rapid topographic change measured by high resolution satellite radar at soufriere hills volcano montserrat 2008 2010 high resolution satellite radar observations of erupting volcanoes can yield valuable information on rapidly changing deposits and geomorphology using the terrasar x tsx radar with a spatial resolution of about 2 m and a repeat interval of 11 days we show how a variety of techniques were used to record some of the eruptive history of the soufriere hills volcano montserrat between july 2008 and february 2010 after a 15 month pause in lava dome growth a vulcanian explosion occurred on 28 july 2008 from a vent that was hidden by dense cloud we were able to show the civil authorities using tsx difference images of surface roughness change that this explosion had not disrupted the dome sufficiently to warrant continuation of a previous precautionary evacuation change difference images also proved to be valuable in mapping new pyroclastic flow deposits the valley occupying block and ash component tended to increase backscatter and the marginal surge deposits to reduce it with the pattern reversing after the event due to erosion and deposition by comparing east and west looking images acquired 12 h apart the deposition of some individual pyroclastic flows can be inferred from change differences some of the narrow upper sections of valleys draining the volcano received many tens of metres of rockfall and pyroclastic flow deposits over periods of a few weeks by measuring the changing radar shadows cast by these valleys in tsx images the changing depth of infill by deposits could be estimated in addition to using the amplitude data from the radar images we also used their phase information within the insar technique to calculate the topography during a period of no surface activity this enabled areas of transient topography crucial for directing future flows to be captured

interactions between a transform fault and arc volcanism in the bismarck sea papua new guinea 1 we present a new interpretation of the geological evolution of the western branch of the bismarck sea seismic lineation bssl region offshore the northwestern coast of papua new guinea from mapping and interpretation of bathymetry and backscatter data acquired aboard r v kilo moana in 2004 at present the schouten islands parallel the papua new guinea coast but this distribution results from the left lateral displacement of some of these volcanic islands by the bismarck sea seismic lineation the trend of the islands and seamounts was initially aligned n s and then displaced by the bssl wei island lies on a large submarine edifice that may have formed as part of a leaky transform subsequent to forming wei island was bisected and its pieces were displaced 45 km using this distance together with the strike slip rate for the bismarck sea seismic lineation predicted from the north bismarck plate south bismarck plate pole the division occurred approximately 385 000 years ago

monitoring lava dome growth during the 2004 2008 mount st helens washington eruption using oblique terrestrial photography abstract we present an analysis of lava dome growth during the 2004 2008 eruption of mount st helens using oblique terrestrial images from a network of remotely placed cameras this underutilized monitoring tool augmented more traditional monitoring techniques and was used to provide a robust assessment of the nature pace and state of the eruption and to quantify the kinematics of dome growth eruption monitoring using terrestrial photography began with a single camera deployed at the mouth of the volcano s crater during the first year of activity analysis of those images indicates that the average lineal extrusion rate decayed approximately logarithmically from about 8 m d to about 2 m d 2 m d from november 2004 through december 2005 and suggests that the extrusion rate fluctuated on time scales of days to weeks from may 2006 through september 2007 imagery from multiple cameras deployed around the volcano allowed determination of 3 dimensional motion across the dome complex analysis of the multi camera imagery shows spatially differential but remarkably steady to gradually slowing motion from about 1 2 m d from may through october 2006 to about 0 2 1 0 m d from may through september 2007 in contrast to the fluctuations in lineal extrusion rate documented during the first year of eruption dome motion from may 2006 through september 2007 was monotonic 0 10 m d to gradually slowing on time scales of weeks to months the ability to measure spatial and temporal rates of motion of the effusing lava dome from oblique terrestrial photographs provided a significant and sometimes the sole means of identifying and quantifying dome growth during the eruption and it demonstrates the utility of using frequent long term terrestrial photography to monitor and study volcanic eruptions

