Meteorites and the Early Solar System, edited by J. F. Kerridge and M. S. Matthews, 165 ... Editor: William Casey, Geochemistry Division. 6233, Sandia National ...
Eos, Vol. 71, No. 46, November 13, 1990 Gubbio, Italy: Iridium as a constraint on the duration and nature of Cretaceous/Ter tiary boundary events, Geology, 16, 77, 1988. Engelhardt, W., and W. Bertsch, Shock in duced planar deformation structures in quartz from the Ries Crater, Germany, Contrib. Mineral Petrol, 20, 203, 1969. French, B. M., and N. M. Short (Eds.), Shock Metamorphism on Natural Materials, 644 pp., Mono Book Corp., Baltimore, Md., 1968. Ganapathy, R., A major meteorite impact on the Earth 65 million years ago: Evidence from the Cretaceous-Tertiary boundary clay, Science, 209, 921, 1980. Ginsburg, R. N., K. Burke, and V. Sharpton, Scientists debate global catastrophes, Geotimes, March, 14, 1989. Kerr, R. A., Huge impact is favored K-T boundary killer, Science, 242, 865, 1988. Kieffer, S. W., P. P. Phakey, and J. M. Chris tie, Shock processes in porous quartzite: Transmission electron microscope observa tions and theory, Contrib. Mineral. Petrol, 59, 41, 1976. Sharpton, V. L., and B. C. Schuraytz, On re ported occurrences of shock-deformed clasts in the volcanic ejecta from Toba Caldera, Sumatra, Geology, 17, 1040, 1989. Stoffler, D., Progressive metamorphism and classification of shocked and brecciated crystalline rocks in impact craters, J. Geophys. Res., 76, 5541, 1971. Stoffler, D., Deformation and transformation of rock-forming minerals by natural and experimental shock processes, 1, Behavior of minerals under shock compression, Fortschr. Mineral, 49, 50, 1972. Stoffler, D., Glasses formed by hypervelocity impact,/. Non Cryst. Solids, 67, 465, 1984. Stoffler, D., A. Bischoff, U. Buchwald, and A. E. Rubin, Shock-effects in meteorites, in Meteorites and the Early Solar System, edited by J. F. Kerridge and M. S. Matthews, 165 pp., Arizona Press, Tucson, 1988.
and, in particular, in support of budget mat ters that pertain to Earth and planetary sci ences. At the recent meeting of the Committee on Public Affairs, it was decided that local legis lative activity in support of AGU positions was indeed of importance and that it would be of benefit to have an informal organiza tion within AGU to help inform legislators on matters vital to the interests of geophysics. Therefore, the committee is planning to es tablish a "Committee of 50," with key people in every state. Each member of this group will be responsible for organizing effective legislative action for geophysics in their state on the district level. Each key person would be assisted by as many AGU members in the state as are willing to participate. It would be the responsibility of each par ticipant in the program to discuss geophysical issues with their representatives both to pro vide helpful information and to advocate spe cific actions. Specific congressional actions that AGU is taking will be communicated to the participants for use as they see fit. While the participants would not be formal repre-
Legislative Action for Earth Science PAGE 1789 In the April 10, 1990, issue of Eos, Frank Eden, then chairman of the AGU Committee on Public Affairs, pointed out that AGU has been an active advocate in Washington in support of science in general and geophysics in particular. This has been achieved by our participation in a successful Congressional Fellows program as well as our being a source of information to Congress and to the admin istration on geophysical matters. Eden also pointed out that it would be important and effective if individual scientists on the local level contacted their congressional represen tatives in support of AGU policy positions
Tom Donahue Chairman, Committee on Public Affairs
The VGP News the Consiglio Nazionale delle Ricerche (CNR), have carried out several airborne re mote-sensing missions over active and recent ly active volcanos in southern Italy. These ac tivities were aimed at exploring the uses of new airborne remote-sensing techniques to provide thermal, lithologic, structural, and geomorphic information in a synoptic format for use in geological mapping and volcanic process studies. In addition, because of the intimate mixture of urban centers and active volcanos in Italy, there was and is substantial interest in assessing the utility of remote-sens ing techniques for civil protection, hazard prediction, and damage reduction as related to volcanic activity. Airborne observations were made over Campi Flegrei, Mount Vesuvius, Mount Etna, and the islands of Vulcano and Stromboli in 1984, 1985, and 1986, with coordinated ground observations. Our observations inves tigated the utility of the various instruments for volcanological research, both for thermal ly active features, and for emplaced features at normal ambient temperatures. Our effort in Italy parallels similar Jet Propulsion Labor atory/NASA observations of actively forming and emplaced volcanic features in Hawaii [e.g., Kahle et al, 1988], in cooperation with the Hawaii Volcanoes Observatory of the U.S. Geological Survey. Both efforts are part of growing international interest in bringing to bear state-of-the-art remote-sensing tech niques on a variety of outstanding volcanological problems.
