volcano dome dynamics at mount st helens deformation and intermittent subsidence monitored by seismicity and camera imagery pixel offsets the surface deformation field measured at volcanic domes provides insights into the effects of magmatic processes gravity and gas driven processes and the development and distribution of internal dome structures here we study short term dome deformation associated with earthquakes at mount st helens recorded by a permanent optical camera and seismic monitoring network we use digital image correlation dic to compute the displacement field between successive images and compare the results to the occurrence and characteristics of seismic events during a 6 week period of dome growth in 2006 the results reveal that dome growth at mount st helens was repeatedly interrupted by short term meter scale downward displacements at the dome surface which were associated in time with low frequency large magnitude seismic events followed by a tremor like signal the tremor was only recorded by the seismic stations closest to the dome we find a correlation between the magnitudes of the camera derived displacements and the spectral amplitudes of the associated tremor we use the dic results from two cameras and a high resolution topographic model to derive full 3 d displacement maps which reveals internal dome structures and the effect of the seismic activity on daily surface velocities we postulate that the tremor is recording the gravity driven response of the upper dome due to mechanical collapse or depressurization and fault controlled slumping our results highlight the different scales and structural expressions during growth and disintegration of lava domes and the relationships between seismic and deformation signals

identification of structural controls in an active lava dome with high resolution dems volcan de colima mexico monitoring the topography of active lava domes is critical for detecting changes that may trigger or influence collapse or explosive activity internal dome structure and conditions are more difficult to elucidate but also play vital roles here we describe the exposure following an explosion of significant scarps in the active dome at volcan de colima mexico that are interpreted as evidence of brittle failure planes and a complex internal dome morphology in the first use of automated 3d computer vision reconstruction techniques structure from motion and multi view stereo sfm mvs on an active volcanic dome we derive high resolution surface models from oblique and archive photographs taken with a consumer camera the resulting 3d models were geo referenced using features identified in a web sourced orthoimage no ground based measurements were required in december 2010 the dome 2 14 106 m3 had a flat upper surface reflecting an overall ductile emplacement regime between then and may 2011 a period of low explosivity was accompanied by a small volume loss 0 4 105 m3 and arcuate steps appeared in the dome surface suggesting the presence of localized planes of weakness the complex array of summit scarps was exposed following a significant explosion in june 2011 and is interpreted to be the surface expression of fault planes in the dome the 1 m resolution dems indicated that the region of greatest volume loss was not coincident with the assumed location of the conduit and that heterogeneity within the dome may have been important during the june explosion

insights into lava dome and spine extrusion using analogue sandbox experiments abstract lava dome formation is a common process at stratovolcanoes involving the shallow intrusion or extrusion of viscous lava and may lead to the rise of spines spines are protrusions observed to extrude episodically during lava dome growth yet the structural and mechanical factors controlling their formation are only partially understood here we provide new detailed insight into lava dome growth and the production of spines using a novel set of analogue experiments extruding sand plaster mixtures from a fixed diameter conduit under isothermal conditions we trace displacement and strain with photogrammetric methods for precise and detailed monitoring of the extrusion process results show initial dome growth forming a steep sided and flat topped shape through extrusion of new material leading to slumping of oversteepening slopes forming a talus spines are found to protrude at a later stage through the dome surface along discrete circular faults that originate from the conduit walls starting a cycle of spine growth and collapse as our spines only appear after prolonged extrusion we relate their appearance to the compaction and strengthening of material within the conduit we find that spine diameter height and volume are positively correlated with increasing cohesion and therefore material strength the spine diameter was also observed to be smaller or equal to the diameter of the underlying conduit as shear extrusion occurs along vertical to outward dipping fault planes for natural domes our findings imply that spine growth may be the consequence of compaction and densification via porosity loss shearing and or outgassing of conduit magma during ascent more efficient compaction will yield wider and taller spines as a result of increasing rock strength our study further highlights the relevance of analogue experiments in the study of lava domes and spines which remain one of the most hazardous and unpredictable features at dome forming volcanoes worldwide

lacustrine shales and oil shales from stellarton basin nova scotia canada organofacies variations and use of polyaromatic hydrocarbons as maturity indicators abstract the post acadian stellarton basin is a small pull apart basin in northern nova scotia the coal brook member which is the main focus of this study contains the thickest and most extensive development of oil shales within the late carboniferous stellarton formation bulk and molecular geochemistry indicate that the organic rich oil shales and black shales contain type i ii kerogen with a mixed assemblage of aquatic and terrestrial organic matter that is dominated by the former biomarker evidence indicates that these sediments were deposited under deep anoxic and fresh to brackish water lake conditions organofacies distinctions were made on the basis of several parameters that are independent of maturity and therefore suggest organic matter changes the organofacies identified are the result of water level fluctuations that are climate controlled all of the aromatic compounds evaluated as maturity parameters were seen to experience alterations in proportion to temperature in the form of either depth or geologic age that can be correlated with maturity these alterations are believed to result from changes in molecular composition maturity parameters based on the alkylbenzothiophenic and alkylnaphthalenic compounds are shown to be effective maturity parameters in lacustrine sequences particularly over the higher maturity ranges where standard maturity parameters based on steranes and hopanes are not effective

explosive dome eruptions modulated by periodic gas driven inflation volcan santiaguito guatemala breathes with extraordinary regularity as the edifice s conduit system accumulates free gas which periodically vents to the atmosphere periodic pressurization controls explosion timing which nearly always occurs at peak inflation as detected with tiltmeters tilt cycles in january 2012 reveal regular 26 6 min inflation deflation cycles corresponding to at least 101 kg s of gas fluxing the system very long period vlp earthquakes presage explosions and occur during cycles when inflation rates are most rapid vlps locate 300 m below the vent and indicate mobilization of volatiles which ascend at 50 m s rapid gas ascent feeds pyroclast laden eruptions lasting several minutes and rising to 1 km vlps are not observed during less rapid inflation episodes instead gas vents passively through the conduit producing no infrasound and no explosion these observations intimate that steady gas exsolution and accumulation in shallow reservoirs may drive inflation cycles at open vent silicic volcanoes

