scholarly journals Scenario-Based Pyroclastic Density Current Invasion Maps at Poorly Known Volcanoes: A Case Study from Changbaishan (China/North Korea)

2020 ◽  
Vol 10 (7) ◽  
pp. 2622
Author(s):  
Anna Maria Lombardi ◽  
Pierdomenico Del Gaudio ◽  
Zhengfu Guo ◽  
Maoliang Zhang ◽  
Guoming Liu ◽  
...  
Keyword(s):  
North Korea ◽  
Density Current ◽  
Rapid Evaluation ◽  
Pyroclastic Density Currents ◽  
Density Currents ◽  
Eruptive History ◽  
Probability Maps ◽  
Changbaishan Volcano ◽  
Global Datasets

Changbaishan volcano (China/North Korea; last eruption in 1903 AD) was responsible for a Volcanic Explosivity Index (VEI) 7 eruption in 946 AD. Approximately 186,000 people live around Changbaishan and 2,000,000 tourists/year visit the volcano. An unrest occurred between 2002 and 2006. Despite the relevant hazard, the eruptive history is poorly known, a condition common to many volcanoes worldwide. Here, we investigate the extension of the areas potentially affected by pyroclastic density currents (PDCs) in case of future eruptions following a scenario-based approach. We perform energy cone runs referred to four scenarios from columns of height 3, 10, 20 and 30 km at different vents. By using global datasets on PDCs, we produce spatial probability maps of PDCs invasion. Empirical laws between covered areas, PDC travelled distances, and heights of collapse are provided. In scenarios 3 and 4, PDCs expand at distances up to 42 km and 85 km, respectively. In scenarios 1 and 2, PDCs invade the touristic area and few main roads. Severe effects emerge from scenarios 3 and 4 with the interruption of the China–North Korea land and aerial connections and PDC. Our approach may serve as guide for the rapid evaluation of the PDC-related hazard at poorly known volcanoes.

scholarly journals Thematic vent opening probability maps and hazard assessment of small-scale pyroclastic density currents in the San Salvador volcanic complex (El Salvador) and Nejapa-Chiltepe volcanic complex (Nicaragua)

2021 ◽  
Vol 21 (5) ◽  
pp. 1639-1665
Author(s):  
Andrea Bevilacqua ◽  
Alvaro Aravena ◽  
Augusto Neri ◽  
Eduardo Gutiérrez ◽  
Demetrio Escobar ◽  
...  
Keyword(s):  
El Salvador ◽  
Small Scale ◽  
Volcanic Complex ◽  
Pyroclastic Density Currents ◽  
Density Currents ◽  
Eruption Style ◽  
San Salvador ◽  
Low Intensity ◽  
Probability Maps ◽  
Cone Model

Abstract. The San Salvador volcanic complex (El Salvador) and Nejapa-Chiltepe volcanic complex (Nicaragua) have been characterized by a significant variability in eruption style and vent location. Densely inhabited cities are built on them and their surroundings, including the metropolitan areas of San Salvador (∼2.4 million people) and Managua (∼1.4 million people), respectively. In this study we present novel vent opening probability maps for these volcanic complexes, which are based on a multi-model approach that relies on kernel density estimators. In particular, we present thematic vent opening maps, i.e., we consider different hazardous phenomena separately, including lava emission, small-scale pyroclastic density currents, ejection of ballistic projectiles, and low-intensity pyroclastic fallout. Our volcanological dataset includes: (1) the location of past vents, (2) the mapping of the main fault structures, and (3) the eruption styles of past events, obtained from critical analysis of the literature and/or inferred from volcanic deposits and morphological features observed remotely and in the field. To illustrate the effects of considering the expected eruption style in the construction of vent opening maps, we focus on the analysis of small-scale pyroclastic density currents derived from phreatomagmatic activity or from low-intensity magmatic volcanism. For the numerical simulation of these phenomena we adopted the recently developed branching energy cone model by using the program ECMapProb. Our results show that the implementation of thematic vent opening maps can produce significantly different hazard levels from those estimated with traditional, non-thematic maps.

scholarly journals Thematic vent opening probability maps and hazard assessment of small-scale pyroclastic density currents in the San Salvador Volcanic Complex (El Salvador) and Nejapa-Chiltepe Volcanic Complex (Nicaragua)

2020 ◽  
Author(s):  
Andrea Bevilacqua ◽  
Alvaro Aravena ◽  
Augusto Neri ◽  
Eduardo Gutiérrez ◽  
Demetrio Escobar ◽  
...  
Keyword(s):  
El Salvador ◽  
Small Scale ◽  
Volcanic Complex ◽  
Pyroclastic Density Currents ◽  
Density Currents ◽  
Thematic Maps ◽  
Eruption Style ◽  
San Salvador ◽  
Low Intensity ◽  
Probability Maps

Abstract. San Salvador Volcanic Complex (El Salvador) and Nejapa-Chiltepe Volcanic Complex (Nicaragua) have been characterized by a significant variability in eruption style and vent location. Densely inhabited cities are in their surroundings, including the metropolitan areas of San Salvador (~2.4 M people) and Managua (~1.4 M people), respectively. In this study we present novel vent opening probability maps for these volcanic complexes, which are based on a multi-model approach that relies on kernel density estimators. Our volcanological dataset includes: (1) the location of past vents, (2) the mapping of the main fault structures, and (3) the eruption styles of past events, obtained from the critical analysis of literature and/or inferred from volcanic deposits and morphological features observed remotely and in the field. In particular, we present thematic vent opening maps, i.e. we consider different hazardous phenomena separately, including lava emission, small-scale pyroclastic density currents, ejection of ballistic projectiles, and low-intensity pyroclastic fallout. To illustrate the effects of considering the expected eruption style in the construction of vent opening maps, we focus on the analysis of small-scale pyroclastic density currents derived from phreatomagmatic activity or from low-intensity magmatic volcanism. For the numerical simulation of these phenomena we adopted the recently developed branching energy cone model by using the program ECMapProb. Our results show that the implementation of thematic maps of vent opening can produce significantly different hazard levels from those estimated with traditional, non-thematic, maps.

