Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Reviews of Geophysics”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
USGS2010

Physical oceanography of continental shelves

Knowledge of the physical oceanography of continental shelves has increased tremendously in recent years, primarily as a result of new current and hydrographic measurements made in locations where no comparable measurements existed previously. In general, observations from geographically distinct continental shelves have shown that the nature of the flow may vary considerably from region to region. Although some characteristics, such as the response of currents to wind forcing, are common to many shelves, the relative importance of various physical processes in influencing the shelf flow field frequently is different. In the last several years, the scientific literature on shelf studies has expanded rapidly, with that for separate regions, to some extent, developing independently because of the variable role played by different physical effects.

Reviews of Geophysics and Space Physics↗
USGS2010

Slab pull and the seismotectonics of subducting lithosphere

This synthesis links many seismic and tectonic processes at subduction zones, including great subduction earthquakes, to the sinking of subducted plate. Earthquake data and tectonic modeling for subduction zones indicate that the slab pull force is much larger than the ridge push force. Interactions between the forces that drive and resist plate motions cause spatially and temporally localized stresses that lead to characteristic earthquake activity, providing details on how subduction occurs. Compression is localized across a locked interface thrust zone, because both the ridge push and the slab pull forces are resisted there. The slab pull force increases with increasing plate age; thus because the slab pull force tends to bend subducted plate downward and decrease the force acting normal to the interface thrust zone, the characteristic maximum earthquake at a given interface thrust zone is inversely related to the age of the subducted plate. The 1960 Chile earthquake ( M w 9.5), the largest earthquake to occur in historic times, began its rupture at an interface bounding oceanic plate <30 m.y. old. However, this rupture initiation was associated with the locally oldest subducting lithosphere (weakest coupling); the rupture propagated southward along an interface bounding progressively younger oceanic lithosphere, terminating near the subducting Chile Rise. Prior to a great subduction earthquake, the sinking subducted slab will cause increased tension at depths of 50–200 km, with greatest tension near the shallow zone resisting plate subduction. Plate sinking not only leads to compressional stresses at a locked interface thrust zone but may load compressional stresses at plate depths of 260–350 km, provided that the shallow sinking occurs faster than the relaxation time of the deeper mantle. This explains K. Mogi's observations of M ≥ 7 thrust earthquakes at depths of 260–350 km, immediately downdip and within 3 years prior to five great, shallow earthquakes of northern Japan. The slab pull model explains the lower layer of double seismic zones as due to tension from the deeper, sinking plate and the upper layer as due to localized in-plate compression, as plate motion is resisted by the bounding mantle. Just downdip of the interface thrust zone, there occurs an aseismic 20°–50° dip increase of subducted plate. This slab bend reflects the summed slab pull force of deeper plate and probably is at the crustal basalt to eclogite phase change. Resistance to subduction provided by a continually developing slab bend may be an important factor in the size of slab pull force delivered to an interface thrust zone.

Reviews of Geophysics↗
USGS2010

The Martian surface

The past four years have been particularly fruitful for Martian research as the enormous volumes of data collected during the Viking mission became readily available to the general science community, and as reformatting of the remote sensing data into cartographic products made the data more useable. The 1:5,000,000‐scale map series is complete, and 1:2,000,000‐scale controlled mosaics of the entire planet are nearing completion. In addition 1:500,000‐scale mosaics have been prepared of about thirty local areas. A uniform scale, digital imaging data base is in preparation (Batson, 1986), and the infrared data have been reformatted to make it more accessible to the general user (Martin and Kieffer, 1985).

Reviews of Geophysics↗
USGS2010

Coincident seismic reflection/refraction studies of the continental lithosphere: A global review.