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

volumetric change quantification of the 2010 merapi eruption using tandem x insar abstract accurate and up to date information on the time varying topography of active volcanoes is crucial for assessing material flows through these volcanic systems and along their surfaces as dome building volcanoes can change on meter scale within short time intervals in active phases conventionally used repeat pass sar interferometry insar often fails due to decorrelation effects while other methods to measure topography like aerial photogrammetry or lidar depend on the availability of the local infrastructure and on good weather conditions here we show the potential of the spaceborne earth observation mission tandem x to monitor topographic changes at active dome building volcanoes in this innovative satellite mission two nearly identical satellites fly in a close formation taking radar images of the earth s surface at the same time in bistatic mode this opens the possibility to generate digital elevation models dems of volcanoes analyzing a series of repeated dems enables assessment of volume changes caused by lava dome activity we apply this method to merapi in indonesia by analyzing the volume changes during the hazardous 2010 eruption during this eruption the old lava dome collapsed and a new lava dome was extruded which collapsed again within twelve days we show three dems derived from bistatic tandem x insar in descending orbit taken before and after the eruption we found a mean volume change of 19 10 6 m 3 in the summit area the two estimates differ by 0 4 10 6 m 3 which is 2 of the average dome volume change the tandem x based results are about 25 lower than reference data which can be explained by the shadow masks that were introduced to exclude geometrically decorrelated areas resulting in conservative volume change estimates

evaluating links between deformation topography and surface temperature at volcanic domes results from a multi sensor study at volcan de colima mexico abstract dome building activity is common at many volcanoes and due to the gravitational instability a dome represents one of the most hazardous volcanic phenomena shallow volcanic processes as well as rheological and structural changes of the dome affecting the fluid transport have been linked to transitions in eruptive activity also hydrothermal alteration may affect the structural integrity of the dome increasing the potential for collapse however mapping the deformation and details of fluid escape at the summit of steep sloped volcanoes and integrating these with other types of data is challenging due to difficult access and poor coverage here we present for the first time the near vertical and near horizontal surface deformation field of a quiescent summit dome and the relationships with degassing and topographic patterns our results are derived from high resolution satellite radar interferometry insar time series based on a year of terrasar x spotlight acquisitions and structure from motion sfm processing of overflight infrared data at volcan de colima mexico the identified deformation is dominated by localized heterogeneous subsidence of the summit dome exceeding rates of 15 cm yr and strongly decreasing over the year 2012 up to the renewal of explosive and extrusive activity in early 2013 we tentatively attribute the deformation to the degassing cooling and contraction of the dome and shallow conduit material we also find that the results strongly differ depending on the chosen insar time series method which potentially overprints the true physical complexities of small scale shallow deformation processes the combined interpretation of the deformation and infrared data reveals a complex spatial relationship between the degassing pathways and the deformation while we observe no deformation across the crater rim fumaroles discontinuities in the deformation field are more commonly observed around the dome rim fumaroles and occasionally on the dome upper surface we propose that the deformation pattern is also linked to processes controlling the fumarole formation and distribution topography permeability and volcanic activity and the lack of direct relationships may be explained by how the influence of these processes varies across the volcanic summit the presented work provides a new approach for safely monitoring the activity and stability of internal dome structures as well as for constraining and validating models of dome degassing pathways and densification processes

photogrammetric monitoring of lava dome growth during the 2009 eruption of redoubt volcano abstract the 2009 eruption of redoubt volcano alaska began with a phreatic explosion on 15 march followed by a series of at least 19 explosive events and growth and destruction of at least two and likely three lava domes between 22 march and 4 april on 4 april explosive activity gave way to continuous lava effusion within the summit crater we present an analysis of post 4 april lava dome growth using an oblique photogrammetry approach that provides a safe rapid and accurate means of measuring dome growth photogrammetric analyses of oblique digital images acquired during helicopter observation flights and fixed wing volcanic gas surveys produced a series of digital elevation models dems of the lava dome from 16 april to 23 september the dems were used to calculate estimates of volume and time averaged extrusion rates and to quantify morphological changes during dome growth effusion rates ranged from a maximum of 35 m 3 s 1 during the initial two weeks to a low of 2 2 m 3 s 1 in early summer 2009 the average effusion rate from april to july was 9 5 m 3 s 1 early rapid dome growth was characterized by extrusion of blocky lava that spread laterally within the summit crater in mid to late april the volume of the dome had reached 36 10 6 m 3 roughly half of the total volume and dome growth within the summit crater began to be limited by confining crater walls to the south east and west once the dome reached the steep north sloping gorge that breaches the crater growth decreased to the south but the dome continued to inflate and extend northward down the gorge effusion slowed during 16 april 1 may but in early may the rate increased again this rate increase was accompanied by a transition to exogenous dome growth from mid may to july the effusion rate consistently declined the decrease is consistent with observations of reduced seismicity gas emission and thermal anomalies as well as declining rates of geodetic deflation or inflation these trends suggest dome growth ceased by july 2009 the volume of the dome at the end of the 2009 eruption was about 72 10 6 m 3 more than twice the estimated volume of the largest dome extruded during the 1989 1990 eruption in total the 2009 dome extends over 400 m down the glacial gorge on the north end of the crater with a total length of 1 km width of 500 m and an average thickness of 200 m

uav based surveying in volcano tectonics an example from the iceland rift abstract in the present work we applied the use of an unmanned aerial vehicle uav a quadcopter and the aerial structure from motion digital photogrammetry image processing technique asfm to study volcano tectonics and tectonic features in an active icelandic rift data have been collected in order to evaluate the holocene deformation in the northern volcanic zone of iceland we mapped 397 structures mainly related to extension fractures and subordinately normal faults in the theistareykir fissure swarm obtaining 1098 and 21 structural data respectively this allowed to reconstruct an overall spreading direction of n108 during holocene times and to calculate a stretch of 1 013 regarding 8 10 ka old lava units deformation in the area is related to both dyke intrusions and extensional tectonics furthermore detailed geological structural field and uav surveys were also performed in two test areas in order to determine data accuracy and the associated reliability of this approach in addition to the above different flight heights were tested suggesting that photo collection with a 12 4 mpx camera at 100 m is efficient to study fracture dilation and kinematics