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 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.

scholarly journals Effective mapping of large ignimbrites by using a GIS-based methodology; case of the Xáltipan ignimbrite from Los Humeros caldera, Mexico

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
Jaime Alberto Cavazos Álvarez ◽  
Gerardo Carrasco-Núñez
Keyword(s):  
Flat Surface ◽  
Volcanic Belt ◽  
Field Measurements ◽  
Volcanic Field ◽  
Pyroclastic Density Currents ◽  
Density Currents ◽  
Eruptive History ◽  
Map Construction ◽  
Mexican Volcanic Belt ◽  
Trans Mexican Volcanic Belt

The Xáltipan ignimbrite (XI) records the largest single-eruption of the Trans-Mexican Volcanic Belt up to date (≥344 km3 uncompacted volume). As most large ignimbrites, the XI presents common challenges when mapping. These are abrupt welding variations, burial by younger units near other volcanic sources, and highly eroded deposits in active-water valleys. In this work, we deal with these issues by integrating classical cartographic techniques such as field measurements, geometric projections of energy lines and construction of geologic sections, with a GIS-based methodology that quantifies the eroded bulk. As a result, we obtained a map with the main XI features that is presented in an interactive format. Furthermore, we discuss the resources used for the map construction and how the results contributed to the interpretation of the eruptive history. These contributions include: 1) the energy lines point to a low-height pyroclastic density currents source, typical of caldera-forming, boiling-over eruptions; 2) the landscape of the XI, coupled with the geologic sections, indicate that in the proximal facies the ignimbrite filled a volcanic field, leaving a radially shaped distribution with a flat surface, while in the distal facies it channelized into a steep mountainous ground; and 3) the geologic sections in the valley areas, where the active rivers highly eroded the original XI deposits, revealed the preferential development of welded zones along channel centers.

scholarly journals Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

2014 ◽  
Vol 6 (2) ◽  
pp. 3261-3302 ◽  
Author(s):  
G. A. Douillet ◽  
B. Taisne ◽  
&amp;Egrave;. Tsang-Hin-Sun ◽  
S. K. Müller ◽  
U. Kueppers ◽  
...  
Keyword(s):  
Shock Waves ◽  
Pore Pressure ◽  
Pyroclastic Density Current ◽  
Density Current ◽  
Pyroclastic Density Currents ◽  
Soft Sediment ◽  
Density Currents ◽  
Ballistic Impacts ◽  
Sediment Deformation ◽  
Soft Sediment Deformation

Abstract. Soft-sediment deformation produces intriguing sedimentary structures and can occur in diverse environments and from a variety of triggers. From the observation of such structures and their interpretation in terms of trigger mechanisms, valuable information can be extracted about former conditions. Here we document examples of syn-eruptive deformation in dilute pyroclastic density current deposits. Outcrops from 6 different volcanoes have been compiled in order to provide a broad perspective on the variety of structures: Ubehebe craters (USA), Tungurahua (Ecuador), Soufrière Hills (Montserrat), Laacher See (Germany), Tower Hill and Purrumbete lake (both Australia). Isolated slumps as well as sinking pseudonodules are driven by their excess weight and occur after deposition but penecontemporaneous to the eruption. Isolated, cm-scale, overturned beds with vortex forms have been interpreted to be the signature of shear instabilities occurring at the boundary of two granular media. They may represent the frozen record of granular, pseudo Kelvin–Helmholtz instabilities. Their recognition can be a diagnostic for flows with a granular basal boundary layer. The occurrence of degassing pipes together with basal intrusive dikes suggest fluidization during flow stages, and can facilitate the development of Kelvin–Helmholtz structures. The occurrence at the base of flow units of injection dikes in some outcrops compared with suction-driven local uplifts in others indicates the role of dynamic pore pressure. Variations of the latter are possibly related to local changes between depletive and accumulative dynamics of flows. Ballistic impacts can trigger unconventional sags producing local displacement or liquefaction. Based on the deformation depth, these can yield precise insights into depositional unit boundaries. Such impact structures may also be at the origin of some of the steep truncation planes visible at the base of the so-called "chute and pool" structures. Finally, the passage of shock waves emanating from the vent may be preserved in the form of trains of isolated, fine-grained overturned beds which may disturb the surface bedding without occurrence of a sedimentation phase in the vicinity of a vent. Dilute pyroclastic density currents occur contemporaneously with seismogenic volcanic explosions. They are often deposited on steep slopes and can incorporate large amounts of water and gas in the sediment. They can experience extremely high sedimentation rates and may flow at the border between traction, granular and fluid-escape boundary zones. These are just some of the many possible triggers acting in a single environment, and reveal the potential for insights into the eruptive mechanisms of dilute pyroclastic density currents.

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