the association of lava dome growth with major explosive activity vei 4 domehaz a global dataset investigation of the global eruptive records of particular types of volcanoes is a fundamental and valuable method of understanding what style of activity can be anticipated in the future and can highlight what might be expected or unusual in particular settings this paper investigates the relationship between large explosions volcanic explosivity index vei 4 and lava dome growth from 1000 ad to present and develops the domehaz database domehaz contains information from 397 dome forming episodes including duration of dome growth duration of pauses in extrusion extrusion rates and the timing and magnitude vei of associated large explosions major explosive activity when associated with dome growth is more likely to occur before dome growth rather than during or at the end of dome forming eruptions in most cases where major explosive activity has been associated with dome growth the eruptions occurred at basaltic andesite to andesitic volcanoes the most common type of dome forming volcano but a greater proportion of dacitic and rhyolitic dome growth episodes were associated with large explosions high extrusion rates 10 m3 s 1 seem to be associated with large explosions and may inhibit degassing or destabilize existing domes leading to explosive decompression large explosions may alternatively be followed by dome growth which represents the clearing of residual magma from the conduit relationships extracted from the global record can be used to construct probability trees for new and ongoing dome forming eruptions or can be used in conjunction with other types of event trees to aid in forecasting volcanic hazards during a crisis especially for volcanoes where data are sparse

submarine landslides around the canary islands the morphology and structure of the submarine flanks of the canary islands were mapped using the gloria long range side scan sonar system bathymetric multibeam systems and sediment echosounders twelve young 2 ma giant landslides have been identified on the submarine flanks of the canary islands up to now older landslide events are long buried under a thick sediment cover due to high sedimentation rates around the canary islands most slides were found on the flanks of the youngest and most active islands of la palma el hierro and tenerife but young giant landslides were also identified on the flanks of the older 15 20 ma but still active eastern islands large scale mass wasting is an important process during all periods of major magmatic activity the long lived volcanic constructive history of the islands of the canary archipelago is balanced by a correspondingly long history of destruction resulting in a higher landslide frequency for the canary islands compared to the hawaiian islands where giant landslides only occur late in the period of active shield growth the lower stability of the flanks of the canaries is probably due to the much steeper slopes of the islands a result of the abundance of highly evolved intrusive and extrusive rocks another reason for the enhanced slope instability is the abundance of pyroclastic deposits on canary islands resulting from frequent explosive eruptions due to the elevated volatile contents in the highly alkalic magmas dike induced rifting is most likely the main trigger mechanism for destabilization of the flanks flank collapses are a major geological hazard for the canary islands due to the sector collapses themselves as well as triggering of tsunamis in at least one case a giant lateral blast occurred when an active magmatic or hydrothermal system became unroofed during flank collapse

dome growth at mount cleveland aleutian arc quantified by time series terrasar x imagery synthetic aperture radar imagery is widely used to study surface deformation induced by volcanic activity however it is rarely applied to quantify the evolution of lava domes which is important for understanding hazards and magmatic system characteristics we studied dome formation associated with eruptive activity at mount cleveland aleutian volcanic arc in 2011 2012 using terrasar x imagery interferometry and offset tracking show no consistent deformation and only motion of the crater rim suggesting that ascending magma may pass through a preexisting conduit system without causing appreciable surface deformation amplitude imagery has proven useful for quantifying rates of vertical and areal growth of the lava dome within the crater from formation to removal by explosive activity to rebirth we expect that this approach can be applied at other volcanoes that host growing lava domes and where hazards are highly dependent on dome geometry and growth rates

localized and distributed erosion triggered by the 2015 hurricane patricia investigated by repeated drone surveys and time lapse cameras at volcan de colima mexico abstract in october 2015 patricia a major category 5 hurricane made landfall in western mexico resulting in 500 mm cumulated rainfall and lahar generation along the southerly directed montegrande valley of volcan de colima we monitored lahar deposition and erosion using time lapse trail cameras and conducted repeated camera drone overflights two days before and after the hurricane using photogrammetric processing we derive a unique dataset of high resolution digital terrain models and study the geomorphologic impacts of a single lahar event results reveal different types of erosion at 8 km distance from the volcano with overland flow and rill networks developing into major erosion gullies exceeding a depth of 4 m as well as bank collapse oversteepening and marginal erosion we find alternating deposition and erosion zones that depend on general slope and valley width and find that the overland flow related erosion is an important contributor to the bulking process of lahars moreover this study shows that camera monitoring is very useful for studying the relationship between volcano landscape evolution and hydrometeorological extremes and for rapid assessment associated with single lahar events