structural architecture of the colima volcanic complex 1 the colima volcanic complex cvc is currently the most active mexican volcano and is located in the western sector of the trans mexican volcanic belt inside the active colima rift a regional n s striking extensional structure the colima rift is filled by a 1 km thick sequence of quaternary lacustrine sediments alluvium and colluvium mostly underling the about 3000 m thick volcanic pile of the cvc in this work we present the results of a detailed morphostructural and field study of quaternary faults and fractures in the cvc and the surrounding area including the regional structures of the colima rift we also present a geometrical modeling of the faults inside the volcano and a numerical model of the gravity induced stress and strain fields of the cvc the study attempts to characterize the geometry kinematics and dynamics of the deformation features of the cvc and relate it with the volcano structure the geology of the substratum and the geodynamic setting of the region our model considers that the observed deformation of the cvc and the surroundings results from the interplay between the active n s trending regional extensional tectonics and the southward spreading of the volcano over its basement forming an e w oriented volcanotectonic graben the interaction between regional tectonics and previously unrecognized volcanic spreading can control magma migration and flank instability in an area where eruptions and sector failures represent a potential high risk for more than 500 000 people

the 26 may 2006 magnitude 6 4 yogyakarta earthquake south of mt merapi volcano did lahar deposits amplify ground shaking and thus lead to the disaster 1 indonesia is repeatedly unsettled by severe volcano and earthquake related disasters which are geologically coupled to the 5 7 cm a tectonic convergence of the australian plate beneath the sunda plate on saturday 26 may 2006 the southern coast of central java was struck by an earthquake at 2254 utc in the sultanate yogyakarta although the magnitude reached only mw 6 4 it left more than 6 000 fatalities and up to 1 000 000 homeless the main disaster area was south of mt merapi volcano located within a narrow topographic and structural depression along the opak river the earthquake disaster area within the depression is underlain by thick volcaniclastic deposits commonly derived in the form of lahars from mt merapi volcano which had a major influence leading to the disaster in order to more precisely understand this earthquake and its consequences a 3 month aftershock measurement campaign was performed from may to august 2006 we here present the first location results which suggest that the yogyakarta earthquake occurred at 10 20 km distance east of the disaster area outside of the topographic depression using simple model calculations taking material heterogeneity into account we illustrate how soft volcaniclastic deposits may locally amplify ground shaking at distance as the high degree of observed damage may have been augmented by the seismic response of the volcaniclastic mt merapi deposits this work implies that the volcano had an indirect effect on the level of earthquake destruction

the ongoing dome emplacement and destruction cyclic process at popocatepetl volcano central mexico the ongoing eruptive activity of popocatepetl volcano has been characterized by emplacement and subsequent destruction of a succession of lava domes between the onset of the current eruption in 1994 and the time of this submission 38 episodes of lava dome formation and removal have been identified each dome has showed particular features related to the magma extrusion process among other manifestations dome emplacement events have been usually accompanied by relatively low intensity protracted explosions referred to as exhalations after variable times of residence emplacements have ended in partial or total destruction of the domes by strong vulcanian explosions that produced sizeable ash plumes with most of them also ejecting incandescent debris onto the volcano flanks here we present a detailed account for the observed activity related to the domes growth and destruction related seismic monitoring signals and morphological features of the domes based on 19 years of visual observations and image analysis we then discuss a model for the process of dome growth and destruction and its hazard implications

collecting field data in volcanic landscapes using small uas suas drones abstract the last several years have seen a very rapid increase in the development and availability of unmanned aerial vehicles systems uav or uas more commonly called drones uas are remotely operated aerial vehicles that can be fixed wing planes helicopters or aerial systems with multiple propellers small versions of uas here called suas in particular have become so prevalent that they can be easily purchased at general retail stores this paper seeks to review and summarize the use of suas in volcanic research given their size low cost and relative durability suas provide a light weight tool platform that is easy to transport to field locations quick to set up and easy to launch and control they require very little launch and recovery space because of these characteristics suas are useful in collecting immediate and real time aerial data especially in remote inaccessible dynamic and or hazardous volcanic environments in volcanic areas suas have been used for mapping sample collection thermal imaging magnetic surveys slope stability studies and as platforms for sensors to measure outgassing of co 2 and so 2 they are also becoming invaluable for real time hazard assessment during and after an eruption they are however limited by their flight time which is greatly affected by wind speeds since they are predominately made of plastic they are also impacted by the high thermal temperatures found in active volcanic areas which can degrade their structure and performance with continued technological improvement however suas have the potential to dramatically improve our ability to collect field data because of additional natural technological and legal challenges related to their use it is critical that users be aware of and adhere to all national and local laws associated with suas

rhyolite lava emplacement dynamics inferred from surface morphology abstract the morphology of a silicic lava is created by the fluid dynamic conditions that operated during flow careful analysis of these features can thus be used to reconstruct emplacement processes we used unoccupied aerial system and structure from motion photogrammetry techniques to collect centimeter scale spatial resolution imagery of the surfaces of south coulee and obsidian dome rhyolite lavas mono inyo craters usa we supplement the newly acquired orthomosaics and digital elevation models with existing imagery of other holocene rhyolite lavas from across the western usa including rock mesa dome south sister or newberry flow south sister or obsidian flow newberry or interlake flow newberry or and banco bonito flow valles caldera nm although many morphologic features exist we restrict our quantitative analyses to the recurrent ridges and blocks of loose rubble that are common to the flows ridge spacing and ridge vergence indicate the ridges are likely folds produced by compression during emplacement pressure ridge spacings range from 27 to 45 m at south coulee and 18 to 34 m on obsidian dome spacing generally decreases with distance from the vent across both lavas ridge amplitudes range from 4 to 17 m at both lavas and show little correlation with distance from the vent the vergence of the crest of the ridges in the flow interiors points back to the source vent which provides strong evidence for endogenous flow and the backward rotation of folds produced by undertow of the underlying lava ridges near flow margins verge towards the flow front demonstrating that exogenous flow becomes increasingly important at the point of advance in both south coulee and obsidian dome block sizes are largest near the vent and gradually decrease towards the flow front the gradual decrease in block size with increasing distance from the vent likely reflects decreasing effusion rates from the conduit we interpret our high resolution field measurements under the lens of analytical solutions to fluid dynamic models to estimate emplacement timescales and associated rates we calculate relatively abbreviated eruptive timescales ranging from 1 month to

