Geophysical and Geological investigations of a major Miocene fault system within the city of Vienna: evidence for active tectonics

2020 ◽  
Author(s):  
Bernhard Salcher ◽  
Jan-Christoph Otto ◽  
Stephanie Neuhuber ◽  
Christopher Lüthgens ◽  
Sabine Grupe ◽  
...  
Keyword(s):  
Fault Zone ◽  
Marine Sediments ◽  
Age Dating ◽  
Coarse Grained ◽  
Fault System ◽  
High Resistivity ◽  
Vienna Basin ◽  
Fine Grained ◽  
Aeolian Deposits ◽  
The City

<p>We present investigations of a major Miocene fault system crossing the city of Vienna by using sedimentological, geophysical, remote sensing and numerical age dating methods. The fault zone is located at the western edge of the Vienna Basin, a c. 55 km wide and c. 200 km long rhomb-shaped pull-apart basin, separating the mountain ranges of the Alps and Carpathians. At its western edge a major sidewall fault, the Leopoldsdorf Fault System  vertically offsets alpine units by up to 5 km. In this study, we focus on Pleistocene fluvial sediments of the Danube deposited along this fault zone. Distribution and facies provide suitable conditions to speculate on Quaternary fault activity. Fluvial gravels rest on top of fine-grained, marine sediments of the Miocene. Quaternary uplift preserved these sediments in the form of terraces that were extensively covered by Pleistocene aeolian deposits (i.e. loess). Later, solifluction affected those fine-grained sediments and obliterated the terrace steps resulting in a relative homogenously inclined top as well as a flat accumulation zone at the toe of the slope. Age brackets of Quaternary deposits are provided from redeposited quartz gravels using cosmogenically produced <sup>26</sup>Al and <sup>10</sup>Be as well as luminescence ages of the loess-like cover sediments.</p><p>The high resistivity contrast of the coarse-grained sediments to the underlying fine-grained marine sediments and the overlying loess deposits provided excellent conditions to infer the geometry of the fluvial deposits. Accordingly, we used electrical resistivity tomography and data derived from driller’s lithologic logs to constrain possible vertical offset of terraces. Possible surface ruptures were discussed by utilizing data from LiDAR-based high-resolution digital elevation models.</p>

scholarly journals Paleogene extension in the Northern Aegean: Colluvial/debris flow deposits of the Early-Middle Eocene in NW Thrace Basin, Turkey

2021 ◽  
Vol 72 (3) ◽  
Author(s):  
Serdar Akgündüz ◽  
Hayrettin Koral
Keyword(s):  
Debris Flow ◽  
Fault Zone ◽  
Middle Eocene ◽  
Late Eocene ◽  
Coarse Grained ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Early Oligocene ◽  
Thrace Basin ◽  
Nw Turkey

The Thrace Basin consists of Paleogene–Neogene deposits that lie in the lowland south of the Strandja highlands in NW Turkey, where metagranitic and metasedimentary rocks occur. The Akalan Formation consisting of colluvial fan/debris flow deposits represents the base of the sequence in the northern Thrace basin where it is bounded by a right lateral strike-slip oblique fault called “The Western Strandja Fault Zone”. This formation exhibits a coarse-grained, angular and grain-supported character close to the fault zone which has releasing-bends. Fine-grained, rounded, and matrix-supported sediments occur away from the contact. During this study, the Akalan Formation is described for the first time as having larger benthic foraminifera (LBF) of Coskinolina sp of Ypresian–Lutetian, Nummulites obesus of early Lutetian, Dictyoconus egyptiensis of Lutetian, Orbitolites sp. of Ypresian–Bartonian, Miliola sp of early–middle Eocene, Idalina grelaudae of early Lutetian–Priabonian, Ammobaculites agglutinans, Amphimorphina crassa, Dentalina sp., Nodosaria sp., Operculina sp., Lenticulina sp., Quinqueloculina sp. and Amphistegina sp. of Eocene. This unit passes upward with a conformity into reefal limestones of the middle/late Eocene–early Oligocene Soğucak Formation. At times, the limestone overlies the conformity, there is an indication of a prograding sedimentary sequence. The new stratigraphic, paleontological, sedimentological and structural findings related to the NW Thrace Basin suggest a strong transtensional/extensional tectonic control for the initial Paleogene sedimentary deposition during the Ypresian–Lutetian period as shown by fossil content of the Akalan Formation. Right lateral-slip extensional tectonics appears to have had activity during the middle–late Eocene transgressive deposition of the Soğucak Formation when the basin became deepened and enlarged.

