flowgo a kinematic thermo rheological model for lava flowing in a channel we present a kinematic self adaptive numerical model to describe the down flow thermal and rheological evolution of channel contained lava as our control volume of lava advances down a channel it cools and crystallizes an increasingly thick and extensive surface crust grows and its heat budget and rheology evolve by estimating down flow heat and velocity loss our model calculates the point at which the control volume becomes stationary giving the maximum distance lava flowing in the channel can extend modeled effusion rates velocities widths surface crust parameters heat budget cooling temperature crystallinity viscosity and yield strength all compare well with field data collected during eruptions at mauna loa k lauea and etna modeled lengths of 25 27 2 5 5 7 and 0 59 0 83 km compare with measured lengths of 25 27 4 and 0 75 km for the three flows respectively over proximal flow portions we calculate cooling crystallization viscosity and yield strength of 1 10 c km 1 0 001 0 01 volume fraction km 1 103 104 pa s and 10 3 102 pa respectively at the flow front cooling crystallization viscosity and yield strength increase to 100 c km 1 0 1 volume fraction km 1 106 107 pa s and 103 104 pa respectively all of which combine to cause the lava to stop flowing our model presents a means of a analyzing lava flow thermo rheological relationships b identifying important factors in determining how far a channel fed flow can extend c assessing lava flow hazard and d reconstructing flow regimes at prehistoric unobserved or remote flows

infrared satellite monitoring at popocatepetl explosions exhalations and cycles of dome growth 1 since december 1994 activity at popocatepetl has evolved through two main phases the first was characterized by elevated seismic activity degassing and emissions of predominantly lithic ash however in march 1996 the volcano entered a magmatic phase which has involved the emplacement of at least eight lava domes within its summit crater we have used infrared radiance data acquired by the goes meteorological satellite alongside ground based geophysical data sets to analyze aspects of this activity we develop a technique to identify magmatic activity at the volcano in the absence of a volcanic heat source the radiance emitted from the hottest pixel pr contained within a 10 10 pixel goes subscene centered on popocatepetl s summit is well correlated with the average radiance emitted by the remaining pixels br because at any given time all pixels within the target box have similar temperatures varying as a function of season cloud cover and solar irradiance however during periods of heightened volcanic activity the radiance emitted by the hottest pixel varies as a function of a time independent volcanic heat source and changes in pr and br become decorrelated allowing volcanic activity to be identified exhalations intermittent ash emissions cannot be identified by routine analysis of goes data because of the low intensity of the associated thermal anomalies explosions however produce distinctive radiance signatures and can be reliably documented two dome growth episodes occurred during our study period one in november december 1998 and the other during february 2000 although the techniques we describe identified the 1998 dome event the 2000 dome went undetected this is explained in terms of their contrasting emplacement styles the 1998 dome was apparent to goes due to the explosions that disrupted its cool carapace scattered hot bombs around the summit cone and exposed its hotter interior to the satellite sensor in contrast the february 2000 dome was not apparent because elevated explosive activity did not accompany its emplacement

birth growth and morphologic evolution of the laghetto cinder cone during the 2001 etna eruption we have undertaken detailed observations of the formation of the laghetto cinder cone a new cone that formed during a 2 week period of intense activity in piano del lago on the upper slopes of mount etna in summer 2001 we describe the events leading to the formation of a small graben the formation of pit craters on the base of the graben the onset of phreatomagmatic activity a transition to intense strombolian activity and a return to phreatomagmatic activity as the eruption came to an end we discuss the reasons for these transitions and describe the morphological development of the cone during these events arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim some of the failure planes we observed were first identified using a flir tm 695 thermal infrared camera this is the first time that infrared thermography has been used to detect instability of volcanic structures results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability

thermal characterization of the vulcano fumarole field ground based thermal infrared surveys can contribute to complete heat budget inventories for fumarole fields however variations in atmospheric conditions plume condensation and mixed pixel effects can complicate vent area and temperature measurements analysis of vent temperature frequency distributions can be used however to characterise and quantify thermal regions within a field we examine this using four thermal infrared thermometer and thermal image surveys of the vulcano fossa fumarole field italy during june 2004 and july 2005 these surveys show that regions occupied by low temperature vents are characterised by distributions that are tightly clustered around the mean i e the standard deviation is low highly peaked positive kurtosis and skewed in the low temperature direction negative skewness this population is associated with wet fumaroles where boiling controls maximum temperature to cause a narrow distribution with a mode at 90 100 c in contrast high temperature vent regions have distributions that are widely spread about the mean i e the standard deviation is high relatively flat negative kurtosis and skewed in the high temperature direction positive skewness in this dry case fumaroles are water free so that maximum temperatures are not fixed by boiling as a result greater temperature variation is possible we use these results to define two vent types at vulcano on the basis of their thermal characteristics 1 concentrated localized regions of high temperature vents and 2 dispersed low temperature vents these occur within a much larger region of diffuse heat emission across which surfaces are heated by steam condensation the heat from which causes elevated surface temperatures for vulcano s lower fumarole zone high and low temperature vents occupied total areas of 3 and 6 m2 respectively and occurred within a larger 430 m2 vent free zone of diffuse heat emission for this lower zone we estimate that 21 43 103 w of heat was lost by diffuse heat emission a further 4 5 103 w was lost by radiation from high temperature vents and 6 5 103 w from low temperature vents thus radiative heat losses from high and low temperature vents within vulcano s lower fumarole zone respectively account for 10 and 15 of the total heat lost from this zone this shows that radiation from open vents can account for a non trivial portion of the total fumarole field heat budget