This item was contributed by R. A. F. Grieve, Energy, Mines and Resources Canada, Ottawa, Ontario; V. L. Sharpton, Lunar and Planetary In stitute, Houston, Tex.; and D. Stoffler, Institute for Planetology, University of Munster, Germany.
Fditorial
sentatives of AGU, it would be hoped that they would support AGU positions in discus sions with their representatives. As to the probabilities of this program hav ing an effect on geophysics, it is instructive to note that there are at least 350 departments of Earth science in universities and colleges in the United States with faculties exceeding 10 members. T h e representatives from the dis tricts in which these colleges and universities exist represent a majority of the House of Representatives. Because of the importance of this effort, Neil Opdyke of the University of Florida has volunteered to organize the activity. Members who are interested in participating in such legislative action on behalf of geophysics ei ther as a key state person or on a local partic ipant basis, should contact Les Meredith at AGU Headquarters in Washington. We hope to have this organization in place and func tioning by next spring, so early responses would be appreciated.
The VGP News: gists, geochemists and
The focal point for penologists.
volcanolo-
Editor: William Casey, Geochemistry Division 6233, Sandia National Laboratories, Albuquer que, NM 87185; tel. 505-846-0196
Remote Sensing of Italian Volcanos PAGES 1789-1791 1
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R. B ianchi , R. Casacchia , A. Coradini , A. M. Duncan , J. E. Guest , A. Kahle , P. Lanciano , D. C. Pieri , and M. Poscolieri 2
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Over the past few years, the authors of this paper, under the auspices of the National Aeronautics and Space Administration and This page may be freely copied.
'Consiglio Nazionale delle Ricerche, Rome, Italy University College of London Observatory, London, U.K. Jet Propulsion Laboratory, Pasadena, Cali fornia Telespazio, Rome, Italy
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Eos, Vol. 71, No. 46, November 13, 1990 Volcanic terranes are often some of the most operationally difficult environments in which geologists must work. First, volcanic landscapes are often extremely rough, pre senting difficulties of access and movement, particularly on fresh lava flows. Where young pyroclastic material is present, slopes are of ten at the angle of repose, difficult to climb, and are impossible to negotiate with vehicles. Thus data gathering on volcanos is often lim ited to accessible areas, which necessarily lim its the generality of the acquired data. Field studies of geologic processes that are dynamic over short time scales and that occur over ex tended areas present additional challenges. A major problem associated with data gathering on erupting volcanos is the difficulty of ac quiring a coherent data set over an entire feature at, or near, the same time. Recent ad vances in the physical modeling of volcanic activity have put even more emphasis on the need for detailed quantitative (temporal) data during the emplacement of various features. Activity of this sort is strongly limited by the number of observers and their mobility, thus remote-sensing techniques become very at tractive. Finally, a problem unique to studies of ac tive or precursive volcanic phenomena is that they involve energy radiated at high tempera tures (300°-1200°C) from molten or plastic silicate materials, making it at once both op erationally dangerous and technically de manding if one desires to accurately charac terize the associated energy flux while such features are forming. It is clear that remotesensing techniques can make a significant contribution in terms of economy of scale, ease of operation, and extension of our per ceptual range to a variety of wavelengths, particularly those in the thermal infrared. Our continuing goal is to study active vol canic processes, including their thermal prop erties, and the lithologic, structural, and mor phologic aspects of already emplaced volcanic features. For this work in Italy we considered the Campi Flegrei volcanic field west of Na ples, Mount Etna, and the nearby Eolian Is lands. All are active or recently active volca nos and all present significant hazards to nearby populations. For Campi Flegrei we at tempted to characterize the surface expres sion of the thermal flux over the entire resur gent caldron. Such information provides im portant boundary conditions for models of the subsurface source of heat, for example, magma chamber and dikes, and also provides a well^calibrated datum for assessing changes in surface thermal expression during future crises. On Etna and the Eolian Islands we carried out multispectral thermal-infraredimaging observations both for geological mapping purposes and for process-related studies. As in other volcanic areas [e.g., Kahle et al, 1988] using NASA's Thermal Infrared Multispectral Scanner (TIMS) instrument, subtle differences in the petrological charac ter (for example, glass content) and surface texture contrast strongly in processed images, permitting mapping of the distribution of lava flows and ash deposits. In addition, us ing NASA's Thematic Mapper Simulator (NS001) instrument, we were able to gather short-wavelength infrared data on the ther mal state of the summit craters of Mount Etna during July 1986. In this paper, we describe the equipment and techniques used to acquire data during
our July 1986 campaign over these areas. We include some examples and analyses of our processed multispectral image data and assess their utility for the study of active and recent ly active volcanos. We believe that multispec tral infrared techniques can address a variety of outstanding problems in volcanology that are difficult or impossible to approach other wise.
