io heat flow from dark volcanic fields abstract dark flow fields on the jovian satellite io are evidence of current or recent volcanic activity we have examined the darkest volcanic fields and quantified their thermal emission in order to assess their contribution to io s total heat flow loki patera the largest single source of heat flow on io is a convenient point of reference we find that dark volcanic fields are more common in the hemisphere opposite loki patera and this large scale concentration is manifested as a maximum in the longitudinal distribution near 200 w consistent with usgs global geologic mapping results in spite of their relatively cool temperatures dark volcanic fields contribute almost as much to io s heat flow as loki patera itself because of their larger areal extent as a group dark volcanic fields provide an asymmetric component of 5 of io s global heat flow or 5 1012 w

global near ir maps from gemini n and keck in 2010 with a special focus on janus patera and kanehekili fluctus abstract we have imaged io in the near infrared 1 5 m with adaptive optics on the 10 m w m keck ii and the gemini north telescopes we have constructed global maps from the data taken in 2010 although numerous hot spots are visible the maps are dominated by two volcanic centers loki patera and kanehekili fluctus we have examined in detail the thermal emission from janus patera and kanehekili fluctus using images obtained between 2003 and 2010 and have created a timeline of volcanic activity at these locations utilizing data from a wide variety of sources based on our data and this timeline we find that the thermal emission from janus patera is relatively steady indicative of an active lava lake the thermal emission from kanehekili fluctus however is quite variable and is indicative of the emplacement of extensive lava flows in 2010 the thermal emission from this location was 10 times higher than ever seen before indicative of a particularly voluminous eruption of lava

io s theothermal sulfur lithosphere cycle inferred from sulfur solubility modeling of pele s magma supply abstract surface deposits of volatile compounds such as water earth or sulfur io on volcanically active bodies suggest that a magmatic distillation process works to concentrate volatiles in surface reservoirs on earth this is the combined hydrologic and tectonic cycle on io sulfurous compounds are transferred from the interior to the surface reservoirs through a combination of a mantle sourced magmatic system vertical cycling of the lithosphere and a sulfur dominated crustal thermal system that we here call the theothermal system we present a geochemical analysis of this process using previously inferred temperature and oxygen fugacity constraints of pele s basaltic magma to determine the behavior of sulfur in the ionian magmas sulfate to sulfide ratios of pele s magma are 4 084 0 6 and 6 442 0 7 log 10 units comparable to or lower than those of mid ocean ridge basalts this reflects the similarity of io s oxidation state with earth s depleted mantle as previously suggested by zolotov and fegley zolotov m y fegley b 2000 geophys res lett 27 2789 2792 our calculated limits of sulfur solubility in melts from pele s patera 1100 1140 ppm are also comparable to terrestrial mid ocean ridge basalts reflecting a compositional similarity of mantle sources we propose that the excess sulfur obvious on io s surface comes from two sources 1 an insoluble sulfide liquid phase in the magma and 2 theothermal near surface recycling

crossing the several scales of strain accomplishing mechanisms in the hinterland of the central andean fold thrust belt bolivia depictions of structures at outcrop regional and tectonic scales enforce horizontal shortening and vertical thickening as the predominant style of deformation at all scales within the hinterland of the central andean fold thrust belt outcrop scale structures document a progression of strain that created 1 flexural slip folds 2 fold flattening via axial planar cleavage 3 vertical stretching via boudinage and late stage faulting and finally 4 kink folding these examples of intraformational deformation are generally concentrated just beyond the tip lines of thrust faults where fault propagation folds and related structures are well developed fault propagation folding accommodated the accrual of strain indicated by outcrop scale structures while the structures themselves indicate how deformation developed within each individual fold fault propagation fold geometries at a regional scale emerge from the construction of regional balanced cross sections the sections were drawn with careful attention to 1 known map relationships 2 field inspection of key contacts 3 bedding orientation data 4 local seismic control and 5 principles of balance the pervasive ese wnw shortening and vertical elongation seen at the outcrop and regional scales developed during the formation of the central andean backthrust belt in the hinterland of the andes the central andean backthrust belt is a large scale west vergent thrust system along the western side of the eastern cordillera in the generally east vergent andean fold thrust belt of bolivia strain accrual within this west verging zone of deformation is proposed to be a taper building mechanism that allowed the fold thrust belt to continue propagating eastward

multi phase volcanic resurfacing at loki patera on io the jovian moon io hosts the most powerful persistently active volcano in the solar system loki patera the interior of this volcanic caldera like feature is composed of a warm dark floor covering 21 500 square kilometres surrounding a much cooler central island the temperature gradient seen across areas of the patera indicates a systematic resurfacing process which has been seen to occur typically every one to three years since the 1980s analysis of past data has indicated that the resurfacing progressed around the patera in an anti clockwise direction at a rate of one to two kilometres per day and that it is caused either by episodic eruptions that emplace voluminous lava flows or by a cyclically overturning lava lake contained within the patera however spacecraft and telescope observations have been unable to map the emission from the entire patera floor at sufficient spatial resolution to establish the physical processes at play here we report temperature and lava cooling age maps of the entire patera floor at a spatial sampling of about two kilometres derived from ground based interferometric imaging of thermal emission from loki patera obtained on 8 march 2015 ut as the limb of europa occulted io our results indicate that loki patera is resurfaced by a multi phase process in which two waves propagate and converge around the central island the different velocities and start times of the waves indicate a non uniformity in the lava gas content and or crust bulk density across the patera

modern and long term evaporation of central andes surface waters suggests paleo archives underestimate neogene elevations abstract central andean paleoelevations reconstructed from stable isotope and paleofloral data imply a large magnitude 2 km miocene to modern surface uplift however the isotopic relationships between precipitation surface waters and soil waters upon which these reconstructions are based remain poorly constrained for both past and in many cases modern conditions we quantify the relationships between central andean precipitation and surface waters by measuring the isotopic composition of 249 stream water samples 18o and d collected between april 2009 and october 2012 the isotopic compositions of stream waters match precipitation along the eastern flank in contrast altiplano surface waters possess a lower d 18o slope 4 59 vs 8 for meteoric waters not observed in precipitation which signals heavy isotope evaporative enrichment in surface waters paleoclimate models indicate that highly evaporative conditions have persisted on the plateau throughout andean uplift and that conditions may have been more evaporative when the andes were lower thus more ancient proxy materials may have a greater evaporative bias than previously recognized and paleoelevation reconstructions from stable isotope based central andean plateau proxy materials likely overstate miocene to present surface uplift we propose altiplano paleoelevations of 1 2 km at 24 5 ma 1 5 2 9 km by 11 45 ma and modern elevations by 6 ma based on the lightest isotopic compositions observed in altiplano proxy materials which are least likely to be influenced by evaporation these constraints limit total late miocene to modern uplift to

loki io a periodic volcano loki is the most powerful volcano in the solar system it has been observed to be in continuous though variable activity since 1979 synthesis of more than a decade of groundbased data suggests that loki eruptions are cyclic with a 540 day period application of a simple lava cooling model to temperatures in loki patera and eruption start and end times implies that brightenings are due to a resurfacing wave propagating across the patera the data are most consistent with lava lake overturn but resurfacing by lava flows cannot be ruled out a porosity gradient in the lake crust could cause lava lake overturn to occur periodically on the timescale observed

counterclockwise rotation of late eocene oligocene fore arc deposits in southern peru and its significance for oroclinal bending in the central andes the results of a paleomagnetic study along the fore arc of southern peru 15 18 s and northern chile 18 19 s are reported from middle to late miocene ignimbrites 7 sites late oligocene to early miocene ignimbrites 72 sites paleogene sediments 20 sites and mesozoic and paleocene volcanics and intrusions 31 sites comparison of locality mean directions with expected paleomagnetic directions indicates vertical axis rotations ranging from 5 2 11 3 clockwise to 55 6 7 0 counterclockwise spatially the magnitude of counterclockwise rotations increases northward from 0 within the chilean fore arc south of 18 30 s to 45 north of 16 30 s in southern peru paleomagnetic rotations recorded in paleogene red beds decrease from late eocene to late oligocene whereas miocene ignimbrites display no evidence of rotation these new results confirm that the rotations recorded in the fore arc of southern peru were acquired at least before 15 ma and probably before 25 ma and thus prior to the late neogene shortening of the sub andes the onset of major andean shortening in the eastern cordillera during the latest eocene earliest oligocene is interpreted to have triggered the bending of the peruvian fore arc the region of the peruvian fore arc with the largest rotations appears to be the fore arc counterpart of the abancay deflection a remarkable ne sw offset in the axis of the eastern cordillera induced by a major regional preorogenic structure we underline that the abancay deflection should be seen as the northwestern boundary and therefore as a key element of the bolivian orocline

lava lakes on io new perspectives from modeling abstract loki patera 310 w 12 n is io s largest patera at 180 km in diameter its morphology and distinct thermal behavior have led researchers to hypothesize that loki patera may either be an active lava lake that experiences periodic overturn or a shallow depression whose floor is episodically resurfaced with thin flows using results from mathematical models we suggest that a better model for loki s behavior is the terrestrial superfast spreading east pacific rise epr near 17 30 south we propose that like at the southern epr loki patera is underlain by a thin persistent magma lens that feeds thin temporary lava lakes within the patera also like the southern epr overspilling of the volcanic depression is rare with most of the lava volume being emplaced via a subsurface network of lava tubes

overriding plate shortening and extension above subduction zones a parametric study to explain formation of the andes mountains mountain building above subduction zones such as observed in the andes is enigmatic and the key parameter controlling the underlying dynamics remains a matter of considerable debate a global survey of subduction zones is presented here illustrating the correlation between overriding plate deformation rate and twelve physical parameters overriding plate velocity subducting plate velocity trench velocity convergence velocity subduction velocity subduction zone accretion rate subducting plate age subduction polarity shallow slab dip deep slab dip lateral slab edge proximity and subducting ridge proximity all correlation coefficients are low r 0 39 irrespective of the global reference frame relative plate motion model or overriding plate deformation model except for the trench velocity 0 33 0 68 exact value depends on adopted global reference frame and subduction velocity which shows an anticorrelation 0 55 0 57 this implies that no individual parameter can explain overriding plate deformation except that trench retreat generally corresponds to extension while an approximately stable trench or trench advance generally corresponds to shortening understanding of the variety of strain patterns is obtained when slab edge proximity and overriding plate velocity are combined orogenesis occurs in overriding plates bordering central regions of wide subduction zones 4000 km when the overriding plate is moving trenchward at 0 2 cm yr e g andes japan because the center of a wide slab offers large resistance to lateral migration the overriding plate effectively collides with the subduction hinge forcing the slab to attain a shallow dip angle e g nazca and japan slabs overriding plate extension is only found close to lateral slab edges or during overriding plate motion away from the center of a wide subduction zone but in the latter scenario maximum extension velocities are much lower than in the former scenario for subduction settings close to lateral slab edges overriding plate motion plays no significant role in overriding plate deformation thus for rapid overriding plate extension the key ingredient is rapid trench retreat which only occurs close to lateral slab edges while for overriding plate shortening the key ingredients are 1 the resistance to rapid trench and hinge retreat which occurs far from lateral slab edges and 2 trenchward overriding plate motion

ridges and tidal stress on io abstract sets of ridges of uncertain origin are seen in twenty nine high resolution galileo images which sample seven locales on io these ridges are on the order of a few kilometers in length with a spacing of about a kilometer within each locale the ridges have a consistent orientation but the orientations vary from place to place we investigate whether these ridges could be a result of tidal flexing of io by comparing their orientations with the peak tidal stress orientations at the same locations we find that ridges grouped near the equator are aligned either north south or east west as are the predicted principal stress orientations there it is not clear why particular groups run north south and others east west the one set of ridges observed far from the equator 52 s has an oblique azimuth as do the tidal stresses at those latitudes therefore all observed ridges have similar orientations to the tidal stress in their region this correlation is consistent with the hypothesis that tidal flexing of io plays an important role in ridge formation