historical eruptions of merapi volcano central java indonesia 1768 1998 abstract information on merapi eruptive activity is scattered and much is remotely located a concise and well documented summary of this activity has been long needed to assist researchers and hazard mitigation efforts and the aim of this paper is to synthesize information from the mid 1700s to the present a descriptive chronology is given with an abbreviated chronology in a table that summarizes events by year assigns preliminary volcanic explosivity index vei ratings and hartmann classifications and provides key references the history of volcano monitoring is also outlined the study reveals that a major difference in eruption style exists between the twentieth and nineteenth centuries although the periodicity between larger events seems about the same during the twentieth century activity has comprised mainly the effusive growth of viscous lava domes and lava tongues with occasional gravitational collapses of parts of oversteepened domes to produce the nuees ardentes commonly defined as merapi type in the 1800s however explosive eruptions of relatively large size occurred to vei 4 and some associated fountain collapse nuees ardentes were larger and farther reaching than any produced in the twentieth century these events may also be regarded as typical eruptions for merapi the nineteenth century activity is consistent with the long term pattern of one relatively large event every one or two centuries based on the long term eruptive record deduced by others from volcanic stratigraphy it is uncertain whether or not a recurrence time model continues to apply to merapi but if so merapi could soon be due for another large event and its occurrence with only modest or inadequately appreciated precursors could lead to a disaster unprecedented in merapi s history because the area around the volcano is now much more densely populated

sector collapse forming at casita volcano nicaragua catastrophic sector collapse occurs when a volcano becomes structurally unable to support its own load one process particularly capable of weakening the edifice is hydrothermal activity it can produce high pore pressures and alter strong rock to clays alteration can extend progressively over long periods 100 yr allowing deformation to develop slowly before collapse an important finding is that structures produced by such deformation are recognizable and could permit collapse prediction we present the case of casita nicaragua where hydrothermal activity has been weakening the edifice core causing flank spreading altering original constructional shape and steepening flank slopes one side is slumping outward producing a crescentic scar with a basal bulge we identify this feature as the site of a potential sector collapse with conditions ripe for failure

instability and collapse of hazardous gas pressurized lava domes an important type of gravitational lava dome failure involves significant internal gas overpressure that influences the failure process for the first time this paper presents a rigorous analysis of the mechanics of gas pressurized dome failure we develop diffusion models to calculate gas overpressures in a lava dome and embed these pressure data into stability analyses to demonstrate how gas pressurization can initiate instability the results bear on the mechanistic understanding of hazardous dome failures gas pressurization can promote deep seated failure and the timing of conduit pressurization can control the timing of dome collapse theory explains why dome collapse can be delayed for cases of oscillating effusion dome collapses and explosive events linked to collapse of lava domes can be hazardous monitoring criteria are considered to anticipate whether or not such collapses are likely to be explosive

coherent circulation changes in the deep north atlantic from 16 n and 26 n transport arrays the meridional overturning circulation moc has been measured by boundary arrays in the atlantic since 2000 over the past decade of measurements however the reported tendencies in overturning circulation strength have differed between 16n and 26n here we investigate these differences by diagnosing their origin in the observed hydrography finding that both arrays show deep waters below 1100 dbar at the western boundary becoming fresher and less dense the associated change in geopotential thickness is about 0 15 m2 s2 between 2004 2009 and 2010 2014 with the shift occurring between 2009 2010 and earlier at 26n than 16n in the absence of a similar density change on the east of the atlantic this mid depth reduction in water density at the west would drive an increase in the shear between the upper and lower layers of north atlantic deep water of about 2 6 sv at 26n and 3 9 sv at 16n these transport anomalies result in an intensifying tendency in the moc estimate at 16n but at 26n the method of correcting the geostrophic reference level results in an opposing reducing tendency of the moc the results indicate that both arrays are observing coherent low frequency changes but that there remain discrepancies in the methods of addressing the geostrophic reference level for boundary arrays measuring ocean circulation

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

10 000 years of explosive eruptions of merapi volcano central java archaeological and modern implications abstract stratigraphy and radiocarbon dating of pyroclastic deposits at merapi volcano central java reveals 10 000 years of explosive eruptions highlights include 1 construction of an old merapi stratovolcano to the height of the present cone or slightly higher our oldest age for an explosive eruption is 9630 60 14 c y b p construction of old merapi certainly began earlier 2 collapse s of old merapi that left a somma rim high on its eastern slope and sent one or more debris avalanche s down its southern and western flanks impoundment of kali progo to form an early lake borobudur at 3400 14 c y b p hints at a possible early collapse of merapi the latest somma forming collapse occurred 1900 14 c y b p the current cone new merapi began to grow soon thereafter 3 several large and many small buddhist and hindu temples were constructed in central java between 732 and 900 a d roughly 1400 1000 14 c y b p explosive merapi eruptions occurred before during and after temple construction some temples were destroyed and or buried soon after their construction and we suspect that this destruction contributed to an abrupt shift of power and organized society to east java in 928 a d other temples sites though were occupied by caretakers for several centuries longer 4 a partial collapse of new merapi occurred 14 c y b p eruptions 700 800 14 c y b p 12 14th century a d deposited ash on the floors of still occupied candi sambisari and candi kedulan we speculate but cannot prove that these eruptions were triggered by the same partial collapse of new merapi and that the eruptions in turn ended caretaker occupation at candi sambisari and candi kedulan a new or raised lake borobudur also existed during part or all of the 12 14th centuries probably impounded by deposits from merapi 5 relatively benign lava dome extrusion and dome collapse pyroclastic flows have dominated activity of the 20th century but explosive eruptions much larger than any of this century have occurred many times during merapi s history most recently during the 19th century are the relatively small eruptions of the 20th century a new style of open vent less hazardous activity that will persist for the foreseeable future or alternatively are they merely low level background activity that could be interrupted upon relatively short notice by much larger explosive eruptions the geologic record suggests the latter which would place several hundred thousand people at risk we know of no reliable method to forecast when an explosive eruption will interrupt the present interval of low level activity this conclusion has important implications for hazard evaluation

