首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
This paper examines the philosophy and evolution of volcanological science in recent years, particularly in relation to the growth of volcanic hazard and risk science. It uses the lens of Science and Technology Studies to examine the ways in which knowledge generation is controlled and directed by social forces, particularly during eruptions, which constitute landmarks in the development of new technologies and models. It also presents data from a survey of volcanologists carried out during late 2008 and early 2009. These data concern the felt purpose of the science according to the volcanologists who participated and their impressions of the most important eruptions in historical time. It demonstrates that volcanologists are motivated both by the academic science environment and by a social concern for managing the impact of volcanic hazards on populations. Also discussed are the eruptions that have most influenced the discipline and the role of scientists in policymaking on active volcanoes. Expertise in volcanology can become the primary driver of public policy very suddenly when a volcano erupts, placing immense pressure on volcanologists. In response, the epistemological foundations of volcanology are on the move, with an increasing volume of research into risk assessment and management. This requires new, integrated methodologies for knowledge collection that transcend scientific disciplinary boundaries.  相似文献   

2.
This paper discusses results from a survey of volcanologists carried out on the Volcano Listserv during late 2008 and early 2009. In particular, it examines the status of volcano monitoring technologies and their relative perceived value at persistently and potentially active volcanoes. It also examines the role of different types of knowledge in hazard assessment on active volcanoes, as reported by scientists engaged in this area, and interviewees with experience from the current eruption on Montserrat. Conclusions are drawn about the current state of monitoring and the likely future research directions, and also about the roles of expertise and experience in risk assessment on active volcanoes; while local knowledge is important, it must be balanced with fresh ideas and expertise in a combination of disciplines to produce an advisory context that is conducive to high-level scientific discussion.  相似文献   

3.
Redefining active volcanoes: a discussion   总被引：2，自引：0，他引：2  
The analysis of the current definitions of active volcanoes indicates that they are empirical, conventional, inaccurate, nongeological, and arbitrarily constraining. Redefinition is therefore needed. One possible approach is to refine the current empirical definitions. A statistically reasonable and practical redefinition using a geologically based time convention-Holocene or 10000 years-is suggested. A set of time conditions according to volcano typology-i.e. 1000; 10000 and 100000 years for high-frequency basaltic shields, andesitic-dacitic composite volcanoes and low-frequency large silicic calderas, respectively-as further refinement of the empirical definition is also envisaged. Devising a phenomenological definition as a theoretical approach is another possibility, but in practice extant diagnostic means are still unsatisfactory to discriminate accurately between dormant and extinct volcanoes. As a consequence of the redefinition, a classification of volcanoes according to their eruptive status is proposed. Redefinition of active volcanoes might increase accuracy in the usage of basic terms in volcanology and influence volcanic hazard assessment and risk mitigation projects.  相似文献   

4.
The study of magmatic plumbing systems of volcanoes (roots of volcanoes) is one of the main tasks facing volcanology. One major object of this research is the Klyuchevskaya group of volcanoes (KGV), in Kamchatka, which is the greatest such group that has been found at any island arc and subduction zone. We summarize the comprehensive research that has been conducted there since 1931. Several conspicuous results derived since the 1960s have been reported, emerging from the study of magma sources, eruptions, earthquakes, deformation, and the deep structure for the KGV. Our discussion of these subjects incorporates the data of physical volcanology relating to the mechanism of volcanic activity and data from petrology as to magma generation. The following five parts can be distinguished in the KGV plumbing system and the associated geophysical model: the source of energy and material at the top of the Pacific Benioff zone at a depth of about 160 km, the region of magma ascent in the asthenosphere, the region of magma storage in the crust-mantle layer at depths of 40–25 km, magma chambers and channelways in the crust, and the bases of volcanic edifices. We discuss and explain the properties of and the relationships between these parts and the mechanisms of volcanic activity and of the KGV plumbing system as they exist today. Methods for calculating magma chambers and conduits, the amount of magma in the system, and its other properties are available.  相似文献   