a post galileo view of io s interior abstract we present a self consistent model for the interior of io taking the recent galileo data into account in this model io has a completely molten core substantially molten mantle and a very cold lithosphere heat from magmatic activity can mobilize volatile compounds such as so 2 in the lithosphere and the movement of such cryogenic fluids may be important in the formation of surface features including sapping scarps and paterae

charting thermal emission variability at amirani with the galileo nims io thermal emission database nited abstract we have examined the variability of thermal emission from lava flows at amirani on io using measurements of radiant flux from detections by the galileo near infrared mapping spectrometer nims between 1996 and 2001 amirani is the longest currently active lava flow field in the solar system and a persistent thermal source in every galileo nims observation that covers its location we have quantified the thermal emission from hot spots correlated with discrete areas of new lava flow emplacement at points along the length of the amirani flow field in high spatial resolution nims observations in 2000 and 2001 where discernible the position of some effusive activity changes from orbit to orbit we find the implied style of emplacement of lava at amirani is consistent with pahoehoe like flows there is an estimated 50 decrease in discharge rate between 1997 and late 2001 perhaps linked to an outburst eruption in the amirani vicinity in february 2001 the variability of thermal emission from amirani is less than that seen at a number of other persistently active ionian volcanoes such as prometheus culann and loki patera all of these volcanoes exhibit large increases and decreases in the absolute magnitude of thermal emission see matson et al 2006 loki patera davies a g et al 2006 icarus 184 460 477 prometheus and davies a g ennis m e 2011 icarus 215 401 416 culann at amirani as at these volcanoes the thermal emission measured between 1996 and 2001 indicates a persistent although variable supply of magma to the surface in high spatial resolution nims observations of hot spots obtained in 2000 and 2001 we estimate the emitted power from active lava flows associated with amirani to be 170 30 gw which corresponds to total effusion rates assuming a basaltic composition from multiple points along the amirani flow of 34 56 m 3 s

lava lake surface characterization by thermal imaging erta ale volcano ethiopia the project sviluppo di sistemi di monitoraggio dipartimento di protezione civile di regione sicilia ingv catania section italy the leverhulme trust the bbc and the ethiopian air force

temperature age and crust thickness distributions of loki patera on io from galileo nims data implications for resurfacing mechanism 1 a high spatial resolution multi wavelength observation by the galileo nims instrument has been analysed to determine the temperature and area distribution of a large portion of the ionian volcano loki patera the temperatures of the cooler components from a two temperature fit to the data can be used to determine ages of the surface the age of the floor along a profile across the floor of the caldera ranges from 10 to 80 days this puts the start of the resurfacing in july early august 2001 yielding a resurfacing rate of approximately 1 km day with the new lava spreading from the sw corner of the caldera in a ne direction this rate is consistent with resurfacing by foundering of the crust on a lava lake however the temperature distribution may also result from the emplacement of flows implied crust thicknesses derived using a lava cooling model range from 2 6 to 0 9 m

global color variations on io abstract visible and near infrared images of io from the galileo spacecraft reveal a surface more colorful than previously thought red yellow green white and black hues decorate the satellite presumably caused by a varied composition of sulfur compounds and silicates almost a third of io is covered by red and orange materials particularly at polar latitudes above 30 these red regions were scarcely distinguishable in the shorter wavelength voyager observations bright red pyroclastic deposits mark the locations of many hot spots plumes and visible surface changes providing a prominent flag of recent volcanic activity io s equatorial regions are dominated by yellow materials which occupy about 40 of the satellite s surface white and gray materials cover about 27 of io primarily in equatorial areas and in localized deposits at high latitudes these are identified with moderate to coarse grained so2 as mapped by the nims instrument on galileo r w carlson et al 1997 geophys res lett 24 2479 2482 greenish yellow materials in small isolated spots on io s anti jupiter hemisphere were recently discovered in 3 km pixel color imaging from orbit 14 unlike other ionian terrains these regions have a negative near infrared spectral slope suggesting contamination by a nonsulfur component only about 1 4 of io s surface is occupied by dark materials which display a variety of visible colors ranging from black to red and green most dark spots have a shallow spectral absorption feature at 0 9 m suggesting magnesium rich silicates rather than black sulfur little large scale alteration in the global color and albedo pattern has occurred between the voyager and galileo eras 90 of the surface appears unchanged despite the vigorous volcanic activity which must have taken place in the intervening 17 years this suggests that over a time scale of decades the bulk of io s resurfacing is restricted to a few small but persistently active areas

lava lakes on io observations of io s volcanic activity from galileo nims during the 2001 fly bys abstract galileo s near infrared mapping spectrometer nims obtained its final observations of io during the spacecraft s fly bys in august i31 and october 2001 i32 we present a summary of the observations and results from these last two fly bys focusing on the distribution of thermal emission from io s many volcanic regions that give insights into the eruption styles of individual hot spots we include a compilation of hot spot data obtained from galileo voyager and ground based observations at least 152 active volcanic centers are now known on io 104 of which were discovered or confirmed by galileo observations including 23 from the i31 and i32 io fly by observations presented here we modify the classification scheme of keszthelyi et al 2001 j geophys res 106 e12 33 025 33 052 of io eruption styles to include three primary types promethean lava flow fields emplaced as compound pahoehoe flows with small plumes 200 km high plumes and rapidly emplaced flow fields and a new style we call lokian that includes all eruptions confined within paterae with or without associated plume eruptions thermal maps of active paterae from nims data reveal hot edges that are characteristic of lava lakes comparisons with terrestrial analogs show that io s lava lakes have thermal properties consistent with relatively inactive lava lakes the majority of activity on io based on locations and longevity of hot spots appears to be of this third type this finding has implications for how io is being resurfaced as our results imply that eruptions of lava are predominantly confined within paterae thus making it unlikely that resurfacing is done primarily by extensive lava flows our conclusion is consistent with the findings of geissler et al 2004 icarus this issue that plume eruptions and deposits rather than the eruption of copious amounts of effusive lavas are responsible for io s high resurfacing rates the origin and longevity of islands within ionian lava lakes remains enigmatic

io s volcanism thermo physical models of silicate lava compared with observations of thermal emission abstract analyses of thermal infrared outbursts from the jovian satellite io indicate that at least some of these volcanic events are due to silicate lava analysis of the january 9 1990 outburst indicates that this was an active eruption consisting of a large lava flow with mass eruption rate of order 10 5 m 3 sec 1 and a sustained area at silicate liquidus temperatures this is interpreted as a series of fire fountains along a rift zone a possible alternative scenario is that of an overflowing lava lake with extensive fire fountaining the january 9 1990 event is unique as multispectral observations with respect to time were obtained in this paper a model is presented for the thermal energy lost by active and cooling silicate lava flows and lakes on io the model thermal emission is compared with earth based observations and voyager iris data the model a provides an explanation of the thermal anomalies on io s surface b provides constraints on flow behavior and extent and infers some flow parameters and c determines flow geometry and change in flow size with time and the temperature of each part of the flow or lava lake surface as a function of its age models of heat output from active lava flows or inactive but recently emplaced lava flows or overturning lava lakes alone are unable to reproduce the observations if the january 9 1990 event is the emplacement of a lava flow the equivalent of 27 such events per year would yield a volume of material sufficient if uniformly distributed to resurface all of io at a rate of 1 cm year

temperature of an active lava channel from spectral measurements kilauea volcano hawaii a narrow band spectroradiometer was used to determine the characteristic temperatures of a very active channeled lava flow for the phase 50 eruption of pu u o o on the east rift zone of kilauea volcano hawaii during the twilight of 19 february 1992 14 spectra of this activity were acquired over a 51 minute interval 18 29 to 19 20 hawaiian standard time hst from which the thermal distribution of energy of two 18 m2 areas one near the center and one near the margin of the flow may be investigated a twocomponent thermal mixing model applied to the data taken of the center of the channel gave in the most powerful instance 1 8x105 w m2 a crust temperature of 940 c a hot component temperature of 1120 c and a hot radiating area of 60 of the total area a simultaneous spectrum acquired near the channeled flow margin yielded a crust temperature of 586 c and a hot area of only 1 2 of the total area radiating at 1130 c average radiant flux densities recorded for the center of the lava channel 1 3x105 w m2 average are much greater than previous measurements of lava lakes 4 9x103 w m2 or recently emplaced lava flows maximum of 7 2x104 w m2 the energetic nature of this eruption is shown by satellite measurements made at 02 33 hst on 22 february 1992 by the advanced very high resolution radiometer in band 2 0 72 1 10 m these show the utility of using existing satellites with moderate resolution 1 km x 1 km pixels and high temporal coverage eight overpasses each day for hawaii as potential thermal alarms for rapidly assessing the hazard potential of large volcanic eruptions

the thermal signature of volcanic eruptions on io and earth abstract we investigate a spectrum based technique to identify the style of active volcanic eruptions on jupiter s moon io thermal remote sensing of io has had to rely primarily on low spatial resolution data similar to low spatial resolution satellite data applied to detecting and charting the temporal evolution of terrestrial hot spots these terrestrial analyses use data from sensors designed to monitor the weather and sea surface temperature on io such low spatial resolution data are used to classify eruption styles modes of emplacement by means of several criteria related to the temporal evolution of the infrared spectrum associated with the eruptive activity at each hot spot which we term thermal signature we find that the ratio of the emission at 2 and 5 m and how this ratio changes with time is often diagnostic of eruption style even in low spatial resolution data tests using thermal data for terrestrial ground truth cases show that our classification system is valid on earth the results of our analysis can be used to aid in the design of future space based instruments that can be used for volcano monitoring on io as well as earth

orogenic tectonism on io 1 we catalog 143 ionian mountains montes and mountain like features mensae tholi plana and small peaks in order to investigate orogenic tectonism on io from this comprehensive list we select 96 mountains for which there are sufficient coverage and resolution to discern spatial relationships with surrounding geologic features three of the 96 mountains are probably volcanoes 92 appear to be tectonic massifs and 1 is ambiguous of the 92 tectonic mountains 38 abut paterae volcanic or volcano tectonic craters with irregular or scalloped margins this juxtaposition is unlikely to be a coincidence as the probability of it occurring by chance is 0 1 we propose instead that orogenic faults may act as conduits for magma ascent thus fueling patera formation near mountains as resurfacing buries a shell of material from io s surface to the base of the lithosphere its effective radius is reduced and it heats up we calculate the lithospheric volume change due to subsidence and thermal expansion as a function of lithospheric thickness conservation of volume dictates that this material must be uplifted at io s surface by estimating the total volume of the mountains we are able to place a lower limit of 12 km on io s lithospheric thickness we hypothesize that in some cases mountain formation may be facilitated by asthenospheric diapirs impinging on the base of the lithosphere the resulting lithospheric swell could focus the compressive stresses that drive orogenic tectonism this model is one of several possible mechanisms for uplifting isolated mountains such as are observed on io

a novel technology for measuring the eruption temperature of silicate lavas with remote sensing application to io and other planets abstract the highly variable and unpredictable magnitude of thermal emission from evolving volcanic eruptions creates saturation problems for remote sensing instruments observing eruptions on earth and on io the highly volcanic moon of jupiter for io it is desirable to determine the temperature of the erupting lavas as this measurement constrains lava composition one method of determining lava eruption temperature is by measuring radiant flux at two or more wavelengths and fitting a blackbody thermal emission function only certain styles of volcanic activity are suitable those where detectable thermal emission is from a restricted range of surface temperatures close to the eruption temperature volcanic processes where this occurs include large lava fountains smaller lava fountains common in active lava lakes and lava tube skylights problems that must be overcome to obtain usable data are 1 the rapid cooling of the lava between data acquisitions at different wavelengths 2 the unknown magnitude of thermal emission which has often led to detector saturation and 3 thermal emission changing on a shorter timescale than the observation integration time we can overcome these problems by using the hot bird detector and a novel advanced digital readout circuit d roic to achieve a wide dynamic range sufficient to image lava on io without saturating we have created an instrument model that allows various instrument parameters including mirror diameter number of signal splits exposure duration filter band pass and optics transmissivity to be tested to determine the detectability of thermal sources on io s surface we find that a short wavelength infrared instrument on an io flyby mission can achieve simultaneity of observations by splitting the incoming signal for all relevant eruption processes and still obtain data fast enough to remove uncertainties in accurate determination of the highest lava surface temperatures observations at 1 and 1 5 m are sufficient for this purpose even with a ten way beam split instrument throughput generates acceptable signal to noise values accurate constraints on lava eruption temperature are also possible with a visible wavelength detector so long as data at different wavelengths are obtained simultaneously and integration time is very short fast integration times are important for examining the thermal emission from lava tube skylights due to rapidly changing viewing geometry during close flybys the technology described here is applicable to instruments observing terrestrial volcanism and for investigating proposed volcanic activity on venus where lava composition is not known