simulations of the 2004 lava flow at etna volcano using the magflow cellular automata model since the mechanical properties of lava change over time lava flows represent a challenge for physically based modeling this change is ruled by a temperature field which needs to be modeled magflow cellular automata ca model was developed for physically based simulations of lava flows in near real time we introduced an algorithm based on the monte carlo approach to solve the anisotropic problem as transition rule of ca a steady state solution of navier stokes equations was adopted in the case of isothermal laminar pressure driven bingham fluid for the cooling mechanism we consider only the radiative heat loss from the surface of the flow and the change of the temperature due to mixture of lavas between cells with different temperatures the model was applied to reproduce a real lava flow that occurred during the 2004 2005 etna eruption the simulations were computed using three different empirical relationships between viscosity and temperature

long term infrared surveillance of lascar volcano contrasting activity cycles and cooling pyroclastics lascar volcano chile erupted on 20 july 2000 generating a 10 km high ash column satellite infrared data have previously indicated that lascar s large vulcanian explosions are preceded by significant cooling within the active crater suggesting that characteristic thermal radiance trends can act as remotely detectable eruption precursors new analyses and data extend the lascar s thermal history to cover all five large vulcanian eruptions occurring over the last 15 years the 2000 eruption follows a formerly undocumented style of infrared radiance variation and indicates that lascar may have modified its activity since 1993 the year of its greatest historical eruption therefore such patterns evident for over a decade at lascar can be unexpectedly modified and this has implications for the way apparent thermal precursors should be treated the largest 1993 eruption produced 8 5 km long pyroclastic flows which the infrared data indicate exhibited exponential cooling over an 8 12 months period

infrared image analysis of volcanic thermal features lascar volcano chile 1984 1992 fifteen landsat thematic mapper tm images of lascar volcano chile recorded between december 1984 and april 1992 document the evolution of a lava dome within the summit crater four of the scenes were acquired at night in every image the two short wavelength infrared bands 5 and 7 have detected thermal radiation from the volcano as a consequence of the planck distribution function the relative response of these two channels depends on the proportions of very hot 600 c surfaces occupying tiny pixel areas and broader regions at moderate temperatures 280 c intercomparison of bands 5 and 7 thereby provides a means for interpreting tm thermal anomalies even in the absence of ground observations pronounced changes in the configuration and intensity of the lascar anomaly suggest that the volcano has experienced at least two cycles of lava dome activity since 1984 the first of these progressed through a cooling period possibly reflecting a reduced flux of magmatic volatiles at the surface and culminated in an explosive eruption on september 16 1986 which appears to have completely destroyed the inferred lava dome the tm data indicate that a new dome had been emplaced by november 1987 more than 15 months before it was first discovered by local observers lascar s style of cyclical effusive and explosive activity is typical of many volcanoes and the remote sensing techniques presented herein could be applied elsewhere

modelling the rapid near surface expansion of gas slugs in low viscosity magmas the ascent of large gas bubbles slugs in vertical cylindrical conduits and low viscosity magmas is simulated using 1d mathematical and 3d computational fluid dynamic cfd models following laboratory evidence the 1d model defines a constant rise velocity for the slug base and allows gas expansion to accelerate the slug nose through the overlying fluid during ascent the evolution of rapidly expanding gas slugs observed in laboratory experiments is reproduced well and at volcano scales predicts at surface overpressures of several atmospheres without requiring any initial overpressure at depth the near surface dynamics increase slug nose velocities through the overlying magma by a factor of c 2 5 and the gas expansion results in pre burst magma surface velocities of c 35m s21 to examine pressure distributions and the forces exerted on a conduit 3d cfd simulations were carried out at volcano scales the vertical single forces during final slug ascent to the surface are c 106 n two orders of magnitude smaller than those associated with verylong period seismic events at stromboli this supports a previous interpretation of these events in which they are generated by gas slugs flowing through changes in conduit geometry rather than being the direct result of slug eruption processes

ground based thermal imaging of lava lakes at erebus volcano antarctica abstract mount erebus a large intraplate stratovolcano dominating ross island antarctica hosts the world s only active phonolite lava lakes the main manifestation of activity at erebus volcano in december 2004 was as the presence of two convecting lava lakes within an inner crater the long lived ray lake 1400 m2 in area was the site of up to 10 small strombolian eruptions per day a new but short lived 1000 1200 m2 lake formed at werner vent in december 2004 sourced by lava flowing from a crater formed in 1993 by a phreatic eruption we measured the radiative heat flux from the two lakes in december 2004 using a compact infrared ir imaging camera daily thermal ir surveys from the main crater rim provide images of the lava lake surface temperatures and identify sites of upwelling and downwelling the radiative heat outputs calculated for the ray and werner lakes are 30 35 mw and 20 mw respectively we estimate that the magma flux needed to sustain the combined heat loss is 250 710 kg s 1 that the minimum volume of the magma reservoir is 2 km3 and that the radius of the conduit feeding the ray lake is 2 m

the distal segment of etna s 2001 basaltic lava flow etna s 2001 basaltic lava flow provided a good example of the distal flow segment between the flow front and stable channel across which the flow evolves from channel contained to dispersed this zone was mapped with meter precision using lidar data collected during 2004 and 2005 these data supported by field mapping show that the flow front comprised eight lobes each 10 to 20 m high the flow front appears to have advanced not as a single unit but as a series of lobes moving forward one lobe at a time primary lobes were centered on the channel axis and marginal lobes were off axis the lobes advanced as breakouts of low yield strength lava from the flow core of the stalled flow front marginal lobes were abandoned and contributed to marginal levees flanking the transitional channel for etna s 2001 flow the transitional channel is 140 m wide 700 m long and fed a 240 m long zone of dispersed flow the change from stable to transitional channel occurred at a major reduction in slope above this the stable channel is 5 2 km long 55 to 105 m wide and bounded by 15 to 25 m high levees and the stable channel is located over a previous channel in a final stage of activity lava ponding at the break in slope that marks the terminus of the stable channel put pressure on the eastern levee causing it to fail liberated lava then fed a final break out to the east similar flow front features occur at other volcanoes indicating that similar processes are characteristic of dispersed flow zones

