thermal monitoring of north pacific volcanoes from space long term thermal modeling of volcanoes using satellite imagery provides an effective tool for monitoring remote yet dangerous volcanoes in the north pacific this region includes volcanoes in alaska the aleutian islands and the kamchatkan peninsula thermal infrared data collected multiple times per day from weather satellites show distinct signatures for three different types of volcanic activity at different volcanic centers near real time automated techniques are being developed to monitor relative changes in radiant temperature at volcanoes in this region radiant temperature values as a function of time are extracted and compared to background values for a series of active volcanoes by establishing a long term thermal record for these volcanoes significant deviations indicative of an impending eruption can be detected this tool is used to search for precursors to explosive eruptions in order to increase warning times and hazard mitigation for these potentially catastrophic events a six year archive of satellite imagery has been compiled for this active region and is available for study

effects of borehole stress concentrations on dipole anisotropy measurements we show both experimentally and theoretically how stress concentrations affect the velocity field around a borehole and how the velocity field influences dipole anisotropy measurements at low frequencies the dipole mode is sensitive to the far field stresses primarily so standard sonic log interpretation correctly yields the direction of maximum stress at higher frequencies the dipole mode is sensitive to near field stress concentrations such that the fast polarization direction is aligned with the direction of minimum tectonic stress these effects combine to produce a crossover in the dipole dispersion curves measured in the fast and slow directions with broad band dipole data the dispersion crossover can be used as an indicator of stress induced anisotropy dominating over weak intrinsic anisotropy

tracking magma volume recovery at okmok volcano using gps and an unscented kalman filter 1 changes beneath a volcano can be observed through position changes in a gps network but distinguishing the source of site motion is not always straightforward the records of continuous gps sites provide a favorable data set for tracking magma migration dense campaign observations usually provide a better spatial picture of the overall deformation field at the expense of an episodic temporal record combining these observations provides the best of both worlds a kalman filter provides a means for integrating discrete and continuous measurements and for interpreting subtle signals the unscented kalman filter ukf is a nonlinear method for time dependent observations we demonstrate the application of this technique to deformation data by applying it to gps data collected at okmok volcano seven years of gps observations at okmok are analyzed using a mogi source model and the ukf the deformation source at okmok is relatively stable at 2 5 km depth below sea level located beneath the center of the caldera which means the surface deformation is caused by changes in the strength of the source during the 7 years of gps observations more than 0 5 m of uplift has occurred a majority of that during the time period january 2003 to july 2004 the total volume recovery at okmok since the last eruption in 1997 is 60 80 the ukf allows us to solve simultaneously for the time dependence of the source strength and for the location without a priori information about the source

improved remote sensing estimates of lava flow cooling a case study of the 1991 1993 mount etna eruption infrared radiance data acquired by the landsat thematic mapper tm provide information regarding the thermal state of active lavas which can be used to estimate flow surface temperatures and thus lava cooling saturation of one or both of tm s short wave infrared swir wavebands has meant however that previous studies of lava flow cooling have approximated what is almost certainly an n thermal component flow surface temperature distribution where n 1 with a single pixel integrated temperature pit we show that the high sensitivity of tm s swir wavebands to the small amount of high temperature e g 1000 c material exposed in hot fractures within the flows cooler e g 200 c surface crust results in the calculation of pits that are higher than the temperature of this crust which is usually the dominant radiative component this causes heat loss from such pixels to be overestimated we present adaptations that allow more realistic heat loss estimates to be produced using tm data by assuming that a second high temperature component contributes to the radiance measured from saturated pixels and by defining an appropriate range for the temperature of the lava crust by analyzing a suite of five tm images acquired during the 1991 1993 eruption of mount etna we present more realistic estimates of how this flow cooled as well as results that show how the flow regime of the lava evolved over time the methods we present will continue to be of use as although the next generation of high spatial resolution sensors such as the landsat 7 enhanced thematic mapper plus etm and the terra advanced space borne thermal emission and reflection radiometer aster will be less susceptible to saturation than tm the problem will still persist

shear slowness measurement by dispersive processing of the borehole flexural mode in sonic well logging the flexural mode generated by a dipole transducer allows measurement of shear slowness in slow formations that is formations in which the shear slowness is slower than the borehole fluid speed the flexural mode is a dispersive borehole mode but many current processing methods do not account for this dispersion the approximate semblance equation is derived to explain what happens when a dispersive wave is processed nondispersively the processing described here is a dispersive analog of the slowness time coherence stc processing used commonly for array sonic waveforms it back propagates waveforms according to model dispersion curves and calculates semblance it is a specialized version of the maximum likelihood ml and least mean squared error lmse estimator for formation shear slowness the dispersive analog of stc is too slow for depth by depth logging but may be a helpful analytic tool a high speed variant dispersive stc dstc eliminates this difficulty by a new wi