tidal dissipation surface heat flow and figure of viscoelastic models of io abstract the distribution of hot spots on io s surface and io s figure constrain models of io s interior voyager observations indicate that most hot spots and volcanic plumes are close to the equator recently however it has been proposed that a large low albedo feature in the south polar region may be the source of 40 of the surface heat flow we calculate spatial distributions of the dissipation rate surface heat flow and the figures of three and four layer maxwell rheology models of io by using the correspondence principle the models are required to satisfy the observed surface heat flow constraint and are consistent with the composition of a dehydrated c2 chondrite they consist of an inviscid fe fes core and viscoelastic silicate mantle and lithosphere layers a comparison of the calculated equilibrium figure with the observed figure of io supports the chosen core radius of 980 km in addition the four layer model has a partially molten asthenosphere a few tens of kilometers thick the preferred three layer model has a mantle shear modulus of 10 10 pa and a viscosity of 2 10 16 pa s consistent with rock properties the tidal dissipation rate for this model is largest along the polar axis integration of the dissipation rate over radius gives a surface heat flow with maxima at the poles and minima near the sub jovian and anti jovian points in contrast the dissipation rate in a molten or partially molten incompressible asthenosphere has maxima near the equator and is close to zero at the poles the asthenosphere dissipation rate is mainly a function of asthenosphere viscosity and thickness the thinner the asthenosphere the smaller is the required viscosity a 50 km thick asthenosphere requires a viscosity of about 10 8 pa s a strong south polar hot spot if it can be confirmed by infrared observation favors dissipation in the mantle but does not exclude dissipation in a partially molten asthenosphere equatorial hot spots and the concentration of prometheus type plumes near the equator favor asthenosphere heating but do not rule out deep mantle dissipation both asthenosphere and deep mantle heating may contribute to io s surface heat flow the properties of magma transport through the lithosphere and the planform of mantle convection might exert a control on the surface expression of heating at greater depth

time variability of io s volcanic activity from near ir adaptive optics observations on 100 nights in 2013 2015 abstract jupiter s moon io is a dynamic target exhibiting extreme and time variable volcanic activity powered by tidal forcing from jupiter we have conducted a campaign of high cadence observations of io with the goal of characterizing its volcanic activity between aug 2013 and the end of 2015 we imaged io on 100 nights in the near infrared with adaptive optics on the keck and gemini n telescopes which resolve emission from individual volcanic hot spots during our program we made over 400 detections of 48 distinct hot spots some of which were detected 30 times we use these observations to derive a timeline of global volcanic activity on io which exhibits wide variability from month to month the timelines of thermal activity at individual volcanic centers have geophysical implications and will permit future characterization by others we evaluate hot spot detection limits and give a simple parameterization of the minimum detectable intensity as a function of emission angle which can be applied to other analyses we detected three outburst eruptions in august 2013 but no other outburst scale events were observed in the subsequent 90 observations either the cluster of events in august 2013 was a rare occurrence or there is a mechanism causing large events to occur closely spaced in time we also detected large eruptions though not of outburst scale within days of one another at kurdalagon patera and sethlaus gabija paterae in 2015 as was also seen in the galileo dataset the hot spots we detected can be separated into two categories based on their thermal emission those that are persistently active for 1 year or more at moderate intensity and those that are only briefly active are time variable and often reach large intensities a small number of hot spots in the latter category appear and subside in a matter of days reaching particularly high intensities although these are not bright enough to qualify as outbursts their thermal signatures follow the same pattern suggesting that a similar mechanism may be responsible for these events though at a smaller scale two eruptions seen at kurdalagon patera in january and april 2015 occurred simultaneously with a brightening of the neutral cloud and plasma torus which are sourced from io s atmosphere a plume at kurdalagon patera such as was seen by new horizons in 2007 could have been responsible for the influx of material that caused these brightenings

volcanic hot spots on io correlation with low albedo calderas comparison of voyager imaging data with voyager 1 infrared observations iris and with ground based telescopic infrared data demonstrates a strong correlation between hot spots and low albedo features reflectivity 0 3 in all visual wavelengths on io most of these low albedo areas occur on the floors of volcanic calderas and many are associated with active or recent volcanism we use this correlation to identify additional hot spots in regions not observed by iris and to model their temperatures the major features discovered by this method are in a ringlike structure in the south polar region centered at 140 w 75 s and amaterasu patera 307 w 38 n our model temperature for the south polar feature is 280 50 k taking account of the high latitudes of these features the estimated global average heat flow from the hot spots becomes 1 8 0 5 w m 2 most of this heat emanates from just a few very large hot spots the global distribution of hot spots is further evidence that io is a dimorphous body the hemisphere centered on 310 w 30 s is much more volcanically active than the opposite hemisphere the styles of heat transfer in io conductive versus convective may be related to the global distribution of hot spots large eruptive plumes and large scale topographic relief the correlation between hot spots and dark areas is due to 1 the absence of the bright materials such as so2 frost which cover most of the surface and 2 the presence of a low albedo substance spectral properties of the low albedo features extracted from the voyager multispectral data are consistent with a number of candidate materials liquid sulfur boiled sulfur silicate sulfur mixtures zinc sulfide fe sulfate and fe chloride quenched sulfur allotropes on the other hand are redder than the low albedo features on io and are incompatible with the elevated temperatures of the hot spots some of the dark caldera floor materials may be liquid sulfur and or thermally altered boiled sulfur liquid sulfur would tend to collect in the topographic depressions and fractured bedrock of the calderas and this would explain the concentration of low albedo material in the calderas the presence of liquid sulfur is also suggested by the hot spot temperature distribution typically 200 400 k and by morphologies suggestive of lava lakes however the liquid boiled sulfur model does not seem to work for babbar and amaterasu paterae and the evidence for liquid sulfur is not conclusive

io evidence for silicate volcanism in 1986 infrared observations of io during the 1986 apparition of jupiter indicate that a large eruptive event occurred on the leading side of io on 7 august 1986 universal time measurements made at 4 8 8 7 and 20 micrometers suggest that the source of the event was about 15 kilometers in radius with a model temperature of 900 kelvin together with previously reported events these measurements indicate that high temperature volcanic activity on the leading side of io may be more frequent than previously thought the inferred temperature is significantly above the boiling point of sulfur in a vacuum 715 kelvin and thus constitutes strong evidence for active silicate volcanism on the surface of io

active volcanism on io global distribution and variations in activity abstract io s volcanic activity has been monitored by instruments aboard the galileo spacecraft since june 28 1996 we present results from observations by the near infrared mapping spectrometer nims for the first 10 orbits of galileo correlate them with results from the solid state imaging system ssi and from groundbased observations and compare them to what was known about io s volcanic activity from observations made during the two voyager flybys in 1979 a total of 61 active volcanic centers have been identified from voyager groundbased and galileo observations of these 41 are hot spots detected by nims and or ssi another 25 locations were identified as possible active volcanic centers mostly on the basis of observed surface changes hot spots are correlated with surface colors particularly dark and red deposits and generally anti correlated with white so 2 rich areas surface features corresponding to the hot spots mostly calderas or flows were identified from galileo and voyager images hot spot temperatures obtained from both nims and ssi are consistent with silicate volcanism which appears to be widespread on io two types of hot spot activity are present persistent type activity lasting from months to years and sporadic events which may represent either short lived activity or low level activity that occasionally flares up sporadic events are not often detected but may make an important contribution to io s heat flow and resurfacing the distribution of active volcanic centers on the surface does not show any clear correlation with latitude longitude voyager derived global topography or heat flow patterns predicted by the asthenosphere and deep mantle tidal dissipation models however persistent hot spots and active plumes are concentrated toward lower latitudes and this distribution favors the asthenosphere rather than the deep mantle tidal dissipation model

possible flexural accommodation on the eastern edge of the altiplano in relation to focussed erosion in the rio la paz drainage system it has been proposed that erosional unloading by focused incision can be accommodated by flexural rebound which in turn potentially exerts a positive feedback on erosion this paper presents morphometric data from the la paz drainage basin in the bolivian andes to illustrate the effects of such a feedback mechanism between erosion and crustal bending the rio la paz is a prominent system with the headwaters on the altiplano and a trunk stream segment that cuts across the cordillera real thereby connecting large portions of the altiplano with the amazon basin the flexural feedback model explains why all drainages beyond the watershed disperse their waters to the altiplano it also provides an explanation for the presence of the highest peaks just next to the location where the la paz river cuts into the bedrock across the cordillera real

tectonic styles and crustal shortening of the central andes pampean flat slab segment in northern chile 27 29 s abstract the andean orogenic belt located in the central andes pampean flat slab segment in northern chile 27 29 s is composed of two major tectonic regions the coastal cordillera and the frontal cordillera to understand their internal tectonic styles history of growth and the shortening absorbed by the upper crustal structure of this segment we combined regional geological mapping data new ages obtained from radiometric u pb dating and a semibalanced and restored cross section 225 18 km in length the results as shown in the previous mesozoic extensional fault systems established in northern chile by the gondwana breakup have played a fundamental role in the orogenic buildup the central structure is characterized by an asymmetric basin upper cretaceous paleocene confined by a doubly vergent fault system composed of inverted faults related to the edges of the mesozoic chanarcillo and lautaro basins the u pb geochronological data obtained from synorogenic volcano sedimentary deposits and the angular unconformities recorded between the cenozoic geological units have revealed that the compressive deformation in this segment started at around 80 ma by tectonic inversion in the eastern coastal cordillera and western frontal cordillera however the presence of paleocene and miocene synorogenic successions at the footwall of the basement reverse faults of the frontal cordillera suggests a migration of andean deformation from the west to the east during the paleocene miocene by propagation of ramps involving inherited basement highs the pre compression restoration makes it possible to estimate 40 94 km of minimum shortening concentrated by inversion anticlines and fault controlled basement highs across the frontal cordillera

multi instrument remote and in situ observations of the erebus volcano antarctica lava lake in 2005 a comparison with the pele lava lake on the jovian moon io abstract the stable persistent active lava lake at erebus volcano ross island antarctica provides an excellent thermal target for analysis of spacecraft observations and for testing new technology in the austral summer of 2005 visible and infrared observations of the erebus lava lake were obtained with sensors on three space vehicles terra aster modis aqua modis and eo 1 hyperion ali contemporaneous ground based observations were obtained with hand held infrared cameras this allowed a quantitative comparison of the thermal data obtained from different instruments and of the analytical techniques used to analyze the data both with and without the constraints imposed by ground truth from the thermal camera data in december 2005 the main erebus lava lake ray lake had an area of 820 m2 surface colour temperatures ranged from 575 k to 1090 k with a broad peak in the distribution from 730 k to 850 k total heat loss was estimated at 23 5 mw the flux density was 29 kw m 2 mass flux was estimated at 64 to 93 kg s 1 the best correlation between thermal emission and emitting area was obtained with aster which has the best combination of spatial resolution and wavelength coverage especially in the thermal infrared the high surface temperature of the lava lake means that hyperion data are for the most part saturated uncertainties introduced by the need to remove incident sunlight cause the thermal emission from the hyperion data to be a factor of about two greater than that measured by hand held thermal camera modis also over estimated thermal output from the lava lake by the same factor of two because it was detecting reflected sunlight from the rest of the pixel area the measurement of the detailed temperature distribution on the surface of an active terrestrial lava lake will allow testing of thermal emission models used to interpret remote sensing data of volcanism on io where no such ground truth exists although the erebus lava lake is four orders of magnitude smaller than the lava lake at pele on io the shape of the integrated thermal emission spectra are similar thermal emission from this style of effusive volcanism appears to be invariant excess thermal emission in most pele spectra compared to erebus at short wavelengths

