the different
crisis and post-crisis phases of this event. Based on three viewpoints: from population, media and other actors, this analysis
attempts to point out the strengths and weaknesses of the official management system, especially by studying the efficiency
and the range of the solutions taken. So, it appears that the management of the June 1991 main crisis (eruption) was a success.
On the other hand, difficulties have occurred with lahars risk management. Indeed, these lahars have obliged the authorities
to protect and relocate thousands of people. In spite of persistent problems, the management system (monitoring/warning/evacuation)
of lahar crises improves year after year. Failures appear especially within the rehabilitation program (protection/rehousing).
Many direct (lack of means, preparedness, coordination, dialog, etc.) and indirect (politico-administrative, socio-economic,
cultural contexts) factors come together to lock the wheels of the institutional response system. They defer the socio-economic
start of this vital northern Philippines area.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Hazardous processes and events from glacier and permafrost areas: lessons from the Chilean and Argentinean Andes 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Glacier and permafrost hazards such as glacial‐lake outburst floods and rock–ice avalanches cause significant socio‐economic damages worldwide, and these processes may increase in frequency and magnitude if the atmospheric temperature rises. In the extratropical Andes nearly 200 human deaths were linked to these processes during the twentieth century. We analysed bibliographical sources and satellite images to document the glacier and permafrost dynamics that have caused socio‐economic damages in this region in historic time (including glacial lake outburst floods, ice and rock–ice avalanches and lahars) to unravel their causes and geomorphological impacts. In the extratropical Andes, at least 15 ice‐dammed lakes and 16 moraine‐dammed lakes have failed since the eighteenth century, causing dozens of floods. Some floods rank amongst the largest events ever recorded (5000 × 106 m3 and 229 × 106 m3, respectively). Outburst flood frequency has increased in the last three decades, partially as a consequence of long‐term (decades to centuries) climatic changes, glaciers shrinkage, and lake growth. Short‐term (days to weeks) meteorological conditions (i.e. intense and/or prolonged rainfall and high temperature that increased meltwater production) have also triggered outburst floods and mass movements. Enormous mass failures of glaciers and permafrost (> 10 × 106 m3) have impacted lakes, glaciers, and snow‐covered valleys, initiating chain reactions that have ultimately resulted in lake tsunamis and far‐reaching (> 50 km) flows. The eruption of ice‐covered volcanoes has also caused dozens of damaging lahars with volumes up to 45 × 106 m3. Despite the importance of these events, basic information about their occurrence (e.g. date, causes, and geomorphological impact), which is well established in other mountain ranges, is absent in the extratropical Andes. A better knowledge of the processes involved can help to forecast and mitigate these events. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
3.
Alejandro Marulanda Aguirre Omar Alfonso Fonseca Tobasura Omar Darío Cardona Arboleda 《水文科学杂志》2013,58(12):2179-2192
ABSTRACTThis paper presents the results of a hydrological study aimed at characterizing flood-prone areas in the urban growth zone in the city of Manizales based on the potential effects of melting of the Nevado del Ruiz glacier, in Caldas, Colombia. These results constitute a basis for decision making regarding possible urban growth zones in Andean areas that face risks from volcanic eruptions producing lahars and floods caused by glacier melt. Conservative estimates of extreme flows in the Chinchiná River in the urban growth area of El Rosario can be obtained by considering the effects of rain triggered by airborne particulate material following a volcanic explosion combined with the effects of glacier melt. The effects of global warming on tropical glaciers contribute to their retreat, leading to their disappearance. Therefore, the worst scenario would take place if these events occurred in the short term as glacier volume decreases with time.
Editor Z.W. Kundzewicz; Associate editor not assigned 相似文献
4.
Eruptions through crater lakes or shallow seawater, referred to here as subaqueous eruptions, present hazards from hydromagmatic explosions, such as base surges, lahars, and tsunamis, which may not exist at volcanoes on dry land. We have systematically compiled information from eruptions through surface water in order to understand the circumstances under which these hazards occur and what disastrous effects they have caused in the past. Subaqueous eruptions represent only 8% of all recorded eruptions but have produced about 20% of all fatalities associated with volcanic activity in historical time. Excluding eruptions that have resulted in about a hundred deaths or less, lahars have killed people in the largest number of historical subaqueous eruptions (8), followed by pyroclastic flows (excluding base surges; 5) tsunamis (4), and base surges (2). Subaqueous eruptions have produced lahars primarily on high (>1000 m), steep-sided volcanoes containing small (<1 km diameter) crater lakes. Tsunamis and other water waves have caused death or destroyed man-made structures only at submarine volcanoes and at Lake Taal in the Philippines. In spite of evidence that magma–water mixing makes eruptions more explosive, such explosions and their associated base surges have caused fewer deaths, and have been implicated in fewer eruptions involving large numbers of fatalities than lahars and tsunamis. The latter hazards are more deadly because they travel much farther from a volcano and inundate coastal areas and stream valleys that tend to be densely settled. 相似文献
5.