influence of extrusion rate and magma rheology on the growth of lava domes insights from particle dynamics modeling abstract lava domes are structures that grow by the extrusion of viscous silicic or intermediate composition magma from a central volcanic conduit repeated cycles of growth are punctuated by collapse as the structure becomes oversized for the strength of the composite magma that rheologically stiffens and strengthens at its surface here we explore lava dome growth and failure mechanics using a two dimensional particle dynamics model the model follows the evolution of fractured lava with solidification driven by degassing induced crystallization of magma the particle dynamics model emulates the natural development of dome growth and rearrangement of the lava dome which is difficult in mesh based analyses due to mesh entanglement effects the deformable talus evolves naturally as a frictional carapace that caps a ductile magma core extrusion rate and magma rheology together with crystallization temperature and volatile content govern the distribution of strength in the composite structure this new model is calibrated against existing observational models of lava dome growth results show that the shape and extent of the ductile core and the overall structure of the lava dome are strongly controlled by the infusion rate the effects of extrusion rate on magma rheology are sensitive to material stiffness which in turn is a function of volatile content and crystallinity material stiffness and material strength are key model parameters which govern magma rheology and subsequently the morphological character of the lava dome and in turn stability degassing induced crystallization causes material stiffening and enhances material strength reflected in non newtonian magma behavior the increase in stiffness and strength of the injected magma causes a transition in the style of dome growth from endogenous expansion of a ductile core to stiffer and stronger intruding material capable of punching through the overlying material and resulting in the development of a spine or possibly inducing dome collapse simulation results mimic development of a megaspine upon the influx of fresh magma which leads to the re direction of magma flow creating a new shear zone and the switching of dome growth from one side to the other our model shows similar dome growth dynamics as observed at soufriere hills volcano montserrat indicating a strong correlation between extrusion rate and its subsequent effect on mechanical properties and variations in magma rheology

co2 forced climate thresholds during the phanerozoic abstract the correspondence between atmospheric co2 concentrations and globally averaged surface temperatures in the recent past suggests that this coupling may be of great antiquity here i compare 490 published proxy records of co2 spanning the ordovician to neogene with records of global cool events to evaluate the strength of co2 temperature coupling over the phanerozoic last 542 my for periods with sufficient co2 coverage all cool events are associated with co2 levels below 1000 ppm a co2 threshold of below 500 ppm is suggested for the initiation of widespread continental glaciations although this threshold was likely higher during the paleozoic due to a lower solar luminosity at that time also based on data from the jurassic and cretaceous a co2 threshold of below 1000 ppm is proposed for the initiation of cool non glacial conditions a pervasive tight correlation between co2 and temperature is found both at coarse 10 my timescales and fine resolutions up to the temporal limits of the data set million year timescales indicating that co2 operating in combination with many other factors such as solar luminosity and paleogeography has imparted strong control over global temperatures for much of the phanerozoic

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

growth and collapse of a littoral lava dome during the 2018 19 eruption of kadovar volcano papua new guinea analyzed by multi sensor satellite imagery abstract growing volcanic islands and lava domes become structurally unstable associated with sectoral collapses explosive volcanism and related hazards this article describes the rare case of a growing and collapsing lava dome at kadovar volcano a small inhabited volcanic island located north of papua new guinea the eruption began on january 5 2018 and was monitored by multi sensor satellite imagery including optical thermal and synthetic aperture radar sar sensors results show that kadovar began a new episode of volcanic activity at the central crater and then also at the eastern coast of the island sar amplitude imagery has made it possible to monitor the birth of a new peninsula on the eastern coast this new peninsula has a blocky appearance and is associated with a localized thermal anomaly which is indicative of an emerging lava dome we analyzed the changes on the island and the peripheral lava dome and found that after a great increase in the size of the area parts of the island and the lava dome then collapsed eastwardly into the ocean on february 9 2018 the sector collapse caused small tsunami waves that hit the neighboring islands a subsequent slower re growth of the lava dome is evident from the satellite data which has reached a final area of 40 000 m this study provides details on the rapid growth and collapse of a peripheral lava dome and a destabilization episode in an island and dome sector and underlines the great value of remote sensing data on remote volcanic islands