temperature and variability of pillan wayland patera and loki patera on io from cassini iss data abstract cassini spacecraft images of io obtained during its flyby of jupiter in late 2000 and early 2001 were used to determine the lava composition and eruption style of three faint hot spots pillan wayland patera and loki patera we found a maximum color temperature of 1130 289 k for pillan and maximum color temperatures of 1297 289 k and 1387 287 k for wayland patera and loki patera respectively these temperatures are suggestive of basaltic lava but an ultramafic composition cannot be ruled out the temperatures with the best signal to noise ratios also suggested basaltic lava and were found to be 780 189 k 1116 250 k and 1017 177 k for pillan wayland patera and loki patera respectively pillan showed constant thermal output within error over three days of observations the data also suggest pillan may be surrounded by topography that blocked emission in the middle of the observation and caused a more dramatic decrease in emission wayland patera s intensity decreased over the three eclipse observations consistent with a cooling lava flow or decreasing effusion rate intensities at loki patera over the course of the observations varied consistent with previous determinations that loki patera is an often quiescent lava lake with periods of overturning fountaining and crustal foundering

a new stereo topographic map of io implications for geology from global to local scales we use voyager and galileo stereo pairs to construct the most complete stereo digital elevation model dem of io assembled to date controlled using galileo limb profiles given the difficulty of applying these two techniques to io due to its anomalous surface albedo properties we have experimented extensively with the relevant procedures in order to generate what we consider to be the most reliable dems our final stereo dem covers 75 of the globe and we have identified a partial system of longitudinally arranged alternating basins and swells that correlates well to the distribution of mountain and volcano concentrations we consider the correlation of swells to volcano concentrations and basins to mountain concentrations to imply a heat flow distribution across io that is consistent with the asthenospheric tidal heating model of tackley et al 2001 the stereo dem reveals topographic signatures of regional scale features including loki patera ra patera and the tvashtar paterae complex in addition to previously unrecognized features including an 1000 km diameter depression and a 2000 km long topographic arc comprising mountainous and layered plains material

surface changes on io during the galileo mission abstract a careful survey of galileo ssi global monitoring images revealed more than 80 apparent surface changes that took place on io during the 5 year period of observation ranging from giant plume deposits to subtle changes in the color or albedo of patera surfaces explosive volcanic activity was discovered at four previously unrecognized centers an unnamed patera to the south of karei that produced a pele sized red ring a patera to the west of zal that produced a small circular bright deposit a large orange ring detected near the north pole of io and a small bright ring near io s south pole only a handful of io s many active volcanoes produced large scale explosive eruptions and several of these erupted repeatedly leaving at least 83 of io s surface unaltered throughout the galileo mission most of the hot spots detected from ssi nims and ground based thermal observations caused no noticeable surface changes greater than 10 km in extent over the five year period surface changes were found at every location where active plumes were identified including acala which was never seen in sunlight and was only detected through auroral emissions during eclipse two types of plumes are distinguished on the basis of the size and color of their deposits confirming post voyager suggestions by mcewen and soderblom icarus 55 1983 191 smaller plumes produce near circular rings typically 150 200 km in radius that are white or yellow in color unless contaminated with silicates and frequently coat their surroundings with frosts of fine grained so2 the larger plumes are much less numerous limited to a half dozen examples and produce oval orange or red sulfur rich rings with maximum radii in the north south direction that are typically in the range from 500 to 550 km both types of plumes can be either episodic or quasi continuous over a five year period repeated eruptions of the smaller so2 rich plumes likely contribute significantly to io s resurfacing rate whereas dust ejection is likely dominated by the tenuous giant plumes both types of plume deposits fade on time scales of months to years through burial and alteration episodic seepages of so2 at haemus montes zal montes dorian montes and the plateau to the north of pillan patera may have been triggered by activity at nearby volcanic centers

loki io new ground based observations and a model describing the change from periodic overturn 1 loki patera is the most powerful volcano in the solar system we have obtained measurements of loki s 3 5 micron brightness from nasa s infrared telescope facility irtf and have witnessed a major change in eruptive behavior while loki brightened by a factor of several every 540 days prior to 2001 from 2001 through 2004 loki remained at a constant intermediate brightness we have constructed a quantitative model of loki as a basaltic lava lake whose solidified crust overturns when it becomes buoyantly unstable by altering the speed at which the overturn propagates across the patera we can match our ground based brightness data in addition we can match other data taken at other times and wavelengths by slowing the propagation speed dramatically we can match the observations from 2001 2004 such slowing could be due to a small change in volatile content in the lava

paleogeographic and tectonic evolution of the pampia terrane in the cambrian new paleomagnetic constraints abstract paleomagnetic magnetic fabric and rock magnetic studies were carried out in the late middle to early late cambrian campanario formation exposed in nw argentina the study also presents preliminary results from the early cambrian metasediments of the puncoviscana formation and from mojotoro intrusive a new paleomagnetic pole c2 was computed for the campanario formation 23 6 n 346 5 e a95 7 0 n 11 sites from the localities of tilcara t terma de reyes r and el perchel ep including previous data from santa victoria oeste m in northernmost argentina a positive fold test was obtained for tilcara locality while a positive regional tilt test was obtained for mean site directions for the four localities this pole can be considered as the representative pole position for the pampia terrane for the late middle to late cambrian previous paleomagnetic data for the same formation from the iruya matancillas locality show an in situ clockwise rotation of about 30 around a vertical axis when compared with the mean pampia pole the same is observed when comparing the early ordovician pole for the santa rosita formation at those localities with the recently obtained coeval pole of the la pedrera formation indicating that local tectonic rotations affected that area these results suggest that previous paleomagnetic interpretations for these late cambrian and early ordovician rocks in the region as recording displacement of the pampia terrane in cambrian times are probably incorrect additionally two virtual geomagnetic poles were computed for the puncoviscana formation tp1 34 5 n 52 3 e a95 5 0 n 22 specimens and tp2 38 3 n 33 6 e a95 5 7 n 14 specimens and one for the mojotoro intrusive mo 9 1 n 345 6 e a95 16 4 n 11 specimens these and previous early cambrian paleomagnetic data from the pampia terrane differ from gondwana coeval reference directions in inclination and or declination lacking a simple pattern

the final galileo ssi observations of io orbits g28 i33 abstract we present the observations of io acquired by the solid state imaging ssi experiment during the galileo millennium mission gmm and the strategy we used to plan the exploration of io despite galileo s tight restrictions on data volume and downlink capability and several spacecraft and camera anomalies due to the intense radiation close to jupiter there were many successful ssi observations during gmm four giant high latitude plumes including the largest plume ever observed on io were documented over a period of eight months only faint evidence of such plumes had been seen since the voyager 2 encounter despite monitoring by galileo during the previous five years moreover the source of one of the plumes was tvashtar catena demonstrating that a single site can exhibit remarkably diverse eruption styles from a curtain of lava fountains to extensive surface flows and finally a 400 km high plume over a relatively short period of time 13 months between orbits i25 and g29 despite this substantial activity no evidence of any truly new volcanic center was seen during the six years of galileo observations the recent observations also revealed details of mass wasting processes acting on io slumping and landsliding dominate and occur in close proximity to each other demonstrating spatial variation in material properties over distances of several kilometers however despite the ubiquitous evidence for mass wasting the rate of volcanic resurfacing seems to dominate the floors of paterae in proximity to mountains are generally free of debris finally the highest resolution observations obtained during galileo s final encounters with io provided further evidence for a wide diversity of surface processes at work on io

io loki patera as a magma sea 1 we develop a physical model for loki patera as a magma sea we calculate the total volume of magma moving through the loki patera volcanic system every resurfacing cycle 540 days and the resulting variation in thermal emission the rate of magma solidification at times reaches 3 106 kg s 1 with a total solidified volume averaging 100 km3 yr 1 a simulation of gas physical chemistry evolution yields the crust porosity profile and the timescale when it will become dense enough to founder in a manner consistent with observations the loki patera surface temperature distribution shows that different areas are at different life cycle stages on a regional scale however there can be coordinated activity indicated by the wave of thermal change which progresses from loki patera s sw quadrant toward the ne at a rate of 1 km d 1 using the observed surface temperature distribution we test several mechanisms for resurfacing loki patera finding that resurfacing with lava flows is not realistic only the crustal foundering process is consistent with observations these tests also discovered that sinking crust has a heat deficit which promotes the solidification of additional magma onto the sinking plate bulking up in the limiting case the mass of sinking material can increase to a mass of 3 times that of the foundering plate with all this solid matter sinking there is a compensating upward motion in the liquid magma this can be in excess of 2 m yr 1 in this manner solid liquid convection is occurring in the sea

radiative temperature measurements at kupaianaha lava lake kilauea volcano hawaii field spectroradiometer data in the wavelength range of 0 4 2 5 m and spectral resolution of 1 5 nm have been used to compute the radiative temperature of the surface of kupaianaha lava lake kilauea volcano hawaii two sets of observations a total of 120 spectra were made on october 12 1987 and january 23 1988 when the lava lake was in a period of active overturning the area of the surface for which temperatures were measured was 0 23 0 55 m2 two numerical models of two and three components have been used to match the measured radiant flux ratios and to describe the surface of the lava pond in terms of radiant area and temperature three stages of activity on the lake surface are identified stage 1 characterized by magma fountaining and overturning events exhibited the hottest crustal temperatures 180 572 c and the largest fractional hot areas 10 3 stage 1 average flux densities were 2 2 104 w m2 the highest recorded for the three stages of activity on either day the largest radiative area of fresh magma was 29 at 1100 c while cooling from magmatic temperatures to newly formed crust at 790 c took place in a matter of seconds stage 2 marked by rifting events between plates of crust exhibited crustal temperatures between 100 and 340 c with fractional hot areas at least an order of magnitude lower than those found for stage 1 average flux densities calculated for three examples of stage 2 activity were 5 3 103 w m2 stage 3 which was quiescent periods when the lake was covered by a thick crust dominated the activity of the lake both temporally and spatially over 90 of the time the characteristic crustal temperature of stage 3 was 80 345 c with most solutions near 200 300 c and fractional hot areas of 10 5 of the viewing area average flux densities for stage 3 were 4 9 103 w m2 for many stage 3 examples a two component model was sufficient to describe the spectral data however for almost all of the stage 1 and 2 examples and the remainder of the stage 3 examples a three component model was required these determinations of lava temperature and radiant area have relevance for satellite and airborne measurements of the thermal characteristics of active volcanoes and indicate that temporal variability of the thermal output of lava lakes occurs on the time scale of seconds to minutes

the variability of volcanic activity at zamama culann and tupan patera on io as seen by the galileo near infrared mapping spectrometer abstract zamama culann and tupan patera are three large persistent volcanic centers on the jovian moon io as part of an ongoing project to quantify contributions from individual volcanic centers to io s thermal budget we have quantified the radiant flux from all suitable observations made by the galileo near infrared mapping spectrometer nims of these volcanoes in some cases filling omissions in previous analyses at zamama after a long period of cooling we see a peak in thermal emission that corresponds with new plume activity subsequently toward the end of the galileo epoch thermal emission from zamama drops off in a manner consistent with a greatly reduced eruption rate and the cooling of emplaced flows culann exhibits possible episodic activity we present the full tupan patera nims dataset and derive new estimates of thermal output and temporal behavior eruption rates at these three volcanoes are on the order of 30 m 3 s 1 consistent with a previous analysis of nims observations of prometheus and nearly an order of magnitude greater than kilauea volcano hawai i earth s most active volcano we propose that future missions to the jovian system could better constrain activity at these volcanoes and others where similar styles of activity are taking place by obtaining data on a time scale of ideally at least one observation per day observations at similar or even shorter timescales are desirable during initial waxing phases of eruption episodes these eruptions are identifiable from their characteristic spectral signatures and temporal behavior