Remote-Sensing Campaign Airborne observations were carried out over southern Italy in July 1986, with simul taneous ground observations. T h e aircraft used was the NASA Ames C-130B. Three flights were undertaken: July 25, daytime data acquisition at Vesuvius and Campi Fle grei; July 25-26, night data at Pompeii and Campi Flegrei; and July 29, daytime data at Vesuvius, Stromboli, Vulcano, and Mount Etna. The primary instrumentation used during the campaign included two multispectral scanners, the TIMS and the NS001. TIMS [Kahle and Goetz, 1983] has six channels cover ing the thermal infrared region of the spec trum between 8 and 12 u,m. It has excellent thermal sensitivity, and internal calibration at the end of each data line. Because of these characteristics, TIMS can be used for accu rate measurements of both the temperature and the spectral radiance of terrestrial sur face materials [Palluconi and Meeks, 1985]. In particular, within the spectral region covered by the instrument, it is possible to recognize absorption bands characteristic of the reststrahlen vibrational modes of the silicate min erals. The NS001 multispectral scanner provides eight channels, seven of which record data in the visible, near-infrared, and shortwave in frared (0.458-2.380 |xm), and the other in the thermal infrared (10.9-12.3 |xm). Inflight calibration is executed for each scan line [NASA, 1986]. T h e NS001 data provides a synoptic view of the composition of the area under study, and also can provide tempera ture information for very hot volcanic fea tures, where the emission of thermal blackbody radiation will peak between 1 and 2 |xm [see Rothery et al., 1988]. Additional instruments aboard the C-130B, which provided auxiliary information, includ ed the Airborne Imaging Spectrometer, a Barnes PRT5 radiometer, and both video and film cameras. T h e AIS, an experimental high-spectral-resolution-imager, has 128 channels between 1.2 and 2.4 |xm. T h e Barnes PRT5, a nonimaging device, measures the apparent ground temperature along the track. Field instruments were also used in the campaign to determine the emissivity of se lected targets, to evaluate atmospheric effects, and to acquire high-spatial-resolution remote ly sensed data over areas of particular inter est. Portable instruments, including the Inframetrics 525 (1525) Thermal Video Scanner and the Raytek hand-held radiometer, were used to measure temperature on the ground at a variety of sites. A portable meteorological station was installed at La Solfatara (Pozzuoli) to record air temperature and wind velocity at ground level for the entire period of oper ations in the Campi Flegrei area. Ground temperatures were measured at selected lo calities by radiometers and thermocouples, This page may be freely copied.
courtesy of the staff of Osservatorio Vesuviano. In addition, during the survey of the Island of Vulcano, the Istituto Internazionale di Vulcanologia and the Istituto di Geofisica della Litosfera provided ground temperature measurements in selected sites close to the main crater. T h e 1525 system was mounted on board an Augusta 109E helicopter (provided courtesy of the Dipartimento della Protezione Civile and the Aeronautica Militare Italiana) during the C130B overflights at all sites. Ground temperatures were measured using the Ray tek radiometer at different altitudes from he licopter both on thermally active areas, and offshore to evaluate effects due to different atmospheric layers.
Image Processing The airborne scanner data were acquired as calibrated digital images. Thus it is possible to produce computer-processed images of real physical quantities such as temperature or spectral emissivity. Alternatively, such im ages can be enhanced to produce the best vi sual separations of subtle features of interest [see Gillespie et al., 1986, 1987]. One goal was to obtain a map of the thermal anomalies of the Campi Flegrei region, and, in particular, the very active area at La Solfatara outside of Pozzuoli. T h e first step in the extraction of this ground temperature data was the calibra tion of the TIMS data. The selected image was then corrected for atmospheric absorp tion and radiance effects that were removed by using LOWTRAN6 program [Kneizys et al., 1983]. As we did not have radiosonde data, the atmospheric model used was "mid-lati tude summer." Ground temperatures ascer tained by LOWTRAN6 and actual field mea surements were in good agreement. T h e cov er photograph (right top) shows a temperature image of La Solfatara obtained from the TIMS channel 1 assuming a con stant surface emissivity of 0.95, with tempera ture displayed in color. At Etna, Stromboli, and Vulcano we were interested in displaying the spectral differ ences between the surface materials rather than temperature differences, in order to map different flow and pyroclastic units. Spectral signatures of volcanic surface materi als have been shown to depend on such phys ical parameters as composition, texture, and amount and degree of ordering of glass. Spectral differences can be well displayed us ing a "decorrelation stretch" (D-stretch) [Gil lespie et al., 1986], a computer image-enhance ment technique that tends to show the spec tral differences in color (hue) and the temperature as brightness (intensity). Computer-processed images for Mount Etna and the Island of Vulcano are shown on the cover (left, and right bottom). These im ages have been calibrated, have had a noise removal algorithm applied, and have been Dstretched. Their interpretation is discussed in the following sections of the paper. It is obvi ous from inspection of the images that there is significant distortion due to flying over ar eas of rapidly changing elevation. Further im age processing is underway at both J PL and CNR to derive images of spectral emissivity that are corrected for atmospheric effects as a function of elevation, and which are geomet rically registered to a Universal Transverse Mercator (UTM) map base.
