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At least 541 records · Page 30Linked to original sources

USGS1998

North American landscape characterization project: The production of a continental scale three-decade Landsat data set

The North American Landscape Characterization (NALC) project is a component of the National Aeronautics and Space Administration (NASA) Landsat Pathfinder program. Pathfinder projects are focused on the investigation of global change utilizing current remote sensing technologies. The NALC project is a cooperative effort between the U. S. Environmental Protection Agency (EPA), the U.S. Geological Survey (USGS), and NASA to make Landsat data available to the widest possible user community for scientific research and general public interest. The NALC project is principally funded by the EPA Office of Research and Development and the USGS's Earth Resources Observation Systems (EROS) Data Center (EDC). The objectives of the NALC project are to produce standardized remote sensing data sets, develop standardized analysis methods, and derive standardized land cover change products for a large portion of the North American continent (the conterminous United States and Mexico) (Lunetta and Sturdevant, 1993). The standard product is the NALC “triplicate”;, consisting of co‐registered Landsat multispectral scanner data for the years 1973, 1986, and 1991 (plus or minus one year), plus co‐registered 3 arcsecond digital terrain elevation data. Processing began with the 1986 scene, which was precision corrected (with full terrain correction) to a 60 meter Universal Transverse Mercator base. Automated cross‐correlation procedures were used to co‐register the 1970's and 1990's data to the 1980's base, and independent verifications of registration quality were performed on all triplicate components. The pertinent metadata were compiled in a relational database, which includes WRS2 path/rows, scene ID's, image dates, solar azimuth and elevation, verification RMSE's, and the number of verification control points. NALC triplicate data sets are being used for a number of applications, including the analysis of urbanization patterns, dynamics of climatic fluctuations, deforestation studies, and vegetation classification and mapping. These data are being distributed through the Earth Observing System Data and Information System (EOSDIS) Information Management System (IMS) at a cost of $15(U.S.) for each triplicate.

Geocarto International↗

USGS2006

Natural history collections: A scientific treasure trove

Natural history collections play an indispensable and often overlooked role in the conservation and management of our Nation’s flora and fauna. Scientific specimens housed in museum collections not only open an important window into the current and past diversity of life on Earth, but also play a vital role in fueling cutting-edge scientific research in many disciplines. The U.S. Geological Survey (USGS) Fort Collins Science Center (FORT) curates a collection of vertebrates from the Intermountain and Southwestern United States that is used by researchers from around the globe. As one of the largest Federal natural history collections in the western United States, the USGS specimen holdings offer unique opportunities to study the fauna of this incredibly diverse and unique region.

Fact Sheet↗

USGS1998

Catalog of the historically active volcanoes of Alaska

Alaska hosts within its borders over 80 major volcanic centers that have erupted during Holocene time (< 10,000 years). At least 29 of these volcanic centers (table 1) had historical eruptions and 12 additional volcanic centers may have had historical eruptions. Historical in Alaska generally means the period since 1760 when explorers, travelers, and inhabitants kept written records. These 41 volcanic centers have been the source for >265 eruptions reported from Alaska volcanoes. With the exception of Wrangell volcano, all the centers are in, or near, the Aleutian volcanic arc, which extends 2500 km from Hayes volcano 145 km west of Anchorage in the Alaska-Aleutian Range to Buldir Island in the western Aleutian Islands (fig. 1). The volcanic arc, a subduction-related feature associated with underthrusting of the Pacific plate beneath the North American plate is divided between oceanic island arc and continental margin segments, the boundary occurring at about 165° W longitude (fig. 1). An additional 7 volcanic centers in the Aleutian arc (table 2; fig. 1 A) have active fumarole fields but no reported historical eruptions. This report discusses the location, physiography and structure, eruptive history, and geology of those volcanoes in Alaska that have experienced one or more eruptions that have been recorded in the written history (i.e., in historical time). It is part of the group of catalogs entitled Catalogue of Active Volcanoes of the World published beginning in 1951 under the auspices of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI). A knowledge of the information contained in such catalogs aids in understanding the type and scale of activity that might be expected during a particular eruption, the hazards the eruption may pose, and even the prediction of eruptions. The catalog will thus be of value not only to the inhabitants of Alaska but to government agencies concerned with emergency response, air traffic operations, and weather, as well as to industry and scientists. The combination of the hazard posed by volcanic ash to jet aircraft and the heavy use of international air routes located parallel to, and on either side of, the Aleutian volcanic arc means that even remote volcanoes in Alaska now pose significant hazards to life and property. Although this report is concerned with historical eruptions from Alaskan volcanoes, other volcanoes in Alaska have erupted in the past 10,000 years and might therefore be expected to erupt again. Several Holocene volcanic centers in the Aleutian arc have no reported historical activity. Elsewhere in Alaska the Bering Sea basalt fields cover large areas of the Yukon Delta, Seward Peninsula, and several of the islands of the Bering Sea. Holocene centers also occur in the Wrangell Mountains and in isolated occurrences in the interior and southeastern Alaska. Eruptions from these centers have occurred within the past several hundred years but none were transcribed in the written record. Moodie and others (1992), however, report oral traditions among the Northern Athapaskan Indians of the southwestern Yukon Territory that may record the second and younger deposition of the White River Ash circa A.D. 720. This lobe of the White River Ash was deposited during the paroxysmal eruption of Churchill volcano in the Wrangell Mountains of eastcentral Alaska (McGimsey and others, 1992; Richter and others, 1995).