thermal image derived dynamics of vertical ash plumes at santiaguito volcano guatemala vertical ash plumes were imaged at santiaguito guatemala using a thermal camera to capture plume ascent dynamics the plumes comprised a convecting plume front fed by a steady feeder plume of the 25 plumes imaged 24 had a gas thrust region within which ascent velocities were 15 50 m s 1 a transition to buoyant ascent occurred 20 to 50 m above the vent where ascent velocities declined to 4 15 m s 1 plumes that attained greater heights had higher heat contents wider feeder plumes and higher buoyant ascent velocities

thermal monitoring of hydrothermal activity by permanent infrared automatic stations results obtained at solfatara di pozzuoli campi flegrei italy 1 a permanent automatic infrared ir station was installed at solfatara crater the most active zone of campi flegrei caldera after a positive in situ calibration of the ir camera we analyze 2175 thermal ir images of the same scene from 2004 to 2007 the scene includes a portion of the steam heated hot soils of solfatara the experiment was initiated to detect and quantify temperature changes of the shallow thermal structure of a quiescent volcano such as solfatara over long periods ambient temperature is the main parameter affecting ir temperatures while air humidity and rain control image quality a geometric correction of the images was necessary to remove the effects of slow movement of the camera after a suitable correction the images give a reliable and detailed picture of the temperature changes over the period october 2004 to january 2007 which suggests that origin of the changes were linked to anthropogenic activity vegetation growth and the increase of the flux of hydrothermal fluids in the area of the hottest fumaroles two positive temperature anomalies were registered after the occurrence of two seismic swarms which affected the hydrothermal system of solfatara in october 2005 and october 2006 it is worth noting that these signs were detected in a system characterized by a low level of activity with respect to systems affected by real volcanic crisis where more spectacular results will be expected results of the experiment show that this kind of monitoring system can be a suitable tool for volcanic surveillance

erratum to lava discharge during etna s january 2011 fire fountain tracked using msg seviri in the paper by gouhier m harris a calvari s labazuy p guehenneux y donnadieu f valade s entitled lava discharge during etna s january 2011 fire fountain tracked using msg seviri bull volcanol 2012 74 787 793 doi 10 1007 s00445 011 0572 y we present data from a doppler radar voldorad 2b this ground based lband radar has been monitoring the eruptive activity of the summit craters of mt etna in real time since july 2009 from a site about 3 5 km sse of the craters examples of applications of this type of radar are reviewed by donnadieu 2012 and shown on the voldorad website http wwwobs univbpclermont fr so televolc voldorad although designed and owned by the observatoire de physique du globe in clermont ferrand opgc france voldorad 2b is operated jointly with the ingv catania italy in the framework of a technical and scientific collaboration agreement between the ingv of catania the french cnrs and the opgc universite blaise pascal in clermontferrand the system also utilizes a dedicated micropatch antenna designed at the university of calabria boccia et al 2010 and owned by ingv the objective of the joint acquisition of the radar data by ingv catania and the opgc is twofold 1 to mitigate volcanic risks at etna by better assessing the hazards arising from ash plumes and 2 to allow detailed study of volcanic activity and its environmental impact in the paper by gouhier et al 2012 we failed to highlight this important collaboration between the ingv catania and the opgc a cooperation essential for the past current and future generation of such valuable data sets specifically we wish to acknowledge the roles of mauro coltelli michele prestifilippo and simona scollo for their important input into this project and pivotal role in setting up and maintaining this collaborative deployment

sediment routing and basin evolution in proterozoic to mesozoic east gondwana a case study from southern australia abstract sedimentary rocks along the southern margin of australia host an important record of the break up history of east gondwana as well as fragments of a deeper geological history which collectively help inform the geological evolution of a vast and largely underexplored region new drilling through cenozoic cover has allowed examination of the cretaceous rift related madura shelf sequence bight basin and identification of two new stratigraphic units beneath the shelf the possibly proterozoic shanes dam conglomerate and the interpreted palaeozoic southern officer basin unit the decoration sandstone recognition of these new units indicates an earlier basinal history than previously known lithostratigraphy of the new drillcore has been integrated with that published from onshore and offshore cores to present isopach maps of sedimentary cover on the madura shelf new palynological data demonstrate progression from more localised freshwater brackish fluvio lacustrine clastics in the early cretaceous foraminisporis wonthaggiensis valanginian to barremian to widespread topography blanketing fully marine glauconitic mudrocks in the mid cretaceous endoceratium ludbrookiae albian geochronology and hf isotope geochemistry show detrital zircon populations from the madura shelf are comparable to those from the southern officer basin as well as cenozoic shoreline and palaeovalley sediments in the region the detrital zircon population from the shanes dam conglomerate is defined by a unimodal 1400 ma peak which correlates with directly underlying crystalline basement of the madura province peak ages of 1150 ma and 1650 ma dominate the age spectra of all other samples indicating a stable sediment reservoir through much of the phanerozoic with sediments largely sourced from the albany fraser orogen and musgrave province directly and via multiple recycling events the madura shelf detrital zircon population differs from published data for the upper cretaceous ceduna delta to the east indicating significant differences in sediment provenance and routing between the ceduna sub basin and central bight basin