全球主要火山灾害及其分布特征 总被引：1，自引：0，他引：1
本文研究了火山灾害各种致灾因子的物理过程和灾害特点,根据文献中记载的全球火山灾害,在进行火山灾害分区研究的基础上,研究了全球火山灾害分布特征.全球主要的火山灾害分布在8个主要区域.有记载的火山灾害在热带占73%,远高于火山喷发分布于热带区的比例.全球两个最强烈的火山灾害分布区都是围绕着位于板块结合部表现为复杂构造结的班达海和加勒比海,而且每一个灾害区都有3条分支.热带区第3个灾害区为中非区,地幔上隆是这里主要的动力学背景.本文还研究了1700年以来火山灾害时间分布特征,以及1993年以来各种火山灾害发生频次. 相似文献
6.
Céline Dumaisnil Jean‐Claude Thouret Guillaume Chambon Emma E. Doyle Shane J. Cronin Surono 《地球表面变化过程与地形》2010,35(13):1573-1590
Lahars (volcanic debris flows) have been responsible for 40% of all volcanic fatalities over the past century. Mount Semeru (East Java, Indonesia) is a persistently active composite volcano that threatens approximately one million people with its lahars and pyroclastic flows. Despite their regularity, the behaviour and the propagation of these rain‐triggered lahars are poorly understood. In situ samples were taken from lahars in motion at two sites in the Curah Lengkong River, on the southeast flank of Semeru, providing estimates of the particle concentration, grain size spectrum, grain density and composition. This enables us to identify flow sediment from three categories of lahars: (a) hyperconcentrated flow, (b) non‐cohesive, clast‐ and matrix‐supported debris flow, and (c) muddy flood. To understand hyperconcentrated flow sediment transport processes, it is more appropriate to sample the active flows than the post‐event lahar deposits because in situ sampling retains the full spectrum of the grain‐size distribution. Rheometrical tests on materials sampled from moving hyperconcentrated flows were carried out using a laboratory vane rheometer. Despite technical difficulties, results obtained on the <63, <180, and <400 µm fractions of the sampled sediment, suggest a purely frictional behaviour. Importantly, and contrary to previous experiments conducted with monodisperse suspensions, our results do not show any transition towards a viscous behaviour for high shear rates. These data provide important constraints for future physical and numerical modelling of lahar flows. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
《自然地理学》2013,34(3):192-215
This work investigates the initial colonization on recent lahar deposits of the northeast slope of Popocatepetl volcano, Mexico, where 29 circular sample plots (1.57 m2) were established to determine the development stages of colonization in four types of habitats: 1997 lahar, 2001 lahar, margins, and terraces at the channel's bottom. Cluster analysis and the Sørensen Index were used to determine the floristic affinity of these lahars. Richness, frequency, percentage of species contribution, plant cover, density, and stem height were analyzed to determine the composition and structure of plant communities. The distribution of these variables reveals that the communities often have a simple internal structure; however, a relationship has already been established between changes in resilience and the age of the four lahars. Thus, floristic composition develops rapidly (1 sp. in terraces, 11 spp. in the margins, 29 spp. in the 2001 lahar, and 34 spp. in the 1997 lahar). Except for the 1997 lahar, however, structural characteristics are poorly developed in other incipient stages. As colonization advances, the affinity among the various components and sectors of the laharic deposits decreases, thus promoting the gradual incorporation of species found on the adjacent gorge slopes. The Principal Components Analysis used to identify other explanatory factors shows that of 15 variables studied, those associated with the morpho-sedimentology, the hydrovolcanic dynamics and stability of deposits (microtopography, thickness of the deposit, clast shapes, length of the deposit, depth of the gorge, and slope processes) explain a large percentage of variance. Only a few species (Lupinus campestris, Alchemilla procumbens and Penstemon gentianoides), are well adapted to poor soils and the effects of intense erosion caused by the flows. 相似文献
8.