5.
A new airborne radar technique can generate digital topographic data for volcanoes at a scale of 10 m spatial and 1–5 m vertical, with a swath width of 6.4 km. Called TOPSAR, the intrument is an interferometric radar flown on the NASA DC-8 aircraft. TOPSAR data permit the quantification of volcano slopes, volumes, and heights, and as such will be valuable for the analysis of lava flows, domes, and lahar channels. This instrument will be flown over several volcanoes in the near future, providing volcanologists with valuable data sets for the analysis of high-resolution topography. We briefly illustrate the potential use of TOPSAR data through examples from Mt Somma and Vesuvius, Italy.  相似文献   

6.
The Earth Resources Technology Satellite makes it feasible for the first time to monitor the level of activity at widely separated volcanoes and to relay these data almost instantancously to one central office. This capability opens a new era in volcanology where the hundreds of normally quiescent but potentially dangerous volcanoes near populated regions around the world can be economically and reliably monitored. A prototype global volcano surveillance system has been established beginning in the fall of 1972 with the help of local scientists on 15 volcanoes in Alaska, Hawaii, Washington, California, Iceland. Guatemala, El Salvador, and Nicaragua. Data on earthquake activity and ground tilt are received 6 to 10 times daily in Menlo Park, California, within 90 minutes of transmission from the sites. Seismic event counters were installed at 19 locations with biaxial borehole tiltineters with 1 microradian sensitivity installed at seven sites. Direct comparison of seismic events that are counted with records from nearby seismic stations show the event counters work quite reliably. An order of magnitude increase in seismic events was observed prior to the eruption of Volcán Fuego in Guatemala in February, 1973. Significant changes in tilt were observed on volcanoes Kilauea. Fuego, and Pacava. This study demonstrates the technological and economic feasibility of utilizing such a volcano surveillance system throughout the world.  相似文献   

7.
Primarily from a philosophical perspective, this paper considers recent and future trends in Earth observations from space of use for assessing environmental risks and for environmental risk management. Attention is focussed on floods, but mention is also made of forest fires, volcanoes, earthquakes and landslides, as well as industrial pollution.  相似文献   

8.
Near-infrared room temperature tunable diode lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in volcanology are still limited to a few examples. Here, we explored the potential of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 mixing ratios, and ultimately for estimating the volcanic CO2 flux. Our field tests were conducted at Campi Flegrei near Pozzuoli, Southern Italy, where the GasFinder was used during three campaigns in October 2012, January 2013 and May 2013 to repeatedly measure the path-integrated mixing ratios of CO2 along cross sections of the atmospheric plumes of two major fumarolic fields (Solfatara and Pisciarelli). By using a tomographic post-processing routine, we resolved, for each of the two fields, the contour maps of CO2 mixing ratios in the atmosphere, from the integration of which (and after multiplication by the plumes’ transport speeds) the CO2 fluxes were finally obtained. We evaluate a total CO2 output from the Campi Flegrei fumaroles of ～490 Mg/day, in line with independent estimates based on in situ (Multi-GAS) observations. We conclude that TDL technique may enable CO2 flux quantification at other volcanoes worldwide.  相似文献   

9.
 Volcanoes in humid tropical environments are frequently cloud covered, typically densely vegetated and rapidly eroded. These factors complicate field and laboratory studies and even the basic identification of potentially active volcanoes. Numerous previous studies have highlighted the potential value of radar remote sensing for volcanology in equatorial regions. Here, cloud- and vegetation-penetrating LHH-band (λ≈24 cm) synthetic aperture radar (SAR) data from the Japanese Earth Resources Satellite (JERS-1) are used to investigate persistently active volcanoes and prehistoric calderas in East Java, Indonesia. The LHH-band JERS-1 SAR produces high-spatial-resolution (18 m) imagery with relatively high incidence angle that highlights structures and topographic variations at or greater than the wavelength scale while minimising geometrical distortions such as layover and foreshortening. These images, along with Internet browse data derived from the Canadian RADARSAT mission, provide new evidence relating regional tectonics to volcanism throughout East Java. Volcanic events, such as caldera collapse at the Tengger caldera, appear to have been partly controlled by northwest-aligned faults related to intra-arc sedimentary basins. Similar regional controls appear important at historically active Lamongan volcano, which is encircled by numerous flank maars and cinder cones. A previously undocumented pyroclastic sheet and debris avalanche deposit from the Jambangan caldera complex is also manifested in the synoptic radar images. At the currently active Semeru volcano these data permit identification of recent pyroclastic flow and lahar deposits. Radar data therefore offer a valuable tool for mapping and hazard assessment at late Quaternary volcanoes. The criteria developed in the analysis here could be applied to other regions in the humid tropics. Received: 25 June 1998 / Accepted: 20 January 1999  相似文献   

