scholarly journals Volcano–glacier interactions on composite cones and lahar generation: Nevado del Ruiz, Colombia, case study

2007 ◽  
Vol 45 ◽  
pp. 115-127 ◽  
Author(s):  
J.C. Thouret ◽  
J. Ramírez C. ◽  
B. Gibert-Malengreau ◽  
C.A. Vargas ◽  
J.L. Naranjo ◽  
...  
Keyword(s):  
Pyroclastic Flows ◽  
Pyroclastic Density Currents ◽  
Density Currents ◽  
Long Term Effects ◽  
Ice Cap ◽  
The North ◽  
Potential Source ◽  
Ice Field

AbstractThe catastrophic lahars triggered by the 13 November 1985 eruption of the ice-clad Nevado del Ruiz volcano, Colombia, demonstrate that the interaction of hot pyroclasts with snow and ice can release 30–50 millionm3 of meltwater in 30–90 minutes. The 1985 eruption caused a 16% loss in area and a 9% loss in volume of snow, firn and ice. Turbulent pyroclastic density currents mechanically mixed with snow and produced meltwater at a rate of 0.5–1.6mms–1. Laboratory experiments suggest that turbulent, fluidized pyroclastic density currents exert mechanical and thermal scour, thereby efficiently transferring heat from hot pyroclasts to snow. Ice cap loss at Nevado del Ruiz continued between 1985 and 2000, representing a ∽52% decline in area and a ∽30% fall in volume. Ice 60–190m thick caps the east and southeast summit plateau, whereas an ice field < 30m thick and devoid of snow is retreating on the north, northeast and west edges. This asymmetrical distribution of ice reflects combined long-term effects of the 1985 eruption and of the post-1985 ice cap retreat. Should volcanic activity resume, steep-sided glaciers can fail and pyroclastic flows and surges can sweep the snowpack and generate mixed avalanches and lahars. Although the potential source of meltwater has decreased since 1985, extensive debris at the ice cap margins can be incorporated to future lahars.

Hazards and Risks at Gunung Merapi, Central Java: A Case Study

2005 ◽  
Author(s):  
Jean-Claude Thouret ◽  
Franck Lavigne
Keyword(s):  
Pyroclastic Flows ◽  
Pyroclastic Density Currents ◽  
Hazard Map ◽  
Density Currents ◽  
Danger Zone ◽  
Merapi Volcano ◽  
Central Java ◽  
Dome Extrusion ◽  
Risk Areas

Of the 1.1 million people living on the flanks of the active Merapi volcano in Java (average population density: 1140 inhabitants per km2), 440 000 live in relatively high-risk areas prone to pyroclastic flows, surges, and lahars. The sixty-one reported eruptions since the mid-1500s killed about 7000 people. For the last two centuries the activity of Merapi has alternated regularly between long periods of lava dome extrusion and brief explosive episodes with dome collapse pyroclastic flows at eight- to fifteen-year intervals. Violent explosive episodes on an average recurrence of twenty-six to fifty-four years have generated pyroclastic flows, surges, tephra falls, and subsequent lahars. The current hazard zone map of Merapi (Pardyanto et al. 1978) portrays three areas, termed the forbidden zone, first danger zone, and second danger zone, based on progressively declining hazard intensity. Revision of the hazard map has been carried out because it lacked the details necessary to outline hazard zones with accuracy (in particular the valleys likely to be swept by lahars), and excluded some areas likely to be devastated by pyroclastic density currents, such as the 22 November 1994 surge. In addition, risk maps were developed in order to incorporate social, technical, and economic elements of vulnerability (Lavigne 1998, 2000) in the decision-making progress. Eruptive hazard assessment at Merapi is based on reconstructed eruptive history, based on eruptive behaviour and scenarios combined with existing models and preliminary numerical modelling (Thouret et al. 2000). The reconstructed past eruptive activity and related damage define the extent and frequency of pyroclastic flows, the most hazardous phenomenon (Camus et al. 2000; Newhall et al. 2000). Pyroclastic flows travelled as far as 9–15 km from the source, pyroclastic surges swept the flanks as far as 9–20 km away from the vent, thick tephra fall buried temples in the vicinity of Yogyakarta 25 km to the south, and subsequent lahars spilled down radial valleys as far as 30 km to the west and south. At least one large edifice collapse has occurred in the past 7000 years (Camus et al. 2000; Newhall et al. 2000).