is io s mantle really molten abstract the tremendous heating dissipated by jovian tides in io s interior is essentially evacuated by an intense volcanic activity so that the heat is removed from the interior to the surface much more by advection than by conduction through the lithosphere the efficiency of this heat pipe cooling process is investigated through numerical models of convection performed in spherical geometry with a permeable top boundary this new heat transfer model provides a cooling twice as efficient as that obtained with an impermeable condition traditionally used in mantle convection modeling the globally averaged temperature varies as ra 1 2 where ra is the rayleigh number whereas the power law exponent is classically 1 4 so that the expected ra would not be in excess of 10 7 if the whole mantle of io is involved in the convection process the major portion could remain solid while a possible molten zone could be confined to a 100 km thick layer between the solid part and the core this model predicts the existence of a strong lithosphere which is required to support the observed topographic amplitude of the io s relief

middle eocene deformation and sedimentation in the puna eastern cordillera transition 23 26 s control by preexisting heterogeneities on the pattern of initial andean shortening the quebrada de los colorados formation at the north end of calchaqui valley in salta province northwest argentina preserves evidence of syndepositional deformation since the middle eocene ca 40 ma that includes 1 an angular unconformity with the underlying salta group paleogene and 2 internal unconformities and changes in vertical facies succession and provenance its fossil record mammalian notoungulates middle eocene is correlatable to the casa grande formation which also unconformably overlies the salta group both units record middle eocene deformation along the eastern border of the puna plateau and outline previous fi rst order mechanical heterogeneities related to the cretaceous rift basin border along the western margin of the puna eocene deformation coincides with thermal magmatic arc and mechanical basin inversion heterogeneities thus the distribution of eocene deformation followed an irregular pattern as a consequence of the heritage of preexisting heterogeneities

two new rare high effusion outburst eruptions at rarog and heno paterae on io observations obtained with the near infrared camera nirc2 coupled to the adaptive optics system on the 10 m w m keck ii telescope on mauna kea hawaii on 15 august 2013 at 15 30 ut revealed two large outburst class volcanic eruptions on io follow up observations five days later showed that both eruptions had substantially faded the most energetic eruption was at rarog patera at a location near 305 w 42 s a smaller one occurred further south at 310 w and 57 s close to heno patera total radiant fluxes at rarog patera on august 15 were of order 500 gw sr m at wavelengths between 2 and 4 m and close to 250 gw sr m at 1 6 m indicative of an effective temperature of 1040 k over an area of 120 km 2 and a total thermal emission of nearly 8 tw at heno patera the 4 m flux measured 250 gw sr m and 90 gw sr m at 2 2 m suggestive of an effective temperature of 720 k over an area of more than 300 km 2 and a total thermal emission of 5 6 tw fits of the davies davies a g 1996 icarus 124 1 45 61 io flow model indicate that these two eruptions are vigorous and the exposed surfaces are mostly very young no older than 4 5 min at rarog patera and a few hours at heno patera the model fits suggest that in both locations lava fountaining is taking place a highly energetic style of volcanism using follow up observations taken between august 20 and september 7 we estimate peak effusion rates between 5 10 4 and 10 5 m 3 s

tectonic shortening and crustal thickness in the central andes how good is the correlation exceptional thickening of continental crust beneath the central andes is believed to be mainly a result of tectonic shortening of the south american plate in neogene time this shortening has been estimated to have contributed as much as 70 80 of the present crustal volume a compilation of published shortening values and our own estimates based on balanced cross sections from the central andes between lat 3 s and 40 s suggest that 70 80 is a maximum rather than an average value for this part of the andes tectonic shortening and the crustal cross section area are only loosely correlated variations in tectonic shortening are more abrupt than those of crustal areas particularly near the northern and southern ends of the altiplano puna high plateau where thick crust is associated with relatively small amounts of shortening shortening there may account for no more than about 30 of the present crustal cross section area the processes that created the remaining crustal area are not clear but are likely to involve poorly constrained pre neogene tectonic shortening moderate magmatic additions to the crust tectonic underplating of material derived from the forearc and possible flow of ductile lower crust along strike

quantifying the energy dissipation of overriding plate deformation in three dimensional subduction models in a subduction system the force and the energy required to deform the overriding plate are generally thought to come from the negative buoyancy of the subducted slab and its potential energy respectively such deformation might involve extension and back arc basin formation or shortening and mountain building how much of the slab s potential energy is consumed during overriding plate deformation remains unknown in this work we present dynamic three dimensional laboratory experiments of progressive subduction with an overriding plate to quantify the force fopd that drives overriding plate deformation and the associated energy dissipation rate opd and we compare them with the negative buoyancy fbu of the subducted slab and its total potential energy release rate bu respectively we varied the viscosity ratio between the plates and the sublithospheric upper mantle with sp um 157 560 and the thickness of the overriding plate with top 0 5 2 5 cm scaling to 25 125 km in nature the results show that fopd fbu has average values of 0 5 2 0 with a maximum of 5 3 and opd bu has average values of 0 05 0 30 with a maximum of 0 41 the results indicate that only a small portion of the negative buoyancy of the slab and its potential energy are used to deform the overriding plate our models also suggest that the force required to deform the overriding plate is of comparable magnitude as the ridge push force furthermore we show that in subduction models with an overriding plate bending dissipation at the subduction zone hinge remains low 3 15 during steady state subduction

near infrared monitoring of io and detection of a violent outburst on 29 august 2013 abstract we present initial data from our campaign to monitor io in the near infrared beginning in august 2013 using 3 8 m adaptive optics imaging at gemini n and 2 5 m disk integrated spectroscopy at nasa s irtf conducted during 2013 2014 these observations are coincident with the isas jaxa exceed mission s continuous monitoring of the io plasma torus and will enable the speculated effects of volcanic outgassing on the torus to be observed directly in addition to enabling an assessment of the frequency and properties of large scale outbursts on 29 august 2013 we detected a powerful eruption designated 201308c on io at 223 5 2 6 w 29 1 1 8 n emitting between 15 and 25 tw this event is one of the most powerful eruptions ever seen on io and falls into the rare outburst class this was the third eruption of this type seen on io in august 2013 an unprecedented occurrence also unprecedented was the charting of the decay in thermal emission over the subsequent days and weeks modeling of the outburst spectrum places a lower bound of 1200 1300 k on the eruption temperature and is suggestive of temperatures 1900 k or higher typically associated with ultramafic lava composition the eruption is likely a highly energetic high volume lava fountain event

high temperature hot spots on io as seen by the galileo solid state imaging ssi experiment high temperature hot spots on io have been imaged at 50 km spatial resolution by galileo s ccd imaging system ssi images were acquired during eclipses io in jupiter s shadow via the ssi clear filter 0 4 1 0 m detecting emissions from both small intense hot spots and diffuse extended glows associated with io s atmosphere and plumes a total of 13 hot spots have been detected over 70 of io s surface each hot spot falls precisely on a low albedo feature corresponding to a caldera floor and or lava flow the hot spot temperatures must exceed 700 k for detection by ssi observations at wavelengths longer than those available to ssi require that most of these hot spots actually have significantly higher temperatures 1000 k or higher and cover small areas the high temperature hot spots probably mark the locations of active silicate volcanism supporting suggestions that the eruption and near surface movement of silicate magma drives the heat flow and volcanic activity of io

the heartbeat of the volcano the discovery of episodic activity at prometheus on io the temporal signature of thermal emission from a volcano is a valuable clue to the processes taking place both at and beneath the surface the galileo near infrared mapping spectrometer nims observed the volcano prometheus on the jovian moon io on multiple occasions between 1996 and 2002 the 5 micron m brightness of this volcano shows considerable variation from orbit to orbit prometheus exhibits increases in thermal emission that indicate episodic though non periodic effusive activity in a manner akin to the current pu u o o kupaianaha afterwards referred to as the pu u o o eruption of kilauea hawai i the volume of material erupted during one prometheus eruption episode defined as the interval from minimum thermal emission to peak and back to minimum from 6 november 1996 to 7 may 1997 is estimated to be 0 8 km3 with a peak instantaneous volumetric flux effusion rate of 140 m3 s 1 and an averaged volumetric flux eruption rate of 49 m3 s 1 these quantities are used to model subsurface structure magma storage and magma supply mechanisms and likely magma chamber depth prometheus appears to be supplied by magma from a relatively shallow magma chamber with a roof at a minimum depth of 2 3 km and a maximum depth of 14 km this is a much shallower depth range than sources of supply proposed for explosive possibly ultramafic eruptions at pillan and tvashtar as prometheus type effusive activity is widespread on io shallow magma chambers containing magma of basaltic or near basaltic composition and density may be common this analysis strengthens the analogy between prometheus and pu u o o at least in terms of eruption style even though the style of eruption appears to be similar effusive emplacement of thin insulated compound pahoehoe flows the scale of activity at prometheus greatly exceeds current activity at pu u o o in terms of volume erupted area covered and magma flux whereas the estimated magma chamber at prometheus dwarfs the pu u o o magma chamber it fits within expectations if the pu u o o chamber were scaled for the greater volumetric flux and lower gravity of io recent volumetric eruption rates derived from galileo data for prometheus were considerably smaller than the rate that produced the extensive flows formed in the 17 years between the voyager and galileo missions these smaller eruption rates coupled with the fact that flows are not expanding laterally may mean that the immediate heat source that generates the prometheus plume is simultaneously running out of available volatiles and the thermal energy that drives mobilization of volatiles this raises the question of whether the current prometheus eruption is in its last throes

io heat flow from small volcanic features abstract we identify nine new faint thermal sources on io via color ratio images constructed from relatively high spatial resolution galileo nims data acquired late in the mission all of these identifications are associated with small dark paterae we utilize nims data to quantify their volcanic thermal emission as 0 53 1012 w or 0 5 of io s total heat flow in addition we refine our previous estimates of the thermal emission from 47 hot spots and highlight several hot spots within the amirani flow field small dark paterae still out number faint close to the limit of detection hot spots identified in high spatial resolution multi wavelength nims data in particular we point out 24 small dark paterae that were scanned by nims at resolutions down to 17 km pixel but had no detectable volcanic thermal emission all dark paterae are expected to have some volcanic thermal emission but the small size and finite number of detectable faint sources limit their contribution to the total heat flow on io compared to small paterae small dark flows are more numerous but must have significantly lower surface temperatures finally we update and summarize our results for the global heat flow on io due to 242 recently active volcanic features including other dark paterae as well as large dark flows the volcanic thermal emission from known hot spots undetected scanned dark patera and outbursts can account for only 56 2 1012 w or 54 of io s total heat flow approximately 49 1012 w or 46 of io s heat flow remains an enigma

composition and location of volatiles at loki patera io abstract volatiles play a critical role in determining the nature of volcanic activity on earth but their role in the volcanism on io is less clear to help determine that role we analyze voyager and galileo images of loki patera loki is the largest caldera in the solar system and io s most powerful volcano however its eruptive behavior is still not understood it appears to be relatively volatile poor in comparison to other sites like pele where volatiles drive a 350 km high plume a resurfacing wave either from spreading flows or from foundering of a lava lake crust periodically sweeps around loki patera photometry from voyager i and ii violet and blue images shows that most of the features in and around loki have colors well matched by macroscopic mixing of sulfur and basalt the dark western portion of the patera has the color of bare basalt assuming such a macroscopic sulfur basalt mix in the voyager i images most of the rest of the patera appears to be covered with a background of 13 38 sulfur we infer this background sulfur was deposited from the nearby plume observed by voyager i and ii the surface of the patera is also dotted by numerous small bright areas which have colloquially been called bergs we find that they are also composed of sulfur with coverage ranging up to 100 darker regions adjacent to the patera such as the southwest overflow are a mixture of intermediate amounts of sulfur and basalt the bathtub ring at the edge of the overflow is again roughly 100 sulfur perhaps with significant amounts of so 2 included colors seen during the voyager ii flyby are also consistent with this general pattern but most of the patera has a sulfur abundance higher than that seen in voyager i while the then dark southern portion is again close to the reflectance of bare basalt we have also analyzed the spatial distribution of the bergs they clearly avoid the inner and outer margins of the patera and they also avoid each other while a simple explanation of the above patterns could be that the bergs are fumarolic sulfur deposited on a periodically resurfaced lava lake crust other observations seem inconsistent with that simple model careful comparison of voyager i and galileo data shows that the largest bergs in the southern patera have survived the intervening 22 years this requires that at least those larger bergs represent some more permanent feature perhaps higher standing kipuka which avoid inundation by the lava resurfacing wave