Eos, Vol. 71, No. 46, November 13, 1990 ra, vertical deformation reached an average rate of about 2 mm/day, with velocity varia tions of up to 4—5 mm/day [Berrino et al, Campi Flegrei 1984], and a new fracture, about 100 m long, opened in the central part of the Solfatara T h e Campi Flegrei, a Quaternary volcanic crater. area located west of Naples, was active for at In December 1984 and again in J u n e 1985 least 50,000 years and its most striking struc we were able to map the radiant energy flux tural element is represented by a caldera, about 12-km across. [Rosi et al, 1983; Thunnel of La Solfatara in the 8 - to 12—|xm region us ing the hand-held 1525 thermal infrared vid et al, 1978; Armienti et al, 1983; hirer et al., eo-imaging instrument, deployed from an 1987]. T h e area, including the islands of IsAugusta 109E helicopter provided by the chia and Procida, represents a complex vol canic system comprised of monogenetic pyro Italian Air Force (Aeronautical Militare Itaclastic vents, aligned in an east-west direction, liana). Comparison of images taken at these times showed some changes, including a dis that fed an activity characterized mainly by a tinct extension of thermal activity through saturated potassic chemical process [Di Girothe northeast wall of La Solfatara along lamo et al, 1984]. T h e beginning of the preprominent fracture trends.The uplift created caldera activity is not well known; however, problems for the Pozzuoli population and the an age of about 45,000 years for the oldest harbor became unusable. Earthquakes dam outcrops at the periphery of the caldera has aged old houses, and the number of build been ascertained [Gillot, 1985]. T h e subse ings evacuated increased progressively. When quent volcanic history of the region has been divided into a precaldera period that includes the initial magnitude 4 earthquake occurred, about 40,000 persons were evacuated from all the activity older than 35,000 years, and the old town of Pozzuoli [Barberi et al, 1984], three postcaldera periods from 35,000 years ago to the present [Rosi et al, 1983]. La Solfa which was fortunate because some of the old er houses collapsed during the earthquakes tara crater, the most hydrothermally active that followed. Due to the Civil Protection De area of Campi Flegrei, was formed at the be partment intervention, however, no one was ginning of the last period of the postcaldera activity, which ended, after a quiescent period killed or seriously injured. of about 3000 years, with the 1538 A.D. In July 1986, our primary objective was to eruption that produced the ash and scoria use TIMS data to provide a thermal datum cone of Monte Nuovo.Very high thermal gra map of the area for use in later surveys. Sub dients have been measured in a number of sequent measurements made with a variety of wells drilled inside the caldera. A maximum instruments of varying sophistication can be temperature of more than 400°C was mea compared with the baseline data set to deter sured at about 3 km depth in a well located mine the evolution thermal features. In addi about 4 km from the caldera center. These tion, such a datum combined with a program measurements and the contact-metamor of regular thermal surveillance would be use phosed rocks found in the wells suggest that ful for comparison with measurements of at present the top of a cooling magma cham other dynamic and periodic geophysical phe ber is at a depth of 4 - 5 km [Rosi et al, 1983; nomena. Armienti et al, 1983]. Giberti et al [1984], us Other important scientific objectives were ing a quasi-conductive regime model, reach the identification of fractures that were ther the conclusion that the magma chamber mally active and the identification of large ar might still contain several cubic kilometers of eas within Campi Flegrei characterized by magma at an average temperature of 1000°C. slight elevations in temperatures above the The geothermal field and the anomalous geobackground. T h e large-scale temperature dis thermal gradient that now characterizes Cam tribution is the surface expression of the heat pi Flegrei are due to the overlapping of two produced by the magma chamber and has a thermal fields generated by a large original shape similar to that of the observed surface pre-ignimbrite magma chamber and by the deformation, which reached a maximum at present magma chamber [Bianchi et al, 1987]. the center of Pozzuoli and decreased radially. The combined manifestation of these two This large-scale temperature distribution can fields appears as thermal anomalies that ex be compared with the gravimetry and magnetend into and migrate within Campi Flegrei. tometry of the area, both of which seem to The circulation of hydrothermal fluids be indicate that Campi Flegrei is characterized neath the area has a strong effect on the loca by the presence of a marked structural tion and intensity of these surface anomalies boundary, probably related to the original within the permeable zone. In addition, re caldera collapse, which caused a strong nega cent drill data indicates that permeable struc tive gravitational anomaly centered south tures exist at various depths. ward of Pozzuoli [Cassano and La Torre, 1987]. Knowledge of these other geophysical charac In the Campi Flegrei area, populated by teristics may be of use in the interpretation of about 400,000 people, two inflation episodes large-scale temperature gradients. T h e tem occurred during the periods 1970-1972 and perature ranges in the Solfatara, as obtained 1982-1984. These events produced a bulge from TIMS data, are comparable to those of about 3.0 m at the height of the activity, near the town of Pozzuoli, located in the mid measured with other field instruments, and dle of the main caldera, with about 72,000 in most of the thermal activity is concentrated in habitants. In 1970 the first bradyseismic crisis the southeast portion of the crater rim and started with serious effects on the population. floor, where the fumarolic activity is also When the uplift reached 80 cm and a seismic more intense. Two more thermally active ar swarm of minor intensity occurred, 3000 per eas are observable next to the Solfatara on the east: the northern one has an elongated sons were evacuated from the old quarter of shape with the major axis oriented NW-SE. the Pozzuoli harbor [Barberi et al, 1984]. An The southern feature is composed of four increase of fumarolic activity occurred in the hot spots that appear slightly colder than the Solfatara area along with earthquakes up to magnitude 4. In the central part of the calde hot features within the Solfatara and also