using satellite radar amplitude imaging for monitoring syn eruptive changes in surface morphology at an ice capped stratovolcano abstract satellite based measurements of synthetic aperture radar amplitude provide a method for monitoring volcanoes during unrest and eruptions even when visual observations are not possible for example due to poor weather or at night and when radar phase measurements are noisy or decorrelated here we use high resolution radar amplitude images from the terrasar x and cosmo skymed satellites to investigate surface changes associated with explosive eruptions of cotopaxi volcano ecuador in august 2015 we generate change difference and amplitude ratio maps spanning the start of explosive activity at cotopaxi which show complex spatial variations in radar amplitude both on and around the summit ice cap that we attribute to a number of processes related to the eruption observed amplitude decreases are caused by crater deepening ashfall onto ice and surface smoothing by ashfall onto slopes facing away from the satellite while amplitude increases are due to deposition of coarse lapilli and wet tephra increased soil saturation due to geothermally driven glacier melting and smoothing of slopes facing towards the satellite we discuss the potential applications of radar amplitude images for monitoring and hazard evaluation at active volcanoes

morphology and growth style of a miocene submarine dacite lava dome at atsumi northeast japan abstract a miocene submarine lava dome at tate iwa atsumi yamagata japan displays well preserved primary morphological features the dome currently rises above a wave cut coastal platform and is 55 m high and 90 180 m across it comprises a massive core and a lava lobe hyaloclastite rim both of which are composed of compositionally uniform feldspar phyric dacite sio2 64 wt the boundary between these two zones is distinct but gradational the massive core consists of homogeneous coherent dacite and is characterized by flow banding along the margin and by columnar joints radiating from the centre to the margin the lava lobe hyaloclastite rim encircles the massive core and consists of a complex of 80 90 dacitic lava lobes and 10 20 hyaloclastite the lava lobes are 1 6 m thick 3 12 m wide and more than 5 m long each lobe consists of a radially columnar jointed core and a glassy rim 10 30 cm thick the hyaloclastite comprises polyhedral dacite clasts 5 100 cm across in a matrix of dacite fragments up to 5 mm across the lava lobes and hyaloclastite have gradational contacts in places paleobathymetric studies based on foraminifera in sediment beneath the dome and the k ar age of the dome suggest that it was extruded in a middle bathyal environment 1500 2000 m below sea level at 12 9 0 6 ma the internal structures of the dome suggest that it formed by a combination of exogenous growth involving extrusions of small dacite lobes and endogenous growth involving a continuous magma supply and simple expansion from the interior the presence of small lava lobes along the rim suggests that the magma had relatively low viscosity at the time of extrusion in spite of its high silica content magma temperatures calculated by two pyroxene and fe ti oxide geothermometers were 999 1042 and 957 1005 c respectively the inferred low viscosity may be attributed to the high temperature of the magma and or a high confining pressure resulting from the deep sea environment

volcano collapse and tsunami generation in the bismarck volcanic arc papua new guinea during a cruise on the r v kilo moana in 2004 we mapped 12 debris avalanches from volcanoes in the bismarck volcanic arc estimated their sizes and computed the size of potential tsunami run up in major local population centers from these features we used the towed side scan instrument hawaii mr1 the hull mounted em120 system for swath bathymetry and backscatter intensity a shallow penetration chirp system several bottom camera tows and selected cores we calibrate our computations with the known tsunami run up of the ritter collapse even the small collapses may have had significant run up on near by coastlines had any of the collapses we have identified occurred in modern times each would affect a presently populated region of the coastline to a moderate or significant degree

merapi 2010 eruption chronology and extrusion rates monitored with satellite radar and used in eruption forecasting abstract despite dense cloud cover satellite borne commercial synthetic aperture radar sar enabled frequent monitoring of merapi volcano s 2010 eruption near real time interpretation of images derived from the amplitude of the sar signals and timely delivery of these interpretations to those responsible for warnings allowed satellite remote sensing for the first time to play an equal role with in situ seismic geodetic and gas monitoring in guiding life saving decisions during a major volcanic crisis our remotely sensed data provide an observational chronology for the main phase of the 2010 eruption which lasted 12 days 26 october 7 november 2010 unlike the prolonged low rate and relatively low explosivity dome forming and collapse eruptions of recent decades at merapi the eruption began with an explosive eruption that produced a new summit crater on 26 october and was accompanied by an ash column and pyroclastic flows that extended 8 km down the flanks this initial explosive event was followed by smaller explosive eruptions on 29 october 1 november then by a period of rapid dome growth on 1 4 november which produced a summit lava dome with a volume of 5 10 6 m 3 a paroxysmal vei 4 magmatic eruption with ash column to 17 km altitude destroyed this dome greatly enlarged the new summit crater and produced extensive pyroclastic flows to 16 km radial distance in the gendol drainage and surges during the night of 4 5 november the paroxysmal eruption was followed by a period of jetting of gas and tephra and by a second short period 12 h of rapid dome growth on 6 november the eruption ended with low level ash and steam emissions that buried the 6 november dome with tephra and continued at low levels until seismicity decreased to background levels by about 23 november our near real time commercial sar documented the explosive events on 26 october and 4 5 november and high rates of dome growth 25 m 3 s 1 an event tree analysis for the previous 2006 merapi eruption indicated that for lava dome extrusion rates 1 2 m 3 s 1 the probability of a large 1872 scale eruption was 10 consequently the order of magnitude greater rates in 2010 along with the explosive start of the eruption on 26 october the large volume of lava accumulating at the summit by 4 november and the rapid and large increases in seismic energy release deformation and gas emissions were the basis for warnings of an unusually large eruption by the indonesian geological agency s center for volcanology and geologic hazard mitigation cvghm and their volcano research and technology development center bpptk in yogyakarta warnings that saved thousands of lives