Numerical age dating of Danube terraces from one fault block (Rauchenwarth) west of the Vienna Basin Transform Fault (Austria)

2020 ◽  
Author(s):  
Stephanie Neuhuber ◽  
Zsófia Ruszkiczay-Rüdiger ◽  
Christopher Lüthgens ◽  
Philip Martin ◽  
Bernhard Salcher ◽  
...  
Keyword(s):  
Danube River ◽  
Age Dating ◽  
Fault System ◽  
Transform Fault ◽  
Vienna Basin ◽  
Fluvial Terrace ◽  
Fluvial Terraces ◽  
Fault Block ◽  
River Bed ◽  
Upper Level

<p>Fluvial terraces within the extensional structure of the Vienna Basin have been dissected by faults related to the sinistral movement of the Vienna Basin Transform Fault System (VBTF, Decker et al., 2005). Each fault block within the basin displays a slightly different succession of terraces regarding their number, elevation, and preservation. Generally, altitudes of terrace bases within the Vienna Basin vary between 5 and 130 m above the recent Danube river bed.</p><p>This study focuses on one clearly confined fault block, the Rauchenwarth Plateau, located south of the Danube. The plateau forms the western part of intra-basinal hills crossing the Vienna Basin and consists mainly of Miocene sediments that are in part covered by quaternary fluvial terrace deposits at different elevations. The entire succession is widely covered by loess or re-deposited aeolian sediments. To depict the formations below the loess cover we use 19 wells to construct three sections crossing the eastern part of the block in E-W and two parallel sections in N-S direction. The sections show that three levels of fluvial terraces at the northern eastern side of the block are preserved. The lowest and highest levels are accessible in gravel pits with well-defined Miocene bases. These two levels with terrace bases ~67 m and ~24 m above the recent Danube contain large quartz cobbles suitable for dating using in-situ produced <sup>26</sup>Al and <sup>10</sup>Be. Sample sets were taken at 11 m (higher terrace) and 14 m (lower terrace) below todays surface. Sandy sediments from the lower level were in addition dated by luminescence on feldspar using the pIRIR 225 signal. Age calculations using the isochron method (Balco and Rovey, 2008) as well as inverse modelling for the upper level suggest burial durations of ~1.2 Ma. Results of age calculations using cosmogenic nuclides as well as luminescence ages for the lower level will be presented at the conference.</p><p><em>Thanks to NKFIH 124807; OMAA 90öu17, the INSU/CNRS, the ANR through the program “EQUIPEX Investissement d’Avenir” and IRD</em></p><p><strong>References </strong></p><p>Balco, G., Rovey, C., 2008. Am. J. of Science 308, 1083-1114.</p><p>Decker, K., et al., 2005. Quat. Sci. Rev. 24, 305-320.</p>

scholarly journals Lithosphere tearing along STEP faults and synkinematic formation of lherzolite and wehrlite in the shallow subcontinental mantle

Solid Earth ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 1099-1121 ◽  
Author(s):  
Károly Hidas ◽  
Carlos J. Garrido ◽  
Guillermo Booth-Rea ◽  
Claudio Marchesi ◽  
Jean-Louis Bodinier ◽  
...  
Keyword(s):  
Grain Size ◽  
Lithospheric Mantle ◽  
Volcanic Field ◽  
Mantle Xenoliths ◽  
Coarse Grained ◽  
Fault System ◽  
Mantle Flow ◽  
Second Phase ◽  
Fine Grained ◽  
Wide Range