sr_nd_pb isotope systematics in amazon and congo river systems constraints about erosion processes abstract 87 sr 86 sr 143 nd 144 nd 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb isotopic ratios and rb sr sm nd u pb and th concentrations have been measured in the suspended loads of the congo and amazon rivers and their tributaries in the dissolved load 87 sr 86 sr rb sr nd sm u pb and th concentrations are also reported these results show that nd sm th and pb are almost insoluble and that their mass balance is controlled by particulates whereas rb sr and u are fractionated between soluble and particulate phases the 87 sr 86 sr ratios can only be interpreted after computing the amount of carbonate recycling and the partitioning for silicates between soluble and insoluble this paper presents a method based on the lead isotopic system that can be used to test the steady state of erosion which is tacitly assumed in many river and erosion studies the results presented show that the steady state is validated in each river of the congo basin and in the lowland rivers of the amazon basin but in not verified in the rivers from the andes rio solimoes and rio madeira 87 sr 86 sr 206 pb 204 pb and 208 pb 204 pb ratios are positively correlated and negatively correlated with 143 nd 144 nd ratios a number of arguments indicate that these correlations are mixing lines the end members being orogenic and shield components respectively for the amazon basin analysis of the river loads shows that the orogenic zone is favoured some 5 times more than the shield on an equal area basis this leads to a reinterpretation of sm nd data for shales and casts some doubts upon the proposition of secular variations in the sm nd ratio of the continental crust

continental growth and the crustal record abstract the continental crust is the archive of earth history the spatial and temporal distribution of the earth s record of rock units and events is heterogeneous with distinctive peaks and troughs in the distribution of ages of igneous crystallisation metamorphism continental margins and mineralisation this distribution reflects the different preservation potential of rocks generated in different tectonic settings rather than fundamental pulses of activity and the peaks of ages are linked to the timing of supercontinent assembly in contrast there are other signals such as the sr isotope ratios of seawater mantle temperatures and redox conditions on the earth where the records are regarded as primary because they are not sensitive to the numbers of samples of different ages that have been analysed new models based on the u pb hf and o isotope ratios of detrital zircons suggest that at least 60 70 of the present volume of the continental crust had been generated by 3 ga the growth of continental crust was a continuous rather than an episodic process but there was a marked decrease in the rate of crustal growth at 3 ga this appears to have been linked to significant crustal recycling and the onset plate tectonics the 60 70 of the present volume of the continental crust estimated to have been present at 3 ga contrasts markedly with the

rates of generation and destruction of the continental crust implications for continental growth less than 25 of the volume of the juvenile continental crust preserved today is older than 3 ga there are no known rocks older than approximately 4 ga and yet a number of recent models of continental growth suggest that at least 60 80 of the present volume of the continental crust had been generated by 3 ga such models require that large volumes of pre 3 ga crust were destroyed and replaced by younger crust since the late archaean to address this issue we evaluate the influence on the rock record of changing the rates of generation and destruction of the continental crust at different times in earth9s history we adopted a box model approach in a numerical model constrained by the estimated volumes of continental crust at 3 ga and the present day and by the distribution of crust formation ages in the present day crust the data generated by the model suggest that new continental crust was generated continuously but with a marked decrease in the net growth rate at approximately 3 ga resulting in a temporary reduction in the volume of continental crust at that time destruction rates increased dramatically around 3 billion years ago which may be linked to the widespread development of subduction zones the volume of continental crust may have exceeded its present value by the mid late proterozoic in this model about 2 6 2 3 times of the present volume of continental crust has been generated since earth9s formation and approximately 1 6 1 3 times of this volume has been destroyed and recycled back into the mantle this article is part of a discussion meeting issue earth dynamics and the development of plate tectonics9

zircon u pb ages and hf isotopes of paleozoic metasedimentary rocks from the habahe group in the qinghe area chinese altai and their tectonic implications abstract as one of the largest accretionary orogens in earth s history the central asian orogenic belt has attracted much attention in the past two decades but there are still many unresolved issues regarding its tectonic nature and evolution this is the case with the chinese altai whose tectonic provenance remains controversial especially for the paleozoic era as the most widely exposed meta sedimentary rocks in the chinese altai the habahe group was previously considered as representing a component of precambrian micro continent forming at a passive continental margin our new u pb data for detrital zircons from the habahe group in the qinghe region of the eastern chinese altai indicate that the strata were deposited from the late silurian to early devonian 427 405 ma and experienced regional metamorphism in the middle devonian 383 9 ma as constrained by the age of youngest detrital zircons 427 13 ma the age 405 3 ma of the tonalite that intrudes the habahe group and the metamorphic age of 383 9 ma additionally the majority of zircons from the habahe group have positive ehf t values 0 22 15 02 these data combined with geochemical features and maturity of the sedimentary rocks indicate an immature provenance for the habahe group with the source materials mainly derived from a juvenile crust with some old continental components the juvenile crust was most likely formed in a subduction zone developing in the chinese altai during early middle paleozoic time new geochemical data presented in this study suggest that the chinese altai was a transitional arc during early paleozoic time similar to the japan type arc with involvements of old continental components therefore it is proposed that the chinese altai was likely rifted from the south margin of the siberia craton probably related to the break up of the rodinia supercontinent and then experienced accretion and reworking with the subduction of the paleo asian ocean during early paleozoic time

a year of lava fountaining at etna volumes from seviri 1 we present a new method that uses cooling curves apparent in high temporal resolution thermal data acquired by geostationary sensors to estimate erupted volumes and mean output rates during short lava fountaining events the 15 minute temporal resolution of the data allows phases of waxing and peak activity to be identified during short 150 to 810 minute long events cooling curves which decay over 8 to 21 hour periods following the fountaining event can also be identified application to 19 fountaining events recorded at etna by msg s seviri sensor between 10 january 2011 and 9 january 2012 yields a total erupted dense rock lava volume of 28 106 m3 with a maximum intensity of 227 m3 s 1being obtained for the 12 august 2011 event the time averaged output over the year was 0 9 m3 s 1 this being the same as the rate that has characterized etna s effusive activity for the last 40 years