Jan Alexander Jenni Barclay Janez Sušnik Sue C. Loughlin Richard A. Herd Amii Darnell Sian Crosweller 《Journal of Volcanology and Geothermal Research》2010
On 20th May 2006 the Soufrière Hills Volcano on the Caribbean island of Montserrat experienced a large dome collapse and intense rainfall generated flash floods. The floods had very high loads of volcanic debris derived both from this and previous eruptions and can thus be classified as lahars. The floods reached unusually high water levels and caused substantial geomorphic change in the Belham Valley. Detailed rainfall and geomorphological data, coupled with the precise timing of events and yewitness accounts have facilitated an assessment of the relative importance of rainfall volume and intensity, older volcanic debris, pre- and syn-flood tephra fall and the extent of pre-flood vegetation damage for the behavior of this and subsequent sediment-laden floods in this setting. The change in runoff behavior was controlled by preexisting vegetation damage and synchronous tephra fall and this was critically important in controlling the impact of these flash floods. Although rainfall intensity and volume have some control on flood occurrence they are not the critical control on flash flood impact on the geomorphology in the Belham Valley. A significant conclusion of this study is that the extreme nature of the flash floods was not caused by extreme rainfall (as is commonly believed to be the primary cause of flash floods) but rather it was the result of changed runoff behaviour caused by the widespread syn-flood tephra deposition and importantly the widespread vegetation damage by volcanic-associated acid rain in the preceding weeks. 相似文献
9.
This paper demonstrates techniques for pre-eruption prediction of lahar-inundation zones in areas where a volcano has not
erupted within living memory and/or where baseline geological information about past lahars could be scarce or investigations
to delimit past lahars might be incomplete. A lahar source (or proximal lahar-inundation) zone is predicted based on ratio
of vertical descent to horizontal run-out of eruptive deposits that spawn lahars. Immediate post-eruption distal lahar-inundation
zones are predicted based on “pre-eruption” distal lahar-inundation zones and on spatial factors derived from a digital elevation
model. Susceptibility to distal lahar-inundation is estimated by weights-of-evidence, by logistic regression and by evidential
belief functions. Predictive techniques are applied using a geographic information system and are tested in western part of
Pinatubo volcano (Philippines). Predictive maps are compared with a forecast volcanic-hazard map through validation against
a field-based volcanic-hazard map. The predictive model of proximal lahar-inundation zone has “true positive” prediction accuracy,
“true negative” prediction accuracy, “false positive” prediction error and “false negative” prediction error that are similar
to those of the forecast volcanic-hazard map. The predictive models of distal lahar inundation zones have higher “true positive”
prediction accuracy and lower “false negative” prediction error than the forecast volcanic-hazard map, although the latter
has higher “true negative” prediction accuracy and lower “false positive” prediction error than the former. The results illustrate
utility of proposed predictive techniques in providing geo-information could be used, howbeit with caution, for planning to
mitigate potential lahar hazards well ahead of an eruption that could generate substantial source materials for lahar formation. 相似文献
10.
J.L. Macías L. Capra J.L. Arce J.M. Espíndola A. García-Palomo M.F. Sheridan 《Journal of Volcanology and Geothermal Research》2008
El Chichón volcano consists of a 2-km wide Somma crater compound cone 0.2 Ma old with peripheral domes with a central crater reactivated several times during the Holocene. The most recent eruption at El Chichón occurred from March 28 to April 4, 1982, resulting in the worst volcanic disaster during historical times in Mexico, killing more than 2000 people and destroying nine towns and small communities. The volcanic hazard map of El Chichón is based on detailed field work that documented twelve eruptions during the last 8000 years, and computer simulations. To validate the results, computer simulations were first performed over pre-1982 topography mimicking the extent of the actual deposits produced and afterwards run over post-1982 topography. These eruptions have produced pyroclastic fall, surge, flow and lahar deposits. Pyroclastic flows have different volumes and Heim coefficients varying from 0.2 (pumice flows), to 0.15 (block-and-ash flows) and 0.10 (ash flows). Simulations using FLOW3D and TITAN2D indicate that pumice flows and block-and-ash flows can fill the moat area and follow main ravines up to distances of ca. 3 km from the crater, with no effect on populations around the volcano. On the other hand, more mobile ash flows related to column-collapse events can reach up to 4 km from the vent, but will always follow the same paths and still not affect surrounding populations. The energy-cone model was used to simulate the outflow of pyroclastic surges based on the 1982 event (H/L = 0.1 and 0.2), and shows that surges may reach some towns around the volcano. 相似文献