new paleoearthquake ages from the western garlock fault implications for regional earthquake occurrence in southern california abstract new paleoseismic investigations on the western segment of the garlock fault at twin lakes california reveal evidence for up to six surface ruptures in the past 5600 years calibrated radiocarbon dates from accelerator mass spectrometer analysis of detrital charcoal constrain the timing of three well defined events at twin lakes to post a d 1450 event a 720 395 b c event g and 3425 2200 b c event i two probable events are also constrained to 625 1525 a d event c and 155 b c a d 615 event e and a possible additional event to 3425 2200 b c and prior to event i our findings offer new insights into mid to late holocene behavior of the western and central segments of the garlock fault and regional fault interactions the timing of the most recent event mre on the western segment likely correlates with the mre at paleoseismic sites on the central segment suggesting that both segments do sometimes rupture together during large earthquakes evidence for events during periods of seismic quiescence on adjacent segments demonstrates that the western and central segments also sometimes rupture independently of one another the occurrence of event g during a lull in seismic strain release at 2 5 ka on faults in the eastern california shear zone ecsz contrasts with other studies that suggest the garlock fault ruptures in phase with ecsz faults our data suggest that seismic strain release on the garlock fault may actually be more in phase with moment release on the mojave section of the san andreas fault and the transverse ranges faults of the los angeles region online material two input files written for the computer program oxcal 4 1 7 and two output files from the oxcal analyses the first input file calibrates and re weights probability density functions pdfs for radiocarbon ages based on stratigraphic ordering and the second input file calculates pdfs for earthquake ages based on radiocarbon ages and stratigraphy bracketing the events

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

new estimates for io eruption temperatures implications for the interior abstract the initial interpretation of galileo data from jupiter s moon io suggested eruption temperatures 1600 c tidal heating models have difficulties explaining io s prodigious heat flow if the mantle is 1300 c although we suggest that temperatures up to 1450 c may be possible in general io eruption temperatures have been overestimated because the incorrect thermal model has been applied much of the thermal emission from high temperature hot spots comes from lava fountains but lava flow models were utilized we apply a new lava fountain model to the highest reported eruption temperature the ssi observation of the 1997 eruption at pillan this resets the lower temperature limit for the eruption from 1600 to 1340 c additionally viscous heating of the magma may have increased eruption temperature by 50 100 c as a result of the strong compressive stresses in the ionian lithosphere while further work is needed it appears that the discrepancy between observations and interior models is largely resolved

near equatorial ctd observations at 85 w in october 1982 ctd data collected about the equator along 85 w between october 8 and 12 1982 are used to investigate stratification changes in the upper 1 km associated with the 1982 83 el nino with respect to the thermal field observed in november 1981 virtually the entire section exhibited downward displacements in the upper kilometer of the water column observed displacements at the depth of the mean thermocline were large 150 m and relatively symmetric about the equator displacements around 1 km depth were near zero this stratification change appears to have been produced by a zonal convergence of mass at temperatures above 15 c with divergence below least square modal decompositions of the vertical displaced profiles revealed significant contributions from modes 1 and 2 with meridional structure consistent with kelvin waves the observations thus support current theories that relate el nino onset in the eastern pacific to anomalous wind forcing in the west

