Lava Flow Surfaces Research Articles

Paving the seafloor: Volcanic emplacement processes during the 2005–2006 eruptions at the fast spreading East Pacific Rise, 9°50′N

The 2005–2006 eruptions near 9°50′N at the East Pacific Rise (EPR) marked the first observed repeat eruption at a mid‐ocean ridge and provided a unique opportunity to deduce the emplacement dynamics of submarine lava flows. Since these new flows were documented in April 2006, a total of 40 deep‐towed imaging surveys have been conducted with the Woods Hole Oceanographic Institution's (WHOI) TowCam system. More than 60,000 digital color images and high‐resolution bathymetric profiles of the 2005–2006 flows from the TowCam surveys were analyzed for lava flow morphology and for the presence of kipukas, collapse features, faults and fissures. We use these data to quantify the spatial distributions of lava flow surface morphologies and to investigate how they relate to the physical characteristics of the ridge crest, such as seafloor slope, and inferred dynamics of flow emplacement. We conclude that lava effusion rate was the dominant factor controlling the observed morphological variations in the 2005–2006 flows. We also show that effusion rates were higher than in previously studied eruptions at this site and varied systematically along the length of the eruptive fissure. This is the first well‐documented study in which variations in seafloor lava morphology can be directly related to a well documented ridge‐crest eruption where effusion rate varied significantly.

Cooling rate of some active lavas determined using an orbital imaging spectrometer

The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from Earth orbit. This paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by NASA's Earth Observing‐1 Hyperion imaging spectrometer. The contiguous nature of the measured radiance spectrum in the 0.4–2.5 μm region means that, although sensor saturation most certainly occurs, unsaturated radiance data are always available from even the hottest, and most radiant, active lava flow surfaces. The increased number of wave bands available allows for the assumption of more complex flow surface temperature distributions in the radiance‐to‐temperature inversion processes. The technique is illustrated by using a hyperspectral image of the active lava lake at Erta Ale volcano, Ethiopia, a well‐characterized calibration target, a time series of three Hyperion images of an active lava flow acquired during a 4 day period at Mount Etna, Sicily, as well as a lava flow erupted at Nyamuragira, Democratic Republic of Congo. The results provide insights into the temperature–radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions, such as NASA's proposed HyspIRI mission.

Variolitic lavas in the axial rift of the Mid-Atlantic Ridge and their origin (Sierra Leone area, 6°18′N)

Altered variolites described for the first time in the axial zone of the MidAtlantic Ridge are repre� sented by rounded globules of andesite (icelandite) composition with light trachyandesite rim embedded in a picrobasaltic matrix. The globules were transferred with picrobasaltic melt and then floated to the surface of lava flow, while formation of leucocratic rims was presumably related to thermodiffusion (Soret effect) in a cooling heterogeneous melt. This heterogeneous melt was formed by penetration of ascending column of picrobasaltic magma in already existing small intracructsal magmatic chamber filled with residual icelandite� type andesite melt and involvement of the latter into a general upward movement. The rapid ascent of the melts in the oceanic spreading zones by means of turbulent flowing caused dispersion of the extragenous melt into small drops in a jet of picrobasaltic magma, without their interaction. Variolites were formed during cool� ing of such heterogeneous lava flow. No signs of liquid immiscibility were found in the studied variolites.