Nearly 50 coincident seismic reflection/refraction studies to depths of at least the Moho provide an improved understanding of the continental lithosphere. Some conclusions include the following: (1) A transparent upper crust, a common observation on vertical reflection profiles, cannot generally be correlated with velocity gradients or low-velocity zones. Rather, a commonly transparent upper crust may be explained by short-wavelength, steeply dipping features in the brittle upper crust and to a lesser degree by signal contamination from source-generated noise. (2) The reflective lower crust in extensional terranes appears to be characterized by a high average seismic velocity (6.6–7.3 km/s) and to consist of laminated high- and low-velocity layers with typical thicknesses of 100–200 m. (3) Landward dipping reflectors observed in the middle to lower crusts of convergent zones have been identified as paired high- and low-velocity slabs which represent oceanic crust and mantle accreted via underplating to the continental margin. (4) The crust-mantle boundary may differ sufficiently when imaged with vertical incidence and wide-angle data to justify the retention, for the present, of the concept of separate reflection and refraction Mohos. While there is good evidence that these features are coincident within measurement uncertainties in most regions, recently recorded data from the Basin and Range admit the possibility for noncoincidence in that area. (5) Upper mantle reflections which cannot be migrated into the lower crust remain rare, despite isolated unequivocal examples. Thus the upper mantle appears to be relatively homogeneous at seismic reflection wavelengths and to lack the laminations inferred for the lower crust. The wide-angle method will likely provide the most reliable information on the velocity structure and physical state of this portion of the lithosphere for some years to come. (6) There appear to be clear and consistent basic differences between convergent and extensional terranes which have been identified from coincident experiments; these differences may be sufficiently universal to infer the tectonic history of poorly exposed terranes. (7) No truly three-dimensional coincident experiment (i.e., including three-dimensional migration) has been conducted, but some three-dimensional data have been collected using both methods. Measurements of attenuation, Poisson's ratio, and anisotropy within the crust using coincident data sets remain frontiers.

Reviews of Geophysics↗
USGS2010

Overview of geomagnetism and paleomagnetism, 1983–1986

Michael Fuller, author of a similar overview four years ago, concluded that “...the next quadrennium promises to be a most interesting one, with plenty to keep us busy.” The 11 review papers that follow support his prediction; research in geomagnetism and paleomagnetism indeed has flourished over the last four years. In this brief overview, I will attempt to summarize what I perceive as important advances during the last quadrennium and to predict where research might lead during the next four years. These observations are seen through the eyes of a very specialized geophysicist; another author undoubtedly would see the past and future much differently.

Reviews of Geophysics↗
USGS2010

Seismology of the continental crust and upper mantle

More seismological studies of the continental crust and sub‐crustal lithosphere of the United States have been completed in the past four years than at any other similar period, and a continued growth in activity is likely to continue for years to come. Several trends account for this phenomenon. First, the interest in seismic reflection studies generated initially by COCORP results in this country [ Brown and others , 1986], and later by the British BIRPS results [ Matthews and Gheadie , 1986], has led to the development of several other seismic reflection programs. Among the most active of these research programs are those of the University of Wyoming [ Smithson and others , 1986], Virginia Polytechnic Institute, CALCRUST [ Henyey , 1986], and the U.S. Geological Survey (USGS) [ Hamilton , 1986]. In Canada, the Lithoprobe program has achieved remarkable results in a variety of geographic locations [ Green et al. , 1986]. A second trend is the resurgence of interest in seismic‐refraction/wide‐angle reflection profiling. The year 1978 marked the beginning of this increased activity when several large projects were conducted in the western U.S., such as the Yellowstone‐Snake River Plain experiment organized by the University of Utah. Since 1979, a large amount of refraction/wide‐angle reflection data has been collected by the USGS and by university groups utilizing large numbers of state‐of‐the‐art industry seismographs in cooperative experiments. A third trend is the increased sophistication of other seismic methods such as teleseismic delay‐time methods, tomography, and receiver‐transfer functions. In these studies, permanent or temporary recording arrays have been used to determine local and regional crustal and upper‐mantle structure with impressive resolution.

Reviews of Geophysics↗
USGS2010

Earthquakes of the Holocene

Geologic studies of earthquakes involve mapping of coseismic surface faulting and secondary deformation from historical events, trenching and geomorphic analysis to define the timing and size of past earthquakes, and investigations of fault zone structure and geometry in both unconsolidated sediments and bedrock. This research is now being referred to as paleoseismology, seismic geology, and earthquake geology. Since the mid-1970s, it has led to some of the most exciting and important contributions to the understanding of earthquake behavior in space and time [Hanks, 1985; Allen, 1986]. The present report is the first of what is hoped will become a regularly contributed summary of the geologic aspects of the study of earthquakes.