Discussion
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colder than the external northern hot spot. We compared our Solfatara map to the only other thermal data available, which was pro duced by Tonelli [1972] by means of airborne and field instruments in the 8 - to 1 4 - and 2 to 5-|xm spectral regions. Even though the two sets of data cannot be considered fully comparable, it seems that the overall shape and location of the hottest radiant areas did not change substantially over 14 years. We made a further comparison between the hot lineaments that can be detected on the basis of our TIMS data and the tectonic features mapped by Rosi and Sbrana [1987] at the Solfatara. There is a good agreement be tween the mapped fractures and the align ments of the hottest points, the majority of which are distributed according to three main structural orientations: N-S, NE-SW and NWSE. There is also good agreement with the results obtained by Cosentino et al. [1984], who analyzed the azimuthal distribution of more than 500 fractures in the whole region. Such data point to a strong association between thermally active fractures within La Solfatara and the regional stress system across Campi Flegrei. Overall mapping of the distribution of surface thermal expression will provide a thermal base map against which the progress of subsequent similar crises can be charted.
Mount Etna Mount Etna is a large, composite, active volcano that rises to over 3300 m above sea level (asl) and has a basal diameter of some 40 km. It is situated on the east coast of Sici ly, just south of the probable junction be tween the African and Eurasian plates. The underlying crust is about 20 km thick. The main construct of Etna is composed of products of mildly alkalic affinity, the Alkalic Series, consisting of hawaiites, mugearites, benmoreites and rare trachytes. The lavas are typically porphyritic with phenocrysts of plagioclase, calcic augite and olivine, but some of the more evolved products are aphanitic. These more evolved products are all prehis toric in age, while during historical time only rather uniform hawaiitic composition lavas have been erupted. T h e eruptive history of the Alkalic Series, from about 150,000 years B.P. to the present, built a succession of part ly overlapping central vent volcanos. The ac tivity of many of these centers terminated in the formation of calderas. The products of the older centers are exposed in the walls of the Valle del Bove, a major horseshoe-shaped depression cut into the eastern flank of the volcano by sector collapse. During historical time, most of the erup tions have been effusive with strombolian ac tivity building cinder cones over the vents in some cases. The summit region is character ized by almost continuous activity including lava effusions, strombolian explosions and pit collapses. This activity on Etna is referred to as "persistent" and is taken to indicate that the central conduit has been "open" for much of historical time. Flank eruptions occur on average about every 6 years as a result of dikes from the central conduit intersecting the surface. Preferred locations for such eruptions are the northeast and southern rifts and small loci of activity on the west flank, low on the southern flank and on the north ern margin of the Valle del Bove. Most of the
Eos, Vol. 71, No. 46, November 13, 1990 lavas are aa, but some pahoehoe flow fields have been produced in historical times. Except for areas traversed by recent flows, the volcano's flanks are vegetated up to about 2000 m asl. Above this there is only sparse vegetation, the surface consisting of lavas erupted during the last few hundred years and scoria and ash cover from summit strom bolian activity. T h e degree of vegetation cov er on historical lavas depends not only on their age but also on altitude and the sector of the volcano on which they occur. The ge ology of Mount Etna is illustrated by a 1:50,000 scale geological map that includes historical lavas up to 1974. Also, two general reviews that provide a detailed summary of current understanding of the volcano are giv en by Romano [1982] and Chester et al [1985]. For Etna and the other surveyed Italian volcanos (Vesuvius, Stromboli, and the Island of Vulcano), multispectral thermal infrared data are particularly useful for detailed com parisons with existing geological maps and for aiding ongoing mapping projects. Subtle shifts in silica content show up as translation and deformation of characteristic spectra in the thermal bands used here (8—12 u,m, 6 bands), resulting in the ability to discriminate between features of differing compositions and textures. TIMS data has also been shown to be very sensitive to weathering processes in lavas, probably related to changes in the glass with exposure [Kahle et al, 1988] and hence can be used as an aid to relative dating of re cent flows. Process-related geomorphic studies of vol canic features benefit from the availability of data taken from aircraft and satellite plat forms. There are several important areas: as sessment of the dimensions, distribution, and character of flows, flow fields, and related de posits; spectral characterization of emplaced flows for investigating the petrological state of lava over entire flows or flow fields; and collection of thermal data from active fea tures, in order to characterize heat loss rates and mechanisms. T h e last point is particular ly relevant for active lava flows, where such data provide an important boundary condi tion for models of flow rheology. In addition, Etna exhibits a variety of haz ards. Around the summit craters, collapses and associated ballistic ejection of large clasts have occasionally resulted in serious injury, and even deaths, among visitors to the Cen tral Crater. Such activity appears to be gener ally difficult to predict; however, the expul sion of volcanic bombs seems to be correlated with collapse and subsequent steam explo sions within the central crater. Increased cal dera activity associated with increased tem peratures may be able to be detected by the use of thermal infrared instruments and thus provide precursive information on strombo lian and microplinian (P. J. Francis et al., un published manuscript, 1990) outbursts at the summit. Another hazard is presented by regular lava eruptions from the flanks, and occasion ally from the summit. In the past, such flows have damaged a number of tramway and skilift pylons and have threatened hotels on the flanks of Etna. Historically, much larger flows from Etna, for example, the 1669 Flow, have often threatened surrounding towns and vil lages. Very recently, during the SeptemberOctober 1989 eruption, a lava flow reached down to about 1200-m elevation, threatening