two classes of volcanic plumes on io abstract comparison of voyager 1 and voyager 2 images of the south polar region of io has revealed that a major volcanic eruption occured there during the period between the two spacecraft encounters an annular deposit 1400 km in diameter formed around the aten patera caldera 311 w 48 s the floor of which changed from orange to red black the characteristics of this eruption are remarkably similar to those described earlier for an eruption centered on surt caldera 338 w 45 n that occured during the same period also at high latitude but in the north both volcanic centers were evidently inactive during the voyager 1 and 2 encounters but were active sometime between the two the geometric and colorimetric characteristics as well as scale of the two annular deposits are virtually identical both resemble the surface features formed by the eruption of pele 255 w 18 s these three very large plume eruptions suggest a class of eruption distinct from that of six smaller plumes observed to be continously active by both voyagers 1 and 2 the smaller plumes of which prometheus is the type example are longer lived deposit bright whitish material erupt at velocities of 0 5 km sec 1 and are concentrated at low latitudes in an equatorial belt around the satellite the very large pele type plumes on the other hand are relatively short lived deposit darker red materials erupt at 1 0 km sec 1 and rather than restricted to a latitudinal band are restricted in longitude from 240 to 360 w both direct thermal infrared temperature measurements and the implied color temperatures for quenched liquid sulfur suggest that hot spot temperatures of 650 k are associated with the large plumes and temperatures 2 in their annuli whereas the large plumes apparently do not two other plumes that occur at either end of the linear feature loki may be intermediate or hybrid between the two classes exhibiting attributes of both additionally loki occurs in the area of overlap in the regional distributions of the two plume classes two distinct volcanic systems involving different volatiles may be responsible for the two classes we propose that the discrete temperatures associated with the two classes are a direct reflection of sulfur s peculiar variation in viscosity with temperature over two temperature ranges 400 to 430 k and 650 k sulfur is a low viscosity fluid orange and black respectively at other temperatures it is either solid or has a high viscosity as a result there will be two zones in io s crust in which liquid sulfur will flow freely a shallow zone of orange sulfur and a deeper zone of black sulfur a low temperature system driven by so 2 heated to 400 to 400 k by the orange sulfur zone seems the best model for the small plumes a system driven by sulfur heated to 650 k by hot or even molten silicates in the black sulfur zone seems the best explanation for the large plume class the large pele type plumes are apparently concentrated in a region of the satellite in which a thinner sulfur rich crust overlies the tidally heated silicate lithosphere so the black sulfur zone may be fairly shallow in this region the prometheus type plumes are possibly confined to the equatorial belt by some process that concentrates so 2 fluid in the equatorial crust

keck ao observations of io in and out of eclipse abstract we present adaptive optics ao observations of io taken with the w m keck ii telescope on 18 december 2001 ut before the satellite went into eclipse and while it was in jupiter s shadow making these kind of io in eclipse observations as well as the associated data reduction and analysis are challenging hence one focus of the paper is to explain the methods and tools used for these data sets for the sunlit images io itself was used as the wavefront reference source while nearby ganymede was used as reference star when io was in eclipse observations were obtained in k l and m bands the sunlit images have been deconvolved using mistral the io in eclipse data were deconvolved with idac and mistral the former gives better results both in absolute photometry and in matching the original images we determined the flux densities of the hot spots from the original io in eclipse data with starfinder as well as from the deconvolved images by integrating the intensity over the relevant areas we determined the highly anisoplanatic psf via a fft method from the original data and used this in starfinder and as a starting psf for idac and mistral we derived temperatures and areal coverage of all 19 spots detected in both k and l band images of io in eclipse we also determined temperatures and areal coverage of the hot spots visible on the l and m band images of sunlit io most volcanoes contain a compact hot core 10 km2 at 600 800 k within a larger area at lower temperatures e g 102 104 km2 at 300 500 k the total heat flow contributed by these active volcanoes is 0 2 w m 2 8 of the average global heat flow measured at 5 20 m by veeder et al j geophys res 99 1994 17095

temperature and area constraints of the south volund volcano on io from the nims and ssi instruments during the galileo g1 orbit analysis of data from darkside and eclipse observations of io by the nims and ssi instruments show that the south volund hot spot is a manifestation of high temperature active silicate volcanism the nims data are fitted with a two temperature model developed from modelling terrestrial lavas which yields a better fit to the data than a single temperature fit the multispectral color temperatures obtained from nims are compared with the brightness temperatures obtained from the ssi instrument and show excellent agreement for the hotter of the two components fitted to the nims data the two components might correspond to a cooled crust which has formed on the surface of an active flow or lava lake at a temperature of approximately 450 k and covering an area of about 50 km and a hotter and much smaller component at a temperature of approximately 1100 k and an area of less than 0 1 km the hot component implies the existence of cracks in the surface crust of a flow or lake through which the hot interior radiates a hot vent area or breakouts of lava forming new flow lobes the ratio of these areas is consistent with the crack to crust ratio of some lava flows and lava lakes on earth

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

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

hot spots on io initial results from galileo s near infrared mapping spectrometer the near infrared mapping spectrometer on galileo has monitored the volcanic activity on io since june 28 1996 this paper presents preliminary analysis of nims thermal data for the first four orbits of the galileo mission nims has detected 18 new hot spots and 12 others which were previously known to be active the distribution of the hot spots on io s surface may not be random as hot spots surround the two bright so2 rich regions of bosphorus regio and colchis regio most hot spots seem to be persistently active from orbit to orbit and 10 of those detected were active in 1979 during the voyager encounters we report the distribution of hot spot temperatures and find that they are consistent with silicate volcanism

