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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

The Stop-and-Go Mechanism: Towards an Integrated Approach to Model Seismicity, Outgassing, Deformation, and Thermal Unrest at Active Volcanoes

Connecting the geophysical and geochemical signals recorded at and above the surface of volcanoes with source mechanisms is fundamental to understand transitions from quiescence to eruption, and to integrate the behavior of volcanoes with their regional seismotectonic and hydrological context. Some of these signals include shallow volcanic tremor, a long-lasting (minutes-to-years) ground vibration detected in volcanic areas during unrest; volcanic outgassing, which shows intriguing periodicities over multiple scales, as revealed by space-borne instruments and by ground-based, high-frequency (~1 Hz), sampling methods; inflation and deflation of volcanic edifices, commonly associated with subsurface volume changes; and large-scale (from a few to tens of km2), low-temperature, thermal anomalies, a newly-discovered signal that has been observed to emerge on volcanic flanks from months-to-years prior to gas- and magma-driven eruptions. Traditionally, these geophysical and geochemical signals have been modelled independently, which limits our interpretation of subsurface processes and thus our assessment of unrest. In this work, we show through lumped-parameter models, numerical simulations, and preliminary laboratory experiments that many of the signals recorded around volcanoes can be integrated into a common “stop-and-go” mechanism. In particular, we found that they can arise spontaneously when taking into account the feedbacks between the temporary accumulation of gas and/or magma in the crust (“stop”), and the diffusive transfer of gas and heat towards the surface (“go”). For example, we find that the “stop-and-go” mechanism can explain: (i) the emergence of monochromatic, broadband, and harmonic tremor; (ii) the periodic components commonly observed in volcanic outgassing time series; (iii) the link between large-scale thermal anomalies and shallow hydrothermal systems; (iv) the reported time lags between large-scale thermal anomalies and deformation; and (v) the breathing of potentially destructive volcanic calderas. The “stop-and-go” mechanism provides a consistent and realistic framework to link multiple geophysical and geochemical signals with the processes leading to volcanic unrest and eruption.

volcanoes↗
DOE OSTI2022

Fluxionality of Subnano Clusters Reshapes the Activity Volcano of Electrocatalysis

The Sabatier activity volcano provides intuitive guide for catalyst design, but also imposes fundamental limitations on the composition and maximal activity of catalysts. Here we show that the ORR activity volcano is shifted and reshaped by the potential-dependent fluxionality of subnano cluster catalysts. Fluxionality causes the typically under-binding Ag/Au to gain optimal activity in the cluster form, and surpass Pt/Pd. Furthermore, isomerization of clusters as a function of the potential breaks linear scaling relationships, enabling surpassing the volcano “apex” relative to the bulk. The effect is likely general for fluxional cluster catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Composition of Magma and Characteristics of the Hydrothermal System of Newberry Volcano, Oregon, From Magnetotellurics

Abstract We use 3‐D magnetotellurics to improve our understanding of the structure and magma composition of Newberry Volcano in Oregon, USA. Newberry is a broad shield volcano with a summit caldera and strongly bimodal magmatism. Newberry has long been the subject of geothermal exploration research, but that work has focused on the volcano's west flank, leaving the caldera largely unstudied with geophysical methods until recently. Our modeling shows a relatively resistive magma reservoir of approximately 50 Ωm. Our work builds upon recent seismic models and petrological analysis to interpret Newberry's magma reservoir as a dry rhyolite with 8–11% partial melt, which matches the seismically determined melt fraction. Finding the conditions within the magma reservoir that allow the resistivity and seismic analysis to come to the same melt fraction helps us narrow down the magma temperature and composition. From this we infer a dry rhyolitic magma at 850 °C. We also image a prominent vertical conductive anomaly along the south rim below the vent that produced the most recent eruption. The anomaly extends from magma reservoir depths of 3 km to 1 km below the surface where it disperses into the caldera fill. We interpret this as the main conduit for magmatic fluids to reach Newberry's hydrothermal system. Other features that our model shows include higher conductivity along the caldera rim and a resistive older pluton on the west flank.