structural control on volcanoes and magma paths from local to orogen scale the central andes case abstract assessing the parameters that control the location and geometry of magma paths is of paramount importance for the comprehension of volcanic plumbing systems and geo hazards we analyse the distribution of 1518 monogenic and polygenic volcanoes of miocene quaternary age of the central volcanic zone of the andes chile bolivia argentina and reconstruct the magma paths at 315 edifices by analysing the morphostructural characteristics of craters and cones then we compare these data with outcropping dykes tectonic structures and state of stress most magma paths trend n s nw se and ne sw in decreasing order of frequency the n s and nw se paths coexist in the northern and southern part of the study area whereas n s paths dominate east of the salar de atacama outcropping dykes show the same trends the regional holocene stress state is given by an e w greatest horizontal principal stress n s and nne ssw reverse faults and folds affect deposits of 4 8 3 2 and 1 3 ma bp especially in the central and southern study areas a few nw se left lateral strike slip faults are present in the interior of the volcanic arc part of which belong to the calama olacapato el toro fault the volcanic chain is also affected by several n s and nw se striking normal faults that offset pliocene and quaternary deposits the results indicate different scenarios of magma tectonic interaction given by n s normal and reverse faults and n s fold hinges that guide volcano emplacement and magma paths magma paths are also guided by strike slip and normal nw se faults especially in the northern part of the study area zones with verticalized strata with bedding striking ne sw also acted as preferential magma paths these data suggest that at convergence zones with continental crust shallow magma paths can be more sensitive to the presence and geometry of upper crustal weakness zones than to the regional state of stress

active volcanism on io as seen by galileo ssi abstract active volcanism on io has been monitored during the nominal galileo satellite tour from mid 1996 through late 1997 the solid state imaging ssi experiment was able to observe many manifestations of this active volcanism including 1 changes in the color and albedo of the surface 2 active airborne plumes and 3 glowing vents seen in eclipse about 30 large scale tens of kilometers surface changes are obvious from comparison of the ssi images to those acquired by voyager in 1979 these include new pyroclastic deposits of several colors bright and dark flows and caldera floor materials there have also been significant surface changes on io during the galileo mission itself such as a new 400 km diameter dark pyroclastic deposit around pillan patera while these surface changes are impressive the number of large scale changes observed in the four months between the voyager 1 and voyager 2 flybys in 1979 suggested that over 17 years the cumulative changes would have been much more impressive there are two reasons why this was not actually the case first it appears that the most widespread plume deposits are ephemeral and seem to disappear within a few years second it appears that a large fraction of the volcanic activity is confined to repeated resurfacing of dark calderas and flow fields that cover only a few percent of io s surface the plume monitoring has revealed 10 active plumes comparable to the 9 plumes observed by voyager one of these plumes was visible only in the first orbit and three became active in the later orbits only the prometheus plume has been consistently active and easy to detect observations of the pele plume have been particularly intriguing since it was detected only once by ssi despite repeated attempts but has been detected several times by the hubble space telescope at 255 nm pele s plume is much taller 460 km than during voyager 1 300 km and much fainter at visible wavelengths prometheus type plumes 50 150 km high long lived associated with high temperature hot spots may result from silicate lava flows or shallow intrusions interacting with near surface so2 a major and surprising result is that 30 of io s volcanic vents glow in the dark at the short wavelengths of ssi these are probably due to thermal emission from surfaces hotter than 700 k with most hotter than 1000 k well above the temperature of pure sulfur volcanism active silicate volcanism appears ubiquitous there are also widespread diffuse glows seen in eclipse related to the interaction of energetic particles with the atmosphere these diffuse glows are closely associated with the most active volcanic vents supporting suggestions that io s atmopshere is dominated by volcanic outgassing globally volcanic centers are rather evenly distributed however 14 of the 15 active plumes seen by voyager and or galileo are within 30 of the equator and there are concentrations of glows seen in eclipse at both the sub and antijovian points these patterns might be related to asthenospheric tidal heating or tidal stresses io will continue to be observed during the galileo europa mission which will climax with two close flybys of io in late 1999

global trench migration velocities and slab migration induced upper mantle volume fluxes constraints to find an earth reference frame based on minimizing viscous dissipation sincetheadventofplatetectonicsdifferentglobalreferenceframeshavebeenusedtodescribethemotionofplatesandtrenches thedifferencein plate motion and trench migration between different reference frames can be substantial up to 4 cm yr this study presents an overview of trench migration velocities for all the mature and incipient subduction zones on earth as calculated in eight different global reference frames calculations show that irrespective of the reference frame 1 trench retreat always dominates over trench advance with 62 78 of the 244 trench segments retreating 2 the mean and median trench velocity are always positive retreating and within the range 1 3 1 5 cm yr and 0 9 1 3 cm yr respectively 3 rapid trench retreat is only observed close to lateral slab edges b1500 km and 4 trench retreat is always slow far from slab edges n2000km thesecalculationsarepredictedbygeodynamicmodelswithavaryingslabwidth inwhichplatemotion trenchmotionandmantleflow result from subduction ofdense slabs suggesting that trenchmotion is indeedprimarily drivenby slab buoyancyforces andthat proximity to alateral slab edge exerts a dominant control on the trench migration velocity despite these four general conclusions significant differences in velocities between such reference frames remain it is therefore important to determine which reference frame most likely describes the true absolute velocities togetanunderstandingoftheforcesdrivingplatetectonicsandmantleconvection itishereproposedthat basedonfluiddynamicconsiderationsand predictions from geodynamic modelling the best candidate is the one which optimises the number of trench segments that retreat minimizes the trench perpendicular trench migration velocity vt in the centre of wide n4000 km subduction zones maximizes the number of retreating trench segments located within 2000 km of the closest lateral slab edge minimizes the average of the absolute of the trench perpendicular trench migration velocity vt forallsubductionzonesonearth andminimizestheglobaluppermantletoroidalvolumeflux to thatresultsfromtrenchmigration and associated lateral slab migration i e slab rollback or slab roll forward calculations show that these conditions are best met in one particular indo atlantic hotspot reference frame where 75 of the subduction zones retreat vt in the centre of wide subduction zones ranges between 3 5 and 1 8 cm yr 83 of the trench segments located within 2000 km of the closest lateral slab edge retreat the average of vt is 2 1 cm yr and to 456 km 3 yr lower limit and 539 km 3 yr upper limit inclusion of all the incipient subduction zones on earth results in slightly greater fluxes of 465 km 3 yr lower limit and 569 km 3 yr upper limit it is also found that this reference frame is close to minimizing the total sub lithospheric uppermantlevolumeflux k associatedwithmotionofcontinentalkeelslocatedbelowthemajorcratons itisstressed however that kisanorder of magnitude smaller than to and thus of subordinate importance in conclusion the indo atlantic hotspot reference frame appears preferable for calculating plate velocities and plate boundary velocities

magmatic differentiation of io abstract if io has been volcanically active through much of its history it must be highly differentiated we present an initial attempt to quantify the differentiation of the silicate portion of io we suggest that on average each part of io has undergone about 400 episodes of partial melting we employ a widely used thermodynamic model of silicate melts to examine the effect of such repeated differentiation despite many caveats including a grossly oversimplistic model of the differentiation process uncertainties in the initial composition of the mantle and the failure to model more than four episodes of partial melting we are able to make some robust conclusions io should have a roughly 50 km thick low density 2600 2900 kg m 3 alkali rich siliceous crust composed primarily of feldspars and nepheline the crustal magmas should have relatively low melting temperatures

variability and geologic associations of volcanic activity on io in 2001 2016 since the end of the galileo epoch ground based observations have been crucial for the continued monitoring and characterization of volcanic activity on jupiter s moon io we compile and analyze observations from the keck and gemini north telescopes between 2001 and 2016 including new and published observations from 2003 2004 2005 2007 2008 2009 2011 2012 2013 and 2016 a total of 88 distinct hot spot sites were detected over the 15 year period 82 of which were detected multiple times and 24 of which were not detected by galileo at thermal infrared wavelengths 1 5 m a variety of analytical methods are utilized to investigate the detections of active volcanism as a surface expression of interior heating geologic associations of hot spots including patera type lava flow type and proximity to mountainous regions are made using the usgs published global geologic map of io williams 2011 we also provide a summary of outburst scale events along with the slightly less bright but more frequent mini outbursts described by de kleer and de pater 2016a we investigate the spatial distribution of volcanic activity on io using nearest neighbor mean pairwise spacing and mean latitude statistics with various classification schemes the analysis confirms previous findings in that the heat dissipation appears to be primarily concentrated in the asthenosphere resulting in a high time averaged surface heat flux at low latitudes our observations show significant spatial deviations do exist from the asthenosphere heat dissipation model while also suggesting a deeper source of magma ascent to be present as well supporting conclusions from previous analyses of primarily spacecraft data veeder et al 2012 hamilton 2013 davies et al 2015 from a temporal perspective there are signs of significant variations in the distribution of global heat flux as volcanoes undetected and probably dormant during the galileo encounters subsequently erupted and remained active during our observations we also use the on 3 8 m radiant intensity timelines of individual hot spots along with the distribution of extensive lava fields in relation to detected activity as a means to investigate possible connections between hot spots and short timescale spatio temporal variations in the global heat flux distribution we conclude that while the global heat flux distribution remains relatively constant over decadal timescales there is evidence that significant deviations do occur potentially as a result of mountain forming processes or triggering mechanisms between eruptions

silicate volcanism on io io is currently emitting 1 1 5 w m 2 of tidal energy as a result of its volcanic activity if the lithosphere is more than 20 km thick as appears probable from the surface relief only a fraction of the tidal energy can be dissipated within the lithosphere otherwise it will become thinner the rest of the tidal energy must be dissipated below the lithosphere io is likely to be highly differentiated as a result of the volcanic activity with a low melting temperature fraction such as basalt near the surface and a high melting temperature fraction such as peridotite at depth if solidus temperatures are reached at depths shallower than the thickness of the basalt layer a partial melt zone will separate an all basalt lithosphere above from a peridotite mantle below and part of the tidal energy will be dissipated by viscous deformation within the melt zone most of the energy dissipated below the lithosphere will be transported upward through the lithosphere as silicate magma which is generated in quantities sufficient to resurface the satellite at a rate of a few tenths of a centimeter a year depending on the lithosphere thickness many of the characteristics of the ionian surface have been explained in terms of sulfur volcanism however most of the features observed can be as readily explained by silicate volcanism and silicates are more consistent with the apparent strength of the surface as implied by the relief simulations of basaltic eruptions indicate that the surface temperatures that would result from basaltic eruptions are similar to those measured by the voyager infrared interferometer spectrometer experiment the high rates of emission by the ionian hot spots imply eruption rates that are high compared with typical terrestrial eruptions an eruption rate of 4000 m3 s 1 may be required to explain loki which is currently emitting 1013 w although the near surface materials are mainly silicate they may contain several percent of volatile components rich in s na and k remobilization of these components by the ongoing silicate eruptions causes the plumes provides material to the torus and gives the satellite its characteristic reflectivity

a close up look at io from galileo s near infrared mapping spectrometer infrared spectral images of jupiter s volcanic moon io acquired during the october and november 1999 and february 2000 flybys of the galileo spacecraft were used to study the thermal structure and sulfur dioxide distribution of active volcanoes loki patera the solar system s most powerful known volcano exhibits large expanses of dark cooling lava on its caldera floor prometheus the site of long lived plume activity has two major areas of thermal emission which support ideas of plume migration sulfur dioxide deposits were mapped at local scales and show a more complex relationship to surface colors than previously thought indicating the presence of other sulfur compounds