second and first baroclinic kelvin modes in the equatorial pacific at intraseasonal timescales 1 topex poseidon sea level and time series from the tao tropical atmosphere ocean array of moorings over 1992 1999 are used to investigate the spatiotemporal characteristics of equatorial kelvin waves in the pacific at period shorter than 180 days spectral analyses show high oceanic energy in two separate bands of period around 70 days and 120 days signals are coherent in both bands all along the equator ocean general circulation model ogcm simulations forced by different wind stress fields are also analyzed and exhibit the same features observed and modeled sea level dynamic height and 20 c isotherm depth band pass filtered around 70 days show an eastward propagation at phase speed of 2 4 2 9 m s 1 typical of the first baroclinic kelvin mode the meridional and vertical structures of the equatorial waves at the onset of the 1997 el nino are also those expected for a first kelvin mode at 120 day period phase speeds meridional and vertical structures are closer to those expected for a second baroclinic mode both modes are nevertheless present in the two frequency bands a simple kelvin wave model shows that the wind at 120 day period seems to force the kelvin waves at the same period however the predominance of second baroclinic mode at 120 day period cannot be explained solely by the characteristics of the wind ogcm simulations rather suggest the importance of internal oceanic processes such as vertical redistribution of energy from first to second baroclinic mode as the waves propagate eastward model outputs over 1984 1999 indicate that these equatorial kelvin waves at 70 and 120 day period may have an effect on el nino since they seem to be stronger at its onset

galileo observations of volcanic plumes on io abstract io s volcanic plumes erupt in a dazzling variety of sizes shapes colors and opacities in general the plumes fall into two classes representing distinct source gas temperatures most of the galileo imaging observations were of the smaller more numerous prometheus type plumes that are produced when hot flows of silicate lava impinge on volatile surface ices of so2 few detections were made of the giant pele type plumes that vent high temperature sulfur rich gases from the interior of io this was partly because of the insensitivity of galileo s camera to ultraviolet wavelengths both gas and dust spout from plumes of each class favorably located gas plumes were detected during eclipse when io was in jupiter s shadow dense dust columns were imaged in daylight above several prometheus type eruptions reaching heights typically less than 100 km comparisons between eclipse observations sunlit images and the record of surface changes show that these optically thick dust columns are much smaller in stature than the corresponding gas plumes but are adequate to produce the observed surface deposits mie scattering calculations suggest that these conspicuous dust plumes are made up of coarse grained ash particles with radii on the order of 100 nm and total masses on the order of 106 kg per plume long exposure images of thor in sunlight show a faint outer envelope apparently populated by particles small enough to be carried along with the gas flow perhaps formed by condensation of sulfurous snowflakes as suggested by the plasma instrumentation aboard galileo as it flew through thor s plume frank l a paterson w r 2002 j geophys res space phys 107 doi 10 1029 2002ja009240 31 1 if so the total mass of these fine nearly invisible particles may be comparable to the mass of the gas and could account for much of io s rapid resurfacing

observations and initial modeling of lava so2 interactions at prometheus io we present observations and initial modeling of the lava so2 interactions at the flow fronts in the prometheus region of io recent high resolution observations of prometheus reveal a compound flow field with many active flow lobes many of the flow lobes are associated with bright streaks of what is interpreted to be volatilized and recondensed so2 radiating away from the hot lava lower resolution color data show diffuse blue to violet areas also near the active flow front perhaps from active venting of so2 not clearly visible in any of the images is a single source vent for the active plume while the size of the proposed vent is probably near the limit of the resolution we expected to see radial or concentric albedo patterns or other evidence for gas and entrained particles above the flow field the lack of an obvious plume vent earlier suggestions that the prometheus type plumes may originate from the advancing flow lobes and the high resolution images showing evidence for large scale volatilization of the so2 rich substrate at prometheus encouraged us to develop a model to quantify the heat transfer between a basaltic lava flow and a substrate of so2 snow we calculate that the vaporization rate of so2 snow is 2 5 10 6 m s 1 per unit area using an estimated 5 m2 s 1 lava coverage rate from change detection images we show that the gas production rate of so2 at the flow fronts is enough to produce a resurfacing rate of 0 24 cm yr 1 at the annulus of prometheus this is much less than other estimates of resurfacing by the prometheus plume while not easily explaining the main prometheus plume our model readily accounts for the bright streaks