the town of Zafferana. Several large (up to 1 m wide) extensional fractures opened along the southeast flank of the volcano, presenting potential new eruption centers at these lower elevations (L. Glaze, personal communication, 1989). Such flows are typically more volumi nous than summit flows [Guest, 1984] and thus present proportionately more hazard to surrounding towns. T h e thermal characteris tics of such fracture systems are clearly im portant in assessing dynamic conditions dur ing eruption crises for both scientific and civil protection purposes (F. Barberi, personal communication, 1989). Our experience at Mount Etna with these techniques appears favorable. We are clearly able to delineate between major flow units and between ash and flow deposits (cover, left). Relative ages of deposits show up as clearly differentiated colors after spectral contrast has been increased using imageprocessing techniques (cover, left). Aa and pahoehoe units are strongly differentiated, even after severe weathering. Flow units are typically visible even through some vegetation coverings and cultural overprints. In some ar eas where conventional geological mapping was difficult due to rough and steep terrain, TIMS data appears to show a more complete and correct depiction of the unit relationships (J. Guest and A. Duncan, personal communi cation, 1989). In some instances, terrain tex tures appear to be strongly correlated with thermal infrared spectral character, due to the radiative efficiency associated with a par ticular roughness, or to a differing petrologi cal character, or both. TIMS images have been compared to the existing CNR 1:50,000 scale geologic map of the volcano [Romano, 1982]. Unfortunately, this map is only updated to the 1974 lava flows. T h e activity of Mt. Etna from 1974 to 1986 (the time in which our TIMS data were collected) has been described in several pa pers, but it has never been reported onto a map. For this reason, some of the informa tion contained in the TIMS imagery is not present in the official cartography and there fore at present, we limit the comparison of the two data sets to the volcanic material pro duced up to 1974. False color composites of TIMS images of bands 5-3-1 show different lithologic units, the color of which can be related to both the composition of the unaltered rock and to the weathering products. T h e latter can be inter preted as chronology indicators. There is good correspondence between the main hues of the TIMS emittance images and the ages of the most important lava flows mapped in the Mt. Etna region. As an example, on the cover photo (left) we observe that the area around the central crater, where recent effu sive activity has been most concentrated, ap pears cyan or blue. Also, the distribution of the magenta-purple areas corresponds ap proximately to the lava flows erupted during the last hundred years. A fairly good agree ment can also be observed between the occur rence of the green areas far from the central craters and the lava flows erupted during the 17th century. Other TIMS images were acquired over the Eolian Islands, including the islands of Stromboli and Vulcano (cover, right bottom). While it appears, particularly for Stromboli, that spectral contrasts corresponding to mapped volcanic units are visible in DThis page may be freely copied.
stretched images, the data were strongly af fected by solar heating. Unfortunately, the data acquisition time for these areas was con trolled by logistical constraints, allowing only a single midday overflight. Thus extraction of information on the thermal character of Stromboli and Vulcano depend on, the prop er deconvolution of topography and accurate modeling of the spectral response as a func tion of slope at thermal wavelengths. This work is currently underway. Beyond this initial report, much work re mains to be done with these data in terms of using laboratory and ground spectrometry data to understand the role played by differ ent weathering products in originating the different color units. In particular, correlative in situ field spectra are important because they provide data under climatic conditions similar to those of the imaged material dur ing the remote-sensing survey. In addition, much more systematic thermal radiance ob servations are required from aircraft and, when possible, from orbit, to help document the time-dependent character of volcanic thermal outputs and their relationship to the occurrence of eruptions in both space and time. For instance, re-flights of these same ar eas of southern Italy with improved U.S. and Italian instrumentation are now proposed for summer of 1991 for many of the volcanic features reported on here, and will allow comparison of active thermal features over a 5-year interval. While far from complete, we feel that stud ies such as this one nevertheless demonstrate an important role for airborne and orbital re mote sensing in the monitoring and study of active volcanos, their products, and the haz ards they may represent, as well as provide baseline scientific data. Hopefully, within the next decade, new instruments available on large orbital platforms, such as the NASA Earth Observing System and the proposed NASA Geostationary Earth Observatory, or even on small satellites, such as a proposed Italian-U.S. Scout-class volcanology mission, will provide daily or even continuous multi spectral imaging capabilities for monitoring the environmental effects of even the Earth's most remote volcanos.