Silica in a Mars analog environment: Ka'u Desert, Kilauea Volcano, Hawaii

Airborne Visible/Near‐Infrared Imaging Spectrometer (AVIRIS) data acquired over the Ka'u Desert are atmospherically corrected to ground reflectance and used to identify the mineralogic components of relatively young basaltic materials, including 250–700 and 200–400 year old lava flows, 1971 and 1974 flows, ash deposits, and solfatara incrustations. To provide context, a geologic surface units map is constructed, verified with field observations, and supported by laboratory analyses. AVIRIS spectral end‐members are identified in the visible (0.4 to 1.2 μm) and short wave infrared (2.0 to 2.5 μm) wavelength ranges. Nearly all the spectral variability is controlled by the presence of ferrous and ferric iron in such minerals as pyroxene, olivine, hematite, goethite, and poorly crystalline iron oxides or glass. A broad, nearly ubiquitous absorption feature centered at 2.25 μm is attributed to opaline (amorphous, hydrated) silica and is found to correlate spatially with mapped geologic surface units. Laboratory analyses show the silica to be consistently present as a deposited phase, including incrustations downwind from solfatara vents, cementing agent for ash duricrusts, and thin coatings on the youngest lava flow surfaces. A second, Ti‐rich upper coating on young flows also influences spectral behavior. This study demonstrates that secondary silica is mobile in the Ka'u Desert on a variety of time scales and spatial domains. The investigation from remote, field, and laboratory perspectives also mimics exploration of Mars using orbital and landed missions, with important implications for spectral characterization of coated basalts and formation of opaline silica in arid, acidic alteration environments.

Rugged lava flows on the Moon revealed by Earth‐based radar

Basaltic volcanism is widespread on the lunar nearside, and returned samples suggest that the mare‐forming magmas had low viscosity that led to primarily sheet‐like deposits. New 70‐cm wavelength radar observations that probe several meters beneath the lunar surface reveal differences in mare backscatter properties not explained by age or compositional variations. We interpret areas of high backscatter and high circular polarization ratio in Maria Serenitatis, Imbrium, and Crisium as having an enhanced abundance of decimeter‐scale subsurface rocks relative to typical mare‐forming flows. The 3.5 b.y survival of these differences implies an initial platy, blocky, or ridged lava flow surface layer with thickness of at least 3–5 m. Such rugged morphology might arise from episodic changes in magma effusion rate, as observed for disrupted flood basalt surfaces on the Earth and Mars, very high flow velocities, or increased viscosity due to a number of factors. Significant information on lunar mare eruption conditions may thus be obtained from long‐wavelength radar probing of the shallow subsurface.

New and revised 14C dates for Hawaiian surface lava flows: Paleomagnetic and geomagnetic implications

Radiocarbon dates have been obtained for 30 charcoal samples corresponding to 27 surface lava flows from the Mauna Loa and Kilauea volcanoes on the Island of Hawaii. The submitted charcoal was a mixture of fresh and archived material. Preparation and analysis was undertaken at the NERC Radiocarbon Laboratory in Glasgow, Scotland, and the associated SUERC Accelerator Mass Spectrometry facility. The resulting dates range from 390 years B.P. to 12,910 years B.P. with corresponding error bars an order of magnitude smaller than previously obtained using the gas‐counting method. The new and revised 14C data set can aid hazard and risk assessment on the island. The data presented here also have implications for geomagnetic modelling, which at present is limited by large dating errors.

Variable effects of cinder-cone eruptions on prehistoric agrarian human populations in the American southwest