Abstract. Subduction-transform edge propagator (STEP) faults are the locus of continual lithospheric tearing at slab edges, resulting in sharp changes in the lithospheric and crustal thickness and triggering lateral and/or near-vertical mantle flow. However, the mechanisms at the lithospheric mantle scale are still poorly understood. Here, we present the microstructural study of olivine-rich lherzolite, harzburgite and wehrlite mantle xenoliths from the Oran volcanic field (Tell Atlas, northwest Algeria). This alkali volcanic field occurs along a major STEP fault responsible for the Miocene westward slab retreat in the westernmost Mediterranean. Mantle xenoliths provide a unique opportunity to investigate the microstructures in the mantle section of a STEP fault system. The microstructures of mantle xenoliths show a variable grain size ranging from coarse granular to fine-grained equigranular textures uncorrelated with lithology. The major element composition of the mantle peridotites provides temperature estimates in a wide range (790–1165 ∘C) but in general, the coarse-grained and fine-grained peridotites suggest deeper and shallower provenance depth, respectively. Olivine grain size in the fine-grained peridotites depends on the size and volume fraction of the pyroxene grains, which is consistent with pinning of olivine grain growth by pyroxenes as second-phase particles. In the coarse-grained peridotites, well-developed olivine crystal-preferred orientation (CPO) is characterized by orthorhombic and [100]-fiber symmetries, and orthopyroxene has a coherent CPO with that of olivine, suggesting their coeval deformation by dislocation creep at high temperature. In the fine-grained microstructures, along with the weakening of the fabric strength, olivine CPO symmetry exhibits a shift towards [010] fiber and the [010] and [001] axes of orthopyroxene are generally distributed subparallel to those of olivine. These data are consistent with deformation of olivine in the presence of low amounts of melts and the precipitation of orthopyroxenes from a melt phase. The bulk CPO of clinopyroxene mimics that of orthopyroxene via a topotaxial relationship of the two pyroxenes. This observation points to a melt-related origin of most clinopyroxenes in the Oran mantle xenoliths. The textural and geochemical record of the peridotites are consistent with interaction of a refractory harzburgite protolith with a high-Mg no. melt at depth (resulting in the formation of coarse-grained clinopyroxene-rich lherzolite and wehrlite) and with a low-Mg no. evolved melt in the shallow subcontinental lithospheric mantle (forming fine-grained harzburgite). We propose that pervasive melt–peridotite reaction – promoted by lateral and/or near-vertical mantle flow associated with lithospheric tearing – resulted in the synkinematic crystallization of secondary lherzolite and wehrlite and had a key effect on grain size reduction during the operation of the Tell–Rif STEP fault. Melt–rock reaction and secondary formation of lherzolite and wehrlite may be widespread in other STEP fault systems worldwide.

scholarly journals Medieval Russia Hand -modelled Ceramics in Rostov the Great (technological analysis)

2018 ◽  
Author(s):  
О.Л. Шарганова
Keyword(s):  
Organic Materials ◽  
Coarse Grained ◽  
Fine Grained ◽  
Cultural Approach ◽  
The City ◽  
Technological Analysis