10.
In early 1983 a campaign was initiated in the U.S.A. to acquire modern optical facilities focusing on the use of imaging detector technology to strengthen our spectroscopic interferometric, imaging and lidar capabilities to solve some of the major aeronomic scientific problems. These scientific problems were addressed by sub-committees for spectroscopic, interferometric, imaging and lidar facilities as well as by the aeronomy modeling and theoretical community. The sub-committees further defined the science and answered the question of how each facility could help solve the posed scientific problems using current capabilities, upgraded systems and new Class I facilities. The individual sub-committee reports are assembled in Volume II of the Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) report. Volume I, synthesized by the Steering Committee, presents a three phase program over the next seven years aimed at the solution of the various CEDAR Science issues as the new facilities are developed.Recently, the CEDAR program expanded to include two additional sub-committee contributions from the radar community (both incoherent scatter, IS, and coherent) covering their roles in addressing the CEDAR Science issues.The solution of major aeronomic scientific problems through the cooperation and coordination of observations using all types of instruments, not exclusively optical, is now the main theme of the CEDAR program. In addition, it is clearly recognized that the global nature of many of the CEDAR Science issues requires the active support and involvement of the worldwide aeronomy scientific community. The scientific challenges are many, and the tasks of coordination and cooperation will be trying. However, the world aeronomy community will be justly rewarded by the resultant strides in understanding of the Coupling, Energetics and Dynamics of the Atmospheric Regions around the globe. This report will provide an overview of the CEDAR program, the types of optical facilities of interest and some of the scientific issues and proposed campaigns resulting from the 28–31 July 1986 CEDAR workshop.  相似文献   

11.
A key question in volcanology is the driving mechanisms of resurgence at active, recently active, and ancient calderas. Valles caldera in New Mexico and Lake City caldera in Colorado are well-studied resurgent structures which provide three crucial clues for understanding the resurgence process. (1) Within the limits of 40Ar/39Ar dating techniques, resurgence and hydrothermal alteration at both calderas occurred very quickly after the caldera-forming eruptions (tens of thousands of years or less). (2) Immediately before and during resurgence, dacite magma was intruded and/or erupted into each system; this magma is chemically distinct from rhyolite magma which was resident in each system. (3) At least 1?km of structural uplift occurred along regional and subsidence faults which were closely associated with shallow intrusions or lava domes of dacite magma. These observations demonstrate that resurgence at these two volcanoes is temporally linked to caldera subsidence, with the upward migration of dacite magma as the driver of resurgence. Recharge of dacite magma occurs as a response to loss of lithostatic load during the caldera-forming eruption. Flow of dacite into the shallow magmatic system is facilitated by regional fault systems which provide pathways for magma ascent. Once the dacite enters the system, it is able to heat, remobilize, and mingle with residual crystal-rich rhyolite remaining in the shallow magma chamber. Dacite and remobilized rhyolite rise buoyantly to form laccoliths by lifting the chamber roof and producing surface resurgent uplift. The resurgent deformation caused by magma ascent fractures the chamber roof, increasing its structural permeability and allowing both rhyolite and dacite magmas to intrude and/or erupt together. This sequence of events also promotes the development of magmatic–hydrothermal systems and ore deposits. Injection of dacite magma into the shallow rhyolite magma chamber provides a source of heat and magmatic volatiles, while resurgent deformation and fracturing increase the permeability of the system. These changes allow magmatic volatiles to rise and meteoric fluids to percolate downward, favouring the development of hydrothermal convection cells which are driven by hot magma. The end result is a vigorous hydrothermal system which is driven by magma recharge.  相似文献   