modis and aster synergy for characterizing thermal volcanic activity abstract volcanic activity is diverse in its manifestations and spans wide temporal and spatial scales monitoring volcanoes with any single sensor system can only provide a limited perspective on the nature of such activity because of trade offs between spatial temporal and spectral resolution spaceborne observations of volcanoes are thus optimized by utilizing data from different and complementary remote sensing instruments this study examines the combined use of the moderate resolution imaging spectroradiometer modis and the advanced spaceborne thermal emission and reflection radiometer aster for analyzing thermal anomalies from four separate volcanoes erta ale ethiopia k lauea hawai i lascar chile and kliuchevskoi russia modis provides a high temporal resolution daily but low spatial resolution 1 km dataset and is used to measure volcanic thermal radiance aster provides relatively high spatial resolution 90 m image data and is used to define the size of thermal features albeit at a poorer temporal frequency erta ale and k lauea have been erupting continuously over the 11 year study period and their thermal emission signatures reveal a persistent baseline on which occasional increases in thermal output associated with more profuse effusions of lava are superimposed kliuchevskoi also displays occasional peaks in thermal activity due to the eruption of lava however intervening periods are characterized by weak or absent thermal anomalies lascar on the other hand provides an example of volcanic activity that is difficult for modis type sensors to detect it is characterized by fumarolic activity that is too low in temperature and too spatially limited to be readily detectable with its coarser instantaneous field of view i e pixel size however high resolution data from aster can be used to supplement and complement the modis dataset beyond characterizing the size of thermal anomalies aster can also provide constraints on their shape location and orientation and is capable of detecting relatively subtle thermal anomalies given its high spatial resolution thermal infrared wavebands these qualities permitted the identification of a thermal precursor to lava flows at kliuchevskoi the precursor which was associated with a rising lava lake is characterized as an increase in the size and intensity of aster detected thermal anomalies situated in the active crater wavelet analysis of the modis dataset was also carried out this revealed the time scales over which radiant output waxed and waned during individual eruptive episodes as well as the repose time between episodes such information might be useful in forecasting the likely duration and onset of future eruptions

intraplate seismicity and stresses in young oceanic lithosphere we have conducted a systematic study of oceanic intraplate seismicity in the period 1964 1983 occurring in lithosphere younger than 35 million years focal mechanisms determined for 26 events using first motions p wave modeling and surface wave amplitude radiation patterns along with 13 previously determined mechanisms indicate a diversity of faulting styles and stress orientations in young oceanic lithosphere there is no evidence for a worldwide transition from extension to compression at a specific lithospheric age tensional axes of normal faulting events are oriented oblique to the spreading direction and do not show extension in the spreading direction congressional axes of thrust events show a weak preferred orientation in the spreading direction presumably due to ridge push stresses however stress axes of thrust events in very young lithosphere age 9 ma do not show a correlation with the spreading direction suggesting that the ridge push force is small near the ridge these observations indicate that tensional stress in the spreading direction is concentrated in a very narrow zone at the ridge axis in agreement with models which assume that the axial region has very little tensile strength normal faulting events occur at greater depths and temperatures than thrust events possibly because rocks under tensional stress have strength maxima at higher temperatures alternatively the depths of the normal faulting events may be a result of the higher thermal gradients at depth in young lithosphere if thermoelastic stresses are important in generating this seismicity differential thermal contraction along fracture zones does not seem to be a significant source of near ridge intraplate seismicity high seismicity rates in young lithosphere noted previously on a global scale seem characteristic of all three major ocean basins additionally most of the total oceanic intraplate moment release takes place in young lithosphere however most of the events and more than 96 of the total moment release of the near ridge intraplate seismicity are contained in five areas two zones in the indian ocean one near chagos bank and the other in the amsterdam st paul region indicate tension parallel to the trend of the plate boundary a region of high seismicity near the east pacific rise between 3 and 7 n shows both normal and thrust faulting while another region on the cocos plate west of the panama fracture zone is characterized by strike slip faulting thrust strike slip and normal faulting events are found in a small seismically active zone of the south central pacific the extremely uneven distribution of seismicity if not a result of the relatively short time period studied 20 years indicates local perturbations strongly affect near ridge seismicity

compressional and shear wave anisotropy in the oceanic lithosphere the ngendei seismic refraction experiment summary synthetic seismogram modelling of seismic refraction data from the 1983 ngendei expedition to the south pacific indicate seismic anisotropy both within the top kilometre of oceanic crust and in the uppermost mantle we calculate average p and s wave velocity versus depth functions for two orthogonal azimuths n3ooe approximately aligned with the fast mantle direction and n120 e close to the fast crustal direction probable lateral heterogeneities at the ngendei site prevent perfect matching of data and synthetic waveforms crustal anisotropy is indicated by a 28 pattern of both p and s wave travel times as a function of azimuth and is consistent with an approximate 0 2 km s difference in p wave velocities and 0 1 km s difference in s wave velocities upper mantle anisotropy is characterized by pn velocity differences of 7 95 8 4 km s l and a nearly uniform s velocity of 4 65 km s we use these velocity profiles and traveltime data to calculate bounds on the properties of the elastic constants of the crust and upper mantle the crustal anisotropy can be explained by a model involving aligned cracks parallel to the original spreading ridge resulting in a fast direction perpendicular to the fossil spreading direction the upper mantle anisotropy is consistent with aligned olivine crystal models in which the fast direction is parallel to the fossil spreading direction for both of these models we use bounds from the ngendei data to place constraints on the physical properties of the lithosphere