using infrared satellite data to drive a thermo rheological stochastic lava flow emplacement model a method for near real time volcanic hazard assessment 1 we combine two flow simulation models to provide a computationally efficient means of predicting the final dimensions of active lava flows by using a stochastic approach to predict all the downhill paths that a lava flow could possibly follow and a thermo rheological model to terminate these paths once the predicted cooling limited length for the flow has been attained this approach allows for rapid assessment of the area likely to be inundated by lava the 1991 1993 eruption of mount etna is used as a case study lava effusion rate exerts a strong control on the maximum length a lava flow can attain and we demonstrate how the model can be driven by time varying effusion rates obtained from infrared satellite data as such data are obtained in near real time this approach allows flow simulations to be updated in a timely manner in response to changing eruption conditions

ducks low cost thermal monitoring units for near vent deployment abstract during 1999 we designed and tested a thermal monitoring system to provide a cheap robust modular real time system capable of surviving the hostile conditions encountered proximal to active volcanic vents in november 2000 the first system was deployed at pu u o o kilauea hawai i to target persistently active vents aside from some minor problems such as sensor damage due to tampering this system remained operational until january 2004 the success of the prototype system led us to use the blueprint for a second installation at stromboli aeolian islands italy this was deployed dug into a bomb proof bunker during may 2002 and survived the april 2003 paroxysmal eruption despite being located just 250 m from the vent in both cases careful waterproofing of connectors and selection of suitable protection has prevented water damage and corrosion in the harsh atmosphere encountered at the crater rim the pu u o o system cost us 10 000 and comprises four modules sensors transmission and power hub repeater station and reception site the sensor component consists of three thermal infrared thermometers housed in pelican cases fitted with germanium arsenide selenium windows two 1 field of view fov sensors allow specific vents to be targeted and a 60 fov sensor provides a crater floor overview a hard wire connection links to a pelican case housed microprocessor modem and power module from here data are transmitted via a repeater site to a dedicated pc at the hawaiian volcano observatory here data are displayed with a delay of 3 s between acquisition and display the modular design allows for great flexibility at stromboli 1 and 15 fov sensor modules can be switched depending changes in activity style and crater geometry in addition a direct line of site to the stromboli reception center negates the repeater site requirement reducing the cost to us 5500 for a single sensor system we have also constructed self contained units with internal data loggers for us 1500 unit these have been tested at kilauea stromboli etna masaya santiaguito fuego pacaya poas soufriere hills villarrica and erta ale these instruments have proved capable of detecting thermal signals associated with 1 gas emission 2 gas jetting events 3 crater floor collapse 4 lava effusion 5 lava flow in tubes 6 lava lake activity 7 lava dome activity and 8 crater lake skin temperature

the changing morphology of an open lava channel on mt etna an open channel lava flow on mt etna sicily was observed during may 30 31 2001 data collected using a forward looking infrared flir thermal camera and a minolta land cyclops 300 thermal infrared thermometer showed that the bulk volume flux of lava flowing in the channel varied greatly over time cyclic changes in the channel s volumetric flow rate occurred over several hours with cycle durations of 113 190 min and discharges peaking at 0 7 m3 s 1 and waning to 0 1 m3 s 1 each cycle was characterized by a relatively short high volume flux phase during which a pulse of lava with a well defined flow front would propagate down channel followed by a period of waning flow during which volume flux lowered pulses involved lava moving at relatively high velocities up to 0 29 m s 1 and were related to some change in the flow conditions occurring up channel possibly at the vent they implied either a change in the dense rock effusion rate at the source vent and or cyclic variation in the vesicle content of the lava changing its bulk volume flux pulses would generally overspill the channel to emplace p hoehoe overflows during periods of waning flow velocities fell to 0 05 m s 1 blockages forming during such phases caused lava to back up occasionally backup resulted in overflows of slow moving a that would advance a few tens of meters down the levee flank compound levees were thus a symptom of unsteady flow where overflow levees were emplaced as relatively fast moving p hoehoe sheets during pulses and as slow moving a units during backup small localized fluctuations in channel volume flux also occurred on timescales of minutes volumes of lava backed up behind blockages that formed at constrictions in the channel blockage collapse and or enhanced flow under around the blockage would then feed short lived wave like down channel surges real fluctuations in channel volume flux due to pulses and surges can lead to significant errors in effusion rate calculations

forecasting lava flow paths by a stochastic approach 1 a stochastic model named downflow is presented to forecast possible lava flow paths with the aim of hazard assessment and mitigation the model relies on the fact that lava flow emplacement is in many cases controlled by topography the potential inundation area of the flow is determined by considering a number of steepest paths over stochastic perturbations of the original topography since the code requires very short computational time and few input data the model proved to be a very useful tool to obtain real time predictions during the initial phase of an eruption the necessary topographic information can be obtained by photogrammetry radar altimetry or laser scanning techniques downflow has been successfully applied to a number of flows including the september 2004 lava flow where updated topographies were available

near real time forecasting of lava flow hazards during the 12 13 january 2011 etna eruption we are grateful to eumetsat for seviri data to nasa for modis data and tonoaafor avhrr data the authors thank one anonymous reviewer and v acocella for their helpful and constructive comments this study was performed with the financial support from the v3 lava project ingv dpc 2007 2009 contract