Bowles‐Martinez, E.↗
DOE OSTI2020

Complex subsurface hydrothermal fluid mixing at a submarine arc volcano supports distinct and highly diverse microbial communities

Hydrothermally active submarine volcanoes are mineral-rich biological oases contributing significantly to chemical fluxes in the deep sea, yet little is known about the microbial communities inhabiting these systems. Here we investigate the diversity of microbial life in hydrothermal deposits and their metagenomics-inferred physiology in light of the geological history and resulting hydrothermal fluid paths in the subsurface of Brothers submarine volcano north of New Zealand on the southern Kermadec arc. From metagenome-assembled genomes we identified over 90 putative bacterial and archaeal genomic families and nearly 300 previously unknown genera, many potentially endemic to this submarine volcanic environment. While magmatically influenced hydrothermal systems on the volcanic resurgent cones of Brothers volcano harbor communities of thermoacidophiles and diverse members of the superphylum “DPANN,” two distinct communities are associated with the caldera wall, likely shaped by two different types of hydrothermal circulation. The communities whose phylogenetic diversity primarily aligns with that of the cone sites and magmatically influenced hydrothermal systems elsewhere are characterized predominately by anaerobic metabolisms. These populations are probably maintained by fluids with greater magmatic inputs that have interacted with different (deeper) previously altered mineral assemblages. However, proximal (a few meters distant) communities with gene-inferred aerobic, microaerophilic, and anaerobic metabolisms are likely supported by shallower seawater-dominated circulation. Furthermore, mixing of fluids from these two distinct hydrothermal circulation systems may have an underlying imprint on the high microbial phylogenomic diversity. Collectively our results highlight the importance of considering geologic evolution and history of subsurface processes in studying microbial colonization and community dynamics in volcanic environments.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Muon radiography applied to volcanoes imaging: the MURAVES experiment at Mt. Vesuvius

Muon radiography is a technique based on the measurement of absorption profiles of muons as they pass through matter. This measurement allows to obtain an image of the inner structure of large volume objects and is suitable to be applied in several fields, such as volcanology, archaeology and civil engeneering. One of the main applications concerns the study of volcanic structures; indeed it is possible to use this technique to measure the mass distribution inside the edifice of a volcano providing useful information to better understand the possible eruption mechanisms. The MURAVES (MUon RAdiography of VESuvius) project aims to the study of the summital cone of Mt. Vesuvius near Naples in Italy, one of the most dangerous active volcanoes in the world. The MURAVES apparatus is a modular, robust muon hodoscope system with a low power consumption, optimized to be used in inhospitable environments like the surroundings of volcanoes. The complete detection system is an array of identical tracking modules, each with an area of 1 m2, based on the use of plasic scintillators. The technologies, the status and the data analysis strategy of the experiment will be presented in this paper.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1978

Volcanoes on the inner planets - Some preliminary comparisons of gross topography

The paper extends previous numerical work on analogs of planetary landform (Pike, 1974, 1978) by concentrating on volcanic edifices rather than impact craters. Two kinds of extraterrestrial volcanic constructs - domes on the lunar maria and calderas on Mars - are compared with terrestrial volcanoes. According to available data, neither type of landform unequivocally resembles a specific class of terrestrial volcano. The quantitative models of volcanoes presented necessarily are statistical because the shapes of volcanic landforms vary over a wide range of values.

Pike, R. J.↗
NASA NTRS1981

Topography of Martian central volcanoes

Results are presented of the topographic mapping of six large central volcanoes on Mars. Stereo images of the volcanoes Olympus Mons, Elysium Mons, Albor Tholus, Ceraunius Tholus, Uranius Tholus and Uranius Patera were acquired by Viking Orbiter 1, and pairs of images were compiled into topographic maps through the use of digital image measurement techniques. Olympus Mons is found to have the general form of a terrestrial basaltic shield constructed almost entirely from lava flows, however with an altitude of 20-23 km and flank slopes averaging about 4 deg; a high nominal density indicates that anomalously dense lithosphere underlies the shield. Uranius Patera is observed to be a similar feature of present relief about 2 km, with its lower flanks buried by later lava flood deposits. Elysium Mons has about 13 km of local relief with average slopes of 4.4 deg, although its upper flank slopes are significantly steeper than those of Olympus Mons, suggesting a shield volcano modified by a terminal phase of mixed volcanic activity. Albor Tholus is found to be a partially buried 3-km shield-like construct, while Ceranius and Uranius Tholus are steeper cone-like features with reliefs of about 6 and 2 km, respectively, which may be lava shield constructs modified by a terminal stage of explosive activity.