morphology of extrusive basalts and its relationship to seismic velocities in the shallow oceanic crust recent seismic experiments have revealed that a shallow low velocity zone is a common feature within the uppermost few hundred meters of very young less than 100 kyr oceanic crust at fast spreading ridges the shape of this zone suggests that the low velocities are related to the constructional morphology of the extrusive layer 2a portion of the crust with this in mind we use simple analytical techniques to study the effects of characteristic morphologic elements of the extrusive basalts on their elastic properties we find that high compliance of the contacts between pillows and pillow fragments can account for all of the observed velocity anomaly voids between pillows are by comparison to their effects on porosity considerably less important radial cooling cracks and voids within the pillows themselves will affect the velocities in direct proportion to their effect on the individual pillows the relatively rapid increase in velocity with age in these very young extrusives can be explained by welding of pillow contacts and stiffening of the individual pillows by infilling of radial fractures both of which may take place without a large reduction in porosity if voids between pillows are filled initially by sediments the cementation of these materials can also cause large increases in velocity without a large addition of mass because of the importance of such subtle variations in morphology there can be no one to one relationship between seismic velocities and porosities within the extrusive layer of the oceanic crust therefore independent measures of crustal porosity must be found for example using sea floor gravity surveys

macroseismic field observations of january 26th 2001 kachchh earthquake and its seismotectonics abstract on the morning of january 26 2001 a devastating earthquake of magnitude mw 7 7 origin time 8 h 46 min 42 9 s struck the kachchh peninsula situated in the western india and was widely felt over the indian subcontinent the epicenter was located northeast of bachau at 23 40 n 70 28 e with a focal depth of 25 km it was the largest earthquake in india during the last five decades maximum intensity x according to the european macroseismic scale 98 ems 98 was observed in the meizoseismal zone an isoseismal map shows an e w trend with an elongation to the southeast direction this earthquake caused widespread damage to poorly built buildings and framed structures up to 300 km from the epicenter zone the damage distribution shows an asymmetric and heterogeneous pattern the intensity attenuation is rapid in the northwest direction and slow towards the east and southeast direction this earthquake produced widespread liquefaction in the banni rann and along the coastal regions the majority of 185 dam sites in the kachchh region suffered minor to major damage from the damage distribution and seismogenic effects it can be inferred that the main shock was initiated along an e w trending fault north northeast of bachau the pear shape isoseismal pattern might be caused by different seismic moment rate release along this propagating rupture

combined use of seviri and modis for detecting measuring and monitoring active lava flows at erupting volcanoes multispectral data acquired by spinning enhanced visible and infrared imager seviri onboard the geostationary platform meteosat second generation msg2 located at 0deg longitude were analyzed to assess the payload suitability for quantitative volcano monitoring in times of good infrared transparency of the troposphere seviri data proved particularly suited to detect the onset of effusive eruptions and to monitor the related lava flows with 15 min refresh rates after development of a code allowing for fast automated processing of the 96 data streams downlinked daily by msg2 thorough monitoring tests were carried out on the 2007 eruptions of stromboli aeolian islands italy and piton de la fournaise reunion island france the results in radiant flux and effusion rate provided by use of thermal mid and short infrared bands of seviri were validated by exploiting simultaneous modis overpasses by terra and aqua up to four times daily

new observations of the shallow seismic structure of young oceanic crust the results are presented of three new experiments carried out on the mid atlantic ridge mar near latitude 23 n using a unique method of studying the seismic structure of the uppermost few hundred meters of the oceanic crust the data were collected using a fixed ocean floor hydrophone receiver and a controllable explosive source that was towed within a few tens of meters of the rugged bottom topography these 1 to 2 km long refraction lines produced for the first time direct observations of the compressional wave velocity structure of the uppermost 200 300 m of the young igneous crust one experiment was carried out over the site of hole 648b of the ocean drilling program on a small volcano within the median valley of the mar the seafloor velocity was observed to be 2 1 km s 1 underlain by an approximately linear velocity gradient of 4 s 1 given that we know the crust at this location consists of fresh basalt lavas with laboratory measured velocities in excess of 5 8 km s 1 porosities at the seafloor of as high as 30 50 are inferred the two other experiments were located over 7 m y old crust near deep sea drilling project site 395 west of the mar separated by only 14 km laterally but by over 1400 m in water depth the experiment positioned in the 100 m thick sediment pond and that located 14 km to the south atop a prominent topographic high produced results that within the data resolution were indistinguishable the velocity of the uppermost basaltic basement was 4 1 km s 1 and the velocity gradient was less than 0 5 s 1 this 2 km s 1 difference in velocity between the two sites is assumed to be a consequence of age related modifications to the physical properties of the crust if the primary change is in only the total porosity then a 15 20 reduction is required to explain these observations this seems unlikely because any such pervasive process would have been previously observed in geophysical and sampling data e g off axis volcanism secondary mineral deposition tectonic compression a combination of many processes acting in unison would be necessary to produce such a decrease in porosity if the geometry of the cracks and voids were modified in just the right way then no change in total porosity is required to explain the velocity difference these on bottom refraction profiles are proven to be practical experiments that can provide precise information on a scale appropriate to many of the ocean floor s geologic features they produce results that may be correlated in a meaningful way with results of ocean drilling and downhole measurements