Reviews of Geophysics↗
USGS2010

Rheology of the lithosphere: Selected topics

We review recent results concerning the rheology of the lithosphere with special attention to the following topics: 1) the flexure of the oceanic lithosphere, 2) deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins, 3) the rheological stratification of the continents, 4) strain localization and shear zone development, and 5) strain-induced crystallographic preferred orientations and anisotropies in body-wave velocities. We conclude with a section citing the 1983–1986 rock mechanics literature by category.

Reviews of Geophysics↗
USGS2010

Geologic nozzles

Sonic velocities of geologic fluids, such as volcanic magmas and geothermal fluids, can be as low as 1 m/s. Critical velocities in large rivers can be of the order of 1–10 m/s. Because velocities of fluids moving in these settings can exceed these characteristic velocities, sonic and supersonic gas flow and critical and supercritical shallow-water flow can occur. The importance of the low characteristic velocities of geologic fluids has not been widely recognized, and as a result, the importance of supercritical and supersonic flow in geological processes has generally been underestimated. The lateral blast at Mount St. Helens, Washington, propelled a gas heavily laden with dust into the atmosphere. Because of the low sound speed in this gas (about 100 m/s), the flow was internally supersonic. Old Faithful Geyser, Wyoming, is a converging-diverging nozzle in which liquid water refilling the conduit during the recharge cycle changes during eruption into a two-phase liquid-vapor mixture with a very low sound velocity. The high sound speed of liquid water determines the characteristics of harmonic tremor observed at the gyeser during the recharge interval, whereas the low sound speed of the liquid-vapor mixture influences the fluid flow characteristics of the eruption. At the rapids of the Colorado River in the Grand Canyon, Arizona, the channel is constricted into the shape of a converging-diverging nozzle by debris flows that enter from tributary canyons. Both subcritical and supercritical flow occur within the rapids. The transport capacity in the rapids can be so great that the river contours the channel to a characteristic shape. This shape can be used to interpret the flood history of the Colorado River over the past 10³–10 5 years. The unity of fluid mechanics in these three natural phenomena is provided by the well-known analogy between gas flow and shallow-water flow in converging-diverging nozzles.

Arizona, Washington, Wyoming↗
USGS2010

Gas transport in unsaturated porous media: The adequacy of Fick's law

The increasing use of natural unsaturated zones as repositories for landfills and disposal sites for hazardous wastes (chemical and radioactive) requires a greater understanding of transport processes in the unsaturated zone. For volatile constituents an important potential transport mechanism is gaseous diffusion. Diffusion, however, cannot be treated as an independent isolated transport mechanism. A complete understanding of multicomponent gas transport in porous media (unsaturated zones) requires a knowledge of Knudsen transport, the molecular and nonequimolar components of diffusive flux, and viscous (pressure driven) flux. The constitutive equations relating these flux components are available from the “dusty gas” model of Mason et al. (1967). This review presents a brief discussion of the underlying principles and interrelationships among each of the above flux mechanisms. Some aspects of these transport mechanisms are, to our knowledge, generally unrecognized in the Earth science literature. The principles underlying the transport mechanisms are illustrated with binary systems; the constitutive equations are then cast in forms thought to be most useful for the study of natural unsaturated zones. The viscous and diffusive fluxes are coupled in the constitutive equations through the Knudsen diffusivities; a knowledge of Knudsen diffusivities is necessary to calculate the viscous component of flux and pressure gradients. The Knudsen diffusivities can be calculated from measurements of the Klinkenberg effect. Two examples are presented showing that in natural systems, very small pressure gradients (1 Pa/m or less) can produce viscous fluxes greater than or equal to diffusive fluxes and that, conversely, pressure gradients of this magnitude can be generated by diffusive processes. The example calculations show that major concentration gradients can be developed for stagnant (zero flux, nonreactive) gases. A method is presented for approximating the viscous and diffusive flux components of gases in a multicomponent system from a knowledge of the concentration profiles of stagnant gases. In subsoil environments, argon and nitrogen are considered to be stagnant gases. Fick's laws are essentially, by definition, inadequate to deal with stagnant gases. In the examples presented, the error associated with estimating the total fluxes of nonstagnant gases by Fick's law, relative to stationary coordinates, ranges from a few percent to orders of magnitude.