Blasius, K. B.↗
NASA NTRS1982

Volcanoes and climate

The evidence that volcanic eruptions affect climate is reviewed. Single explosive volcanic eruptions cool the surface by about 0.3 C and warm the stratosphere by several degrees. Although these changes are of small magnitude, there have been several years in which these hemispheric average temperature changes were accompanied by severely abnormal weather. An example is 1816, the "year without summer" which followed the 1815 eruption of Tambora. In addition to statistical correlations between volcanoes and climate, a good theoretical understanding exists. The magnitude of the climatic changes anticipated following volcanic explosions agrees well with the observations. Volcanoes affect climate because volcanic particles in the atmosphere upset the balance between solar energy absorbed by the Earth and infrared energy emitted by the Earth. These interactions can be observed. The most important ejecta from volcanoes is not volcanic ash but sulfur dioxide which converts into sulfuric acid droplets in the stratosphere. For an eruption with its explosive magnitude, Mount St. Helens injected surprisingly little sulfur into the stratosphere. The amount of sulfuric acid formed is much smaller than that observed following significant eruptions and is too small to create major climatic shifts. However, the Mount St. Helens eruption has provided an opportunity to measure many properties of volcanic debris not previously measured and has therefore been of significant value in improving our knowledge of the relations between volcanic activity and climate.

Toon, O. B.↗
NASA NTRS1984

Ancient Volcano-Tectonic Structures of the Olympus Mons Region, Mars

Two old volcano-tectonic collapse structures are exposed north and northeast of the huge shield volcano, Olympus Mons. They are semicircular and were probably low shield volcanoes similar to Alba Patera, but whose central portions have subsided or collapsed. They form the basement upon which younger volcanic materials of Alba Patera Olympus Mons have been emplaced. The oldest structure, Acheron Fossae is over 700 km across and is north of Olympus Mons. It has a surface of considerable relief broken by graben and extensive en echelon and parallel fractures and faults with varied displacements. Acheron Fossae is the most densely cratered in the Olympus Mons region. The structure must have formed very early in martian time. The second is Halex Fossae, northeast of Olympus Mons. Where exposed, it is cut by a series of arcuate grabens that become closer spaced toward its center. The radii of the fractures indicate that the structure may be at least 250 km across and centered beneath the Olympus Plains. Lava flows appear to have issued from some of the arcuate fractures and to have flowed radially away from the center of Halex Fossae. North of Halex Fossae, material of the same age as Halex Fossae overlaps Acheron Fossae. The density of craters on the Halex Fossae material (3,200-4,400 >1km/10 6 km 2 indicates an old age for its formation but one younger than that of Acheron Fossae. These two ancient volcanic-tectonic structures are evidence that the Olympus Mons region has been the locus of major volcanism over much of martian history.

Elliot C Morris↗
NASA NTRS1984

Topography of the shield volcano, Olympus Mons on Mars

Olympus Mons, one of the largest known shield volcanoes in the solar system, covers an area of more than 3.2 x 10 to the 5th sq km and has a diameter of more than 600 km, excluding its vast aureole deposits. The structure is five times larger than the largest shield volcano on the earth. It is situated on the north-west flank of the Tharsis volcanic region, a broad topographic rise on the Martian surface. The volcano has three physical subdivisions: the summit caldera, the terraced upper flanks, and the lower flanks, which terminate in a scarp 2-10 km high that nearly surrounds the structure. A large block of images of the Tharsis region, including Olympus Mons, was obtained by the Viking mission. A topographic map of Olympus Mons is presented here, which has been compiled using various combinations of stereo pairs of these images, together with stereoscopic perspective views generated by image processing techniques.

Wu, S. S. C.↗
NASA NTRS1984

Sulfur volcanoes on Io?

The unusual rheological properties of sulfur are discussed in order to determine the distinctive volcanic flow morphologies which indicate the presence of sulfur volcanoes on the Saturnian satellite Io. An analysis of high resolution Voyager imagery reveals three features which are considered to be possible sulfur volcanoes: Atar Patera, Daedalus Patera, and Kibero Patera. All three features are distinguished by circular-to-oval central masses surrounded by irregular widespread flows. The central zones of the features are interpreted to be domes formed of high temperature sulfur. To confirm the interpretations of the satellite data, molten sulfur was extruded in the laboratory at a temperature of 210 C on a flat surface sloping 0.5 deg to the left. At this temperature, the sulfur formed a viscous domelike mass over the event. As parts of the mass cooled to 170 C the viscosity decreased to a runny stage, forming breakout flows. It is concluded that a case can be made for sulfur volcanoes on Io sufficient to warrant further study, and it is recommended that the upcoming Galileo mission examine these phenomena.

Greeley, R.↗
NASA NTRS1984

Geochemical constraints on magma processes in a peralkaline system - The Paisano volcano, west Texas

Petrographic and trace element data from a continuous stratigraphic sequence of flows from the peralkaline Paisano Volcano in west Texas are used to delineate magnetic processes responsible for the chemical evolution of this volcano. It is shown that crystal fractionation of the phenocrystic assemblage explains the main compositional variation, but magma mixing of a less evolved melt composition also affected the chemical evolution of the volcano.