Для изучения гончарных традиций древнерусского населения Ростова Великого были использованы материалы из двух раскопов на территории города. Технологическое изучение керамики проводилось по методике А. А. Бобринского в рамках историко-культурного подхода. Преобладали традиции отбора сильнозапесоченных глин и составления формовочных масс по рецепту Г + Д + О. Традиция использования шамота фиксируется преимущественно в смешанном виде в рецепте Г + Д + Ш + О. Хронологических особенностей в распространении этих традиций не выявлено. Постепенные изменения касаются только рецепта Г + Д + О: это переход от крупной дресвы к более мелкой и от большей концентрации дресвы к меньшей, что было прослежено по керамике Григорьевского раскопа. Сопоставление материалов двух раскопов выявило некоторые особенности в традициях отбора глин, а также дало возможность предположить перемешанность нижних пластов Конюшенного раскопа. Выяснилось также, что существует определенная связь традиций изготовления орнаментированной посуды и использования шамота в качестве примеси. To study pottery traditions of the Medieval Russia population in Rostov the Great, materials retrieved from two excavation trenches in the city were used. The technological examination of the ceramics was based on A. A. Bobrinsky’s methodology with the use of the historical and cultural approach. Traditions of selecting oversanded clay and using the ’clay + broken stone + organic materials’ formula predominated. The tradition of using grog is recorded mainly in a mixed formula: ’clay + broken stone + grog + organic materials’. No chronological characteristics in the spread of these traditions were identified. Gradual changes occurred only in the ’clay + broken stone + organic materials’ formula and consisted in a shift from coarse-grained broken stone to fine-grained broken stone and from larger broken stone quantities to smaller grit quantities and can be traced in the ceramics from the Grigoryevsky excavation trench. Comparison of the materials from these two excavation pits identified some specific features of clay selection and also suggested that the lower layers of the Konyushenny excavation trench had been dislodged. A certain linkage of traditions of making ornamented vessels and using grog as temper was also established.

Vertical movement at the Alpine-Carpathian border (Hainburg Hills) calculated from numerical ages of cave sediments

2020 ◽  
Author(s):  
Lukas Plan ◽  
Stephanie Neuhuber ◽  
Susanne Gier ◽  
Esther Hintersberger ◽  
Christopher Lüthgens ◽  
...  
Keyword(s):  
Vertical Displacement ◽  
Vertical Movement ◽  
Danube River ◽  
Age Dating ◽  
Vienna Basin ◽  
Danube Basin ◽  
Base Level ◽  
Pristine Sample ◽  
Aeolian Deposits ◽  
Bedrock Surface

<p>The Hainburg Hills form an elevated range at the south of the Male Karpaty mountains and separate the Vienna Basin from the Danube Basin. They consist of Variscian magmatic and metamorphic rocks covered with anchimetamorphic Mesozoic carbonates. The area west of the Hainburg Hills is well-known for its thermal sulfuric spa since Roman times. About 30 karst caves have been mapped in the area that show signs of hydrothermal or sulphuric acid speleogenesis.</p><p>Two of these caves vertically separated by 92 m were numerically dated using terrestrial cosmogenic <sup>26</sup>Al and <sup>10</sup>Be in quartz washed into a cave and <sup>230</sup>Th/U of calcite rafts. In addition, aeolian cover sediments were investigated using luminescence age dating.</p><p>The upper c. 15 m wide and c. 20 m high cave chamber was completely filled with large, well-rounded quartz cobbles in a red matrix. The matrix contains over 30% clay and consists of quartz, K-feldspar, muscovite, chlorite, hematite, kaolinite, illite, and smectite. The occurrence of smectite in combination with the small grain size indicates soil forming processes in the B-horizon. We conclude that fluvial gravels –similar to modern ones of the Danube river - were transported into the cave together with a matrix originating from a soil cover. In-situ produced cosmogenic <sup>10</sup>Be and <sup>26</sup>Al in five quartz cobbles was used to calculate the time of sediment emplacement into the cave. Results indicate a depositional age of c. 4.5 Ma using the isochron technique.</p><p>The lower cave was investigated using calcite rafts that form at the surface of cave pools using the <sup>230</sup>Th/U dating method. One sample of thin, sharp-edged, and uncoated cave rafts gave the youngest age of c.0.32 Ma. Two other samples were more overgrown and gave older ages between 0.38 and 0.44 Ma. The pristine sample is best suited to reflect the time when the base level was close to the cave.</p><p>Rates of vertical displacement vary between 30 and 35 m/Ma for the last 4 Ma and between 150 and 160 m/Ma for the last 0.32 Ma and document an increase of uplift/incision for the region. These numbers compare well to published rates from the unglaciated surroundings that also range from a maximum of 140 m/Ma to a minimum of 20-25 m/Ma and are generally much lower compared to formerly glaciated areas in the Alps and GPS measured uplift (c. 1000 m/Ma).</p><p>The luminescence age of 14.6 ± 0.1 ka recorded in cover sands show that sediments they overly much older gravels. This implies sediments were repeatedly eroded from the top of the karstified bedrock surface. The aeolian sediments are primarily preserved in depressions within the bedrock surface. Therefore, the age may represent the end of a phase of intense aeolian activity when wind velocities decreased sufficiently to cause sand accumulation. This period is the peak in Western and Central Europe periglacial activity and accompanied by formation of aeolian deposits. The ages are comparable to aeolian deposits in the Vienna Basin area and cover sediments from the Transdanubian Range.</p>