a thermodynamical model for rainfall triggered volcanic dome collapse 1 dome forming volcanic eruptions typically involve the slow extrusion of viscous lava onto a steep sided volcano punctuated by collapse and the generation of hazardous pyroclastic flows we show an unequivocal link between the onset of intense rainfall and lava dome collapse on short time scales within a few hours and develop a simple thermodynamical model to explain this behavior the model is forced with rainfall observations from the soufriere hills volcano montserrat and suggests that when the dome is in a critical state a minimum rainfall rate of approximately 15 mm hr 1 for 2 3 hr could trigger a dome collapse

insights into caldera and regional structures and magma body distribution from lava domes at rotorua caldera new zealand abstract lava domes emplaced after caldera forming eruptions are often the only clue to the structure of the caldera and to the regional structure at the time of caldera formation this is because the deposits from the subsequent eruptions commonly bury subsidence controlling caldera faults and regional cross faults within calderas other calderas and lava domes in the taupo volcanic zone tvz new zealand have been previously reported to show strong regional control at rotorua caldera there is a general lack of surface expression of faults but rhyolite lava domes are well exposed and aligned with regional structures that have been mapped outside of the caldera our summary of published data and new observations allows these lava domes to be subdivided into three groups based upon their petrology geochemistry relative age and spatial distribution 1 the kaikait huna group of pre collapse 451 ka crystal rich domes at the caldera boundary 2 the utuhina group of crystal poor high alkali post collapse domes c 200 ka surrounding the locus of collapse and directly related to the earlier 240 ka mamaku ignimbrite eruption and 3 the ruamata group of crystal rich more calcic less devitrified post collapse 60 36 ka domes further out from the collapse locus mapping of the morphology and internal structures of the utuhina group domes shows an ene wsw elongation direction and vent alignment which is parallel to and down strike of a the extensional rift orientation independently mapped either side of the caldera b the local caldera morphology and c structures mapped at nearby okataina caldera complex a second nw se trending orientation in the caldera morphology is parallel to a pre collapse basement fabric and has partially controlled the locations of the domes a third orientation is hinted at through consistent n s striking flow bands within ngongotaha dome which are parallel with a gravity anomaly we suggest that this orientation is a n s section of a caldera ring fault that links regional structures and was utilised during caldera collapse a subsequent dike intrusion also used this structure erupting a fissure style dome that contains radiating flow bands which mimic the orientation of the feeder dike however the structure morphology and location of post collapse lava domes generally echo the unburied regional structures outside the caldera indicating that dike intrusion also occurred along regional structures we suggest that the regional structures at rotorua caldera which are similar to those at okataina caldera complex show that the kink in the orientation of the rift across the tvz to the se of rotorua was active to at least 240 ka and possibly earlier this kink is significant due to its proximity and influence on both rotorua and okataina caldera systems and their associated geothermal fields we conclude that internal structures such as flow bands and morphology of lava domes are direct consequences of the shape and location of the feeder dike which in turn is controlled by the structure of the caldera and region we also suggest that lava dome eruptions at rotorua were from a series of small related nestled magma bodies a key outcome of this study is the reconstruction of the wider structure of the caldera and surrounding structure based upon the localised internal features distribution and morphology of related lava domes

morphological and structural changes at the merapi lava dome monitored in 2012 15 using unmanned aerial vehicles uavs abstract dome building volcanoes undergo rapid and profound topographic changes that are important to quantify for the purposes of hazard assessment however as hazardous lava domes often develop on high altitude volcanoes that exhibit steep sided topography it is challenging to obtain direct field access and thus to analyze these morphological and structural changes merapi volcano in indonesia is a type example of such a volcano as soon after its 2010 eruption a new lava dome developed this dome was partially destroyed during six distinct steam driven explosions that occurred between 2012 and 2014 here we investigate the topographic and structural changes associated with these six steam driven explosions by comparing close range photogrammetric data obtained before and after these explosions to accomplish this we performed two uav campaigns in 2012 and 2015 by applying the structure from motion sfm technique we are able to construct three dimensional point clouds assess their quality by comparing them to a terrestrial laser scanning tls dataset and generate high resolution digital elevation models dems and photomosaics the comparison of these two dems and photomosaics reveals changes in topography and the appearance of fractures in the 2012 dataset we find a dense fracture network striking to the nnw sse in the post eruptive 2015 dataset we see that this nnw sse fracture trend is much more strongly expressed we also detect the formation of aligned and elongated explosion craters which are associated with the removal of over 200 000 m3 of dome material most of which 70 was deposited outside the crater region therefore this study suggests that the locations of the steam driven explosions at merapi volcano were controlled by the reactivation of preexisting structures moreover some of the newly developed and reactivated fractures delineate a block on the southern slope of the dome which could become structurally unstable and potentially lead to rock avalanche hazards this study therefore demonstrates the significance of characterizing structural fingerprints during the development of lava domes and exemplifies the value of topographic and fracture mapping which is becoming increasingly feasible when using uavs even on high and steep stratovolcanoes