subaqueous intermediate to silicic composition explosive volcanism a review abstract mass flow deposits of pyroclastic debris commonly consist of two parts a lower coarse grained basal section and an upper finer grained bedded section subaqueous pyroclastic flow deposits particularly those derived from a vertically directed eruption appear better sorted than their subaerial counterparts because of the efficient sorting characteristics of water compared to air subaqueous deposits frequently are depleted in bubble wall pumice that floats off and vitric ash that remains in suspension hence the deposits show a relative enrichment of crystals especially at the bases from 1 flotation and suspension of the vitric material and 2 ingestion of water at the head of the flow a subaqueous volcaniclastic flow deposit may contain evidence indicative of both turbulent and non turbulent movement the flow may have had a turbulent head and non turbulent body or flow transformations may have occurred from 1 collapse of the eruption column 2 changes in slope and in the velocity of the flow and or 3 the amount of water mixed into the flow retention of heat in the subaqueous environment may be enhanced by lateral eruptions high eruption rates large eruptive volumes and little or no mixing of pyroclastic debris with water the lack of welded subaqueous deposits in the geologic record may be a result of 1 effusive rather than explosive eruptions in a deep water environment 2 explosive phreatic disintegration of pyroclastic flows in a shallow subaqueous environment and or 3 the inability of subaerial pumiceous pyroclastic flows to penetrate the land water interface characteristics of explosive intermediate to silicic composition subaqueous volcanic eruptions also have been summarized in terms of 1 environment of the eruption 2 orientation of the eruption and 3 composition of the juvenile debris these three aspects of explosive subaqueous volcanism are ideal end members and gradations no doubt occur

insights into the october november 2010 gunung merapi eruption central java indonesia from the stratigraphy volume and characteristics of its pyroclastic deposits abstract the 2010 eruption of merapi was the second most deadly in the historic record of this volcano claiming over 380 lives by relating the observations of this eruption with detailed examination of deposit distribution stratigraphy and sedimentology a reconstruction of the properties of the pyroclastic density currents pdcs is presented including the valley controlled block and ash flows bafs and widespread energetic pyroclastic surges the distribution volume and mobility characteristics of all types of pdc during the eruption sequence show evidence for levels of intensity unseen since the large scale 1872 and 1930 eruption phases especially during the climactic events of october 26 and november 5 many tephra falls interbedded with pdc units show that most dome collapse events occurred along with and between explosive vulcanian eruptions the 2010 eruption produced very long runout bafs reaching 16 1 km in the kali gendol on november 5 this runout could be explained by its large volume 20 million m 3 around 10 times that of previous merapi bafs during the last 130 years major avulsion of these dense bafs to form overbank deposits became more common through the eruptive sequence as the valley was progressively filled with successive pdc deposits spreading avulsed bafs were a particular hazard downstream of 10 km where the landscape is less dissected less clear however is why pyroclastic surges extended up to 10 km from the vent on november 5 and 6 4 km on october 26 these expanded much farther from baf margins 2 km than ever seen before at merapi in one location they were decoupled from valley centered bafs with high momentum traveling initially laterally across steep valley systems before draining downslope at this site on the western side of the upper gendol at around 3 km from source surge decoupling was apparently exacerbated by upstream collision and deflection of high flux hot and gas rich bafs against the cliffs of gunung kendil the 1 4 km long cliff face was impacted directly for the first time in 2010 events and may have been responsible for the formation of larger than normal turbulent ash rich clouds above bafs these results imply that future eruption events under the present summit and upper flow path configuration are also highly likely to generate wide dispersal pyroclastic surges and extreme hazard especially now that dense forest has been destroyed on the upper southern slopes of the volcano