modvolc near real time thermal monitoring of global volcanism modvolc is a non interactive algorithm developed at the hawaii institute of geophysics and planetology higp that uses low spatial resolution 1 km pixel size infrared satellite data acquired by the moderate resolution imaging spectroradiometer modis to map the global distribution of volcanic thermal anomalies in near real time modvolc scans the level 1b modis data stream on a pixel by pixel basis for evidence of pixel and sub pixel sized high temperature radiators once a hot spot has been identified its details location emitted spectral radiance time satellite observation geometry are written to ascii text files and transferred via ftp to higp from where the results are disseminated via the internet http modis higp hawaii edu in this paper we review the underlying principles upon which the algorithm is based before presenting some of the results and data that have been obtained since its inception we show how modvolc reliably detects thermal anomalies at a large number of persistently and sporadically active volcanoes that encompass the full range of common eruptive styles including erebus antarctica colima mexico karymsky kamchatka popocatepetl mexico etna italy and nyiragongo democratic republic of congo amongst others we also present a few cautionary notes regarding the limitations of the algorithm and interpretation of the data it provides

seismic anisotropy observed in upper oceanic crust seismic anisotropy in the upper 150om of oceanic basement has been observed by polarization analysis of three component bore hole seismometer records the most convincing evidence for the anisotropy is shear wave splitting for explosive sources at four azimuths compressional wave particle motion deviations suggestive of anisotropy are also observed but they may be caused by lateral inhomogeneities the anisotropy was not resolved by travel time analysis the observed velocities and particle motions in the horizontal plane can be modelled to within a standard deviation by assuming a perfectly elastic homogeneous anisotropic layer 2 with hexagonal symmetry and a horizontal symmetry axis the most probable cause of the anisotropy is preferred crack orientation

seismotectonics of the himalayan collision zone geometry of the underthrusting indian plate beneath the himalaya fault plane solutions and well determined focal depths of medium sized earthquakes topography and landsat imagery in conjunction with seismicity maps cross sections and available geological information are used to investigate the present tectonics of the himalayan continental collision zone most of the accurately located epicenters of events along the himalayan arc 78 e 95 e that occurred between 1961 and 1981 are concentrated in a narrow zone about 50 km wide lying between the northerly dipping main boundary mbt and main central mct thrusts most of these events are located just south of the mct though the epicenters of the events are in general well located their depths as determined by teleseismic travel time data are very unreliable events with accurately determined depths obtained from identification of surface reflected phases define a simple planar zone from about 10 km and 20 km depth with an apparent dip of about 15 this result is all the more remarkable considering that the events used were located along about an 1800 km length of the himalyan arc except for one all available focal mechanisms of events within this zone indicate shallow 30 north dipping thrusts this shallow north dipping zone apparently defines a part of the detachment that separates the underthrusting indian plate from the lesser himalayan crustal block the spatial extent and the geometry of this interplate thrust zone strongly indicate that the mbt and nearby subsidiary surface and blind thrusts rather than the mct are currently the most active structures of the himalayan arc we suggest that the great himalayan earthquakes m 8 occur along the same detachment surface as defined by the thrust type medium sized events events located to the south of the mbt and beneath the ganges foredeep show normal faulting with t axes perpendicular to the himalayan trend the above results suggest that the indian continental plate is underthrusting the himalayan crustal blocks in a relatively coherent and simple geometry and that this geometry is not much different from that observed along oceanic subduction zones the november 19 1980 earthquake that occurred near the mct near 88 5 e shows a predominantly strike slip focal mechanism one of the nodal planes of this mechanism is transverse to the himalayan structural grain and moreover this plane has a trend similar to that of the recently mapped yadong gulu rift in the tethyan himalaya and in southern tibet just northeast of the earthquake we interpret this predominantly left lateral strike slip mechanism to indicate a possible genetic relationship between transverse structural features in the underthrusting indian plate the kishangang basement fault and the upper himalayan blocks and tibet

conclusion recommendations and findings of the red seed working group red seed stands for risk evaluation detection and simulation during effusive eruption disasters and combines stakeholders from the remote sensing modelling and response communities with experience in tracking volcanic effusive events the group first met during a three day long workshop held in clermont ferrand france between 28 and 30 may 2013 during each day presentations were given reviewing the state of the art in terms of a volcano hot spot detection and parameterization b operational satellite based hot spot detection systems c lava flow modelling and d response protocols during effusive crises at the end of each presentation set the four groups retreated to discuss and report on requirements for a truly integrated and operational response that satisfactorily combines remote sensors modellers and responders during an effusive crisis the results of collating the final reports and follow up discussions that have been on going since the workshop are given here we can reduce our discussions to four main findings 1 hot spot detection tools are operational and capable of providing effusive eruption onset notice within 15 min 2 spectral radiance metrics can also be provided with high degrees of confidence however if we are to achieve a truly global system more local receiving stations need to be installed with hot spot detection and data processing modules running on site and in real time 3 models are operational but need real time input of reliable time averaged discharge rate data and regular updates of digital elevation models if they are to be effective the latter can be provided by the radar photogrammetry community 4 information needs to be provided in an agreed and standard format following an ensemble approach and using models that have been validated and recognized as trustworthy by the responding authorities all of this requires a sophisticated and centralized data collection distribution and reporting hub that is based on a philosophy of joint ownership and mutual trust while the next chapter carries out an exercise to explore the viability of the last point the detailed recommendations behind these findings are detailed here