Reviews of Geophysics↗
USGS1983

Petroleum potential of wilderness lands in the Western United States

In 1982-83, the U.S. Geological Survey (USGS) conducted an investigation of the oil and gas potential of the designated and proposed Wilderness Lands in the Western United States. The scope of this study was limited to the assessment of conventional recoverable petroleum resources occurring in the designated and proposed Wilderness Lands of the Western United States that are administered under four Federal agencies: Bureau of Land Management (BLM), U.S. Forest Service (USFS), National Park Service (NPS), and Fish and Wildlife Service (FWS). The total area of the study included approximately 74 million acres of Wilderness Lands in these 11 Western States: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. The 74 million acres represent 31 percent of the total Federal lands within these 11 Western States. Approximately 49 percent of all the lands in these States are federally owned. The objective of this study was to assemble through various means all the available pertinent information that could be brought together within the USGS and integrate these data into a computer-based digital cartographic data system that was focused upon the single issue of reviewing the known geological and geophysical data to determine the geologic characteristics favorable or unfavorable for the occurrence of petroleum resources in these Wilderness Lands. In a joint effort in the USGS between the Geologic Division (GD) and the National Mapping Division (NMD) all of the mappable information used in this study was prepared and processed by using digital cartographic techniques. These include digitizing the location and boundaries of the Wilderness Lands; acreage calculations; the boundaries of the USGS petroleum provinces; and the geologic and tectonic boundaries within each petroleum province and State. In addition, searches were conducted on well data files which provided the locations and geologic information on over 5,000 wells drilled within or immediately adjacent to the Wilderness Lands. An analysis of all the geologic characteristics favorable or unfavorable for petroleum occurrence in conjunction with the geologic settings for the Wilderness Lands scattered within the framework of the petroleum provinces was performed by a team of geologists on each of the wilderness tracts. The geologic characteristics reviewed for each tract included the presence or absence of the following: adequate source beds and reservoir rocks; adequate trapping mechanisms; favorable thermal and maturation histories; presence of petroleum seeps or adjacent wells with shows or production; and the presence of favorable sedimentary rock sections underlying volcanic terrane or faulted and overthrust areas. A description of the geology and geologic framework is provided for each State along with an explanation of the interpretative geology and evaluation of the petroleum potential within the locale of each of the wilderness tracts. The assessment of the petroleum resources on the Wilderness Lands was completed in two separate stages. In the first stage the geologists evaluated the geological characteristics for the favorability or lack of favorability for the occurrence of oil and natural gas within each wilderness tract and assigned a qualitative rating for each tract's potential for the occurrence of recoverable oil and gas resources. In the second stage in evaluating the petroleum potential for the wilderness tracts, an effort was made to arrive at a quantitative assessment within the framework of the USGS's latest published resource estimates which are made on a province basis. The geologic characteristics evaluated for the favorability of petroleum occurrence within each of the clusters of wilderness tracts were the determining factors for the subjective assessments of the petroleum potential for each wilderness tract occurring within the respective basin or province. The quantitative resource assessments are subjectively determined as to the richness and potential of the wilderness tracts relative to the total petroleum potential for the respective petroleum province within which they occur. The results of the qualitative analysis of the petroleum potential of the Wilderness Lands are tabulated by total acreages for each wilderness tract as classified by its potential rating. These tabulations are made for the Wilderness Lands by petroleum province, by State, and for the total Wilderness Lands in the 11 Western States. A summary is provided of the petroleum potential by acreage for all the Wilderness Lands in the Western United States by State and for the total 11 States. At least 34 percent of the total acreage for Wilderness Lands, or approximately 25 million acres, may have the geologic characteristics necessary for the occurrence of petroleum resources in varying amounts (high, medium, and low potential). An additional 33 percent of the Wilderness Lands may have some limited potential where small sedimentary areas are mixed within igneous and metamorphic terranes, but are more likely to fall in the low to zero potential. Finally, 33 percent of the Wilderness Lands probably have no petroleum potential because they are located in terranes with predominantly igneous and (or) metamorphic rocks that are unfavorable for the occurrence of petroleum. The quantitative petroleum assessments for the Wilderness Lands in the Western United States represent a part of the total estimate of the remaining undiscovered oil and natural gas for the 38 petroleum provinces, as defined by Dolton and others in USGS Circular 860 in 1981, within which the Wilderness Lands occur. The undiscovered recoverable oil for the Wilderness Lands in the Western States is estimated to range from 0.555 to 1.490 billion barrels with a mean estimate of 0.834 billion barrels. The undiscovered recoverable natural gas is estimated to range from 5.536 to 16.639 trillion cubic feet with a mean estimate of 9. 729 trillion cubic feet. Each range corresponds to the 95 and 5 percent probabilities of more than the respective amounts. The estimates reported at the 95 percent and 5 percent probabilities and the mean estimates for oil and gas are summarized for the separate States and the aggregated totals. A series of printed maps, one for each Western State, accompanies this report (Miscellaneous Investigations Series Maps I-1537-I-1547, in press) and shows in color the location and qualitative petroleum potential of the Wilderness Lands studied, with BLM identification of tracts; the boundary locations of all major Federal and Indian lands; the boundaries and identification of the USGS petroleum provinces; and other base information. A pamphlet will accompany each State map describing the geology of the State and the local geology relative to the position of the wilderness tracts and their petroleum potential. These maps were compiled by using traditional cartographic techniques from digitally produced graphics and are published as separate sheets for each State at a scale of 1:1,000,000.