12.
Introduction South China Sea (SCS) is located in the convergence zone between Euro-Asian plate, Pacific plate (Philippine plate) and Indian plate. Interactions of three plates made the crust of this region suffer tectonic stress in many directions and made the South China Sea be in the complex environ-ment of the tectonic stress. There are four different marginal types in the surrounding of the South China Sea: The tectonic zone of the rifting margin in the north of SCS, the NS direct…  相似文献   

13.
Visual observations of the activities of three gas-water-lithoclast (“mud”) volcanoes in the Pugachevo group in the Makarov District of Sakhalin Island were used to analyze the dynamics of these volcanoes. Our analysis confirmed the previous inference that a multirank periodicity is present in the eruptions of the volcanoes, with the periodicity being comparatively frequent and low in magnitude for the eruptions (every 1–2 years) at the Glavnyi or Central volcano and a very long but violent (every 65–70 years) at all the three volcanoes. Comparison of this periodicity with a similar periodicity observed in natural seismicity in the adjacent, highly seismic Uglegorsk District shows that the two phenomena are relatively independent. The natural seismicity in the form of large earthquakes is superimposed upon the gas-water-lithoclast volcanism mostly to serve as a trigger. The high-rank periodicity of 65–70 years noted above may be related to 11–22-year cycles of solar activity. Analysis of the orohydrographic setting in the area shows that the location of the present low-lying basin with volcanoes inside was formerly occupied by a dome uplift with a major gas field that controlled the generation of these volcanoes; it continues to drive their activity, causing a continued gradual subsidence or collapse of the deep basin with volcanoes, thus providing evidence of the high gas potential in the area of study.  相似文献   

14.
The idea of two separate storm time ring currents, a symmetric and an asymmetric one has accepted since the 1960s. The existence of a symmetric equatorial ring current was concluded from Dst. However, the asymmetric development of the low-latitude geomagnetic disturbance field during storms lead to the assumption of the real existence of an asymmetric ring current. I think it is time to inquire whether this conception is correct. Thus, I have investigated the development of the low-latitude geomagnetic field during all the magnetic local times under disturbed and quiet conditions. The storm on February 6–9, 1986 and a statistical analysis of many storms has shown that the asymmetry does not vanish during the storm recovery phase. The ratio between the recovery phase asymmetry and the main phase asymmetry is low only for powerful storms. Storms of moderate intensity show the opposite. The global picture of the field evolution of the February storm shows clear differences at different local times. For instance the main phase and recovery phase start time does not coincide with Dst. Also the ring current decay is not the same at different local times. Therefore, Dst gives an incorrect picture of the field development. Moreover, asymmetry does not disappear during international quiet days as the investigation of the low-latitude geomagnetic field shows. Considering all these observations, I think we must revise our ideas about the ring current. In my opinion only one ring current exists and this is an asymmetric one. This asymmetry increases during storms and develops rather fast to more or less symmetric conditions. However, in no case is itjustified to conclude from Dst that a symmetric ring current exists.  相似文献   

15.
This paper discusses approaches to creating an infrastructure for the integration of diverse systems and resources, both in earth sciences in general and in volcanology in particular, proposes types of technological design solutions for methodological and intellectual support of distributed information research on basic science and applied research during the creation and development of the information space for a science center.  相似文献   

16.
琼北火山区是中国的主要火山群之一。笔者应用HDS - 1型快速数字闪烁测氡仪对琼北火山群马鞍岭和雷虎岭段的火山及断裂活动性进行了勘测和研究 ,对荣山 -岭南断裂进行了重点测量 ,查明了该断裂的具体位置 ,研究了火山及断裂的气体释放特征。发现Rn(氡 ) ,Th(钍 )的变化与断裂构造有密切关系 ,在Ⅰ ,Ⅱ测线上Th ,Rn异常对断裂的反映相当好。根据Th ,Rn的展布特征和浓度变化比较深入地分析了断裂的活动性。在雷虎岭西南 ,荣山 -岭南断裂活动性最强 ,而且 ,自西北向东南断裂规模及活动性均有增强的趋势。此外 ,还对火山的活动性进行了讨论和分析  相似文献   