dipole dispersion crossover and sonic logs in a limestone reservoir analyses of sonic logs in a horizontal well provide new information about mechanical properties of rocks made possible by recent developments in our understanding of acoustic wave propagation in prestressed formations most sections of this horizontal well exhibit azimuthal shear isotropy indicating isotropic stresses in the plane perpendicular to the well trajectory leading to stable wellbore conditions however two sections show dipole dispersion crossovers that confirm the presence of stress induced shear anisotropy caused by a difference between the maximum and minimum stresses in the plane perpendicular to the well trajectory the two dipole dispersions are obtained by processing the recorded waveforms by a modified matrix pencil algorithm the fast shear direction is estimated from alford rotation of the cross dipole waveforms one section of the well exhibits the fast shear direction parallel to the overburden stress as the maximum stress direction whereas the other section has the fast shear direction parallel to the horizontal stress that is larger than the overburden stress the cause of this change in the fast shear direction is believed to be the well s penetration into a 3 ft thick bed with lower porosity and permeability and significantly higher elastic stiffnesses than those in the other part of the homogeneous high permeability reservoir a stiff bed is likely to have greater stresses in its plane than perpendicular to it which would make the horizontal stresses greater than the vertical

structural interpretation of the great earthquakes of the last millennium in the central himalaya abstract a major question about the himalaya remains open does a great earthquake like the mw 8 1 1934 earthquake release all the strain stored by the tibet india convergence during the preceding interseismic period and only that strain or can it also release a background store of energy that remained unreleased through one or more earlier earthquakes and so potentially engender giant events or a relatively random sequence of events to consider this question the history of the great earthquakes of the last millennium is investigated here by combining data provided by the historical archives of kathmandu trenches through surface ruptures isoseismal damage mapping seismites and the instrumental record in the kathmandu basin the location of the epicenter of the 1934 earthquake was determined from the arrival of high energy p waves that caused sedimentary dikes and ground fractures perpendicular to the epicenter azimuth the epicenter of the mw 7 6 1833 earthquake can therefore be determined analogously from dike orientation and its location to the ne of kathmandu indicates an overlap with the mw 8 1 1934 rupture the 1934 earthquake released strain not released by the 1833 earthquake comparison of the historical records of earthquakes in kathmandu with 14c ages from paleo seismic trenches along the himalayan front suggests that 1 the 1344 kathmandu event ruptured the surface as far away as kumaon and was therefore a giant mw 8 6 earthquake and 2 the 1255 event that destroyed kathmandu is attested by surface ruptures in central and western nepal and by seismites in soft sediment as far away as kumaon geometric and rheologic controls for the different types of ruptures during the medium mw 7 great mw 8 and giant mw 8 4 earthquakes are illustrated in structural cross sections it is found that the epicenters of great himalayan earthquakes are located on the basal thrust farther north or close to the locked zone which is defined from geodetic measurements of regional deformation during the interseismic period this suggests that great earthquakes initiate in a wide transition zone between exclusively brittle and exclusively creeping regimes the extent of which depends on the dip of the main himalayan thrust the succession of the great earthquakes during the last millennium has released all the 20 m millennial himalayan convergence even in the central seismic gap which has been locked since 1505 the millennial seismic release rate is close to the convergence rate nonetheless no evidence of a succession of characteristic earthquakes has been found the 1100 1833 and 1934 earthquakes in the eastern himalaya are characterized neither by constant displacement nor by constant recurrence furthermore some great earthquakes do not release all the strain elastically stored by the himalayan and tibetan upper crust after the 1255 event there was still the potential for a slip of several meters for the mw 8 1 1505 event this suggests a rather random release of seismic energy great earthquakes could occur anytime and in any part of the central himalaya furthermore a future giant earthquake of mw 8 6 cannot be excluded

risk evaluation detection and simulation during effusive eruption disasters lava ingress into a vulnerable population will be difficult to control so that evacuation will be necessary for communities in the path of the active lava followed by post event population infrastructural societal and community replacement and or relocation there is a pressing need to set up a response chain that bridges scientists and responders during an effusive crisis to allow near real time delivery of globally standard products for a timely and adequate humanitarian response in this chain the scientific research groups investigating lava remote sensing and modelling need to provide products that are both useful to and trusted by the crisis response community requirements for these products include a formats that can be immediately integrated into a crisis management procedure and b in an agreed and stable standard a review of current capability reveals that we are at a point where the community can provide such a response as is the aim of the red seed risk evaluation detection and simulation during effusive eruption disasters working group this book is the first production of this group and is intended not only as a directory of current capabilities and operational service providers but also as a statement of intent and need while providing a simulation designed to demonstrate how a truly pan disciplinary response to an effusive crisis could work