Two ∼ 900 BP cinder-cone eruptions in the American Southwest affected prehistoric human populations in different ways, mostly because of differences in the eruption styles and area affected. Primary pre-eruption cultural factors that may have led to successful adaptation to the eruptions include decision-making at the family or household level, low investment in site structures, dispersion of agricultural sites in varied environments, and settlement spread over a large area so that those who were less affected could shelter and feed evacuees. Sunset Crater, near Flagstaff, Arizona, produced about 8 km 2 lava flow fields and a ∼ 2300-km 2 tephra blanket in an area that had been settled by prehistoric groups for at least 1000 years. Local subsistence relied on agriculture, primarily maize, and > 30 cm tephra cover rendered 265 km 2 of prime land unfarmable. This area was apparently abandoned for at least several generations. A > 500-km 2 area was probably marked by collapsed roofs and other structural damage from the fallout. If the eruption occurred during the agricultural season, the fallout would also have significantly damaged crops. The eruption did have some benefits to local groups because lower elevation land, which had previously been too dry to farm, became agriculturally productive due to 3–8 cm of tephra ‘mulch’ and some temporary soil nutrient improvements. This previously uninhabited land became the site of significant year-round settlement and farming, eventually containing some of the largest pueblo structures ever built in the region. New agricultural techniques were developed to manage the fallout mulch. The eruption also affected ceramic production and trading patterns, and volcano-related ritual behavior – the production of maize-impressed lava-spatter agglutinate – was initiated. Little Springs Volcano, about 200 km northwest of Sunset Crater, is a small spatter rampart around a series of vents that produced about 5 km 2 of lava flow fields, about 1 km 2 of land severely affected by ballistic fall, and no significant tephra fall. The small area affected resulted in much less disruption of human activities than at Sunset Crater. Farming was still possible right up to the edge of the lava flows, which became attractive sites for settlements. Most sites along the lava flows have habitation and storage structures at the base of the flow and a series of small, apparently little-used, structures on the blocky lava flow above. These lava surface structures may have been defensive in nature. In addition, trails were constructed on the blocky lava flow surface. These trails, whose access points are difficult to recognize from below, appear to have been used for rapid movement across the flows, and may also have been defensive in nature. Spatter-agglutinate blocks containing ceramic sherds within them, similar to the maize-impressed spatter agglutinate at Sunset Crater, were made at Little Springs and carried to a nearby habitation site. In arid and semiarid lands such as northern Arizona, tephra fall is a mixed blessing. Thick cinder blankets (> 20–30 cm) render land uninhabitable, but thinner (3–8 cm) deposits can serve to conserve soil moisture, regulate soil temperature (thus lengthening the growing season), and, by lowering soil pH, provide a temporary (decades to a century or two) increase in available phosphorus, an important nutrient for growth. The mulch opened up new lands for settlement but likely only lasted for a century or two before reworking reduced its effects.

An alternative isochron method for measuring cosmogenic 3He in lava flows

This study evaluates an alternative isochron method designed to improve the precision and the accuracy of the measurement of cosmogenic 3He ( 3He c) and the calibration of 3He c production rates in lava flows. While the accuracy of the standard two-steps routine ((i) crushing, (ii) melting) may be affected by possible crushing-induced release of matrix-sited 3He c, this new isochron technique does not involve the preliminary crushing step. Such advance is thus potentially able to improve the accuracy of 3He c determination. Moreover this method has the advantage to yield cosmogenic 3He concentrations using only one type of extraction technique. Cosmogenic 3He isochrons can be built successfully measuring the 3He and 4He concentrations of several phenocrysts replicates fused in vacuo, provided that these aliquots have identical magmatic 3He/ 4He ratios, identical 3He c concentrations and variable magmatic helium contents. When plotted in the 3He/ 4He vs 1/ 4He space, such a suite of data define a straight line whose intercept yield the magmatic ( 3He/ 4He) mag ratio, and whose slope is the cosmogenic 3He concentration. The frequent addition of radiogenic 4He ( 4He ⁎) may be easily accounted taking advantage of a property that is characteristic of non-eroded lava flows: the 3He c/ 4He ⁎ ratio is not time-dependent. This radiogenic correction of the isochron slope involves the R-factor, whose calculation requires that the U and Th abundances in the phenocrysts and the host lava be known, as well as the diameter and the shape of the analyzed minerals. This correction also requires that all the analyzed aliquots have identical radiogenic 4He concentration. The isochron method was tested on surface samples of three Quaternary basalt flows from Mount Etna and Mauna Loa (aged of 6 ±1, 8.2 ± 0.1 and 41 ± 3 ka). The obtained data set yielded statistically robust isochrons and cosmogenic 3He concentrations that are not significantly different from those obtained with the standard method. Importantly, for samples with high magmatic/cosmogenic 3He ratio, the isochron technique offers both better accuracy and precision than the standard two-steps method. This alternative technique should thus open new perspectives for the particularly important task of 3He c production rate calibrations from lava flow surfaces.