neoarchean metagabbro and charnockite in the yinshan block western north china craton petrogenesis and tectonic implications abstract properly calibrating the magmatic record of mantle and crustal origin in archean granite greenstone terranes is crucial for understanding the petrogenetic and geodynamic processes that generated early continental landmasses this geochronological and geochemical study documents a neoarchean bimodal metaplutonic suite of metagabbro and charnockite from the yinshan block north china craton the meta gabbroic rocks show an sio 2 range from 45 9 to 51 7 and high mgo content from 6 7 to 16 4 with enrichment in ba and light rare earth elements la n yb n 3 11 5 99 and depletion in high field strength elements together with their enriched whole rock nd nd t 0 23 to 1 49 and zircon hf hf t 0 1 6 9 isotopic signatures relative to the archean depleted mantle in the craton these rocks are supposed to originate from the second stage high temperature partial melting of refractory depleted mantle that experienced prior basaltic magma extraction and subsequent metasomatism by subduction related fluids the associated charnockites range in sio 2 from 61 3 to 69 6 and exhibit a magnesian calc alkalic and metaluminous character with variable sr y and la n yb n ratios these elemental features plus their evolved isotopic compositions nd t 0 93 1 85 zircon hf t 0 3 to 2 5 are consistent with partial melting of newly underplated mafic lower crustal protolith in combination with widespread occurrence of metasomatized lithospheric mantle derived magmas e g high mg basalts sanukitoid suites and juvenile crust extracted potassic granites in the ncc during late neoarchean time such a mafic and felsic magma association not only attests to the establishment of a craton scale subduction related metasomatized sub continental lithospheric mantle but also encapsulates a scenario of coupled lithospheric mantle crust formation at 2 7 ga and juvenile crustal reworking at 2 5 ga within a modern style convergent continental margin possibly featuring episodic slab break off events

the 5 april 2003 vulcanian paroxysmal explosion at stromboli volcano italy from field observations and thermal data abstract the 5 april 2003 paroxysmal explosion at stromboli volcano was one of the strongest explosive events of the last century it occurred while the effusive eruption begun on 28 december 2002 and finished on 22 july 2003 was still on going and the summit craters of the volcano were obstructed in this paper we present a reconstruction of the sequence of events based on thermal and visual images collected from helicopter before during and immediately after the paroxysm one month before the blast ash emission and temperature increase at the bottom of the summit craters were observed an increasing amount of juvenile components in the emitted ash during march suggested that the magma level within the crater was rising accordingly hot degassing vents at the bottom of the summit craters were not persistent and the craters remained almost entirely obstructed by talus accumulation until the paroxysm occurred three minutes before the explosion we recorded a significant increase in temperature inside crater 1 accompanied by a thicker gas plume thirty two seconds before the blast reddish ash was emitted from crater 1 the paroxysm produced a vulcanian explosion that opened the feeder conduit obstructed for over three months the blast was accompanied by a shock wave recorded by the ingv seismic network at 07 13 37 gmt explosions with hot material started from crater 1 and after 15 s propagated to crater 3 about 100 m away the velocity of ejecta was 80 m s 1 and increased when the eruptive plumes from both craters merged together during the vulcanian phase an eruptive column rose 1 km above the top of the volcano and explosions continued mainly at crater 3 the paroxysm lasted about 9 min with bombs up to 4 m wide falling on the village of ginostra on the west flank of the island and destroying two houses this event signalled the start of the declining phase of the effusive eruption suggesting that the feeder conduit was returning to its former steady conditions with open vents and continuous mild strombolian activity

lava flow thermal analysis using three infrared bands of remote sensing imagery a study case from mount etna 2001 eruption abstract infrared remotely sensed data can be used to estimate heat flux and thermal features of active volcanoes the model proposed by crisp and baloga crisp j baloga s 1990 a model for lava flows with two thermal components journal of geophysical research 95 1255 1270 for active lava flows considers the thermal flux a function of the fractional area of two thermally distinct radiant surfaces the larger surface area corresponds to the cooler crust of the flow the smaller one to fractures in the crust in this model the crust temperature t c the temperature of the cracks t h and the fractional area of the hottest component f h represent the three unknowns to work out the simultaneous solution of the planck equation dual band technique for two distinct shortwave infrared swir bands allows to estimate any two of the parameters t c t h f h if the third is assumed dozier j 1981 a method for satellite identification of surface temperature fields of subpixel resolution remote sensing environment 11 221 229 the airborne sensor mivis was flown on mount etna during the july august 2001 eruption this hyperspectral imaging spectrometer offers 72 bands in the swir range and 10 bands in thermal infrared tir region of the spectrum which can be used to solve the dual band system without any assumptions therefore we can combine three spectral mivis bands to obtain simultaneous solutions for the three unknowns here the procedure for solving such a system is presented it is then demonstrated that a tir channel is required to better pinpoint solutions to the 2 components model finally the spatial and statistical characteristic of the resultant mivis derived temperature and flux distributions are introduced and statistics for each hot spot investigated

thirty years of satellite derived lava discharge rates at etna implications for steady volumetric output 1 we present a 30 year long data set of satellite derived time averaged lava discharge rates tadr for mount etna volcano sicily italy spanning 1980 2010 and comprising 1792 measurements during 23 eruptions we use this to classify eruptions on the basis of magnitude and intensity as well as the shape of the tadr time series which characterizes each effusive event we find that while 1983 1993 was characterized by less frequent but longer duration effusive eruptions at lower tadrs 2000 2010 was characterized by more frequent eruptions of shorter duration and higher tadrs however roughly the same lava volume was erupted during both of these 11 year long periods so that the volumetric output was linear over the entire 30 year period increasing at a rate of 0 8 m3 s 1 between 1980 and 2010 the cumulative volume record can be extended back in time using data available in the literature this allows us to assess etna s output history over 5 centuries and to place the current trend in historical context we find that output has been stable at this rate since 1971 at this time the output rate changed from a low discharge rate phase which had characterized the period 1759 to 1970 to a high discharge rate phase this new phase had the same output rate as the high discharge rate phase that characterized the period 1610 1669 the 1610 1669 phase ended with the most voluminous eruption of historic times

