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New Insights from Applications of Lidar Technologies to Lava Flow Studies

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New Insights from Applications of Lidar Technologies to Lava Flow Studies Seeing the True Shape of Earth’s Surface themed issue How lava fl ows: New insights from applications of lidar technologies to lava fl ow studies K.V. Cashman1, S.A. Soule2, B.H. Mackey3, N.I. Deligne1, N.D. Deardorff 1, and H.R. Dietterich1 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA 2Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA 3Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA ABSTRACT availability of high-resolution digital topog- fi rst review the history, goals, and strategies of raphy is poised to revolutionize the study of lava fl ow research and describe the capabilities Mafi c lava fl ows are common; for this rea- mafi c lava fl ows. (and limitations) of both ALS and TLS imaging son, they have long been a focus of volcano- of volcanic landscapes before providing an over- logical studies. However, fi eld studies of both INTRODUCTION view of recent applications of lidar technology older and active fl ows have been hampered to lava fl ow studies. We then discuss the poten- by diffi culties in fi eld access; active fl ows are Mafi c lava fl ows are a persistent and wide- tial of lidar to improve our understanding of the hot, whereas older fl ows have rough and jag- spread form of volcanic activity that, while hazards and dynamics of mafi c lava fl ows. ged surfaces that are diffi cult to traverse. rarely fatal, pose a common threat to commu- As a result, morphometric studies of lava nities around the world. Central to lava fl ow BACKGROUND fl ows have generally lagged behind theoreti- hazard assessment is the construction of proba- cal studies of fl ow behavior. The advent of bilistic fl ow hazard maps and development of Lava fl ow studies have been critical to vol- laser scanning (LS) (i.e., lidar, light detection tools for real-time prediction of fl ow paths, fl ow canology as a science, as illustrated by early and ranging) technologies, both airborne advance rates, and fi nal fl ow lengths. Construc- founding of volcano observatories at Vesuvius, mapping (ALSM) and terrestrial (TLS), tion of lava fl ow hazard maps requires accurate Italy (in 1841, at a time when it was having fre- is promoting detailed studies of lava fl ows information on the areal distribution and tem- quent effusive eruptions) and Kilauea, Hawaii by generating data suitable for production poral history of effusive activity, in addition to (in 1912). The frequency of mafi c lava fl ows in of high-resolution digital elevation models probable vent locations. Accurate prediction of these locations, and at other locations around the (DEMs). These data are revolutionizing both fl ow paths and advance rates requires not only world (such Etna, Italy; Piton de la Fournaise, the visual and quantitative analysis of lava rapid assessment of eruption conditions (espe- Reunion; and Iceland), and the potential for fl ows. First and foremost, this technology cially eruption rate) but also improved mod- renewed volcanism near major population cen- allows accurate mapping of fl ow boundaries, els of lava fl ow emplacement. Together these ters (such as Auckland, New Zealand, and Mexico particularly in vegetated areas where bare dual goals of lava fl ow hazard mapping prior City, Mexico) pose unique hazards to surround- earth imaging dramatically improves map- to eruptive activity, and predictive modeling in ing populations. A compilation of eruptive ping capabilities. Detailed imaging of fl ow response to eruption initiation, demand accurate volumes (magnitude) and eruption rates (inten- surfaces permits mapping and measurement documentation of preexisting topography, past sity; Fig. 1) shows that, except in unusual cases of fl ow components, such as channels, surface fl ow volumes and areal coverage, syneruptive (e.g., Tazieff, 1977), historic lava fl ows have folds, cracks, blocks, and surface roughness. variations in lava fl ux, and an improved under- rarely exceeded mass eruption rates of 106 kg/s Differencing of preeruptive and posteruptive standing of the controls on fl ow advance. (an intensity index of 9; Pyle, 2000); this con- DEMs allows analysis of fl ow thickness vari- All of these needs are met by new laser altim- trasts with eruption rates of 107–109 kg/s (inten- ations, which can be related to the dynamics etry (lidar, light detection and ranging) tech- sity index 10–12) for most explosive eruptions. of lava emplacement. Multitemporal imaging nologies that are radically changing the ways in Figure 1 also shows that lava fl ows can persist of active fl ows provides information not only which we view and study volcanic landscapes from weeks to years, and thus pose a long-lived on the rates