Mcdonough, W. F.↗
NASA NTRS1986

Application of photogrammetry to the study of volcano-glacier interactions on Mount Wrangell, Alaska

Most Alaskan volcanoes are glacier covered and provide excellent opportunities to study interactions between glaciers and volcanoes. The present paper is concerned with such a study, taking into account the Mt. Wrangell (4317 m) which is the northernmost active volcano (solfatara activity) on the Pacific Rim (62 deg N; 144 deg W). While the first photographs on the summit of Mt. Wrangell were published more than 75 years ago, research there began in 1953 and 1954. Satellite images reveal activity at the summit of Mt. Wrangell. However, the resolution is not sufficient for conducting important measurements regarding ice volume losses. For this reason, vertical aerial photographs of the summit were obtained, and a field trip to the summit was conducted. Aspects of photogrammetry are discussed, taking into account questions of ground control, aerial photography, topographic mapping, digital cross sections, and orthophotos.

Benson, C. S.↗
NASA NTRS1987

Long, paired A'A/Pahoehoe flows of Mauna Loa: Volcanological significance and insights they provide into volcano plumbing systems

The long lava flows of Mauna Loa, Hawaii have been cited as Earth's closed analogs to the large Martian flows. It is therefore important to understand the flow mechanics and characteristics of the Mauna Loa flows and to make use of these in an attempt to gain insights into Martian eruptive processes. Two fundamentally different kinds of long lava flows can be distinguished on Hawaiian volcanoes as in Martian flows. The two kinds may have identical initial viscosities, chemical compositions, flow lengths, and flow volumes, but their flow mechanisms and thermal energy budgets are radically different. One travels a distance set by the discharge rate as envisaged by Walker and Wadge, and the other travels a distance set mainly by the eruption duration and ground slope. In the Mauna Loa lavas, yield strength becomes an important flow morphology control only in the distal part of a'a lavas. The occurrence of paired flows on Mauna Loa yields insights into the internal plumbing systems of the volcano, and it is significant that all of the volume of the a'a flow must be stored in a magma chamber before eruption, while none of the volume of the pahoehoe needs to be so stored. Differentiation between the two kinds of flows on images of Martian volcanoes is possible and hence an improved understanding of these huge structures is acquired.

Rowland, Scott K.↗
NASA NTRS1987

Large-scale volcano-ground ice interactions on Mars

In the present investigation of Martian volcano-ground ice interaction processes, a numerical model is developed that encompasses conductive heat transport, surface radiation, heat transfer to the atmosphere, and H2O phase-changes in an ice-rich permafrost over which lave flows erupt, followed by the intrusion of sills. An examination is made of the two large scale interaction regions formed near Aeolis Mensae and near the volcano Hadriaca Patera, northeast of Hellas. The inferred channel discharges are compared to discharge rates calculated for lava-ground ice interactions, showing that meltwater (probably accumulated under the surface) was rapidly released at a discharge rate that was limited by soil permeability. The volcano-ground ice interactions have been an important Martian geologic process, and could account for the palagonites constituting the Martian dust.

Squyres, Steven W.↗
NASA NTRS1991

Relative chronology of Martian volcanoes

Impact cratering is one of the major geological processes that has affected the Martian surface throughout the planet's history. The frequency of craters within particular size ranges provides information about the formation ages and obliterative episodes of Martian geologic units. The Barlow chronology was extended by measuring small craters on the volcanoes and a number of standard terrain units. Inclusions of smaller craters in units previously analyzed by Barlow allowed for a more direct comparison between the size-frequency distribution data for volcanoes and established chronology. During this study, 11,486 craters were mapped and identified in the 1.5 to 8 km diameter range in selected regions of Mars. The results are summarized in this three page report and give a more precise estimate of the relative chronology of the Martian volcanoes. Also, the results of this study lend further support to the increasing evidence that volcanism has been a dominant geologic force throughout Martian history.

Landheim, R.↗
NASA NTRS1989

Remote sensing of volcanos and volcanic terrains

The possibility of using remote sensing to monitor potentially dangerous volcanoes is discussed. Thermal studies of active volcanoes are considered along with using weather satellites to track eruption plumes and radar measurements to study lava flow morphology and topography. The planned use of orbiting platforms to study emissions from volcanoes and the rate of change of volcanic landforms is considered.

Mouginis-Mark, Peter J.↗