Acknowledgments T h e authors would like to thank a variety of people without whom this cooperative in ternational work would not have been possi ble. Diane Wickland of NASA Headquarters, Washington, D.C., labored mightily to clear a number of procedural issues that allowed the deployment of the NASA aircraft. We would like to thank the NASA C-130B flight crews and support people from the Ames Research Center, Moffett Field, Calif., for their hard work and commitment to carrying out this mission. We would also like to thank Major Tommaso Caragnano and his A-109E heli copter flight crew of the Aeronautica Militare, Rome, Italy, for their expert piloting and support, and also helicopter pilots and crews from the Italian Navy. T h e encouragement and support from Di rector Franco Barberi of the Gruppo Nazion ale per Volcanologia, Pisa, Italy, and from Di rector Giuseppe Luongo and his staff at the Osservatorio Vesuviano, Naples, Italy, are both greatly appreciated. Operational and lo-
Eos, Vol. 71, No. 46, November 13, 1990 gistical support of the Istituto Internazionale di Vulcanologia in Catania, Italy, is also ap preciated. Ron Alley of Jet Propulsion Labo ratory, Pasadena, Calif., processed the TIMS images displayed here. We also thank J PL colleagues Gordon Hoover, Rich Walker, Elsa Abbott, and Mike Abrams, and Enrico Flamini at CNR, Rome, Italy, for help in a num ber of thorny operational and postprocessing areas. Marcello Fulchignoni, then of CNR Reparto Planetologia, Rome, helped conceive the original mission concept with David C. Pieri, JPL. This work was carried out under contract to the Land Processes Program of NASA, and to the National Research Council of Italy Strategic Project for the Climate and Envi ronment of Southern Italy. Additional sup port was provided by the Italian Ministry of Civil Protection and the Italian Air Force. Publication of remote-sensing images of Mount Etna, La Solfatara, and Vulcano (cov er photographs) is approved by the Italian government under respective Stato Maggiore dell'Aeronautica Authorizations 1050 (Octo ber 20, 1989), 659 (June 9, 1988), and 498 (April 27, 1990).
References Armienti, P., F. Barberi, H. Bizouard, R. Clocchiatti, F. Innocenti, N. Metrich, M. Rosi, and A. Sbrana, Magma evolution within a shallow magma chamber: T h e Phlaegrean Fields case,y. Volcanol. Geotherm. Res., 17, 289, 1983. Barberi, F., G. Corrado, F. Innocenti, and G. Luongo, Phlaegrean Fields 1982-1984: Brief chronicle of a volcano emergency in a densely populated area, Bull. Vulcanol., 47— 2, 175, 1984. Berrino, G., G. Corrado, G. Luongo, and B. Toro, Ground deformation and gravity changes accompanying the 1982 Pozzuoli uplift, Bull. Volcanol, 47-2, 187, 1984. Bianchi R., A. Coradini, C. Federico, G. Giberti, P. Lanciano, J. P. Pozzi, G. Sartoris, and R. Scandone, Modeling of surface de formation in volcanic areas: T h e 19701974 and 1982-1984 crises of Campi Fle grei, Italy, J. Geophys. Res., 92, 139, 1987. Cassano, E., and P. La Torre, Geophysics of the Phelgrean Fields, Quad. Ric. Sci, 114, 103, 1987. Chester, D. K., A. M. Duncan, J. E. Guest, and C. R. J. Kilburn, Mount Etna: The Anat omy of a Volcano, p. 330, Chapman and Hall, London, 1985. Cosentino, D., D. De Rita, R. Funiciello, M. Parotto, F. Salvini, and E. Vittori E., Frac ture system in Phlegrean Fields (Naples, Southern Italy), Bull. Vulcanol., 47-2, 247, 1984. Di Girolamo, P., M. R. Ghiara, L. Lirer, R. Munno, G. Rolandi, and D. Stanzione, Vul canologia e petrografia dei Campi Flegrei, Bol. Soc. Geol. Hal, 103, 349, 1984. Giberti, G., S. Moreno, and G. Sartoris, Ther mal history of Phlaegrean Fields (Italy) in the last 50,000 years: A schematic numeri cal model, Bull. Volcanol, 44-2, 331, 1984. Gillespie, A. R., A. B. Kahle, and R. E. Walk er, Color enhancement of highly correlated images, 1, Decorrelation and HSI contrast stretches, Remote Sens. Environ., 20, 209, 1986. Gillespie, A. R., A. B. Kahle, and R. E. Walk