Circular↗
USGS2007

MT+, integrating magnetotellurics to determine earth structure, physical state, and processes

As one of the few deep-earth imaging techniques, magnetotellurics provides information on both the structure and physical state of the crust and upper mantle. Magnetotellurics is sensitive to electrical conductivity, which varies within the earth by many orders of magnitude and is modified by a range of earth processes. As with all geophysical techniques, magnetotellurics has a non-unique inverse problem and has limitations in resolution and sensitivity. As such, an integrated approach, either via the joint interpretation of independent geophysical models, or through the simultaneous inversion of independent data sets is valuable, and at times essential to an accurate interpretation. Magnetotelluric data and models are increasingly integrated with geological, geophysical and geochemical information. This review considers recent studies that illustrate the ways in which such information is combined, from qualitative comparisons to statistical correlation studies to multi-property inversions. Also emphasized are the range of problems addressed by these integrated approaches, and their value in elucidating earth structure, physical state, and processes. ?? Springer Science+Business Media B.V. 2007.

Conference Paper↗
USGS1982

Mineral resource potential map of the Whitewater Wilderness Study Area, Riverside and San Bernardino counties, California

Geological, geochemical, and geophysical evidence, together with a 'review of historical mining and prospecting activities, suggests that most of the Whitewater Wilderness Study Area has low potential for all types of mineral and energy resources- including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. One small area in the southern part of the study area shows evidence of gold and silver mineralization, and this locality has a low to moderate potential for the discovery of low-grade gold and silver resources.

California↗
USGS1982

Mineral resource potential map of the Bighorn Mountains Wilderness Study Area (CDCA-217), San Bernardino County, California

Geological, geochemical, and geophysical evidence, together with a review of historical mining and prospecting activities, suggests that most of the Bighorn Mountains Wilderness Study Area has low potential for the discovery of all types of mineral and energy resources-including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. Low-grade mineralization has been documented in one small area near Rattlesnake Canyon, and this area has low to moderate potential for future small-scale exploration and development of precious and base metals. Thorium and uranium enrichment have been documented in two small areas in the eastern part of the wilderness study area; these two areas have low to moderate potential for future small-scale exploration and development of radioactive-mineral resources.