dome growth and coulee spreading controlled by surface morphology as determined by pixel offsets in photographs of the 2006 merapi eruption abstract at many explosive volcanoes viscous domes extrude which are destroyed by complete or partial collapses although the growth and development of silicic domes and the associated flow and collapse mechanisms are of vital importance for understanding the occurrence and scale of pyroclastic flows quantitative measurements of dome deformations are limited we report on a sequence of photographs taken of a growing and deforming dome a sequence in 2006 featuring the merapi dome taken from similar camera positions allow the application of a digital image correlation algorithm the aim being to detect and explore the temporal evolution of pixel offsets the results suggest that the dome underwent deformation in two regions between september and october 2006 i dome growth and spreading at the volcano summit and ii coulee flow through a narrow canyon the latter is associated with strain localization and flow acceleration which indicates that the displacements and flow velocities at silicic domes are governed by the topographic structure into which the flows develop the downslope motion of the distal parts of the flow and apron slumps continued during episodes of dome extrusion by gravitational spreading an analysis of the 2006 merapi dome and coulee displacement also provides insights into processes that may occur along the newly established southerly eruption direction which also may have influenced pyroclastic flows associated with the 2010 eruption

high spatial resolution imagery helps map deposits of the large vei 4 2010 merapi volcano eruption and their impact the 26 october 23 november 2010 eruption is merapi s largest event vei 4 over the past 140 years we used high spatial resolution hsr imagery from geoeye pleiades ikonos and spot5 satellites to assess the extent and effects of the pyroclastic density currents pdcs and subsequent lahars we have tracked the geomorphic and structural fracturing changes of merapi s summit crater and dome between 2008 and 2012 the 4 september 2011 geoeye image shows that due to the explosive eruption the summit area lost about 10 106 m3 the eruption enlarged the sse trending gendol breach to be 1 3 0 3 0 2 km the 2010 tephra and pdc deposits covered about 26 km2 in the two catchments of gendol and opak rivers on merapi s south flank i e 60 75 of the total pdc deposit area with a total bulk volume of 45 106 m3 the tephra fall deposit covered an area of about 1300 km2 with a range in volume of 18 21 106 m3 supervised and object oriented classification on hsr imagery enables us to map in detail the pdc deposits across the gendol opak catchment we delineated 16 spectrally and or texturally distinct units of pdc deposits and compared them with previously published results they encompass high energy surge deposits within ca 8 km of the summit valley confined pdc deposits channeled as far as 16 5 km in the gendol river and widespread overbank pdc with ash cloud surge deposits on valley margins

volcano tectonic control of merapi s lava dome splitting the november 2013 fracture observed from high resolution terrasar x data abstract volcanism at active andesite dacite volcanoes is often associated with the formation and collapse of circular shaped protrusions of extruded highly viscous lava the so called domes which are emplaced in the near summit region growing domes may experience stable and instable structural phases with a gradual transition in between dome collapse and the break off of instable blocks of viscous lava may lead to pyroclastic flows one of the most lethal hazards at stratovolcanoes at merapi volcano indonesia a new dome started growing in the summit region in the amphitheater formed in the course of the climactic 2010 eruption three years later the dome reached a height of approximately 100 m and diameters of 220 and 190 m with a plateau like surface area of 40 000 m2 approximately on 18 11 2013 an explosion occurred without identified precursors leaving a major fracture cutting the complete dome structure based on high resolution terrasar x satellite radar imagery we could identify the linear fracture traceable over 200 m in the long axis up to 40 m wide after geocoding of the radar amplitude imagery the fractures azimuthal trend could be compared to other structural lineaments indicative of a significant nnw sse structural direction that has formed on merapi volcano in the past the merapi dome fractured in a nw se direction and is consistent with the alignment of regional tectonic structures and of anticipated directions of pyroclastic flows the fracture may be part of a larger volcano tectonic system and may affect the dynamics and the stability of the merapi dome