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

lahars at merapi volcano central java an overview abstract merapi volcano in central java is one of the most active volcanoes in the world at least 23 of the 61 reported eruptions since the mid 1500s have produced source deposits for lahars the combined lahar deposits cover about 286 km 2 on the flanks and the surrounding piedmonts of the volcano at merapi lahars are commonly rain triggered by rainfalls having an average intensity of about 40 mm in 2 h most occur during the rainy season from november to april and have average velocities of 5 7 m s at 1000 m in elevation a wide range of facies may be generated from a single flow which may transform downvalley from debris flow to hyperconcentrated streamflow because of the high frequency and magnitude of the lahar events lahar related hazards are high below about 450 600 m elevation in each of the 13 rivers which drain the volcano hazard zone maps for lahar were produced by pardyanto et al volcanic hazard map merapi volcano central java 1 100 000 geol surv of indonesia bandung ii 4 1978 and the japanese indonesian cooperation agency master plan for land conservation and volcanic debris control in the area of mt merapi jakarta 1980 but these maps are of a very small scale to meet modern zoning requirements more recently a few large scale maps 1 10 000 and 1 2000 scale and risk assessments have been completed for a few critical river systems

imaging the 2013 explosive crater excavation and new dome formation at volcan de colima with terrasar x time lapse cameras and modelling abstract the summit region of steep volcanoes hosting lava domes often displays rapid geomorphologic and structural changes which are important for monitoring the source region of hazards explosive crater excavation is often followed by new lava dome growth which is one of the most dynamic morphometric changes that may occur at volcanoes however details of these crater formations and the ensuing new dome growth remain poorly studied a common problem is the lack of observational data due to hazardous field access and the limited resolution of satellite remote sensing techniques this paper describes the destructive constructive crater activity at volcan de colima mexico which occurred between january and march 2013 the crater geometry and early dome formation were observed through a combination of high resolution terrasar x spotmode satellite radar images and permanently installed monitoring cameras this combined time lapse imagery was used to identify ring shaped gas emissions prior to the explosion and to distinguish between the sequential explosion and crater excavation stages which were followed by dome growth by means of particle image velocimetry the digital flow field is computed from consecutive camera images showing that vertical dome growth is dominant at the beginning the upward growth is found to grade into spreading and a lateral growth domain after approximately two months of gradually filling the excavated craters with new magma the dome overflows the western margin of the crater and develops into a flow that produces block and ash flow hazards we discuss and compare the observations to discrete element models allowing us to mimic the vertical and lateral growth history of the dome and to estimate the maximum strength of the bulk rock mass moreover our results allow a discussion on the controls of a critical dome height that may be reached prior to its gravitational spreading

thermal photogrammetric imaging a new technique for monitoring dome eruptions abstract structure from motion sfm algorithms greatly facilitate the generation of 3 d topographic models from photographs and can form a valuable component of hazard monitoring at active volcanic domes however model generation from visible imagery can be prevented due to poor lighting conditions or surface obscuration by degassing here we show that thermal images can be used in a sfm workflow to mitigate these issues and provide more continuous time series data than visible light equivalents we demonstrate our methodology by producing georeferenced photogrammetric models from 30 near monthly overflights of the lava dome that formed at volcan de colima mexico between 2013 and 2015 comparison of thermal models with equivalents generated from visible light photographs from a consumer digital single lens reflex dslr camera suggests that despite being less detailed than their dslr counterparts the thermal models are more than adequate reconstructions of dome geometry giving volume estimates within 10 of those derived using the dslr significantly we were able to construct thermal models in situations where degassing and poor lighting prevented the construction of models from dslr imagery providing substantially better data continuity than would have otherwise been possible we conclude that thermal photogrammetry provides a useful new tool for monitoring effusive volcanic activity and assessing associated volcanic risks

how the variety of satellite remote sensing data over volcanoes can assist hazard monitoring efforts the 2011 eruption of nabro volcano abstract satellite remote sensing is becoming an increasingly essential component of volcano monitoring especially at little known and remote volcanoes where in situ measurements are unavailable and or impractical moreover the synoptic view captured by satellite imagery over volcanoes can benefit hazard monitoring efforts by monitoring we mean both following the changing styles and intensities of the eruption once it has started as well as nowcasting and eventually forecasting the areas potentially threatened by hazardous phenomena in an eruptive scenario here we demonstrate how the diversity of remote sensing data over volcanoes and the mutual interconnection between satellite observations and numerical simulations can improve lava flow hazard monitoring in response to effusive eruption time averaged discharge rates tadrs obtained from low spatial high temporal resolution satellite data e g modis seviri are complemented compared and fine tuned with detailed maps of volcanic deposits with the aim of constraining the conversion from satellite derived radiant heat flux to tadr maps of volcanic deposits include the time varying evolution of lava flow emplacement derived from multispectral satellite data e g eo ali landsat sentinel 2 aster as well as the flow thickness variations retrieved from the topographic monitoring by using stereo or tri stereo optical data e g pleiades planetscope aster finally satellite derived parameters are used as input and validation tags for the numerical modelling of lava flow scenarios our strategy is applied to the first historic eruption of nabro volcano eritrea occurred in june 2011 this eruptive event was characterized by the extraordinary quantity of so2 emitted into the atmosphere and the extent of the long lava flows which had a significant impact on the inhabitants of the eritrea ethiopia border region despite the low population density because of its remote position little was known about this eruption regarding the quantity of volcanic deposits and the timing and mechanisms of their emplacement we found that the total volume of deposits calculated from differences of digital elevation models dems is about 580 106 m3 of which about 336 106 m3 is the volume of the main lava flow that advanced eastward beyond the caldera multi spectral satellite observations indicate that the main lava flow had reached its maximum extent 16 km within about 4 days of the eruption onset on midnight 12 june lava flow simulations driven by satellite derived parameters allow building an understanding of the advance rate and maximum extent of the main lava flow showing that it is likely to have reached 10 5 km in one day with a maximum speed of 0 44 km h