Alaska↗

USGS2007

Mineral resource of the month: industrial sand and gravel

With many diverse uses, industrial sand and gravel, also known as silica sand, is one of the most important nonmetallic minerals in the world. Industrial sand and gravel is a mining industry term used for sands that have a very high percentage of silicon dioxide, or greater than 95 percent quartz. Deposits of industrial sand and gravel can be found virtually everywhere on Earth, but are less widespread than deposits of common construction sand and gravel. Industrial sand and gravel is distinctive in grain size, hardness, inertness and resistance to high temperature and chemical action. Beverage containers, fiberglass insulation, fiber-optic cables and light bulbs are just some of today’s many products produced from industrial sand and gravel.

Geotimes↗

USGS2018

Euler-vector clustering of GPS velocities defines microplate geometry in southwest Japan

I have used Euler-vector clustering to assign 469 GEONET stations in southwest Japan to k clusters ( k = 2, 3,..., 9) so that, for any k , the velocities of stations within each cluster are most consistent with rigid-block motion on a sphere. That is, I attempt to explain the raw (i.e., uncorrected for strain accumulation), 1996–2006 velocities of those 469 Global Positioning System stations by rigid motion of k clusters on the surface of a spherical Earth. Because block geometry is maintained as strain accumulates, Euler-vector clustering may better approximate the block geometry than the values of the associated Euler vectors. The microplate solution for each k is constructed by merging contiguous clusters that have closely similar Euler vectors. The best solution consists of three microplates arranged along the Nankaido Trough-Ryukyu Trench between the Amurian and Philippine Sea Plates. One of these microplates, the South Kyushu Microplate (an extension of the Ryukyu forearc into the southeast corner of Kyushu), had previously been identified from paleomagnetic rotations. Relative to ITRF2000 the three microplates rotate at different rates about neighboring poles located close to the northwest corner of Shikoku. The microplate model is identical to that proposed in the block model of Wallace et al. (2009, https://doi.org/10.1130/G2522A.1) except in southernmost Kyushu. On Shikoku and Honshu, but not Kyushu, the microplate model is consistent with that proposed in the block models of Nishimura and Hashimoto (2006, https://doi.org/10.1016/j.tecto.2006.04.017) and Loveless and Meade (2010, https://doi.org/10.1029/2008JB006248) without the low-slip-rate boundaries proposed in the latter.

southwest Japan↗

USGS2010

The sedimentology and dynamics of crater-affiliated wind streaks in western Arabia Terra, Mars and Patagonia, Argentina