and locations of individual fl ow that are continually resurfaced by lava fl ows. hazard. However, the duration and frequency of lobes, but also measurement of pulsed lava The development of lidar using both airborne effusive activity also provide unique opportuni- transport. Together these new measurement (ALSM, airborne laser scanner mapping) and ties for volcanologists to study active volcanic capabilities can be used to test proposed mod- ground-based, or terrestrial (TLS) laser scan- processes. These dual motivations, i.e., hazard els of channel formation, lava tube formation, ners has dramatically improved the resolution and opportunity, work together to make loca- rates of fl ow advance, and fl ow conditions of digital topography available for lava fl ow tions of frequent lava fl ow activity the focal within lava channels; they also provide new research. This technology not only allows col- point for testing and applying new innovations ways to assess the hazard and risk posed by lection of better data on the spatial distribution in technology. Here we frame the primary ques- lava fl ow inundation. Early published stud- and volumes of older lava fl ows, but also pro- tions related to lava fl ows by reviewing both the ies illustrate the potential of applying lidar to vides views of active fl ows that offer new insights types of information required for hazard assess- volcanic terrain; it is clear, however, that the into the processes that formed them. Here we ment and, briefl y, some of the technological Geosphere; December 2013; v. 9; no. 6; p. 1664–1680; doi:10.1130/GES00706.1; 16 fi gures. Received 31 March 2011 ♦ Revision received 6 September 2011 ♦ Accepted 7 September 2011 ♦ Published online 11 October 2013 1664 For permission to copy, contact [email protected] © 2013 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/9/6/1664/3346138/1664.pdf by guest on 26 September 2021 How lava fl ows 12 Mauna Loa etry also affect fl ow length. To date, models of high resolution radiometer), and MODIS (mod- Kilauea fl ow coverage and dynamics have been limited, erate resolution imaging spectroradiometer); for Pyle 10 in part, by the resolution of both preeruptive and reviews, see Oppenheimer, 1998; Wright et al., posteruptive digital topography. Here we show 2004]. These satellites provide images with low 103s ways in which high-resolution lidar-generated spatial (1–4 km/pixel) but high temporal resolu- 8 DEMs can improve our understanding of how tion, and therefore can be used for whole fl ow lava fl ows resurface the landscape. fi eld monitoring. Although fl ow widths are com- 106s Intensity Index 6 monly smaller than individual pixels, the inten- Technological Advances in Lava Flow sity of thermal emissions records the fractional 109s 4 Mapping: Short History pixel areas occupied by active fl ows, allowing 0 2 468 fl ow area to be determined and converted to Magnitude Index Studies of lava fl ows have advanced in tan- effusion rate, given suffi cient calibration data Figure 1. Illustration of the range in magni- dem with technological advances. For much of (e.g., Pieri and Baloga, 1986; R. Wright et al., tudes and frequency of some historic mafi c human history, accounts of lava fl ow behavior 2001). Higher resolution thermal imaging data lava fl ows. Magnitude (M) and intensity (I) and impact were based on close observation, can be obtained using airborne (e.g., Realmuto indices are from Pyle (2000) and are defi ned and ranged in form from the rich oral traditions et al., 1992) and hand-held (e.g., Harris et al., as M = log erupted mass (kg) – 7 and I = of the Hawaiians (e.g., Cronin and Cashman, 2005; Ball and Pinkerton, 2006) thermal imag- log eruption rate (kg/s) + 3. Data are from 2007; Swanson, 2008) to the detailed draw- ing cameras that provide high spatial resolution, Lockwood and Lipman (1987), Wolfe et al. ings and careful descriptions of seventeenth and but usually at the expense of both spatial and (1987), and Pyle (2000). eighteenth century activity at Italian volcanoes temporal coverage. Etna and Vesuvius (e.g., Scarth, 2009). The early Satellite-based radar images have the advan- nineteenth century saw the addition of both a tages of both seeing through cloud cover and innovations that have contributed to lava fl ow theoretical framework for Earth history (deep having higher resolution than satellite-based studies. We return to lava fl ow hazards at the time) and technological advances in drafting thermal imaging techniques. Radar-generated end of this review, to illustrate ways in which and mapping techniques that propelled both the DEMs (e.g., from SRTM, Shuttle Radar Topog- lidar technology, in particular, is shaping new Scrope and Poulett (1825) study of the volcanoes raphy Mission; http://www2.jpl.nasa.gov/srtm/) methods of volcanic hazard and risk assessment.
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