Microwave palaeointensities from Holocene age Hawaiian lavas: Investigation of magnetic properties and comparison with thermal palaeointensities

Sixteen C 14 -dated Hawaiian surface lava flows spanning 0–4.5 ka have been investigated using the microwave perpendicular applied field palaeointensity technique and classical thermal Thellier–Thellier palaeointensity technique in parallel. The overall microwave experimental success rate is 63% compared to 59% in the thermal experiments. Nineteen percent of the microwave results are deemed to be first class compared to 52% of the thermal results. High palaeointensities and a large amount of within-flow variation are seen in the microwave results with reliable palaeointensity estimates ranging from 25.10 to 82.94 μ T. These variations do not appear to be systematically related to variations in rock magnetic properties such as mineralogy, grain size, texture or oxidation state. The flow-means from the microwave and thermal studies agree for 9 of the 13 flows that can be directly compared and the average difference between the two techniques is not significantly different from zero. Neither experimental technique produces mean palaeointensities systematically lower or more precise than the other, suggesting that the differences seen are a reflection of natural within-flow variation rather than experimental technique.

Lava flow identification and aging by means of lidar intensity: Mount Etna case

An application of light detection and ranging (lidar) intensity for the identification and mapping of different lava flows from the Mount Etna (Italy) active volcano is described. In September 2004 an airborne lidar survey was flown over summit sectors of Mount Etna. The information derived from lidar intensity values was used to compare the lava flows with respect to their age of emplacement. Analyzed lava flows vary in age between those dating prior to A.D. 1610 and those active during the survey (2004–2005 eruptions). The target‐emitter distance, as well as surface roughness and texture at the lidar footprint scale, is the main parameter controlling the intensity response of lava flows. Variations in the roughness and texture of surfaces at a meter scale result from two main processes, initial lava cooling and subsequent surface weathering; both lead to variations in the original surface roughness of the flow. In summary: (1) initially, from the time of emplacement, the lidar intensity of lava flow surfaces decreases and (2) about 6 years after emplacement the lidar intensity of lava surfaces starts to increase with the age of flows. Lidar capability in terms of geometric (accuracy of ∼1 m in plan position and less than 1 m in elevation) and spectral (lidar intensity depends on surface reflection at λ = 1.064 μm) information can thus be effectively used to map lava flows and to define a relative chronology of lava emplacement.

The boundary between continental rifting and sea-floor spreading in the Woodlark Basin, Papua New Guinea

Abstract Seismic reflection, bathymetry, acoustic imagery and magnetic data are presented that encompass the boundary between rifting of the Papuan continent and westward propagating sea-floor spreading in the Woodlark Basin. West of the spreading tip, the southern margin is characterized by large fault blocks, which were tilted to the south on north-dipping normal faults during the current rifting phase, and graben further south where previous rifting failed. The northern margin is devoid of large offset normal faults and its subsidence from near sea level requires synrift flow of the lower crust. The margin asymmetry primarily reflects across-strike differences in the prerift geology, morphology and rheology. Horst and graben with 3 km relief below sea level occur adjacent to the spreading tip. Although heat flow data imply greater crustal thinning to the south of Moresby continental seamount, seismicity shows that deformation is currently focused on the Moresby normal fault that bounds its northern side. Based on logging results from ODP Leg 180 and semblance analysis, depth conversion of seismic reflection data show that Moresby Fault has a dip ≥29°, which is compatible with an earthquake slip plane of 30°–33°. Directly east of Moresby Seamount, the first spreading segment is identified on the basis of magnetic, bathymetry and sidescan data to comprise two ring dykes in the west and Cheshire Seamount in the east. A seismic reflection line crossing the western ring dyke shows an intrusive body that cuts Moresby Fault at depth. Currently, intrusive rocks have only reached the surface near the ring dyke, leaving flat-lying synrift sediments, sills (?) and surface lava flows overlying the main intrusive body. The boundary between continental rifting and sea-floor spreading in the Woodlark Basin is spatially abrupt, although the processes overlap in time. The progression from rifting to spreading is characterized by a decrease in sedimentation as the margins are progressively thinned, subside below sea level, are eroded less and trap sediments in proximal basins. The post-rift sedimentation near the continent–ocean boundary is hemipelagic and drapes breakup topography without a distinct breakup unconformity. Synrift sediments, deposited above the 8.4 Ma rift onset unconformity and prior to breakup, are characterized by rotated sections (with parallel or diverging reflectors) as well as by ponded sections that onlap bounding fault blocks where local extension has ceased. Splayed reflectors representing sediment deposition on rotating fault blocks do not characterize the full synrift section, but only those times and places where extension is localized.