satellite based evidence for a large hydrothermal system at piton de la fournaise volcano reunion island 1 hydrothermal systems are active structures present at many volcanoes their characterization is essential as they reveal the evolution of the magmatic source and may play a role in the eruptive style many studies have already suggested the existence of a shallow hydrothermal system beneath the summit craters at piton de la fournaise volcano la reunion although there is still no clear evidence here we present new arguments on the basis of satellite based data acquired during april 2007 eruption suggesting the existence of a large hydrothermal system beneath the dolomieu crater at piton de la fournaise so2 released during the collapse phase of the dolomieu crater april 6 13 has been estimated at 935 244 kilotons whereas erupted so2 calculated from lava effusion rates was found to be clearly insufficient 179 89 kilotons we suggest that the excess of so2 originated from a large hydrothermal system suddenly opened by the collapse

a change in the geodynamics of continental growth 3 billion years ago models for the growth of continental crust rely on knowing the balance between the generation of new crust and the reworking of old crust throughout earth s history the oxygen isotopic composition of zircons for which uranium lead and hafnium isotopic data provide age constraints is a key archive of crustal reworking we identified systematic variations in hafnium and oxygen isotopes in zircons of different ages that reveal the relative proportions of reworked crust and of new crust through time growth of continental crust appears to have been a continuous process albeit at variable rates a marked decrease in the rate of crustal growth at 3 billion years ago may be linked to the onset of subduction driven plate tectonics

volcanology 2020 how will thermal remote sensing of volcanic surface activity evolve over the next decade abstract volcanological remote sensing spans numerous techniques wavelength regions data collection strategies targets and applications attempting to foresee and predict the growth vectors in this broad and rapidly developing field is therefore exceedingly difficult however we attempted to make such predictions at both the american geophysical union agu meeting session entitled volcanology 2010 how will the science and practice of volcanology change in the coming decade held in december 2000 and the follow up session 10 years later looking backward and forward volcanology in 2010 and 2020 in this summary paper we assess how well we did with our predictions for specific facets of volcano remote sensing in 2000 the advances made over the most recent decade and attempt a new look ahead to the next decade in completing this review we only consider the subset of the field focused on thermal infrared remote sensing of surface activity using ground based and space based technology and the subsequent research results this review keeps to the original scope of both agu presentations and therefore does not address the entire field of volcanological remote sensing which uses technologies in other wavelength regions e g ultraviolet radar etc or the study of volcanic processes other than the those associated with surface mostly effusive activity therefore we do not consider remote sensing of ash gas plumes for example in 2000 we had looked forward to a golden age in volcanological remote sensing with a variety of new orbital missions both planned and recently launched in addition exciting field based sensors such as hand held thermal cameras were also becoming available and being quickly adopted by volcanologists for both monitoring and research applications all of our predictions in 2000 came true but at a pace far quicker than we predicted relative to the 2000 2010 timeframe the coming decade will see far fewer new orbital instruments with direct applications to volcanology however ground based technologies and applications will continue to proliferate and unforeseen technology promises many exciting possibilities that will advance volcano thermal monitoring and science far beyond what we can currently envision

a relation between lava discharge rate thermal insulation and flow area set using lidar data 1 a simple linear relation can be used to link time averaged discharge rate tadr and lava flow area a the relation applies to given insulation conditions as described by the characteristic flow surface temperature te and will vary from case to case depending on rheological and topographic influences on flow spreading most flows have insulation conditions that change through time modifying the relationship between tadr and area as insulation conditions evolve using lidar data we can define tadr the flow area that the discharge feeds and te allowing generation of a case specific relation to convert satellite data derived flow areas to tadr for etna s 2006 lava flow field we obtain a relation whereby tadr 5 6 10 6 a for well insulated conditions te 100 c and tadr 1 5 10 4 a for poorly insulated conditions te 600 c

from sediments to their source rocks hf and nd isotopes in recent river sediments unraveling continental evolution from the sedimentary record requires an understanding of time integrated erosion laws that link sediments to their source rocks and the extent to which erosion laws vary in different erosion systems detrital zircons from the frankland river southwestern australia define a continental growth curve that is strikingly similar to the nd in shales curve for the australian continent this suggests that the detrital zircon data can be used as a good proxy for the sedimentary record through time the advantage is that the age distribution of the zircons allows the contributions from different source regions to be determined for any sediment sample using integrated hf and u pb isotopes in detrital zircons and nd isotope ratios of bulk recent sediments along the frankland river the relative contributions of different source terrains have been determined and expressed through an erosion parameter k which relates the proportions of the material from different source rocks in the sediments to the proportions of those source rocks present in the overall catchment of the sediments analyzed the results suggest that values of k 4 6 are representative of mature river systems that sample large source areas and that these should be used to reevaluate models of the evolution of the continental crust that were generally limited by the assumption of k for the gondwana supercontinent k values of 4 6 indicate that at least 50 of the present day volume of the continental crust was generated by the end of the archean

a chronology of the 1991 to 1993 mount etna eruption using advanced very high resolution radiometer data implications for real time thermal volcano monitoring between december 1991 and march 1993 a continuous effusive eruption at mount etna built a 7 6 km2 lava flow field flows extended to within 1 km of the town of zafferana before a successful artificial diversion was carried out higher up the volcano during this eruption the spaceborne advanced very high resolution radiometer avhrr acquired 308 images on which the activity could be detected since these data can be freely and directly available such coverage potentially allows regular real time monitoring ground observations and a flow map that we produced using a spot image and electronic distance measurement allowed us to develop and test data extraction techniques avhrr radiance maps were consistent with known locations of surface activity these documented the transition from channel to tube fed phases the changing threat to zafferana and flow diversion quantitative analysis of the avhrr data enabled estimation of active lava area thermal flux effusion rates and total flow field volume our estimates for eruption rate and total flow field volume 5 6 to 7 6 m3 s and 220 106 to 300 106 m3 respectively are in agreement with published ground based estimates of 5 8 m3 s and 235 106 m3 these correlations demonstrate the high degree of confidence that can now be placed in interpretations of avhrr time series for eruptions where ground based data are scanty