inverting multispectral thermal time series images of volcanic eruptions for lava emplacement models we present a novel method for interpreting time series of multispectral observations of volcanic eruptions we show how existing models relating to radiance and area emplacement can be generalized into an integration convolution of a net area emplacement nae function and a coolingfunction assumingallsurfacesfollowthesamecoolingcurve thenaedescribesthevari ation in the rate of emplacement of hot material with time and temperature while the cooling func tion describes the cooling of a hot surface with time discretizing the integration convolution equation yields an underdetermined matrix equation that we solve using second order tikhonov regularization to stabilize the solution we test the inversion by modelling plausible nae surfaces calculating the radiances adding noise and inverting for the original surface three or more spec tralbands are requiredtocapture theoverallshapeofthenae andrecovering specificquantitiesis difficult single wavebands that yield flat kernels recover the total area emplacement curve rate of increase of hot area the integral of the nae with respect to temperature surprisingly well due to their property of conserving nae suggesting novel methods for calculating area emplacement rates and effusion rates from time series of satellite images and radiometer measurements gold open access this article is published under the terms of the cc by 3 0 license

charting thermal emission variability at pele janus patera and kanehekili fluctus with the galileo nims io thermal emission database nited abstract using the nims io thermal emission database nited a collection of over 1000 measurements of radiant flux from io s volcanoes davies a g et al 2012 geophys res lett 39 l01201 doi 10 1029 2011gl049999 we have examined the variability of thermal emission from three of io s volcanoes pele janus patera and kanehekili fluctus at pele the 5 m thermal emission as derived from 28 night time observations is remarkably steady at 37 10 gw m 1 re affirming previous analyses that suggested that pele an active rapidly overturning silicate lava lake janus patera also exhibits relatively steady 5 m thermal emission 20 3 gw m 1 in the four observations where janus is resolved from nearby kanehekili fluctus janus patera might contain a pele like lava lake with an effusion rate qf of 40 70 m3 s 1 it should be a prime target for a future mission to io in order to obtain data to determine lava eruption temperature kanehekili fluctus has a thermal emission spectrum that is indicative of the emplacement of lava flows with insulated crusts effusion rate at kanehekili fluctus dropped by an order of magnitude from 95 m3 s 1 in mid 1997 to 4 m3 s 1 in late 2001

io s loki patera modeling of three brightening events in 2013 2016 abstract loki patera is one of the most dramatically time variable volcanic features on io exhibiting episodic brightening events every 1 3 years that may produce over 15 of io s global heat flow we observed three such brightening events with adaptive optics imaging at the keck and gemini n telescopes over the course of 70 nights of observation in 2013 2016 the high cadence and multi wavelength nature of the observations provides constraints on models for activity at loki patera the matson et al 2006 model for loki patera as an overturning basaltic magma sea is adapted to fit the observations of all three events in particular we adjust the details of the overturn progression and modify the lava thermal properties to include dependencies on temperature and porosity to improve the fit to the data the preferred models find overturn front propagation velocities of 1 2 1 7 km day corresponding to resurfacing rates of 1500 2200 m2 s the time intervals of 440 540 days between successive events are roughly consistent with the 540 day period calculated by rathbun et al 2002 for events prior to 2001 the best coverage was obtained for the 2016 brightening model fits to this event require a lava bulk thermal conductivity of 0 55 0 75 w m k with the best fit obtained for a value of 0 7 w m k and an average porosity that decreases during cooling for all three events the overturn front appears to propagate around the patera in the clockwise direction opposite to what has been inferred for past brightening events there is evidence that the overturn may be more complex than a single propagating wave perhaps involving multiple simultaneous resurfacing waves as well as portions of the patera that are active even after the nominal bright phase has ended the measured intensities are anomalously low when loki patera is viewed at high emission angles suggestive of topographic shadowing due to a raised area or the edge of the depression in which the magma sea resides

the topographic imprint of a transient climate episode the western andean flank between 15 5 and 41 5 s mountain range topography is determined by the complex interplay between tectonics and climate however often it is not clear to what extent climate forces topographic evolution and how past climatic episodes are reflected in present day relief the andes are a tectonically active mountain belt encompassing various climatic zones with pronounced differences in rainfall erosion and glacier extent under similar plate boundary conditions in the central to south western andes climatic zones range from hyperarid desert with mean annual rainfall of 5 mm a 22 5 s to year round humidity with 2500 mm a 40 s the andes thus provide a unique setting for investigating the relationship between tectonics climate and topography we present an analysis of 120 catchments along the western andean watersheds between 15 5 and 41 5 s which is based on srtmv3 90m data and new medium resolution rainfall tropical rainfall measurement mission trmm dataset for each basin we extracted geometry relief and climate parameters to test whether andean topography shows a climatic imprint and to analyze how climate influences relief our data document that elevation and relief decrease with increasing rainfall and descending snowline elevation furthermore we show that local relief reaches high values of 750 m in a zone between 28 s to 35 s during pleistocene glacial stages this region was affected by the northward shifting southern hemisphere westerlies which provided moisture for valley glacier formation and extended glacial coverage as well as glacial erosion in contrast the southern regions between 35 s to 40 s receive higher rainfall and have a lower local relief of 200 m probably related to an increased drainage density we distinguish two different climatically controlled mechanisms shaping topography 1 fluvial erosion by prolonged channel hillslope coupling which smoothes relief and 2 erosion by valley glaciers that generates relief finally our results suggests that the catchment scale relief of the andes between 28 s to 35 s is characterized by a pronounced transient component reflecting past climatic conditions copyright 2010 john wiley sons ltd

post solidification cooling and the age of io s lava flows abstract the modeling of thermal emission from active lava flows must account for the cooling of the lava after solidification models of lava cooling applied to data collected by the galileo spacecraft have until now not taken this into consideration this is a flaw as lava flows on io are thought to be relatively thin with a range in thickness from 1 to 13 m once a flow is completely solidified a rapid process on a geological time scale the surface cools faster than the surface of a partially molten flow cooling via the base of the lava flow is also important and accelerates the solidification of the flow compared to the rate for the semi infinite approximation which is only valid for very deep lava bodies we introduce a new model which incorporates the solidification and basal cooling features this model gives a superior reproduction of the cooling of the 1997 pillan lava flows on io observed by the galileo spacecraft we also use the new model to determine what observations are necessary to constrain lava emplacement style at loki patera flows exhibit different cooling profiles from that expected from a lava lake we model cooling with a finite element code and make quantitative predictions for the behavior of lava flows and other lava bodies that can be tested against observations both on io and earth for example a 10 m thick ultramafic flow like those emplaced at pillan patera in 1997 solidifies in 450 days at which point the surface temperature has cooled to 280 k and takes another 390 days to cool to 249 k observations over a sufficient period of time reveal divergent cooling trends for different lava bodies examples lava flows and lava lakes have different cooling trends after the flow has solidified flows cool faster thin flows solidify and cool faster than flows of greater thickness the model can therefore be used as a diagnostic tool for constraining possible emplacement mechanisms and compositions of bodies of lava in remote sensing data

three decades of loki patera observations abstract we present observations of io s loki patera taken with the 10 m keck telescopes between 1998 and 2016 adding these data to those published by rathbun and spencer 2006 and the gemini data of de kleer and de pater 2016a 2017 results in a database of 3 5 3 8 m emission from loki patera over almost 3 decades data presented here contain adaptive optics ao observations of io s sunlit hemisphere at wavelengths between 1 6 and 5 m ao observations of io in eclipse at 2 5 m and non ao observations of io in eclipse at 1 6 12 m the non ao data were taken in september of 1999 during the early phase of a brightening event that was documented by howell et al 2001 dual component io flow model ifm fits to our 1999 observations show a mostly cool lava crust over almost the entire patera floor with a relatively small hotter component making up less than 1 of the total area consistent with previous observations the 30 year timeline of loki patera revealed that after an apparent cessation of or change in brightening events in 2002 loki patera became active again in 2009 the more recent activity may have a slightly shorter periodicity than observed by rathbun et al 2002 and the direction of flow propagation appears to have reversed since 2009 the flow direction is in the clockwise direction starting in the north or north east corner and propagating along the patera towards the south west during the galileo era the propagation was in the counter clockwise direction starting in the south west and propagating towards the east both the 30 year timeline and the 1 6 12 m spectrum that was obtained during the brightening event in 1999 agree well with matson et al s 2006 overturning lava lake model as modified by de kleer and de pater 2017

building the central andes through axial lower crustal flow 1 the orogen scale morphology of the central andes which are longitudinally symmetric at 19 s correlates with the modern geometry of the subducting nazca slab but is largely independent of local bedrock geology or precipitation crustal thickness as measured by the cross strike width of the orogen above 3000 m and the cross sectional area of the crust is not well correlated with observed magnitudes of upper crustal shortening in our interpretation the large scale morphology is instead correlated with and controlled by lithospheric scale processes and subduction dynamics using a semianalytic three dimensional newtonian viscous flow model we produce andean like topography and distribution of upper crustal shortening during subduction of an oceanic lithosphere eastward beneath the andes provided that 1 the more steeply dipping slab segment beneath the central andes is overlain by the weak lower or middle crust 2 the flat slab subduction segments to the north and south of this zone are overlain by the strong middle and lower crust and 3 the steeply dipping central slab segment is overlain by a narrow centrally localized zone of increased crustal shortening the resulting model orogen displays substantial orogen parallel flow in the weak lower crust above the steep slab zone orogen parallel flow does not penetrate into the regions of stronger lower crust above the flat slab segments resulting in a broad plateau topped orogen above the central slab segment and narrow but high orogenic segments above the flat slab region redistribution of material through lower crust flow can account for the observed mismatch between crustal volume and upper crustal shortening in the central andes and may explain young 10 ma crustal thickening and surface uplift that has been argued for in some regions

density structure of io and the migration of magma through its lithosphere we model the density structure of the outer several tens of kilometers of io on the basis of the assumption that condensed volatiles mainly so2 exist at shallow depths in a mafic to ultramafic lithosphere which has a finite porosity due to its accumulation as a mixture of pyroclastic and effusive volcanic deposits which include condensed volatiles the porosity decreases with increasing depth due to pressure driven compaction and temperature driven melting of the volatiles and this controls the bulk density structure of the lithosphere we also model the densities of ascending magmas as a function the types and amounts of volatiles that are available in their source regions the relative densities of the accumulated volcanic deposits and of the magmas rising through them control whether the magmas will erupt at the surface or will stall to form intrusions which can grow into magma reservoirs we find that the depths at which magma reservoirs may exist are strongly influenced by the void space fraction in surface deposits and only weakly controlled by the mass fraction of so2 in the deposits and the mass fraction of so2 in the magmas once nucleated a reservoir has the potential to grow to a very large vertical extent 15 km total height before the magma immediately beneath its roof is again buoyant relative to the surrounding rocks the presence of large volume reservoirs may explain the great extent of the larger lava flow fields seen on io and the longevity of some eruptions the presence of very soluble volatiles such as water in magmas would have virtually no effect on these findings because these volatiles would influence the densities of magmas only very near the surface though they would even in very small amounts then have a dramatic effect on the explosivities of eruptions

io heat flow from dark paterae abstract dark paterae on the jovian satellite io are evidence of recent volcanic activity some paterae appear to be entirely filled with dark volcanic material while others have only partially darkened floors dark paterae have area and heat flow longitudinal distributions that are bimodal as well as anti correlated with the longitudinal distribution of mountains on io at a global scale as part of our study of io s total heat flow we have examined the darkest paterae and quantified their thermal emission in order to assess their contribution this is the first time that the areas of the dark material in these paterae have been measured with such precision and correlated with their thermal emission dark paterae yield a significantly larger contribution to io s heat flow than dark volcanic fields dark paterae including loki patera yield at least 4 10 13 w or 40 of io s total heat flow in comparison dark flow fields yield 10 13 w or 10 of io s total heat flow of the total heat loss from dark paterae loki patera alone yields 10 13 w or 10 of io s total thermal emission

io s thermal emission from the galileo photopolarimeter radiometer galileo s photopolarimeter radiometer instrument mapped io s thermal emission during the i24 i25 and i27 flybys with a spatial resolution of 2 2 to 300 kilometers mapping of loki in i24 shows uniform temperatures for most of loki patera and high temperatures in the southwest corner probably resulting from an eruption that began 1 month before the observation most of loki patera was resurfaced before i27 pele s caldera floor has a low temperature of 160 kelvin whereas flows at pillan and zamama have temperatures of up to 200 kelvin global maps of nighttime temperatures provide a means for estimating global heat flow