first recorded eruption of mount belinda volcano montagu island south sandwich islands the modvolc satellite monitoring system has revealed the first recorded eruption of mount belinda volcano on montagu island in the remote south sandwich islands here we present some initial qualitative observations gleaned from a collection of satellite imagery covering the eruption including modis landsat 7 etm aster and radarsat 1 data modvolc thermal alerts indicate that the eruption started sometime between 12 september and 20 october 2001 with low intensity subaerial explosive activity from the island s summit peak mount belinda by january 2002 a small lava flow had been emplaced near the summit and activity subsequently increased to some of the highest observed levels in august 2002 observations from passing ships in february and march 2003 provided the first visual confirmation of the eruption aster images obtained in august 2003 show that the eruption at mount belinda entered a new phase around this time with fresh lava effusion into the surrounding icefield modis radiance trends also suggest that the overall activity level increased significantly after july 2003 thermal anomalies continued to be observed in modis imagery in early 2004 indicating a prolonged low intensity eruption and the likely establishment of a persistent summit lava lake similar to that observed on neighboring saunders island in 2001 our new observations also indicate that lava lake activity continues on saunders island

seismic anisotropy of fractured rock a simple method for including the effects of geologically realistic fractures on the seismic propagation through fractured rocks can be obtained by writing the effective compliance tensor of the fractured rock as the sum of the compliance tensor of the unfractured background rock and the compliance tensors for each set of parallel fractures or aligned fractures the compliance tensor of each fracture set is derivable from a second rank fracture compliance tensor for a rotationally symmetric set of fractures the fracture compliance tensor depends on only two fracture compliances one controlling fracture compliance normal the other tangential to the plane of the fractures the stiffness tensor which is more useful in the consideration of elastic wave propagation through rocks can then be obtained by inversion the components of the excess fracture compliance tensor represent the maximum amount of information that can be obtained from seismic data if the background rock is isotropic and the normal a

error analysis of subpixel lava temperature measurements using infrared remotely sensed data summary when remote sensing users are asked to define their requirements for a new sensor the big questionthatalwaysarisesis willthetechnicalspecificationsmeetthescientificrequirements herein wediscussquantitativerelationshipsbetweeninstrumentalspectralandradiometric characteristics and data exploitable for lava flow subpixel temperature analysis this study was funded within the framework of esa activities for the ir gmes global monitoring for environment and security element mission requirements in 2005 subpixel temperature retrieval from satellite infrared data is a well established method that is well documented in the remote sensing literature however there is little attention paid to the error analysis on estimated parameters due to atmospheric correction and radiometric accuracy of the sensor in this study we suggest the best spectral bands combination to estimate subpixel temperature parameters we also demonstrate that poor atmospheric corrections may vanish the effectiveness of the most radiometrically accurate instrument

a review of algorithms for detecting volcanic hot spots in satellite infrared data since the 1980s application of thermal infrared satellite data for volcano monitoring has rapidly evolved to become a proven operational tool due to the large quantities of data provided by sensors in polar and geostationary orbits as well as the sheer number of active volcanoes on earth processing and managing such data sets requires an enormous amount of workforce a number of algorithms have been developed to facilitate detection location and tracking of hot spots of active volcanoes a collation and review of hot spot detection algorithms developed and applied by the volcanological community reveals three main types which have been applied to date contextual fixed threshold and temporal the founding algorithms for these three classes are vast modvolc and rst respectively through comparison with manually based detections the performance of each algorithm was tested for sustained lava flows etna and stromboli strombolian activity stromboli lava dome growth and collapse augustine and fumarole fields vulcano it is shown that as the number of correctly identified anomalies increases so too does the number of false positives although each of the algorithms operates well within the limits and criteria of their design requirements and application under current data restraints no algorithm can be expected to perform perfectly

time dependent volcano source monitoring using interferometric synthetic aperture radar time series a combined genetic algorithm and kalman filter approach 1 modern geodetic methods allow continuous monitoring of deformation fields of volcanoes the acquired data contribute significantly to the study of the dynamics of magmatic sources prior to during and after eruptions and intrusions in addition to advancing the monitoring techniques it is important to develop suitable approaches to deal with deformation time series here we present test and apply a new approach for time dependent nonlinear inversion using a combination of a genetic algorithm ga and a kalman filter kf the ga is used in the form presented by shirzaei and walter 2009 and the kf implementation now allows for the treatment of monitoring data as a full time series rather than as single time steps this approach provides a flexible tool for assessing unevenly sampled and heterogeneous time series data and explains the deformation field using time consistent dislocation sources following synthetic tests we demonstrate the merits of time consistent source modeling for interferometric synthetic aperture radar insar data available between 1992 and 2008 from the campi flegrei volcano in italy we obtained multiple episodes of linear velocity for the reservoir pressure change associated with a parabolic surface deformation on the volcano these data may be interpreted via differential equations as a linear flux to the shallow reservoir that provides new insight into how both the shallow and deep reservoirs communicate beneath campi flegrei the synthetic test and case study demonstrate the robustness of our approach and the ability to track and monitor the source of systems with complex dynamics it is applicable to time dependent optimization problems in volcanic and tectonic environments in other tectonic environments in other areas and allows understanding of the spatiotemporal extent of a physical process in quantitative manner