erosion of archean continents the sm nd and lu hf isotopic record of barberton sedimentary rocks abstract knowing the composition nature and amount of crust at the surface of the early earth is crucial to understanding the early geodynamics of our planet yet our knowledge of the hadean archean crust is far from complete limited by the poor preservation of archean terranes and the fact that less attention has been paid to the sedimentary record that tracks erosion of these ancient remnants to address this problem and get a more comprehensive view of what an archean continent may have looked like we investigated the trace element and sm nd lu hf isotopic records of archean metasedimentary rocks from south africa we focused our study on sandstone and mudstone from drill core in the fig tree group 3 23 3 26 ga of the barberton granite greenstone belt but also analyzed the 3 4 ga buck reef cherts and still older 3 5 3 6 ga meta igneous rocks from the ancient gneiss complex swaziland based on principal component analysis of major and trace element data the fig tree metasedimentary rocks can be classified into three groups crustal detritus rich sediments si rich sediments and ca fe rich sediments the detritus rich sediments have preserved the sm nd and lu hf isotopic signatures of their continental sources and hence can be used to constrain the composition of crust eroded in the barberton area in the paleoarchean period based on sm nd ratios we estimate that this crust was more mafic than today with an average sio 2 content of 60 5 2 wt this composition is further supported by isotopic mixing calculations suggesting that the sedimentary source area contained equal proportions of mafic ultramafic and felsic rocks this implies that the archean crust exposed to weathering was more mafic than today but does not exclude a more felsic composition at depth neodymium and hf crustal residence ages show that the eroded crust was on average 300 400 ma older than the deposition age of the sediments which highlights the importance of intracrustal reworking of older crust at 3 2 ga in the barberton area the si rich sediments have slightly positive e nd t 3 23ga but extremely radiogenic e hf t 3 23ga up to 11 based on analyses of 3 4 ga buck reef cherts we suggest that the radiogenic hf isotopic signature of the si rich sediments can be accounted for by the old chert clasts or detrital silicified rock fragments present in the rocks the latter have extremely high lu hf ratios such that their e hf values would increase dramatically by about 100 epsilon units every 100 ma in the ca fe rich sediments one sample contains carbonate that preserves the typical rare earth element features of seawater precipitates the initial nd isotopic composition of this sample e nd t 3 23ga 1 7 is within the range of previous estimates for archean anoxic seawater

the growth of the continent through geological time studied by nd isotope analysis of shales abstract we determined the nd isotopic composition and the sm nd ratios in a series of australian shales ranging from 0 2 gy to 3 3 gy the first result of this study is the constancy of the sm nd ratio in these shales as in granitoids secondly the initial 143nd 144nd ratio gives a regular curve decreasing through geological time both results confirm that shales are representative samples of the continental crust when insoluble elements like ree are studied we calculated their nd model ages of crustal differentiation the model ages regularly decrease with the stratigraphic ages and after 2 gy the curve flattens and tends to an asymptotic value at around 1 8 gy the significance of the shales is that they represent a mixture of continental materials and we consider the model age of such a mixture directly linked with the mean age of the continental portion feeding the sedimentary basin from these results we deduce a quantitative model of the growth curve of the continental source of the shales taking into account the effects of erosion which selectively sample recent mountains relative to shield areas we propose that the results obtained here are representative of the whole gondwana continent having studied the case of the australian shales we try to extend our study first we applied our quantitative approach to the recent results obtained by o nions et al on north atlantic provinces the continental growth curves obtained by our inversion procedure are quite distinct from the australian shales showing the regional character of shales with these two cases studied we try to compare our results with the already developed model for continental growth the consideration of the surface conservative versus surface non conservative models clearly show the non uniqueness of the geological interpretation of the growth curve on the other hand we have calculated for each case the recycling rate versus geological time by comparing the growth curve with the hurley rand province age curve such recycling increases with time in agreement with the data obtained on nd and sr initial ratios on granitoids

effusive to explosive transition during the 2003 eruption of stromboli volcano the persistent explosive activity of stromboli volcano italy ceased in december 2002 and correlated with the onset of a seven month long effusive eruption on the volcano flank from new vents that opened just below the summit craters we intensively monitored this effusive event collecting and interpreting in real time an extensive multiparametric geophysical data set the resulting data synergy allowed detailed insights into the conduit dynamics that drove the eruption and the transition back to the typical strombolian activity we present a direct link between gas flux magma volume flux and seismicity supporting a gas driven model whereby the balance between gas flux and gas overpressure determines whether the system will support effusive or explosive activity this insight enabled us to monitor the migration of the magma column up the conduit and to explain the onset of explosive activity

a nd isotope investigation of sediments related to crustal development in the british isles the times of original fractionation of the sm and nd component of clastic sediments from a mantle source crustal residence age have been estimated from sm nd model ages calculated relative to a depleted mantle evolution in this way the provenance and evolution of selected precambrian and phanerozoic sediments and metasediments from the british isles have been examined whereas some archaean and early proterozoic sediments have sm nd model ages that are close to their stratigraphic age the phanerozoic sediments analysed have model ages as much as 2 0 ga in excess of their stratigraphic age a more detailed study of lower palaeozoic sediments deposited on the northern margin of the iapetus ocean provides evidence for a marked change of provenance in the ordovician after the deposition of the dalradian supergroup a component with comparatively high143nd 144nd and sm nd ratio presumably basaltic is present in the sediments throughout the accretionary prism crustal residence age estimates average about 1 5 ga for both these lower palaeozoic sediments and modern pelagic clays and collectively fail to provide any evidence for significant continental growth during the phanerozoic