Wind streaks comprise recent aeolian deposits that have been extensively documented on Venus, Earth and Mars. Martian wind streaks are among the most abundant surface features on the planet and commonly extend from the downwind margins of impact craters. Previous studies of wind streaks emerging from crater interior deposits suggested that the mode of emplacement was primarily related to the deposition of silt-sized particles as these settled from plumes. We have performed geologic investigations of two wind streaks clusters; one situated in western Arabia Terra, a region in the northern hemisphere of Mars, and another in an analogous terrestrial site located in southern Patagonia, Argentina, where occurrences of wind streaks emanate from playas within maar craters. In both these regions we have identified bedforms in sedimentary deposits on crater floors, along wind-facing interior crater margins, and along wind streaks. These observations indicate that these deposits contain sand-sized particles and that sediment migration has occurred via saltation from crater interior deposits to wind streaks. In Arabia Terra and in Patagonia wind streaks initiate from crater floors that contain lithic and evaporitic sedimentary deposits, suggesting that the composition of wind streak source materials has played an important role in development. Spatial and topographic analyses suggest that regional clustering of wind streaks in the studied regions directly correlates to the areal density of craters with interior deposits, the degree of proximity of these deposits, and the craters' rim-to-floor depths. In addition, some (but not all) wind streaks within the studied clusters have propagated at comparable yearly (Earth years) rates. Extensive saltation is inferred to have been involved in its propagation based on the studied terrestrial wind streak that shows ripples and dunes on its surface and the Martian counterpart changes orientation toward the downslope direction where it extends into an impact crater. ?? 2009 Elsevier B.V.

Geomorphology↗

USGS1998

Evolution of cutoffs across meander necks in Powder River, Montana, USA

Over a period of several decades, gullies have been observed in various stages of forming, growing and completing the cutoff of meander necks in Powder River. During one episode of overbank flow, water flowing over the down-stream bank of the neck forms a headctu. The headcut migrates up-valley, forming a gully in its wake, until it has traversed the entire neck, cutting off the meander. The river then follows the course of the gully, which is subsequently enlarged as the river develops its new channel. The complete process usually requires several episodes of high water: in only one of the five cases described herein was a meander cutoff initiated and completed during a single large flood.

Earth Surface Processes and Landforms↗

USGS2017

Influence of pore pressure change on coseismic volumetric strain

Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

Earth and Planetary Science Letters↗

USGS1997

Debris-flow mobilization from landslides

Field observations, laboratory experiments, and theoretical analyses indicate that landslides mobilize to form debris flows by three processes: ( a ) widespread Coulomb failure within a sloping soil, rock, or sediment mass, ( b ) partial or complete liquefaction of the mass by high pore-fluid pressures, and ( c ) conversion of landslide translational energy to internal vibrational energy (i.e. granular temperature). These processes can operate independently, but in many circumstances they appear to operate simultaneously and synergistically. Early work on debris-flow mobilization described a similar interplay of processes but relied on mechanical models in which debris behavior was assumed to be fixed and governed by a Bingham or Bagnold rheology. In contrast, this review emphasizes models in which debris behavior evolves in response to changing pore pressures and granular temperatures. One-dimensional infinite-slope models provide insight by quantifying how pore pressures and granular temperatures can influence the transition from Coulomb failure to liquefaction. Analyses of multidimensional experiments reveal complications ignored in one-dimensional models and demonstrate that debris-flow mobilization may occur by at least two distinct modes in the field.

Annual Review of Earth and Planetary Sciences↗

USGS2005

Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index Composites

The Advanced Very High Resolution Radiometer (AVHRR) is a broad-band scanner with four to six bands, depending on the model. The AVHRR senses in the visible, near-, middle-, and thermal- infrared portions of the electromagnetic spectrum. This sensor is carried on a series of National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES), beginning with the Television InfraRed Observation Satellite (TIROS-N) in 1978. Since 1989, the United States Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) has been mapping the vegetation condition of the United States and Alaska using satellite information from the AVHRR sensor. The vegetation condition composites, more commonly called greenness maps, are produced every week using the latest information on the growth and condition of the vegetation. One of the most important aspects of USGS greenness mapping is the historical archive of information dating back to 1989. This historical stretch of information has allowed the USGS to determine a 'normal' vegetation condition. As a result, it is possible to compare the current week's vegetation condition with normal vegetation conditions. An above normal condition could indicate wetter or warmer than normal conditions, while a below normal condition could indicate colder or dryer than normal conditions. The interpretation of departure from normal will depend on the season and geography of a region.