shear wave anisotropy from dipole shear logs in oceanic crustal environments the deployment of a downhole dipole shear sonic imaging dsi tool during odp legs 174b hole 395a and 176 hole 735b marked the first opportunities to measure high resolution shear wave velocity and vs anisotropy profiles in the shallow oceanic crust along mid ocean ridge environments hole 395a is located in 7 ma crust approximately 100km east of the mid atlantic ridge and 100km south of the kane fracture zone at this site dsi data were recorded from 100 600 mbsf and allow for azimuthal anisotropy to be determined as a function of crustal depth the magnitude of vs anisotropy varies with depth from less than 2 in low porosity flows at the bottom of the hole to approximately 12 in highly fractured pillow basalts and breccias associated with active aquifers the orientation of the fast vs direction also varies considerably over depth with a mean value between n75 80e which is roughly parallel to the direction of plate spreading and the tensional axis of ridge axis earthquakes evidence of stress induced anisotropy is not observed in the shear wave data electrical and acoustic borehole images clearly show subhorizontal pillow contacts and morphological features over a large range of orientations in hole 395a but few vertical fractures therefore we interpret the local variation in the magnitude and direction of vs anistropy to be due the structural alignment of fractured pillows and flows not to horizontal differential stresses or to transform parallel fracturing at this distance from the plate boundary

determination of nehrp site class of seismic recording stations in the northwest himalayas and its adjoining area using hvsr method local site characteristics play an important role in controlling the damage pattern during earthquakes eqs these site characteristics may vary from simple to complex and can be estimated by various field tests in addition extended nakamura s method which uses horizontal to vertical spectral ratio hvsr based on available eq records also available for site class sc determination in this study scs for 90 recording stations which are maintained by program for excellence in strong motion studies pesmos located in the northwestern himalayas and the adjoining areas are determined using extended nakamura s technique average hvsr curves obtained at majority of the recording stations are found matching with the existing literature predominant frequency f peak from average hvsr curve at each recording station is then used for the determination of sc original sc given by pesmos is purely based on geology and not based on comprehensive soil investigation exercise in this study the sc which is based on the average hvsr curves is found matching with sc given by pesmos for a majority of recording stations however for considerable number of recording stations a mismatch is also found which is consistent with the existing literature in addition sc based on national earthquake hazard reduction program nehrp scheme is proposed based on f peak for all the 90 recording stations

an investigation of seismic anisotropy due to cracks in the upper oceanic crust at 45 n mid atlantic ridge summary a detailed seismic refraction survey using three 3 component ocean bottom seismographs over young 1 1 3 4 ma old mid atlantic ridge at 45 n recorded compressional wave velocity anisotropy in the upper crust of about 5 per cent and associated particle motion deviations of up to 8 the magnitudes and azimuths of these anisotropic variations suggest that they are generated by sets of subparallel near vertical water filled cracks in layer 2 the directions of the cracks cannot be determined uniquely but they lie between the seafloor spreading and the ridge axis directions in the range 30 60 with respect to the ridge axis we explain this unexpected crack orientation by the occurrence of cracking and fracturing induced in the upper crust as it moves away from the spreading axis the principal horizontal stresses responsible for this fracturing are parallel and perpendicular to the ridge axis the apparently negligible seismic influence exerted by ridge parallel sets of shallow cracks observed at the ridge axis is explained by their infilling by sediment and hydrothermal precipitates and by their closure under ridge normal compression we find a normal oceanic crustal velocity structure that can be explained by decreasing numbers of open cracks with increasing depth through the upper 2 km of the crust lateral variability across the 25 km square survey is limited in magnitude typically 0 05 s variations in delay times and the observed travel times are consistent with a model of the crust in which the isovelocity surfaces at depth are a subdued copy of the basement topography

estimating slowness dispersion from arrays of sonic logging waveforms acoustic wave propagation in a fluid filled borehole is affected by the type of rock which surrounds the hole more specifically the slowness dispersion of the various body wave and borehole modes depends to some extent on the properties of the rock we have developed a technique for estimating the dispersion relations from data acquired by full waveform digital sonic array well logging tools the technique is an extension of earlier work and is based on a variation of the well known prony method of exponential modeling to estimate the spatial wavenumbers at each temporal frequency this variation known as the forward backward method of linear prediction models the spatial propagation by purely real valued wavenumbers the prony exponential model is derived from the physics of borehole acoustics under the assumption that the formation does not vary in the axial or azimuthal dimensions across the aperture of the receiver array but can vary arbitrarily in the radial dimension the exponential model fits

borehole flexural modes in anisotropic formations a perturbation method of solution is an efficient way of analyzing elastic wave propagation along a borehole in anisotropic formations the perturbation model allows us to calculate changes in the modal dispersion curves caused by the differences in elastic constants between the anisotropic formation of interest and a reference or unperturbed isotropic formation the equivalent isotropic constants in the reference formation are obtained from the appropriate compressional and shear wave velocities for the selected propagation and polarization directions of the flexural mode this choice of the unperturbed solution means that the required perturbation is minimal resulting in enhanced accuracy of the perturbed solution computational results are presented for the dispersion curves of borehole flexural waves in a transversely isotropic ti formation as a function of borehole deviation from the ti symmetry axis in addition radial distributions of displacement and stress fields associated with the flexura