evolution of lava flow fields at mount etna 27 28 october 1999 observed by landsat 7 etm landsat 7 enhanced thematic mapper etm data are presented which document the thermal characteristics of a series of lava flows emplaced at mount etna volcano sicily during 27 28 october 1999 by examining the composition of the short wave infrared swir signal emitted from the flow surface we identified distinctive flow units the first unit appears to comprise recently active lava flows with relatively cool crusts which by virtue of the integrity of this crust as determined from the etm data we infer are stationary or barely moving the second unit is characterized by much higher levels of swir radiance consistent with a channel fed active flow unit analysis of the swir data confirm that this is fed by a lava channel the properties of which are consistent with vigorously active channels observed on kilauea hawaii model predictions of the maximum length that such flows could attain compare favorably with the actual flow lengths observed in the etm data indicating that the cooler flows had indeed stopped advancing and may have attained a cooling limited rather than volume limited maximum length our observations and modeling provide a physical corroboration for the supposition made by wadge 1978 in his analysis of the shape of lava flow fields on mount etna which in the cooling limited case principal flows are active one after the other and not at the same time

remote sensing of active volcanoes the synoptic coverage offered by satellites provides unparalleled opportunities for monitoring active volcanoes and opens new avenues of scientific inquiry thermal infrared radiation can be used to monitor levels of activity which is useful for automated eruption detection and for studying the emplacement of lava flows satellite radars can observe volcanoes through clouds or at night and provide high resolution topographic data in favorable conditions radar inteferometery can be used to measure ground deformation associated with eruptive activity on a centimetric scale clouds from explosive eruptions present a pressing hazard to aviation therefore techniques are being developed to assess eruption cloud height and to discriminate between ash and meterological clouds the multitude of sensors to be launched on future generations of space platforms promises to greatly enhance volcanological studies but a satellite dedicated to volcanology is needed to meet requirements of aviation safety and volca

using the landsat thematic mapper to detect and monitor active volcanoes an example from lascar volcano northern chile the landsat thematic mapper tm offers a means of detecting and monitoring thermal features of active volcanoes using the tm we have discovered a prominent thermal anomaly on lascar volcano northern chile data from two short wavelength infrared channels of the tm show that material within a 300 m diameter pit crater was at a temperature of at least 380 c on two dates in 1985 the thermal anomaly closely resembles in size and radiant temperature the anomaly over the active lava lake at erta ale in ethiopia an eruption took place at lascar on september 16 1986 tm data acquired on october 27 1986 revealed significant changes within the crater area we find that lascar is in a much more active state than any other volcano in the central andes and for this reason it merits further careful monitoring our studies show that the tm is capable of confidently identifying thermal anomalies less than 100 m in size at temperatures of above 150 c and thus it offers a valuable means of monitoring the conditions of active or potentially active volcanoes particularly those in remote regions

relationship between the tibetan plateau heating and east asian summer monsoon rainfall 1 this study reveals the close correspondence between the interannual variability of the dominant east asian summer rainfall pattern and the diabatic heating over the tibetan plateau in both spring and summer the heating fluctuation over the tibetan plateau is associated with two wave like circulation patterns which bear the characteristics of forced rossby wave emanating away from the deep heating the wave like pattern in turn affects the east asian summer rainfall because of the persistent heating over the tibetan plateau from spring to summer and its possible effect on the surrounding areas the heating index defined in this study can be used as a good predictor for the jja heating and precipitation distributions evidences shown suggest that external conditions other than the sst anomaly must be considered to understand the interannual variability of the east asian summer rainfall

image based measurement of flux variation in distal regions of active lava flows 1 understanding the processes involved with the advance of lava flows is critical for improving hazard assessments at many volcanoes here we describe the application of computer vision and oblique photogrammetric techniques to visible and thermal images of active a flows in order to investigate distal flow processes at mount etna sicily photogrammetric surveys were carried out to produce repeated topographic data sets for calculation of volumetric lava flux at the flow fronts velocity profiles from a distal channel were obtained by rectification of a thermal image sequence and are used to investigate the rheological properties of the lava significant variations of the magma flux were observed and pulses of increased flux arrived within the flow front region on timescales of several hours the pulses are believed to be the distal result of more frequent flux changes observed in the vent region hence they reflect the importance of flow processes which are believed to cause the coalescence of flux pulses along the channel system as well as short period variations in effusion rate in considering advance processes for the individual flow fronts it must be assumed that they were fed by a highly unsteady flux which was volumetrically at least an order of magnitude lower than that observed near the vent