Jeffrey Myer Byrnes

Relationships between pahoehoe surface units, topography, and lava tubes at Mauna Ulu, Kilauea Volcano, Hawaii

Lava flow field development at Mauna Ulu was analyzed by characterizing pahoehoe surface units and their distribution relative to pre-Mauna Ulu topography and the main lava tube system. Four pahoehoe surface units were identified in the field and described on the basis of color, surface texture, and morphology: broad, flat sheets (unit I), networks of interconnected glassy-surfaced toes (unit II), late stage breakout lobes of viscous toes (unit III), and irregular surfaces exhibiting meter-scale roughness, which typically occur as channels (unit IV). The distribution of these units was mapped on high-resolution aerial photographs using an automated supervised classification technique; Geographical Information Systems (GIS) analyses utilized digitized ∼6 m (20 foot) contour interval topography of the pre-Mauna Ulu surface and the mapped lava tube network to assess the influence of topography and lava tubes on the emplacement of surface flows. The four pahoehoe units represent variations in emplacement conditions, on the basis of the various flow regimes (sheet, toe, and channel) and surface textures (smooth/glassy and rough) displayed. These surface units show a limited correlation to pre-Mauna Ulu topography based on their mean underlying slopes. The higher flow rates indicated by the channelized surfaces of unit IV are spatially correlated with higher (22.2°) mean underlying slopes relative to those of the sheets of unit I (14.2°) and the toe networks representing units II (15.2°) and III (15.9°). The distribution of the four units does not appear to be directly related to their proximity to the largest scale of lava tubes, suggesting two possible scenarios: the main lava tubes do not significantly affect surface unit emplacement within the study area and/or these tubes do not preferentially emplace any of the four units identified in this study.

Analysis of Venusian steep‐sided domes utilizing stereo‐derived topography

[1] The morphology and topography of 23 Venusian steep-sided domes are analyzed to examine possible emplacement mechanisms. Stereo radargrammetric techniques are used with Magellan synthetic aperture radar image data (∼100 m resolution) to generate digital elevation models for the domes (∼1 km horizontal resolution). Heights of the domes range from 390 to 1590 m, aspect ratios (height/diameter) range from 0.01 to 0.07, and volumes range from 73 to 1790 km 3 . Dome morphology varies along a continuous trend that is directly related to the aspect ratio. Domes with a low aspect ratio tend to be sunken in their centers, whereas domes with higher aspect ratios have flat to convex surfaces. Domes with the highest aspect ratios have central peaks. These trends are likely due to slight variations in the thickness of the crust and, possibly, effusion rates. Episodic emplacement is also inferred to be a significant process for the formation and growth of some of the domes in this sample.

Applications of high-resolution satellite remote sensing for northern Pacific volcanic arcs

There has been a dramatic increase in the remote-sensing data volume being acquired from Earth orbit over the past two decades. Although none of these satellite instruments were designed specifically to monitor volcanic eruptions, many government agencies and university partnerships are currently utilizing them for this task. Most rely on high temporal/moderate spatial resolution instruments (e.g., MODIS, AVHRR, GOES) to monitor transient and temporally variable anomalies such as eruption clouds and hot spots. The uses of these instruments for such purposes are detailed in Chapters 3, 4 and 6. However, in order to better develop a quantitative scientific basis from which to model transient geological and meteorological hazards as well as map small-scale phenomena, higher spatial/spectral resolution datasets are commonly needed. Whereas moderate-resolution data may be frequently received directly from the satellite at many institutes globally, access to, and temporal frequency of, coverage from high-resolution instruments has been limited because much of the data must be specially acquired and purchased using a few government (e.g., ASTER, ETM+) and commercial (e.g., IKONOS, QuickBird) providers. Despite this, high-resolution data use has increased greatly as their capabilities have become recognized. The data from these sensors are particularly useful for numerous aspects of volcanic remote sensing. For example, high spatial resolution/multispectral thermal infrared data are critical for monitoring low-temperature anomalies and mapping both chemical and textural variations on volcanic surfaces. The data can also be integrated into a near-real time monitoring effort that is based primarily on high temporal/moderate spatial resolution orbital data. This synergy allows small-scale activity to be targeted for science and response, and the establishment of a calibration baseline between each sensor. The focus of this chapter is to highlight how these high spatial resolution (<100 m/pixel) data, commonly with more spectral capabilities, are being used for volcanic mapping and monitoring in the North Pacific region. A review of volcanic remote-sensing research using these data is presented with attention paid to case studies of new research. These studies showcase the capabilities of higher resolution sensors to map pyroclastic flows and detect changes over time in those flows (Mt. Augustine Volcano), and to document detection of volcanic terrains using a fusion approach of data from the visible to the radar wavelengths (Westdahl Volcano).