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

the vertical structure of the zonal pressure gradient in the eastern equatorial pacific ctd data from the epocs and norpax experiments were used to construct a mean zonal pressure gradient profile between 110 w and 150 w for the 1979 to 1981 pre el nino time period the mean zonal pressure gradient referenced to 100 dbar had a value of 4 5 10 7 m s 2 at the surface and decreased to within two standard errors of zero at 200 dbar below this depth the mean was not significantly different from zero deviations from this mean were not related to fluctuations of the zonally averaged zonal wind stress between 150 w and 110 w rather the largest deviations in the boreal springs of 1979 and 1980 appeared to be associated first with vertical mode kelvin wave pulses propagating eastward along the equator the 1979 81 mean profile was also used as a reference to examine variations in zonal pressure gradient during the 1982 83 enso event the sea surface was more sharply sloped upward from the east to west in april and september 1982 before arid near the beginning of the event the surface slope was below normal in april and october 1983 vertical profiles of the zonal pressure gradient deviations showed large high vertical mode contributions during the vent than in the prevent samples

upper equatorial pacific ocean current and salinity variability during the 1996 1998 el nino la nina cycle the recent el nino la nina cycle exhibited striking patterns of current and salinity variability in the upper equatorial pacific ocean this evolution is described from mid 1996 through 1998 using a remarkable data set of 35 meridional conductivity temperature depth ctd acoustic doppler current profiler adcp sections along with buoy data the sections nominally from 8 s to 8 n between 165 e and 95 w were occupied over the course of 27 months a wide range of current variability was sampled with currents that appeared or disappeared some time during the cycle including an equatorially trapped eastward surface current the equatorial undercurrent the northern branch of the south equatorial current and the north equatorial countercurrent basin wide interannual changes in upper ocean and pycnocline zonal transports were as large as 64 32 106 m3 s 1 changes in the salinity structure included a deep and fresh mixed layer in the central equatorial pacific that built up during the el nino and was then disrupted by upwelled salty water with the onset of la nina a very fresh mixed layer observed in the eastern equatorial pacific late in the el nino and a reduction in the strength of the meridional equatorial salinity gradient within the pycnocline to one third of the usual value during the el nino finally the zonal transports above the thermocline from 5 s to 5 n were well correlated with the rate of change of warm water volume west of the individual ctd adcp sections

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

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

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

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

ground based observations of time variability in multiple active volcanoes on io abstract since before the beginning of the galileo spacecraft s jupiter orbital tour we have observed io from the ground using nasa s infrared telescope facility irtf we obtained images of io in reflected sunlight and in eclipse at 2 3 3 5 and 4 8 m in addition we have measured the 3 5 m brightness of an eclipsed io as it is occulted by jupiter these lightcurves enable us to measure the brightness and one dimensional location of active volcanoes on the surface during the galileo era two volcanoes were observed to be regularly active loki and either kanehekili and or janus at least 12 other active volcanoes were observed for shorter periods of time including one distinguishable in images that include reflected sunlight these data can be used to compare volcano types and test volcano eruption models such as the lava lake model for loki

volcanic history geologic analysis and map of the prometheus patera region on io data from jupiter s moon io returned by the galileo spacecraft have been used to create a geologic map of prometheus patera its associated flow field and nearby features we have identified the location of the vent that fed the prometheus flow field during the galileo epoch in the north eastern portion of the main prometheus flow field this vent is the probable source of a small sulphur rich plume previous studies suggested that the vent may be atop a tectonic fault but we find that the vent is offset from the putative fault it is plausible that in the past magma exploited the fault to reach the surface at prometheus patera but subsequent magma cooling in the conduit could have caused an obstruction preventing further eruptions from providing significant contributions to the prometheus flow field we also speculate on how a new prometheus plumbing system may be fed by mafic magmas after melt stalls in magma reservoirs during its ascent through the lithosphere from the mantle

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 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

prometheus io s wandering plume unlike any volcanic behavior ever observed on earth the plume from prometheus on io has wandered 75 to 95 kilometers west over the last 20 years since it was first discovered by voyager and more recently observed by galileo despite the source motion the geometric and optical properties of the plume have remained constant we propose that this can be explained by vaporization of a sulfur dioxide and or sulfur snowfield over which a lava flow is moving eruption of a boundary layer slurry through a rootless conduit with sonic conditions at the intake of the melted snow can account for the constancy of plume properties