Fact Sheet↗

USGS2024

Assessing influence from wastewater treatment facilities on Glorieta Creek and the Pecos River within Pecos National Historical Park, New Mexico, February–October 2022

The Pecos National Historical Park protects 2.9 miles of the Pecos River and part of Glorieta Creek within the park boundaries. Updated water-quality data can assist resource managers in determining if effluent from two nearby wastewater treatment plants (WWTPs) is affecting the quality of the water in the Pecos River and Glorieta Creek within the park. Water samples were collected four times in 2022 at two WWTP outfalls, two locations on Glorieta Creek, and two locations on the Pecos River. Water quality parameters (dissolved oxygen, water temperature, pH, turbidity, specific conductance) were measured in the field, and samples were collected and analyzed for major ions, trace elements, rare earth elements, nutrients, bacteria, and per- and polyfluoroalkyl substances (PFAS). Specific conductance values in all samples collected from Glorieta Creek exceeded the New Mexico Surface Water Quality Standard (NMWQS) of 300 microsiemens per centimeter at 25 degrees Celsius. Concentrations of dissolved oxygen in three samples collected from Glorieta Creek and one sample for the Pecos WWTP did not meet the standard for high-quality cold-water use. Concentrations of Escherichia coli in samples from the Pecos WWTP exceeded the NMWQS of 235 colony-forming units per 100 milliliters during every sampling event. Concentrations of E. coli in samples collected from two sites on Glorieta Creek in August exceeded the NMWQS. The chemical signature of water from Glorieta Creek indicated groundwater and (or) septic system contributions. Water samples collected from the Pecos River all had similar chemical signatures of calcium-bicarbonate type. Although concentrations of several trace elements were higher in samples from Glorieta Creek than in samples from the Pecos River, no concentrations exceeded the drinking-water standards. No concentrations exceeded aquatic life standards except for copper concentrations in two samples from the downstream location on Glorieta Creek. The trace element signature and the gadolinium anomalies in the WWTP samples indicate anthropogenic contributions. Eleven of the 28 PFAS compounds analyzed were detected in samples during this study, with the treated wastewater effluent samples having the highest total PFAS concentrations. The total PFAS concentrations in samples from Glorieta Creek decreased by an order of magnitude as the creek flowed downstream. At the downstream site on the Pecos River, there was only one sample that had a detection of PFAS.

New Mexico↗

USGS2000

Milestones in Antarctic Ice Sheet history: Preliminary results from Leg 188 drilling in Prydz Bay Antarctica

The Antarctic Ice Sheet is one of the great features of our planet. It plays a pivotal role in global atmospheric circulation and the sea-ice zone around it produces cold waters that control much of the ocean’s deep circulation. The Antarctic Ice Sheet is also the largest store of fresh water on earth and controls short-term sea level changes. The history of the Antarctic Ice Sheet has been pieced together from various sources. For the late Quaternary, ice cores contain a detailed record of accumulation, air temperature and atmospheric composition. For the Cenozoic, information has come from distal marine oxygen isotope records, records of detrital output from the continent and fragmentary outcrops in ice-free areas on the continent. These records have been augmented by drilling on the Antarctic continental margin to try and recover direct evidence of glacial ice and to investigatethe transition from pre-glacial to the full polar glacial conditions that we see today.