scholarly journals Lithosphere tearing along STEP faults and synkinematic formation of lherzolite and wehrlite in the shallow subcontinental mantle

2019 ◽  
Author(s):  
Károly Hidas ◽  
Carlos J. Garrido ◽  
Guillermo Booth-Rea ◽  
Claudio Marchesi ◽  
Jean-Louis Bodinier ◽  
...  
Keyword(s):  
Grain Size ◽  
Lithospheric Mantle ◽  
Volcanic Field ◽  
Mantle Xenoliths ◽  
Coarse Grained ◽  
Fault System ◽  
Mantle Flow ◽  
Second Phase ◽  
Fine Grained ◽  
Wide Range

Abstract. Subduction-Transform Edge Propagator (STEP) faults are the locus of continual lithospheric tearing at slab edges, resulting in sharp changes in the lithospheric and crustal thickness and triggering lateral and/or near-vertical mantle flow. However, the mechanisms at the lithospheric mantle scale are still poorly understood. Here, we present the microstructural study of olivine-rich lherzolite, harzburgite and wehrlite mantle xenoliths from the Oran volcanic field (Tell Atlas, NW Algeria). This alkali volcanic field occurs along a major STEP fault responsible for the Miocene westward slab retreat in the westernmost Mediterranean. Mantle xenoliths provide a unique opportunity to investigate the microstructures in the mantle section of a STEP fault system. The microstructures of mantle xenoliths show a variable grain size ranging from coarse granular to fine-grained equigranular textures uncorrelated with modal variations. The major element composition of the mantle peridotites provides temperature estimates in a wide range (790–1165 °C) but in general, the coarse-grained and fine-grained peridotites suggest deeper and shallower provenance depth, respectively. Olivine grain size in the fine-grained peridotites depends on the size and volume fraction of the pyroxene grains, which is consistent with pinning of olivine grain growth by pyroxenes as second phase particles. In the coarse-grained peridotites, well-developed olivine crystal preferred orientation (CPO) is characterized by orthorhombic and [100]-fiber symmetries, and orthopyroxene has a coherent CPO with that of olivine, suggesting their coeval deformation by dislocation creep at high-temperature. In the fine-grained microstructures, along with the weakening of the fabric strength, olivine CPO symmetry exhibits a shift towards [010]-fiber and the [010]- and [001]-axes of orthopyroxene are generally distributed subparallel to those of olivine. These data are consistent with deformation of olivine in the presence of low amounts of melts and the precipitation of orthopyroxenes from a melt phase. The bulk CPO of clinopyroxene mimics that of orthopyroxene via a topotaxial relationship of the two pyroxenes. This observation points to a melt-related origin of most clinopyroxenes in the Oran mantle xenoliths. The textural and geochemical record of the peridotites are consistent with interaction of a refractory harzburgite protolith with a high-Mg# melt at depth (resulting in the formation of coarse-grained clinopyroxene-rich lherzolite and wehrlite), and with a low-Mg# evolved melt in the shallow subcontinental lithospheric mantle (forming fine-grained harzburgite). We propose that pervasive melt-peridotite reaction – promoted by lateral and/or near-vertical mantle flow associated with lithospheric tearing – resulted in the synkinematic crystallization of secondary lherzolite and wehrlite and played a key effect on grain size reduction during the operation of the Rif-Tell STEP fault. Melt-rock reaction and secondary formation of lherzolite and wehrlite may be widespread in other STEP fault systems worldwide.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