Factors affecting the accuracy of thermal imaging cameras in volcanology

Volcano observatories and researchers are recognizing the potential usefulness of thermal imaging cameras both before and during volcanic eruptions. Obvious applications include measurements of the surface temperatures of active lava domes and lava flows to determine the location of the most active parts of these potentially hazardous features. If appropriate precautions are taken, the new generation of thermal imaging cameras can be used to extract quantitative as well as qualitative information on volcanic activity. For example, they can be used to measure the temperature of lava on eruption and to reveal how the crust cools during flow emplacement. This is important for the validation of lava flow models. To ensure that meaningful temperatures are collected, thermal imaging data must be corrected for instrumental errors, emissivity of the surface being imaged, atmospheric attenuation, viewing angle and surface roughness. Controlled laboratory experiments have been undertaken to determine the emissivity of smooth and rough samples and the effects of viewing angle and to quantify the errors. Measured emissivities range from 0.973 ± 0.002 for smooth samples of basalt and 0.984 ± 0.004 for rough samples. Errors in emissivity‐corrected temperatures are within ±15°C for lava at 1100°C. Variations from individual sensor receptors, which provide individual pixel temperature data, were found to be 0.6% and instrumental errors of the cameras used were 0.1%. Apparent temperatures were found to vary by less than the instrumental error for viewing angles up to 30 degrees from normal to lava, and thereafter increased by ∼1°C per degree. By increasing the apparent viewing distance of a small vent on Mount Etna from 1.5 to 30 m, the maximum temperature is shown to decrease by 53°C due to integrated averaging of radiance over increased pixel areas. At a viewing distance of 250 m the maximum temperature decreased by ∼200°C with a further 75°C decrease due to atmospheric attenuation for a relative humidity of 50%. However, errors in relative humidity measurements can lead to atmospheric attenuation correction inaccuracies up to 200°C at viewing distances of 1 km. We show how temperatures measured using thermal imaging cameras can be corrected to give improved estimates of temperature distributions on the surface of active lava flows.

Geology of the Gusev cratered plains from the Spirit rover transverse

The cratered plains of Gusev traversed by Spirit are generally low‐relief rocky plains dominated by impact and eolian processes. Ubiquitous shallow, soil‐filled, circular depressions, called hollows, are modified impact craters. Rocks are dark, fine‐grained basalts, and the upper 10 m of the cratered plains appears to be an impact‐generated regolith developed over intact basalt flows. Systematic field observations across the cratered plains identified vesicular clasts and rare scoria similar to original lava flow tops, consistent with an upper inflated surface of lava flows with adjacent collapse depressions. Crater and hollow morphometry are consistent with most being secondaries. The size‐frequency distribution of rocks >0.1 m diameter generally follows exponential functions similar to other landing sites for total rock abundances of 5–35%. Systematic clast counts show that areas with higher rock abundance and more large rocks have higher thermal inertia. Plains with lower thermal inertia have fewer rocks and substantially more pebbles that are well sorted and evenly spaced, similar to a desert pavement or lag. Eolian bed forms (ripples and wind tails) have coarse surface lags, and many are dust covered and thus likely inactive. Deflation of the surface ∼5–25 cm likely exposed two‐toned rocks and elevated ventifacts and transported fines into craters creating the hollows. This observed redistribution yields extremely slow average erosion rates of ∼0.03 nm/yr and argues for very little long‐term net change of the surface and a dry and desiccating environment similar to today's since the Hesperian (or ∼3 Ga).