scholarly journals Mass mortality of Northern Map Turtles (Graptemys geographica)

2015 ◽  
Vol 129 (1) ◽  
pp. 80 ◽  
Author(s):  
Jordan Catrysse ◽  
Emily Slavik ◽  
Jonathan Choquette ◽  
Ashley E. Leifso ◽  
Christina M. Davy
Keyword(s):  
Lake Erie ◽  
Mass Mortality ◽  
Species At Risk ◽  
Long Term Effects ◽  
North Shore ◽  
The North ◽  
The Poor ◽  
Map Turtles ◽  
Graptemys Geographica

We report a mass mortality of Northern Map Turtles (Graptemys geographica [LeSueur, 1817]) on the north shore of Lake Erie, Ontario, Canada. Thirty-five dead adult females were recovered from a nesting area over a period of four weeks. Predation and boat strikes were both excluded as potential cause of death, but the actual cause could not be determined because of the poor condition of the carcasses. Other possible explanations for the mortality include poisoning, drowning, and infection with an unidentified pathogen. Mass mortality in long-lived species, such as turtles, can have long-term effects on population growth and is a cause for concern in a species at risk.

Challenges to Overcome and Scaffolding to Build on

2019 ◽  
Vol 9 (3) ◽  
pp. 50-67
Author(s):  
Hao Yang ◽  
Zhiqiang Ma
Keyword(s):  
Teacher Perceptions ◽  
Flipped Classroom ◽  
Public University ◽  
Test Results ◽  
Learning Behavior ◽  
Long Term Effects ◽  
Exploratory Case Study ◽  
Flipped Classrooms

While current research on the flipped classroom generally focuses on test results and (or) student/teacher perceptions as a measurement of its pedagogical efficacy, students' adaptation to it and the essential conditions for its application are rarely explored. This exploratory case study aims to rectify this by examining how university students adapted to flipped classrooms implemented in a public university in East China. The findings suggest that while the flipped model is impeded by entrenched polarity between students in terms of their learning dispositions and academic competence, students do develop a prototype of theories of learning, a sense of better self through learning from their peers and an awareness of the importance of intrinsic motivation. A gradualist approach is thus proposed for implementing flipped classrooms, which requires longitudinal studies accordingly to understand its long-term effects on learning behavior hitherto left unexplored.

scholarly journals Geodetic work at the archaeological site Tell el-Retaba

2018 ◽  
Vol 17 (2) ◽  
pp. 65-80
Author(s):  
Eva Stopková
Keyword(s):  
Spatial Data ◽  
Statistical Modelling ◽  
Archaeological Site ◽  
The North ◽  
Digital Elevation ◽  
North Eastern ◽  
Elevation Model ◽  
Modern Technologies

The paper summarizes the geodetic contribution for the Slovak team within the joint Polish-Slovak archaeological mission at Tell el-Retaba in Egypt. Surveying work at archaeological excavations is usually influenced by somewhat specific subject of study and extreme conditions, especially at the missions in the developing countries. The case study describes spatial data development according to the archaeological conventions in order to document spatial relationships between the objects in excavated trenches. The long-term sustainability of surveying work at the site has been ensured by detailed metadata recording. Except the trench mapping, Digital Elevation Model has been calculated for the study area and for the north-eastern part of the site, with promising preliminary results for further detection and modelling of archaeological structures. In general, topographic mapping together with modern technologies like Photogrammetry, Satellite Imagery, and Remote Sensing provide valuable data sources for spatial and statistical modelling of the sites; and the results offer a different perspective for the archaeological research.

scholarly journals Perceptions of Final Beneficiaries about the Performance of Cross-sector Partnerships: A Case Study Applied to the 2008 Zaragoza International Exhibition on Water and Sustainable Development

2019 ◽  
Vol 11 (14) ◽  
pp. 3860
Author(s):  
José María Agudo-Valiente ◽  
Pilar Gargallo-Valero ◽  
Manuel Salvador-Figueras
Keyword(s):  
Sustainable Development ◽  
Public Awareness ◽  
International Exhibition ◽  
Long Term Effects ◽  
Governmental Organizations ◽  
Non Governmental Organizations ◽  
Increasing Demand ◽  
The City