er, Color enhancement of highly correlated images, 2, Channel ratio and "chromaticity" transformation techniques, Remote Sens. En viron., 22, 343, 1987. Gillot, P. T., T h e recent volcanic activity in the Gulf of Naples: Compared evolution of Ischia and Phlaegrean Fields, paper pre sented at the IAVCEI Scientific Assembly, Giardini Naxos, 1985. Guest, J. E., Styles of eruption and flow mor phology on Mt. Etna, Mem. Soc. Geol. Ital, 23, 49, 1984. Kahle, A. B., Surface emittance, temperature, and thermal inertia derived from Thermal Infrared Multispectral Scanner (TIMS) data for Death Valley, California, Geophys ics, 52, 858, 1987. Kahle, A. B., and A. H. Goetz, Mineralogic information from a new airborne Thermal Infrared Multispectral Scanner, Science, •222, 24, 1983. Kahle, A. B., A. R. Gillespie, E. A. Abbott, M. J. Abrams, R. E. Walker, G. Hoover, and J. Lockwood, Relative dating of Hawaiian lava flows using multispectral thermal in frared images: A new tool for geologic mapping of young volcanic terranes,y. Geophys. Res., 93, 15,239, 1988. Kneizys, F. X., E. P. Shettle, W. O. Gallery, J. H. Chetwynd, Jr., L. W. Abreu, J. E. A. Shelby, S. A. Clough, and R. W. Fenn, At mospheric transmittance/radiance: Com puter code LOWTRAN6, Environ. Res. Pap. 846, Tech. Rep. AFGL-TR-83-0187, Air Force Geophys. Lab., Bedford, Mass., 1983. Lirer, L., G. Luongo, and R. Scandone, On the volcanological evolution of Campi Fle grei, Eos Trans. AGU, 68, 226, 1987. NASA, C-130B Aircraft Experimenter's Hand book, Washington, D.C., 1986. Palluconi, F. D., and G. R. Meeks, Thermal Infrared Multispectral Scanner (TIMS): An investigator's guide to TIMS data, Publ. 8532, Jet Propul. Lab., Pasadena, Calif., 1985. Romano, R., Mount Etna Volcano, Mem. Soc. Geol. Ital, 23, 1982. Rosi, M., and A. Sbrana, Phlaegrean Fields, Quad. Ric. Sci., 114, 60, 1987.
Earth Rotation: Theory and Observation PAGE 1791 Hetmut Moritz and Ivan I. Meuller, Ungar Pub., New York, 1987, $85.00, distributed by Harper and Row. Reviewed by Jean O. Dickey, Jet Propulsion Labo ratory, California Institute of Technology, Pasade na The rotation of the solid Earth, as moni tored from observatories fixed on the Earth's crust, is not constant. T h e measurements re veal minute but complicated changes of up to several parts in 10 in the speed of the Earth's rotation, corresponding to several milliseconds in the length of the day (LOD) and even larger variations in polar motion. Earth studies have embarked on a new era with the advent of highly accurate space geo8
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Rosi, M., A. Sbrana, and C. Principe, The Phlaegrean Fields: structural evolution, vol canic history and eruptive mechanisms, J. Volcanol. Geotherm. Res., 17, 273, 1983. Rothery, D. A., P. W. Francis, and C. A. Wood, Volcano monitoring using short wavelength infrared data from satellites,/. Geophys. Res., 93, 7993, 1988. Thunnel, R., A. Federman, S. Sparks, and D. Williams, T h e origin and volcanological sig nificance of the Y-5 ash layer in the Medi terranean, Quat. Res., 12, 241, 1978. Tonelli, A. M., Termografia all'infrarosso da stazioni a terra e dall'aereo, Quad. Ric. Sci., 83, 218,1972.
News Papike Appointed Director of IOM PAGE 1791 James Papike was appointed director of the Institute of Meteoritics in the Department of Geology and Presidential Professor at the University of New Mexico, Albuquerque, on July 1, 1990. Papike succeeded Klaus Keil, who moved to the University of Hawaii to di rect the Planetary Geoscience Division at the Hawaii Institute of Geosciences. The newly constituted IOM will emphasize planetary volcanic processes through the study of achondritic meteorites, the Moon, and Earth, and the origin of primitive solar system materials and planetary formation through the study of chondritic meteorites. Microbeam techniques (STEM, EMP, SEM, SIMS, ICP/MS with laser) will constitute the major analytical thrust with STEM, EMP, SEM, and ICP/MS facilities in place in the Geology Department at UNM and access available to a new Cameca 4f ion microprobe at Sandia National Laboratories, Albuquer que, N. Mex.
detic techniques and the availability of com plementary geophysical data sets. Techniques utilized include laser-ranging to the Moon and artificial satellites, and very long baseline interferometry (VLBI). Comparisons between techniques indicate that Earth rotation is rou tinely determined at the 0.05-0.10 millisec ond level (approximately 2—5 cm at the equa tor), with higher accuracy in some cases. Geophysically interesting variations are detectable at these levels. T h e analysis and under standing of these phenomena draw upon and contribute to meteorology, oceanography, as tronomy, celestial mechanics, seismology, tec tonics, and geodynamics. Changes in Earth orientation are caused by the deformation of the solid Earth and by ex changes of angular momentum between the solid and fluid parts of the Earth, as well as by exchanges of angular momentum with ex traterrestrial objects. Changes in Earth rota-