Statistical distribution of tumuli on pahoehoe flow surfaces: Analysis of examples in Hawaii and Iceland and potential applications to lava flows on Mars

Spatial distributions of tumuli on lava flow surfaces can be quantitatively linked to subsurface inflation processes. Three distinct styles of flow emplacement are studied: (1) lava flows undergo inflation that changes as a function of space and time resulting in random spatial distributions of tumuli, (2) lava flows with preferred pathways result in systematic clustering of inflation features, and (3) established tubes or narrow pahoehoe flows produce chains of tumuli. Statistical analyses are required to distinguish between styles one and two. Comparison of the spatial distribution of tumuli on a portion of a lava flow at Mauna Ulu with the Poisson distribution indicates that tumuli are randomly distributed on the flow surface, typical of style one emplacement where small‐scale topographic variability and low slope influence development of preferred pathways that evolve over time. At Thrainsskjoldur, direct statistical comparisons to the Poisson spatial distribution are inconclusive but nearest‐neighbor analysis indicates significant clustering. An initially random spatial distribution is inferred that developed preferred pathways and systematic clustering of inflation features, as with style two. At Elysium Planitia on Mars, the flow margin is significantly deficient in inflation features, while away from the margin, the flow exhibits a random spatial distribution of tumuli typical of style one emplacement. The flow is interpreted as multiple units or a single flow that migrated in space during emplacement. At the 1843 flow on Mauna Loa, tumuli occur on a linear trend, consistent with style three emplacement.

Cones and craters on Mount Pavagadh, Deccan Traps: Rootless cones?

Rootless cones, also (erroneously) called pseudocraters, form due to explosions that ensue when a lava flow enters a surface water body, ice, or wet ground. They do not represent primary vents connected by vertical conduits to a subsurface magma source. Rootless cones in Iceland are well studied. Cones on Mars, morphologically very similar to Icelandic rootless cones, have also been suggested to be rootless cones formed by explosive interaction between surface lava flows and ground ice. We report here a group of gentle cones containing nearly circular craters from Mount Pavagadh, Deccan volcanic province, and suggest that they are rootless cones. They are very similar morphologically to the rootless cones of the type locality of Mývatn in northeastern Iceland. A group of three phreatomagmatic craters was reported in 1998 from near Jabalpur in the northeastern Deccan, and these were suggested to be eroded cinder cones. A recent geophysical study of the Jabalpur craters does not support the possibility that they are located over volcanic vents. They could also be rootless cones. Many more probably exist in the Deccan, and volcanological studies of the Deccan are clearly of value in understanding planetary basaltic volcanism.

Elbrus active Volcano and its geological history

Using the new geological map of the Elbrus Volcano (scale 1:50 000) and the new isotopic datings of the volcanic rocks, the formation history of Elbrus Volcano was found to include a pre-caldera, a caldera, and a post-caldera cycle, during which the modern Elbrus stratovolcano was formed. The Early and The Late period of the volcano's evolution have been identified in the two latter cycles. ignimbrite horizons, as well as breaks in volcanic activity, represented by moraine deposits resting on the surface of lava flows in the same volcanic rock sequence. This map shows that the formation history of the Elbrus Volcano included a pre-caldera cycle, a caldera cycle, the onset of which was marked by a powerful explosive eruption, responsible for the caldera formation, and a post-caldera cycle which resulted in the formation of the present-day Elbrus stratovolcano. It is important to note that each of the two latter cycles in- cluded The Early and The Late period of the evolution of the volcano. No pre-caldera volcanic rocks have been found confidently thus far. These are supposed to include the outliers of tra- chyandesite lava flows found in the mouth of the Khudes River (up to 200 m thick) and of trachybasalt lava flows (120-150 m thick) in the upper reaches of the Tyzyl River.