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

constraints on magma flux from displacements data at merapi volcano java indonesia the displacement field has been monitored in the vicinity of the crater rim at mount merapi indonesia from 1993 to 1997 during this period the volcanic activity has been quasicontinuous with dome growth explosions and pyroclastic flows we measured a nine point network every year with the global positioning system static method interpretation of results is conducted with a three dimensional elastostatic boundary elements code that takes into account topography fractures and complex magma source geometry the inversion technique yields an estimate of the variation with time of the boundary conditions at the magma duct interface together with the probability associated with the best model the young s modulus of the equivalent continuum is found to be very low of the order of 1 gpa a feature which suggests that a viscoelastic behavior may be more appropriate for this rock mass given the observed seismic velocities for the domain of interest a striking compatibility is outlined between observed deformations and the rate of occurrence of multiphase seismic events once the main fractures of the structure have been taken into consideration this suggests that the summit elastic or viscoelastic deformation field is controlled by the magma flux within the duct rather than by magma pressure variations in addition a nonelastic displacement has been identified at the westernmost point of the network this was considered critical for the stability of the summit structure a concern whose validity has been verified a posteriori by the july 1998 explosion

the geological evolution of merapi volcano central java indonesia merapi is an almost persistently active basalt to basaltic andesite volcanic complex in central java indonesia and often referred to as the type volcano for small volume pyroclastic flows generated by gravitational lava dome failures merapi type nuees ardentes stratigraphic field data published and new radiocarbon ages in conjunction with a new set of 40k 40ar and 40ar 39ar ages and whole rock geochemical data allow a reassessment of the geological and geochemical evolution of the volcanic complex an adapted version of the published geological map of merapi wirakusumah et al 1989 peta geologi gunungapi merapi jawa tengah geologic map of merapi volcano central java 1 50 000 is presented in which eight main volcano stratigraphic units are distinguished linked to three main evolutionary stages of the volcanic complex proto merapi old merapi and new merapi construction of the merapi volcanic complex began after 170 ka the two earliest proto merapi volcanic edifices gunung bibi 109 60 ka a small basaltic andesite volcanic structure on merapi s north east flank and gunung turgo and gunung plawangan 138 3 ka 135 3 ka two basaltic hills in the southern sector of the volcano predate the merapi cone sensu stricto old merapi started to grow at 30 ka building a stratovolcano of basaltic andesite lavas and intercalated pyroclastic rocks this older merapi edifice was destroyed by one or possibly several flank failures the latest of which occurred after 4 8 1 5 ka and marks the end of the old merapi stage the construction of the recent merapi cone new merapi began afterwards mostly basaltic andesite pyroclastic and epiclastic deposits of both old and new merapi 11 792 90 14c years bp cover the lower flanks of the edifice a shift from medium k to high k character of the eruptive products occurred at 1 900 14c years bp with all younger products having high k affinity the radiocarbon record points towards an almost continuous activity of merapi since this time with periods of high eruption frequency interrupted by shorter intervals of apparently lower eruption rates which is reflected in the geochemical composition of the eruptive products the holocene stratigraphic record reveals that fountain collapse pyroclastic flows are a common phenomenon at merapi the distribution and run out distances of these flows have frequently exceeded those of the classic merapi type nuees ardentes of the recent activity widespread pumiceous fallout deposits testify the occurrence of moderate to large subplinian eruptions vei 3 4 during the mid to late holocene vei 4 eruptions as identified in the stratigraphic record are an order of magnitude larger than any recorded historical eruption of merapi except for the 1872 ad and possibly the october november 2010 events both types of eruptive and volcanic phenomena require careful consideration in long term hazard assessment at merapi

thermal hydrologic mechanism for rainfall triggered collapse of lava domes hazardous gravitational collapses involving hot lava domes can be triggered by intense rainfall both in periods of active dome growth and volcanic repose the collapses can evolve into energetic failures involving as much as 90 of the dome or 100 3 10 6 m 3 of dome lava retrogressively removed over several hours under standing such potentially lethal phenomena is vital but traditional explanations for rain induced slope failure are problematic for rainfall on hot typically 400 8c crystalline lava in this paper we quantitatively develop a new thermal hydrologic mechanism that can cause such failures pressure buildup within fissures due to effusive gas trapped by a rain saturated dome carapace results in increased destabilizing forces and the loss of mass strength and ultimately results in failure of the dome our mechanistic models are consistent with field observations and provide a quantification of threshold rainfall intensities and durations required to trigger failure

deflation and inflation of a large magma body beneath uturuncu volcano bolivia insights from insar data surface lineaments and stress modelling summary the voluminous ash flow eruptive products in the central andes imply that there are major magma bodies however how these magma bodies develop and change in time and space are not understood in this study we analyse the deformation activity of the uturuncu volcano sw bolivia from 2003 to 2009 using a satellite radar interferometry insar data set we find that the strength and the pattern of the present deformation can be explained by a pressurized source such as an inflating flat topped magma body at 22 9 km depth below the surface furthermore we examine the optical remote sensing data to perform a lineament analysis which shows in a geographic information system gis that a girdle of river streams and faults encircle the volcano at radial distance of approximately 15 km using numerical stress models we locate a magma body beneath the volcano and find that the lineaments are best explained by a deflating flat topped magma body at approximately 18 2 km depth which is consistent with the insar study thus both the independent analysis of insar and lineament data suggest the presence of a horizontally extended flat topped magma body beneath uturuncu the location depth is in agreement with or just above a prominent seismic low velocity zone consequently although the sign of deformation caused by the herein constrained magma body differs the similar geometry and similar location suggest them to be similar possibly indicating longevity of a magma storage region