California↗
USGS2006

Abstracts of the Annual Meeting of Planetary Geologic Mappers, Nampa, Idaho 2006

Approximately 18 people attended this year's mappers meeting, and many more submitted abstracts and maps in absentia. The meeting was held on the campus of Northwest Nazarene University (NNU), and was graciously hosted by NNU's School of Health and Science. Planetary mapper Dr. Jim Zimbelman is an alumnus of NNU, and he was pivotal in organizing the meeting at this location. Oral and poster presentations were given on Friday, June 30. Drs. Bill Bonnichsen and Marty Godchaux led field excursions on July 1 and 2. USGS Astrogeology Team Chief Scientist Lisa Gaddis led the meeting with a brief discussion of the status of the planetary mapping program at USGS, and a more detailed description of the Lunar Mapping Program. She indicated that there is now a functioning website (http://astrogeology.usgs.gov/Projects/PlanetaryMapping/Lunar/) which shows which lunar quadrangles are available to be mapped. Like other USGS-published maps, proposals to complete a lunar geologic map must be submitted to the regular Planetary Geology & Geophysics (PGG) program for peer review. Jim Skinner (USGS) later presented the progress of the 1:2.5M-scale map of the lunar Copernicus quadrangle, and demonstrated the wide range of data that are available to support these maps. Gaddis and Skinner encouraged the community to submit proposals for generating lunar geologic maps, and reminded us that, as for all planetary maps, the project must be science-driven. Venus mapper Jim Zimbelman of the Smithsonian Institution (SI) presented the progress for his V-15 and V-16 quadrangles; Vicki Hansen (University of Minnesota Duluth) showed her preliminary work on V-45. Zimbelman addressed an issue that has been plaguing the community: 'delinquent Venus mappers'. In short, there were a number of Venus maps funded in the early 1990s under the Venus Data Analysis Program (VDAP). Unfortunately, funding for this program was cut before many Venus maps could be completed, resulting in about 10 Venus maps that were initially assigned but have shown little or no progress in many years. Zimbelman announced that he was not going to be able to complete quadrangle V-27 that he was assigned under VDAP, and was therefore returning that quadrangle to the community; he invited people to propose to PGG to map this quadrangle. Dave Williams of Arizona State University (ASU) reported on the progress of his global Io map. His mapping team recently received the completed, controlled global mosaic (using Voyager and Galileo images) from the USGS; this will be the basemap for their geologic mapping. Furthermore, the three team members (Laszlo Keszthelyi, David Crown and Dave Williams) have calibrated their individual mapping techniques by each mapping the same region for comparison. Thomas Doggett (ASU) showed progress on the global Europa map that was awarded to Ron Greeley. There was some consternation expressed on the methodology for determining relative ages of the lineaments; it was suggested that Vicki Hansen contact Patricio Figueredo (Exxon) directly, because Figueredo is the one who has been developing the lineament mapping techniques. Mars remains the most popular planet to map. Kevin Williams (SI) and Corey Fortezzo (SI) presented progress on their 1:500K maps in the Margaritifer Terra region of Mars. Jim Zimbelman described his 1:1M Medusae Fossae map, which is nearing completion. Peter Mouginis-Mark (University of Hawai'i) reported progress on his 1:200K maps of Tooting crater and of the Olympus Mons summit caldera. Jim Skinner discussed the progress of his and Ken Herkenhoff?s (USGS) map (1:500K) on the Olympia Cavi region of Mars? north pole, and Eric Kolb (USGS) presented work that he and Ken Tanaka (USGS) are completing on the Martian south pole. David Crown of the Planetary Science Institute (PSI) reported on numerous 1:500K and 1:1M maps in the Hellas and Hesperia regions of Mars. Frank Chuang (PSI) discussed progress on mapping the Deuteronilus Mensae reg

Open-File Report↗
USGS2018

The San Andreas Fault System--Complexities along a major transform fault system and relation to earthquake hazards

The San Andreas Fault System is a 1300-km-long transform boundary that accommodates motion between the North American and Pacific Plates. New technologies and data reveal rich details about the present configuration of faults, distribution of strain and associated seismic hazard on this complex network of faults. This contribution provides a brief summary of the geologic history of the San Andreas Fault System, followed by an introduction to recent research that has changed understanding of the hazards along the main faults. Organized by region, we highlight a selection of recent research using new geodetic techniques, improved topographic data, advanced geochronologic methods, and high-resolution geophysics. The contribution ends with a review of the historic earthquakes on the San Andreas and San Jacinto Faults, comparing these to past ruptures interpreted from paleoseismic studies.

California↗
USGS2024

Two-million-year eruptive history of Laguna del Maule volcanic field

The Laguna del Maule (LdM) volcanic field, which surrounds the 54-km 2 lake of that name, covers ∼500 km 2 of mountainous glaciated terrain with Quaternary lavas and tuffs that extend 40 km westward from the Argentine frontier and 30 km north-south from the Río Campanario to Laguna Fea. Complementing recent investigations of postglacial volcanism and the ongoing geophysical unrest around the lake, we here review the longer eruptive history that spanned the entire Quaternary.

Journal of South American Earth Sciences↗