Mechanical stratigraphy in the western equatorial region of Mars based on thrust fault–related fold topography and implications for near-surface volatile reservoirs

Variations in lithology and pore-volatile pressure influence the distribution of layer and interface strength (mechanical stratigraphy) within the crust. In this paper, we show how mechanical stratigraphy can be inferred from the topography of thrust fault‐related folds. A thrust fault propagating upward through mechanically wellstratified crust induces the nucleation of secondary backthrust faults. Because such backthrusts are not predicted (and do not occur) in mechanically homogeneous crust, the presence of backthrusts can be used to map variations in the mechanical strength of the crust (e.g., bedding planes, volatilesaturated reservoirs). Dip directions of faults indicate the presence of strength discontinuities within thrust-related folds. We show that the slopes of fault-related fold limbs are reliable indicators of fault-dip direction. We then apply this slopeasymmetry approach to thrust-related folds on Mars. We find that thrust-related folds that have secondary backthrusts are spatially correlated with a general lithologic sequence of lava flows overlying older impact ejecta and young lobate ejecta craters on the lava-flow surface—evidence of nearsurface volatiles such as water ice. We demonstrate that secondary backthrusts within fault-related folds in the western equatorial region of Mars formed because of volatileenhanced mechanical stratification of lavaflow and ejecta lithologic sequences.

On the retrieval of lava-flow surface temperatures from infrared satellite data

Research Article| October 01, 2003 On the retrieval of lava-flow surface temperatures from infrared satellite data Robert Wright; Robert Wright 1Hawaii Institute of Geophysics and Planetology, University of Hawaii, 2525 Correa Road, Honolulu, Hawaii 96822, USA Search for other works by this author on: GSW Google Scholar Luke P. Flynn Luke P. Flynn 1Hawaii Institute of Geophysics and Planetology, University of Hawaii, 2525 Correa Road, Honolulu, Hawaii 96822, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Robert Wright 1Hawaii Institute of Geophysics and Planetology, University of Hawaii, 2525 Correa Road, Honolulu, Hawaii 96822, USA Luke P. Flynn 1Hawaii Institute of Geophysics and Planetology, University of Hawaii, 2525 Correa Road, Honolulu, Hawaii 96822, USA Publisher: Geological Society of America Received: 03 Mar 2003 Revision Received: 03 Jul 2003 Accepted: 05 Jul 2003 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2003) 31 (10): 893–896. https://doi.org/10.1130/G19645.1 Article history Received: 03 Mar 2003 Revision Received: 03 Jul 2003 Accepted: 05 Jul 2003 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Robert Wright, Luke P. Flynn; On the retrieval of lava-flow surface temperatures from infrared satellite data. Geology 2003;; 31 (10): 893–896. doi: https://doi.org/10.1130/G19645.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The dual-band method has been widely used as the basis for determining lava surface temperatures from infrared satellite data; the method is based on the assumption that such surfaces can be described in terms of two end-member thermal components—hot cracks within a thermally homogeneous crust. The recent launch of the first orbiting hyperspectral imaging system, Hyperion, onboard the National Aeronautics and Space Administration Earth Observing-1 (EO-1) satellite heralds a new era of space-based hyperspectral data collection that will allow more detailed models of lava-flow surface temperatures to be developed and parameterized. To this end, we have analyzed thermal images of active pahoehoe lava flows collected on Kilauea volcano, Hawaii, by using a forward-looking infrared (FLIR) 595 PM ThermaCAM, in order to assess the number of thermal components required to characterize the surface temperatures of active lava-flow surfaces. The FLIR images show that an active lava-flow surface comprises a continuum of temperatures that define distinctive temperature distributions. Numerical model results reveal that the two-component dual-band method fails to resolve any of the major properties of the temperature distributions contained in these data (i.e., mode, skew, range, or dispersion). However, modeling five to seven thermal components allows all significant properties of the subpixel temperature distributions contained within the FLIR images to be determined. Thus, although the hyperspectral data provided by the EO-1 Hyperion yield as many as 66 wavebands in the 0.5–2.5 μm atmospheric window, useable data in 9–13 of these should be sufficient to perform accurate temperature characterization of active lava-flow surfaces from space. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Preeruptive inflation and surface interferometric coherence characteristics revealed by satellite radar interferometry at Makushin Volcano, Alaska: 1993–2000