JOIDES Journal↗

USGS1988

The formation and failure of natural dams

Of the numerous kinds of dams that form by natural processes, dams formed from landslides, glacial ice, and late-neoglacial moraines present the greatest threat to people and property. Landslide dams form in a wide range of physiographic settings. The most common types of mass movements that form landslide dams are rock and debris avalanches; rock and soil slumps and slides; and mud, debris, and earth flows. The most common initiation mechanisms for dam-forming landslides are excessive rainfall and snowmelt and earthquakes. Landslide dams can be classified into six categories based on their relation with the valley floor. Type I dams (11% of 184 landslide dams from around the world that we were able to classify) do not reach from one valley side to the other. Type II dams (44%) span the entire valley floor, in some cases depositing material high on opposite valley sides. Type III dams (41%) move considerable distances both upstream and downstream from the landslide failure. Type IV dams (<1%) are rare and involve the contemporaneous failure of material from both sides of a valley. Type V dams (<1%) also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river. Type VI dams (3%) involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side. Many landslide dams fail shortly after formation. In our sample of 73 documented landslide-dam failures, 27% of the landslide dams failed less than 1 day after formation, and about 50% failed within 10 days. Over-topping is by far the most common cause of failure. The timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry; material characteristics of the blockage; rate of inflow to the impoundment; size and depth of the impoundment; bedrock control of flow; and engineering controls such as artificial spill-ways, diversions, tunnels, and planned breaching by blasting or conventional excavation. Glacial-ice dams can produce at least nine kinds of ice-dammed lakes. The most dangerous are lakes formed in main valleys dammed by tributary glaciers. Failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam. Cold polar-ice dams generally drain supraglacially or marginally by downmelting of an outlet channel. Warmer, temperate-ice dams tend to fail by sudden englacial or subglacial breaching and drainage. Late-neoglacial moraine-dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries. These late-neoglacial dams pose hazards because (1) they are sufficiently young that vegetation has not stabilized their slopes, (2) many dam faces are steeper than the angle of repose, (3) these dams and lakes are immediately downslope from steep crevassed glaciers and near-vertical rock slopes, and (4) downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks. The most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls, rockfalls, or snow or rock avalanches. Melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms. Natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam. Although data are few, for the same potential energy at the dam site, ownstream flood peaks from the failure of glacier-ice dams are smaller than those from landslide, moraine, and structed earth-fill and rock-fill dam failures. Moraine-dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 10 11 -10 12 joules. Differences in flood peaks natural-dam failures appear to be controlled by dam characteristics and failure mechanisms.

Geological Society of America Bulletin↗

USGS2022

gTOOLS, an open-source MATLAB program for processing high precision, relative gravity data for time-lapse gravity monitoring

gTOOLS is an open-source software for the processing of relative gravity data. gTOOLS is available in MATLAB and as a compiled executable to be run under the free MATLAB Runtime Compiler. The software has been designed for time-lapse (temporal) gravity monitoring. Although programmed to read the Scintrex CG-5 and CG-6 gravimeters output data files, it can be easily modified to read data files from other gravimeters. The software binds together single-task processing modules within a very simple user interface that is based on one text file. Gravity processing involves three modules: (a) gravimeter calibration; (b) automatic processing of gravity data to find adjusted gravity differences; and (c) post processing of results. Each module is optional and runs independently from the others. Data processing includes (a) averaging out the measurements noise, and correction for solid Earth tides, and ocean loading, and residual instrumental drift, and (b) calculate the residual instrumental drift and gravity differences between the base station and monitoring sites, and their uncertainties, by a weighted least square analysis of the gravity data. The software allows the automatic processing of a gravity campaign spanning multiple days in a single run. The software is tested on gravity data from 2015 eruption at Cotopaxi volcano, Ecuador.

Computers & Geosciences↗

USGS2007

Postseismic relaxation associated with transient creep rheology

[1] Perfettini and Avouac (2004) postulated that both the aftershock rate (assumed proportional to the local stressing rate) and the postseismic relaxation are driven by the loading imposed by postseismic slip on the brittle creep fault zone (BCFZ), the downdip extension of the fault zone below the coseismic rupture. I explore the consequences of that hypothesis for a long, strike-slip fault in the case where the BCFZ rheology is compatible with ordinary transient creep (creep strain proportional to log e (1 + t / τ 2 )). Because the important relaxation occurs near the bottom of the coseismic rupture, I calculate the postearthquake response with a model in which the BCFZ is represented by a viscoelastic half-space below the coseismic rupture. I find that both the predicted postseismic relaxation and the cumulative number of aftershocks can be approximated by the same temporal dependence N MO ( t ) = a MO (1−(1 + t / τ ) 1− p )/( p − 1), where t is the time after the earthquake and a MO , τ , and p are the constants chosen to fit either data set. Notice that d N MO ( t )/d t = ( a MO / τ )/(1 + t / τ ) p is the modified Omori law used to describe the rate of aftershock occurrence. Thus, the modified Omori law can be understood as a consequence of the Perfettini–Avouac hypothesis (aftershocks driven by slip on the BCFZ) and a BCFZ rheology compatible with ordinary transient creep. Moreover, the temporal dependence N MO ( t ) has been shown to fit postseismic surface deformation following at least 9 earthquakes. I also show that the conventional, one-dimensional, spring-block model of a BFCZ with a rheology compatible with ordinary transient creep leads to the same temporal dependence ( N MO ( t )).