NEW CONSTRAINTS ON THE GEOMETRY, KINEMATICS, AND TIMING OF DEFORMATION ALONG THE SOUTHERN SEGMENT OF THE PAPOSO FAULT ZONE, ATACAMA FAULT SYSTEM, NORTHERN CHILE

2017 ◽  
Author(s):  
Rachel C. Ruthven ◽  
◽  
John S. Singleton ◽  
Nikki M. Seymour ◽  
Jerry F. Magloughlin ◽  
...  
Keyword(s):  
Fault Zone ◽  
Fault System ◽  
Northern Chile ◽  
Atacama Fault System

scholarly journals Balanced Sparsity for Efficient DNN Inference on GPU

2019 ◽  
Vol 33 ◽  
pp. 5676-5683 ◽  
Author(s):  
Zhuliang Yao ◽  
Shijie Cao ◽  
Wencong Xiao ◽  
Chen Zhang ◽  
Lanshun Nie
Keyword(s):  
Deep Neural Networks ◽  
General Purpose ◽  
Coarse Grained ◽  
Efficient Computation ◽  
Model Accuracy ◽  
Sparse Model ◽  
Model Inference ◽  
Fine Grained ◽  
Practical Inference ◽  
Speed Up

In trained deep neural networks, unstructured pruning can reduce redundant weights to lower storage cost. However, it requires the customization of hardwares to speed up practical inference. Another trend accelerates sparse model inference on general-purpose hardwares by adopting coarse-grained sparsity to prune or regularize consecutive weights for efficient computation. But this method often sacrifices model accuracy. In this paper, we propose a novel fine-grained sparsity approach, Balanced Sparsity, to achieve high model accuracy with commercial hardwares efficiently. Our approach adapts to high parallelism property of GPU, showing incredible potential for sparsity in the widely deployment of deep learning services. Experiment results show that Balanced Sparsity achieves up to 3.1x practical speedup for model inference on GPU, while retains the same high model accuracy as finegrained sparsity.

scholarly journals Submarine lava deltas of the 2018 eruption of Kīlauea volcano

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
S. Adam Soule ◽  
Michael Zoeller ◽  
Carolyn Parcheta
Keyword(s):  
Grain Size ◽  
Pore Pressure ◽  
Mechanistic Model ◽  
Large Fraction ◽  
Volcanic Hazards ◽  
Lava Flows ◽  
Coarse Grained ◽  
Fine Grained ◽  
Fine Grain ◽  
Delta Formation

AbstractHawaiian and other ocean island lava flows that reach the coastline can deposit significant volumes of lava in submarine deltas. The catastrophic collapse of these deltas represents one of the most significant, but least predictable, volcanic hazards at ocean islands. The volume of lava deposited below sea level in delta-forming eruptions and the mechanisms of delta construction and destruction are rarely documented. Here, we report on bathymetric surveys and ROV observations following the Kīlauea 2018 eruption that, along with a comparison to the deltas formed at Pu‘u ‘Ō‘ō over the past decade, provide new insight into delta formation. Bathymetric differencing reveals that the 2018 deltas contain more than half of the total volume of lava erupted. In addition, we find that the 2018 deltas are comprised largely of coarse-grained volcanic breccias and intact lava flows, which contrast with those at Pu‘u ‘Ō‘ō that contain a large fraction of fine-grained hyaloclastite. We attribute this difference to less efficient fragmentation of the 2018 ‘a‘ā flows leading to fragmentation by collapse rather than hydrovolcanic explosion. We suggest a mechanistic model where the characteristic grain size influences the form and stability of the delta with fine grain size deltas (Pu‘u ‘Ō‘ō) experiencing larger landslides with greater run-out supported by increased pore pressure and with coarse grain size deltas (Kīlauea 2018) experiencing smaller landslides that quickly stop as the pore pressure rapidly dissipates. This difference, if validated for other lava deltas, would provide a means to assess potential delta stability in future eruptions.

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