Pilot reports in January 1995 and geologic field observations from the summer of 1996 indicate that a relatively small explosive eruption of Makushin, one of the more frequently active volcanoes in the Aleutian arc of Alaska, occurred on 30 January 1995. Several independent radar interferograms that each span the time period from October 1993 to September 1995 show evidence of ∼7 cm of uplift centered on the volcano's east flank, which we interpret as preeruptive inflation of a ∼7‐km‐deep magma source (ΔV = 0.022 km3). Subsequent interferograms for 1995–2000, a period that included no reported eruptive activity, show no evidence of additional ground deformation. Interferometric coherence at C band is found to persist for 3 years or more on lava flow and other rocky surfaces covered with short grass and sparsely distributed tall grass and for at least 1 year on most pyroclastic deposits. On lava flow and rocky surfaces with dense tall grass and on alluvium, coherence lasts for a few months. Snow and ice surfaces lose coherence within a few days. This extended timeframe of coherence over a variety of surface materials makes C band radar interferometry an effective tool for studying volcano deformation in Alaska and other similar high‐latitude regions.

Amazonis Planitia: The role of geologically recent volcanism and sedimentation in the formation of the smoothest plains on Mars

Amazonis Planitia, located between the two main volcanic provinces on Mars (Tharsis and Elysium), is characterized by extremely smooth topography at several scale lengths, as smooth as oceanic abyssal plains topography on Earth. We use Mars Global Surveyor (MGS) data (primarily very high resolution Mars Orbiter Laser Altimeter (MOLA) topography and derivative slope maps, gradient maps, and detrended maps) to examine the surface morphology of Amazonis Planitia and the stratigraphic relationships among previously mapped and newly defined units. These new data reveal the presence of a 1300 km diameter Noachian impact basin in northwest Amazonis Planitia and an extensive Late Hesperian lava flow unit that appears to have originated from the Olympus Mons source area prior to aureole formation. The presence of this previously unrecognized flow unit strongly suggests that Olympus Mons activity dates back to at least the Hesperian, as did activity on the Tharsis Montes. Emplacement of this ∼100 meter thick flow unit formed a barrier along the northern margin of Amazonis Planitia which had a profound influence on the subsequent geologic history of the region. Formation of Olympus Mons aureole deposits created an eastern topographic barrier, and subsequent Tharsis Montes lava flows entered the basin from the south, flowing around the aureole. These three barriers (degraded Noachian crater rim, proto‐Olympus Mons flow unit, and Olympus Mons aureole) caused subsequent lava flows and outflow channel effluents, primarily from the Elysium region to the west, to pond on the floor of Amazonis Planitia, preferentially smoothing the terrain there. Mars Orbiter Camera (MOC) images substantiate that at least two very fluid lava flows alternated with fluvial episodes from Elysium Planitia, flowing through Marte Valles onto the floor of the Amazonis Planitia basin. Within Amazonis Planitia, MOC images show flow‐like textures heavily mantled by sediments, and radar data reveal the presence of rough lava flow surfaces underlying the sedimentary debris. These data thus suggest that the unique smoothness of Amazonis Planitia is the result of deposition of thin fluid lava flows and fluvial sediments in an enclosed basin. Crater counts suggest that the most recent resurfacing may have occurred in the latest Amazonian Period, in the last 1% of the history of Mars. In light of its unique history, it is somewhat ironic to note that Amazonis Planitia was originally thought to be a typical young Martian surface and therefore used to name the Amazonian era.