lava and ice interaction at stratovolcanoes use of characteristic features to determine past glacial extents and future volcanic hazards structures resulting from lava and ice interaction are common at glaciated stratovolcanoes during summit eruptions at stratovolcanoes meltwater is produced and travels freely down steep slopes and thin permeable valley glaciers eroding the ice and enlarging preexisting glacial drainages as a result eruptions in this environment have produced few catastrophic floods lava flowing into the open channels and voids in the glaciers becomes confined and grows thicker filling the available space and producing steep sided bodies with smooth bulbous contact surfaces quenching of lava against ice or by water forms small scale features such as tensional fractures and glass as the amount of meltwater in contact with the lava increases the type and abundance of smaller scale features become similar to those produced during subglacial eruptions into meltwater lakes identification of large and small scale lava ice contact features in the field can be used to reconstruct paleoglacial extent and combined with geochronology of lavas to determine past paleoclimate an understanding of lava ice interaction allows us to better assess the hazards posed by future eruptions at glaciated volcanoes

textural history of recent basaltic andesites and plutonic inclusions from merapi volcano mt merapi in central java is one of the most active stratovolcanoes on earth and is underlain by a multistage plumbing system crystal size distribution analyses csd were carried out on recent merapi basaltic andesites and co eruptive magmatic and plutonic inclusions to characterise the crystallisation processes that operate during storage and ascent and to obtain information on respective time scales the basaltic andesites exhibit log linear kinked upwards csd curves for plagioclase and clinopyroxene that can be separated into two main textural populations large plagioclase phenocrysts 1 6 mm make up one population but correspond to crystals with variable geochemical composition and reflect a period of crystal growth at deep to mid crustal levels this population was subsequently influenced by crystal accumulation and the onset of crustal assimilation including the incorporation of high ca skarn derived xenocrysts textural re equilibration is required for these crystals to form a single population in csd a second episode of crystal growth at shallower levels is represented by chemically homogenous plagioclase crystals 1 6 mm in size crustal assimilation is indicated by for example oxygen isotopes and based on the csd data crystallisation combined with contamination is likely semi continuous in these upper crustal storage chambers the csd data observed in the basaltic andesite samples are remarkably consistent and require a large volume steady state magmatic system beneath merapi in which late textural equilibration plays a significant role plagioclase csds of co eruptive magmatic and plutonic inclusions may contain a third crystal population 1 mm not found in the lavas this third population has probably formed from enhanced degassing of portions of basaltic andesite magma at shallow crustal levels which resulted in increased crystallinity and basaltic andesite mush inclusions a suite of coarse plutonic inclusions is also present that reflects crystallisation and accumulation of crystals in the deep merapi plumbing system as deduced from csd patterns and mineral assemblages

modeling the density at merapi volcano area indonesia via the inverse gravimetric problem 1 merapi is a high risk andesitic volcano in central java indonesia very little information is known about the detailed regional density structure around merapi and its neighbor volcano merbabu we compute a subsurface three dimensional 3 d model of anomalous density for the volcanoes merapi and merbabu in central java indonesia by inversion of the gravity field as input for the inversion methodology gravity observations from 443 points whose 3 d coordinates are determined by gps are used the inversion algorithm is based on an explorative approach to fit a least squares condition including a balancing factor between the minimization of the residuals and the anomalous mass a mean density about 2242 kg m3 for the region of merapi and merbabu has been computed by least squares adjustment results of the inversion show major low density contrasts up to 242 kg m3 and positive structures about 264 kg m3 referred to the determined mean density a density anomaly relative high with densities up to 264 kg m3 is connecting the volcanoes in a 152 course from nw to se and might be built of older basaltic lava low density contrasts about 242 kg m could be found in agreement with magnetotelluric and electromagnetic results generally the identified high and low density bodies are in agreement with the results of other geophysical methods such as electromagnetic and magnetotelluric prospecting or geological formations and structures a porosity about 21 is derived for the largest negative density bodies about 242 kg m3 furthermore the density model gives some new information about the controversial origin of a hill formation near merapi and is also used to discuss the possible existence of a shallow magma chamber which is also a controversial subject generally the density model serves as basic information for the interpretation of geodetic and geophysical observations and confirms existing results from magnetotellurics electromagnetics and seismic data interpretation

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes i we report the first measurements of volcanic gases with an unmanned aerial vehicle uav the data were collected at la fossa crater vulcano italy during april 2007 with a helicopter uav of 3 kg payload carrying an ultraviolet spectrometer for remotely sensing the so 2 flux 8 5 mg d 1 and an infrared spectrometer and electrochemical sensor assembly for measuring the plume co 2 so 2 ratio by multiplying these data we compute a co 2 flux of 170 mg d 1 given the deeper exsolution of carbon dioxide from magma and its lower solubility in hydro thermal systems relative to so 2 the ability to remotely measure co 2 fluxes is significant with promise to provide more profound geochemical insights and earlier eruption forecasts than possible with so 2 fluxes alone the most ubiquitous current source of remotely sensed volcanic gas data

modeling river bed morphology roughness and surface sedimentology using high resolution terrestrial laser scanning 1 recent advances in technology have revolutionized the acquisition of topographic data offering new perspectives on the structure and morphology of the earth s surface these developments have had a profound impact on the practice of river science creating a step change in the dimensionality resolution and precision of fluvial terrain models the emergence of hyperscale survey methods including structure from motion photogrammetry and terrestrial laser scanning tls now presents the opportunity to acquire 3 d point cloud data that capture grain scale detail over reach scale extents translating these data into geomorphologically relevant products is however not straightforward unlike traditional survey methods tls acquires observations rapidly and automatically but unselectively this results in considerable noise associated with backscatter from vegetation and other artifacts moreover the large data volumes are difficult to visualize require very high capacity storage and are not incorporated readily into gis and simulation models in this paper we analyze the geomorphological integrity of multiscale terrain models rendered from a tls survey of the braided river feshie scotland these raster terrain models are generated using a new computationally efficient geospatial toolkit the topographic point cloud analysis toolkit topcat this performs an intelligent decimation of point cloud data into a set of 2 5 d terrain models that retain information on the high frequency subgrid topography as the moments of the locally detrended elevation distribution the results quantify the degree of terrain generalization inherent in conventional fluvial dems and illustrate how subgrid topographic statistics can be used to map the spatial pattern of particle size grain roughness and sedimentary facies at the reach scale