io in the near infrared near infrared mapping spectrometer nims results from the galileo flybys in 1999 and 2000 galileo s near infrared mapping spectrometer nims observed io during the spacecraft s three flybys in october 1999 november 1999 and february 2000 the observations which are summarized here were used to map the detailed thermal structure of active volcanic regions and the surface distribution of so2 and to investigate the origin of a yet unidentified compound showing an absorption feature at 1 m we present a summary of the observations and results focusing on the distribution of thermal emission and of so2 deposits we find high eruption temperatures consistent with ultramafic volcanism at pele such temperatures may be present at other hot spots but the hottest areas may be too small for those temperatures to be detected at the spatial resolution of our observations loki is the site of frequent eruptions and the low thermal emission may represent lavas cooling on the caldera s surface or the cooling crust of a lava lake high resolution spectral observations of emakong caldera show thermal emission and so2 within the same pixels implying that patches of so2 frost and patches of cooling lavas or sulfur flows are present within a few kilometers from one another thermal maps of prometheus and amirani show that these two hot spots are characterized by long lava flows the thermal profiles of flows at both locations are consistent with insulated flows with the amirani flow field having more breakouts of fresh lava along its length prometheus and amirani each show a white ring at visible wavelengths while so2 distribution maps show that the highest concentration of so2 in both ring deposits lies outside the white portion visible measurements at high phase angles show that the white deposit around prometheus extends into the so2 ring this suggests that the deposits are thin and that compositional or grain size variations may occur in the radial direction so2 mapping of the chaac region shows that the interior of a caldera adjacent to chaac has almost pure so2 the deposit appears to be topographically controlled suggesting a possible origin by liquid flow

volcanism on io estimation of eruption parameters from galileo nims data 1 galileo near infrared mapping spectrometer nims data of volcanic thermal emission are analyzed to determine the power output of a number of ionian volcanoes from which are calculated volumetric eruption rates a two temperature model is used to determine surface temperatures and power output portions of prometheus and six other volcanoes are found to be in excess of 1100 k areas of prometheus are at temperatures close to 1500 k these are minimum eruption temperatures and are consistent with basaltic silicate volcanism for the 14 volcanoes in g1innspec01 volumetric eruption rates e are constrained between 3 and 300 m3 s for basaltic and ultramafic compositions actual e values lie between these limits the small crack fractions hot area to warm area ratio implied from these fits are indicative of a relatively quiescent eruption style such as the emplacement of a pahoehoe or a a flow field the volumetric eruption rates derived from the nims data are greater than those observed in similar styles of volcanism on earth it is apparent that for similar eruption styles the areal extent of activity is greater on io than on earth derived flow thicknesses range from 0 1 to 13 m

observations of horizontal velocities and vertical displacements in the equatorial pacific ocean associated with the early stages of the 1982 83 el nino abstract pacific near equatorial absolute velocity data and ctd o2 observations collected from the r v conrad in the northern fall of 1982 are presented quite by chance the cruise took place during the early stages of the 1982 83 el nino the data obtained are generally consistent with the fundamental ideas about el nino onset in that abnormal eastward flow near the surface and large thermocline depressions were observed these changes are quantified by comparing with previously collected data and are discussed in terms of simple equatorially trapped wave dynamics the results indicate that first and second mode disturbances probably kelvin waves were prominent in the equatorial pacific in the fall of 1982

thermal signature eruption style and eruption evolution at pele and pillan on io the galileo spacecraft has been periodically monitoring volcanic activity on io since june 1996 making it possible to chart the evolution of individual eruptions we present results of coanalysis of near infrared mapping spectrometer nims and solid state imaging ssi data of eruptions at pele and pillan especially from a particularly illuminating data set consisting of mutually constraining near simultaneous nims and ssi observations obtained during orbit c9 in june 1997 the observed thermal signature from each hot spot and the way in which the thermal signature changes with time tightly constrains the possible styles of eruption pele and pillan have very different eruption styles from september 1996 through may 1999 pele demonstrates an almost constant total thermal output with thermal emission spectra indicative of a long lived active lava lake the nims pillan data exhibit the thermal signature of a pillanian eruption style a large vigorous eruption with associated open channel or sheet flows producing an extensive flow field by orbit c10 in september 1997 the high mass eruption rate high liquidus temperature at least 1870 k eruption at pillan is the best candidate so far for an active ultramafic magnesium rich komatiitic flow on io a style of eruption never before witnessed the thermal output per unit area from pillan is however consistent with the emplacement of large open channel flows magma temperature at pele is 1600 k if the magma temperature is 1600 k it suggests a komatiitic basalt composition the power output from pele is indicative of a magma volumetric eruption rate of 250 to 340 m3 s 1 although the pele lava lake is considerably larger than its terrestrial counterparts the power and mass fluxes per unit area are similar to active terrestrial lava lakes