keck observations of eruptions on io in 2003 2005 abstract we report observations of four energetic volcanic eruptions on io at tupan patera on ut 8 march 2003 tung yo patera on ut 28 may 2004 sui jen patera on ut 30 may 2004 and south of babbar patera on ut 31 may 2005 the tung yo sui jen and south of babbar paterae eruptions are in locations where no activity had been seen before our observations were obtained at near infrared wavelengths 1 2 4 7 m with the 10 m keck telescope equipped with adaptive optics we report single and two temperature blackbody fits as well as single component and dual component io flow model ifm fits davies 1996 icarus 124 45 61 to all four eruptions where applicable we use 2 m and 5 m radiant fluxes the 2 5 m radiant flux ratio and radiant flux density of each thermal source to constrain the likely style of volcanic eruption all eruptions are characterized by a high temperature ifm component ranging from 1475 to 900 k from a relatively small area

growth of the central andean plateau by tectonic segmentation is controlled by the gradient in crustal shortening abstract crustal deformation orocline formation and growth of the central andean plateau as well as the mutual relations of these processes with climate are a matter of international debate earthquake focal mechanism fault kinematic paleomagnetic and cross section balancing data are paramount for understanding the morphotectonic evolution of this noncollisional orogen but collectively await an explanation in terms of a comprehensive kinematic model we offer such a model that approximates simple shear in plan view and that predicts the kinematics of first order fault zones in the southern central andes the model indicates that segmentation of the upper crust into rhomb shaped domains confined by transpressive ranges resulted from the decrease in crustal shortening with distance to the central bend of the andes an anastomosing network of kinematically coupled reactivated orogen parallel and newly formed ne trending deformation zones encompassing components of sinistral and dextral strike slip res

lithospheric evolution of the andean fold thrust belt bolivia and the origin of the central andean plateau we combine geological and geophysical data to develop a generalized model for the lithospheric evolution of the central andean plateau between 188 and 208 s from late cretaceous to present by integrating geophysical results of upper mantle structure crustal thickness and composition with recently published structural stratigraphic and thermochronologic data we emphasize the importance of both the crust and upper mantle in the evolution of the central andean plateau four key steps in the evolution of the andean plateau are as follows 1 initiation of mountain building by 70 ma suggested by the associated foreland basin depositional history 2 eastward jump of a narrow early fold thrust belt at 40 ma through the eastward propagation of a 200 400 km long basement thrust sheet 3 continued shortening within the eastern cordillera from 40 to 15 ma which thickened the crust and mantle and established the eastern boundary of the modern central andean plateau removal of excess mantle through lithospheric delamination at the eastern cordillera altiplano boundary during the early miocene appears necessary to accommodate underthrusting of the brazilian shield replacement of mantle lithosphere by hot asthenosphere may have provided the heat source for a pulse of mafic volcanism in the eastern cordillera and altiplano at 24 23 ma and further volcanism recorded by 12 7 ma crustal ignimbrites 4 after 20 ma deformation waned in the eastern cordillera and interandean zone and began to be transferred into the subandean zone long term rates of shortening in the fold thrust belt indicate that the average shortening rate has remained fairly constant 8 10 mm year through time with possible slowing 5 7 mm year in the last 15 20 myr we suggest that cenozoic deformation within the mantle lithosphere has been focused at the eastern cordillera altiplano boundary where the mantle most likely continues to be removed through piecemeal delamination d 2005 elsevier b v all rights reserved

toward noncontacting seismology buried land mines and chemical waste may providethe contrast in elastic properties within the soil needed toachieve detection via near surface seismic methods thehazardous nature of these targets strongly indicates the useof noncontacting sources and receivers a home madeultrasonic parametric array allows us to insonify the soilwith an intense beam of sound this acoustic energy isconverted to elastic waves in the soil our noncontactingseismometer is a microwave doppler vibrometer that candetect seismic waves even through grass we believe thatdevelopments along these lines will ultimately lead to theability to probe large areas of the near surface in a safe andreliable fashion without physically touching the ground

comparison of crustal thickening budget and shortening estimates in southern peru 12 14 s implications for mass balance and rotations in the bolivian orocline two fundamental questions of interest with regard to the andean plateau are the mass balance of material needed to create and sustain a 3 4 km high plateau and the relationship between the plateau and the bending of the bolivian orocline the link be tween these two questions is the distribution of shortening through the central andes is crustal shortening suffi cient to support an isostatically compensated 60 70 km thick crust is differential shortening between the hinge of the orocline and its limbs suffi cient to account for both physiographic curvature and measured rotations three dimensional 3 d models of deformation within curved orogens require in addition to paleomagnetic data viable two dimensional estimates of dis placements to this end we present new map data and use those data to derive estimates of shortening across the northern margin of the andean plateau the cross section extent from the eastern edge of the volcanic arc to the foreland basin is approximately one half of the physiographic width of the andean plateau in peru cross sectional shortening estimates in southern peru 12 14 s provide a preferred estimate of 123 km or 40 short ening with a minimum estimate of 58 km or 25 shortening and maximum estimate of 333 km or 65 shortening the largest con trolling factor on the magnitude of shorten ing is where basement becomes involved in thrust belt deformation using our preferred shortening estimate the differential shorten ing between our cross section on the northern margin of the bolivian orocline 12 14 s and cross sections across the axis of the bolivian orocline 17 18 s is 177 km corresponding to 23 of rotation the differential shortening for the young younger than 15 ma defor mation of the altiplano and subandean re gion between 12 14 s and 17 18 s is 88 km correlating to 11 5 of rotation while dif ferential shortening can account for young younger than 15 ma vertical axis rotations it cannot completely account for early 45 35 ma rotations 37 15 this suggests that forearc rotations refl ect both bending due to differential shortening 12 as well as block rotations 25 30 which facilitated defor mation in a tightening core and transported material toward the center of the orocline the preferred estimate of shortening is well short of the required 240 300 km of shorten ing needed to account for a 60 70 km thick crust under the entire plateau this suggests that for an isostatically equilibrated crust either 1 there is a signifi cant amount of shortening 100 150 km in the western half of the plateau that is hidden by the volcanic arc or 2 crustal material is being added to the peruvian section of the andean plateau most likely through lower crustal fl ow

chilean flat slab subduction controlled by overriding plate thickness and trench rollback how flat slab geometries are generated has been long debated it has been suggested that trenchward motion of thick cratons in some areas of south america and cenozoic north america progressively closed the asthenospheric wedge and induced flat subduction here we develop time dependent numerical experiments to explore how trenchward motion of thick cratons may result in flat subduction we find that as the craton approaches the trench and the wedge closes two opposite phenomena control slab geometry the suction between ocean and continent increases favoring slab flattening while the mantle confined within the closing wedge dynamically pushes the slab backward and steepens it when the slab retreats as in the peru and chile flat slabs the wedge closure rate and dynamic push are small and suction forces generate in some cases flat subduction we model the past 30 m y of subduction in the chilean flat slab area and demonstrate that trenchward motion of thick lithosphere 200 300 km currently 700 800 km away from the peru chile trench reproduces a slab geometry that fits the stress pattern seismicity distribution and temporal and spatial evolution of deformation and volcanism in the region we also suggest that varying trench kinematics may explain some differing slab geometries along south america when the trench is stationary or advances the mantle flow within the closing wedge strongly pushes the slab backward and steepens it possibly explaining the absence of flat subduction in the bolivian orocline

oligocene to present shallow subduction beneath the southern puna plateau abstract the southern puna plateau is a conspicuous example of a high elevation orogenic plateau in a non collisional setting this orogenic sector is currently located above an anomalously shallow subduction segment in which timing and relation to upper plate tectonics have been widely overlooked this subduction segment here referred to as the southern puna shallow subduction spss is characterized by a 200 km wide shallow area located at 300 km from the trench at a depth of 100 120 km and dipping 10 12 to the east to determine the onset of the spss and its link to the tectonic and magmatic activity in this region we analyzed the tectonomagmatic record of the southern puna plateau from preexisting datasets also we present a new approach based on global subduction data that provides a straightforward methodology to extract potential paleo slab angles from the bedrock arc record this analysis reveals that a pronounced eastward arc front migration and magmatic broadening took place at 26 ma and was preceded by 4 ma of reduced magmatic activity which we link to the inception of the spss as expected in shallow subduction settings a change to basement cored distributed deformation south of 25 s in the southern puna plateau coincides with the beginning of shallow subduction also the spss is coincident with the enigmatic post eocene intraplate deformation of the otumpa hills located at 950 km from the trench we suggest that this succession of events is not fortuitous and that the development of the spss impacted directly the overriding plate since the oligocene contributing to the building of one of the largest topographies 3 km and thickest orogenic crusts 70 60 km on earth the shallow subduction would have acted jointly with cenozoic changes in plate kinematics and climate enhancing andean orogenesis at studied latitudes

evaluation of sulfur flow emplacement on io from galileo data and numerical modeling galileo images of bright lava flows surrounding emakong patera have been analyzed and numerical modeling has been performed to assess whether these flows could have resulted from the emplacement of sulfur lavas on io images from the solid state imaging ssi camera show that these bright white to yellow emakong flows are up to 370 km long and contain dark sinuous features that are interpreted to be lava conduits 300 500 m wide and 100 km long near infrared mapping spectrometer nims thermal emission data yield a color temperature estimate of 344 k 60 k 131 c within the emakong caldera we suggest that these bright flows likely resulted from either sulfur lavas or silicate lavas that have undergone extensive cooling pyroclastic mantling and or alteration with bright sulfurous materials the emakong bright flows have estimated volumes of 250 350 km3 similar to some of the smaller columbia river basalt flows if the emakong flows did result from effusive sulfur eruptions then they are orders of magnitude greater in volume than any terrestrial sulfur flows our numerical modeling results show that sulfur lavas on io could have been emplaced as turbulent flows which were capable of traveling tens to hundreds of kilometers consistent with the predictions of sagan 1979 and fink et al 1983 our modeled flow distances are also consistent with the measured lengths of the emakong channels and bright flows modeled thermal erosion rates are 1 4 m d 1 for flows erupted at 140 180 c which are consistent with the melting rates of kieffer et al 2000 the emakong channels could be thermal erosional in nature however the morphologic signatures of thermal erosion channels cannot be discerned from available images there are planned galileo flybys of io in 2001 which provide excellent opportunities to obtain high resolution morphologic and color data of emakong patera such observations could along with further modeling provide additional information to better constrain whether sulfur lavas produced the emakong flows

response of intracontinental deformation in the central andes to late cenozoic reorganization of south american plate motions new stratigraphic chronologic and fault kinematic data from the quebrada del toro in northwestern argentina provide a detailed view of late cenozoic kinematic reorganization in the southern central andes the quebrada del toro is a thrust bounded basin filled with 2 km of synorogenic clastic deposits ranging in age from early miocene to holocene as observed elsewhere in northwestern argentina faults in the quebrada del toro record an early phase of horizontal nw se contraction beginning between early and late miocene and ending after 0 98 ma and a later phase of horizontal ne sw contraction beginning between late miocene and 4 17 ma and still active these results require both kinematic regimes to have been active between 4 17 and 0 98 ma compatible with timing and kinematic data from the adjacent central andes and best explained by a temporal pattern of serial recurrence of the kinematic regimes a hypothesis that intraplate deformation in the central andes is driven by the absolute motion of the south american plate with respect to the hotspot reference frame is tested by comparing quebrada del toro kinematics to plate reconstructions and space based geodetic results nazca south america relative motion and absolute nazca plate motion show consistent azimuths throughout the past 20 5 myr in contrast absolute south american plate motion azimuths mimic the changing contraction directions determined from intraplate andean faults although the timing of the south american plate motion change is poorly resolved by current data it is compatible with the quebrada del toro data absolute upper plate motion might control intraplate kinematics along many of the earth s convergent margins