17.
2 and δ13C in soil gas were measured at three active subduction-related stratovolcanoes (Arenal and Poás, Costa Rica; Galeras, Colombia). In general, Rn, CO2 and δ13C values are higher on the lower flanks of the volcanoes, except near fumaroles in the active craters. The upper flanks of these volcanoes have low Rn concentrations and light δ13C values. These observations suggest that diffuse degassing of magmatic gas on the upper flanks of these volcanoes is negligible and that more magmatic degassing occurs on the lower flanks where major faults and greater fracturing in the older lavas can channel magmatic gases to the surface. These results are in contrast to findings for Mount Etna where a broad halo of magmatic CO2 has been postulated to exist over much of the edifice. Differences in radon levels among the three volcanoes studied here may result from differences in age, the degree of fracturing and faulting, regional structures or the level of hydrothermal activity. Volcanoes, such as those studied here, act as plugs in the continental crust, focusing magmatic degassing towards crater fumaroles, faults and the fractured lower flanks. Received: 16 December 1997 / Accepted: 27 January 2000  相似文献   

18.
Published gravity data on active volcanoes generally reflecteither the low density scoriaceous/pumiceous deposits that are localized within ring-fracture collapse depressions, such as the calderas of mature silicic volcanoes,or the high density frozen magma conduits that occur beneath basaltic shields and cones. The intensive gravity surveys reported here over three complex andesite volcanoes reveal features of both types. Their multi-component gravity fields have crater-centred positive anomalies (1–2 km diameter) surrounded by broader zones of negative gravity with similar amplitudes but greater width (5–10 km). The former are thought to reflect sub-crater magma pipes ofnormal density (ca. 2.5–2.6 Mg m−3) surrounded by pyroclastic scoria, ashes and occasional lava flows of muchlower net density (1.8–2.4 Mg m−3) which, in turn, account for the negative anomalous zones because the deeper, more consolidated and older parts of these andesite volcano edifices have more normal densities (2.3–2.6 Mg m−3).The low density materials are particularly interesting because they appear to have filled topographic depressions to depths of several hundred metres, especially where old caldera-like structures have been postulated from the steep gravity gradients over perimeter ring faults. A model is developed whereby short periods of caldera collapse, associated with intermittent, large high level magma bodies, are interspersed by normal crater-like activity with narrow sub-surface magma pipes. Dominantly pyroclastic activity from summit craters generates the materials that gradually fill earlier-formed topographic depressions. This study demonstrates the unique value of detailed gravity surveys, combined with surface geological information, for modelling and understanding the evolution of active volcano summit regions.  相似文献   

19.
Large thrust earthquakes and volcanic eruptions   总被引：2，自引：0，他引：2  
Forty-eight hours after the occurrence of the May 22, 1960 (M W =9.5) Chile earthquake, Puyehue volcano initiated its eruptive activity. The closeness in space and time of both phenomena provides us with a unique opportunity to examine the possible causal relationship between the sudden strain change and the mechanism of the eruption. From the slip distribution of the 1960 event (Barrientos andWard, 1990) and a static propagator technique, which allows for variable slip faults in vertically heterogeneous media, I calculate the strain field and its depth dependence in the region beneath the volcano. The presented semi-analytical formalism can be applied to any two-dimensional dipping fault. Calculations show extension at the surface of the order of 40 strain, in agreement with what was observed in triangulation networks in the central valley about 50 km oceanward from the line of volcanoes. The amplitude of the strain field beneath the volcano is uniform up to a depth of 20 km and decreases downward. The sudden extension of the region is thought to be the main factor in facilitating the eruption of the volcano. It is postulated that strain beneath the volcano triggered the eruption of the Puyehue-Cordón Caulle volcanic system because it was in a mature stage of its eruptive cycle and there was lack of eruptive activity in other volcanoes located along the 1960 rupture region in the immediate period following the earthquake.  相似文献   

20.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号