Using the 2008 Zaragoza International Exhibition “Water and sustainable development” as a case study, this paper aims to respond to the increasing demand for measurements of the effects and the implications of the performance of cross-sector partnerships from the perspective of their intended final beneficiaries. A contingency framework for measuring the short-, medium- and long-term effects of the 2008 Zaragoza International Exhibition is developed based on a “results chain” or “logic model”. Our results highlight that there are positive long-term synergies between the two main purposes of the 2008 Zaragoza International Exhibition; first, to increase public awareness of and commitment to the problems of water and sustainable development and, second, to make the city of Zaragoza better known internationally and to modernize its infrastructures. Although respondents to our survey consider that the long-term effects on the city are greater, the main short- and medium-term effects are related to awareness of water problems, sustainable development and non-governmental organizations. These results are in tune with what has happened around the city in the last 10 years providing indirect validity both to our study and to the proposed methodology.

scholarly journals Precipitation record since AD 1600 from ice cores on the central Tibetan Plateau

2008 ◽  
Vol 4 (3) ◽  
pp. 175-180 ◽  
Author(s):  
T. Yao ◽  
K. Duan ◽  
B. Xu ◽  
N. Wang ◽  
X. Guo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ice Core ◽  
Ice Cores ◽  
The North ◽  
Northern Tibetan Plateau ◽  
Central Tibetan Plateau ◽  
Precipitation Record ◽  
Ice Field ◽  
The 19Th Century

Abstract. Lack of reliable long-term precipitation record from the northern Tibetan Plateau has constrained our understanding of precipitation variations in this region. We drilled an ice core on the Puruogangri Ice Field in the central Tibetan Plateau in 2000 to reveal the precipitation variations. The well dated part of the core extends back to AD 1600, allowing us to construct a 400-year annual accumulation record. This record shows that the central Tibetan plateau experienced a drier period with an average annual precipitation of ~300 mm in the 19th century, compared to ~450 mm in the wetter periods during 1700–1780 and the 20th century. This pattern agrees with precipitation reconstructions from the Dunde and Guliya ice cores on the northern Plateau but differs from that found in the Dasuopu ice cores from the southern Plateau The north-south contrasts in precipitation reconstruction reveals difference in moisture origin between the south Tibetan Plateau dominated by the Asian monsoon and the north Tibetan Plateau dominated by the continental recycling and the westerlies.

Recognizing long-runout pyroclastic flow deposits using paleomagnetism of ash

2019 ◽  
Vol 131 (11-12) ◽  
pp. 1783-1793 ◽  
Author(s):  
Geoffrey A. Lerner ◽  
Shane J. Cronin ◽  
Gillian M. Turner ◽  
Elisa J. Piispa
Keyword(s):  
Hazard Identification ◽  
Pyroclastic Flows ◽  
Density Currents ◽  
Long Runout ◽  
Key Indicator ◽  
Magnetic Remanence ◽  
Flow Deposit ◽  
Large Populations ◽  
The Matrix

Abstract Quantifying the spread of >600 °C pyroclastic flows (more broadly termed pyroclastic density currents—PDCs) is important because they regularly cause major volcanic catastrophes. Far from volcanic flanks, non-welded PDC deposits can be difficult to distinguish from cold-emplaced volcano-sedimentary units. A key indicator of high temperature is the coherence of magnetic remanence among different lithic clasts in a deposit. In long-runout PDCs, distal deposits are dominated by ash particles (<2 mm diameter), often lacking clasts large enough for conventional paleomagnetic sampling. Here we demonstrate a method of consolidating and sampling oriented blocks of friable ash material with a strengthening compound. This method was used to show that a >25 km runout mass-flow deposit from the 2518-m-high Mt. Taranaki (New Zealand) was emplaced as a hot PDC, contrary to an earlier cold lahar interpretation. We corroborate the results from ash with data from clast samples at some sites and show that the matrix was emplaced at temperatures of at least 250 °C, while clasts were deposited at up to 410 °C. Our case-study raises concerns for hazard-identification at stratovolcanoes worldwide. In the Mt. Taranaki case we demonstrate that PDCs traveled >9 km farther than previously estimated—also well beyond the “normal” PDC hazard zones at stratovolcanoes (10 or 15 km from source). Thus, attention should be paid to deposits in the 15–25 km range in other volcanic settings, where large populations are potentially unaware of PDC risk.

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