Journal of Geophysical Research B: Solid Earth↗

USGS2020

Automated location correction and spot height generation for named summits in the coterminous United States

Spot elevations published on historical U.S. Geological Survey topographic maps were established as needed to enhance information imparted by the quadrangle’s contours. In addition to other features, labels were routinely placed on mountain summits. While some elevations were established through field survey triangulation, many were computed during photogrammetric stereo-compilation. Today, Global Navigation Satellite System (GNSS) receivers have replaced expensive triangulation methods. However, since GNSS measurements require visiting the feature location, a national dataset containing high-accuracy spot elevations has not yet been created. Consequently, modern U.S. Topo maps are devoid of mountain peak or other spot elevations. Still, topographic map users continue to demand the display of spot heights. Therefore, a pilot study was conducted to evaluate the feasibility of automatically generating elevation values at named U.S. summits using available elevation data. The devised method uses an uphill stepping technique to find the most likely highest point in subsequently higher-resolution elevation models. Resulting elevation values are compared to other published sources. Results from 196 summits indicate that values derived from lidar are generally higher, whereas those populated from the one-third arc-second USGS Seamless 3DEP elevation dataset are generally lower. A thorough understanding of these relationships require the evaluation of more points.

International Journal of Digital Earth↗

USGS2023

Quantification of geodetic strain rate uncertainties and implications for seismic hazard estimates

Geodetic velocity data provide first-order constraints on crustal surface strain rates, which in turn are linked to seismic hazard. Estimating the 2-D surface strain tensor everywhere requires knowledge of the surface velocity field everywhere, while geodetic data such as Global Navigation Satellite System (GNSS) only have spatially scattered measurements on the surface of the Earth. To use these data to estimate strain rates, some type of interpolation is required. In this study, we review methodologies for strain rate estimation and compare a suite of methods, including a new implementation based on the geostatistical method of kriging, to compare variation between methods with uncertainty based on one method. We estimate the velocity field and calculate strain rates in southern California using a GNSS velocity field and five different interpolation methods to understand the sources of variability in inferred strain rates. Uncertainty related to data noise and station spacing (aleatoric uncertainty) is minimal where station spacing is dense and maximum far from observations. Differences between methods, related to epistemic uncertainty, are usually highest in areas of high strain rate due to differences in how gradients in the velocity field are handled by different interpolation methods. Parameter choices, unsurprisingly, have a strong influence on strain rate field, and we propose the traditional L -curve approach as one method for quantifying the inherent trade-off between fit to the data and models that are reflective of tectonic strain rates. Doing so, we find total variability between five representative strain rate models to be roughly 40 per cent, a much lower value than roughly 100 per cent that was found in previous studies (Hearn et al .). Using multiple methods to tune parameters and calculate strain rates provides a better understanding of the range of acceptable models for a given velocity field. Finally, we present an open-source Python package (Materna et al .) for calculating strain rates, Strain_2D, which allows for the same data and model grid to be used in multiple strain rate methods, can be extended with other methods from the community, and provides an interface for comparing strain rate models, calculating statistics and estimating strain rate uncertainty for a given GNSS data set.

Geophysical Journal International↗

USGS2009

Floods of water and lava in the Columbia River Basin: Analogs for Mars

The Columbia River Basin (CRB) is home to the best studied examples of two of the most spectacular geologic processes on Earth and Mars: flood volcanism and catastrophic water floods. Additionally, features formed by a variety of eolian, glacial, tectonic, and mass-wasting processes can also be seen in the CRB. These terrains provide exceptional terrestrial analogs for the study of similar processes on Mars. This field guide describes four one-day trips out of Moses Lake, Washington, to observe a wide variety of Mars analogs.

Oregon, Washington↗