exploring the limits of identifying sub pixel thermal features using aster tir data abstract understanding the characteristics of volcanic thermal emissions and how they change with time is important for forecasting and monitoring volcanic activity and potential hazards satellite instruments view volcanic thermal features across the globe at various temporal and spatial resolutions thermal features that may be a precursor to a major eruption or indicative of important changes in an on going eruption can be subtle making them challenging to reliably identify with satellite instruments the goal of this study was to explore the limits of the types and magnitudes of thermal anomalies that could be detected using satellite thermal infrared tir data specifically the characterization of sub pixel thermal features with a wide range of temperatures is considered using aster multispectral tir data first theoretical calculations were made to define a thermal mixing detection threshold for aster which quantifies the limits of aster s ability to resolve sub pixel thermal mixing over a range of hot target temperatures and pixel areas then aster tir data were used to model sub pixel thermal features at the yellowstone national park geothermal area hot spring pools with temperatures from 40 to 90 c and at mount erebus volcano antarctica an active lava lake with temperatures from 200 to 800 c finally various sources of uncertainty in sub pixel thermal calculations were quantified for these empirical measurements including pixel resampling atmospheric correction and background temperature and emissivity assumptions

shear wave polarization anisotropy in the upper mantle beneath honshu japan shear wave polarization anisotropy in the wedge portion of the upper mantle between a subducting plate and the earth s surface is investigated using three component seismograms of intermediate depth and deep earthquakes recorded at 14 local stations in honshu japan eighty nine high quality seismograms were selected from a period of 3 years the data used in this study are restricted such that incidence angles are smaller than the critical angle of 30 to the earth s surface in order to avoid phase shifts in the shear wave train to find directions of the maximum and minimum velocities in split shear waves where shear waves are resolved into two phases with the maximum time separation each set of the two horizontal component seismograms is rotated in the horizontal plane the split shear waves thus obtained are again recombined after the correction of anisotropy and the anisotropy corrected particle motion is compared with the focal mechanism for a cross check of the observed anisotropy directions of the maximum axes are plotted on azimuthincidence angle stereograms at each station the stereograms and the cross sections of seismic ray paths show that 1 the anisotropic material is distributed at intermediate location between earthquake sources and receiving stations and 2 the anisotropic region is separated into two parts one in the north of the present study area with the polarization of the maximum velocity shear wave trending 0 to 30 from the north north anisotropy and the other in the south with it trending 90 to 120 south anisotropy the maximum time delays between the two shear waves along a vertical seismic ray is about l s for both the anisotropic regions the horizontal extent of the anisotropic area in the north is 50 km at depths of 50 to 150 km perhaps prevalent in west honshu however the depth of anisotropic material is not well constrained because of insufficient coverage of seismic ray paths and angles if we assume the vertical extent of the anisotropic material to be 100 km the maximum velocity contrast would be 4 if we adopt a crack alignment model for the observed anisotropy cracks are inferred to be distributed vertically trending 0 to 30 in the north and 90 to 120 in the south if we assume an olivine alignment model olivine crystals are inferred to be aligned in the north with the a axis of the slip direction trending 0 to 30 and the slip plane normal to the b axis being vertical and in the south anisotropy with the axis trending 90 to 120 and the slip plane being horizontal

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

time series analysis of infrared satellite data for detecting thermal anomalies a hybrid approach we developed and tested an automated algorithm that analyzes thermal infrared satellite time series data to detect and quantify the excess energy radiated from thermal anomalies such as active volcanoes our algorithm enhances the previously developed modvolc approach a simple point operation by adding a more complex time series component based on the methods of the robust satellite techniques rst algorithm using test sites at anatahan and k lauea volcanoes the hybrid time series approach detected 15 more thermal anomalies than modvolc with very few if any known false detections we also tested gas flares in the cantarell oil field in the gulf of mexico as an end member scenario representing very persistent thermal anomalies at cantarell the hybrid algorithm showed only a slight improvement but it did identify flares that were undetected by modvolc we estimate that at least 80 modis images for each calendar month are required to create good reference images necessary for the time series analysis of the hybrid algorithm the improved performance of the new algorithm over modvolc will result in the detection of low temperature thermal anomalies that will be useful in improving our ability to document earth s volcanic eruptions as well as detecting low temperature thermal precursors to larger eruptions

the initial phases of the 2008 2009 mount etna eruption a multidisciplinary approach for hazard assessment accepted for publication in journal of geophysical research copyright 2010 american geophysical union

lava effusion rate definition and measurement a review measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics as well as for monitoring efforts during on going eruptions however its exact definition remains a source of confusion and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales or measured using different approaches thus our aims are to 1 define effusion rate terminology and 2 assess the various measurement methods and their results we first distinguish between instantaneous effusion rate and time averaged discharge rate eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began the ultimate extension of this is mean output rate this being the final volume of erupted lava divided by total eruption duration whether these values are total values i e the flux feeding all flow units across the entire flow field or local i e the flux feeding a single active unit within a flow field across which many units are active also needs to be specified no approach is without its problems and all can have large error up to 50 however good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here there are three important factors to consider and state when measuring giving or using an effusion rate first the time period over which the value was averaged second whether the measurement applies to the entire active flow field or a single lava flow within that field and third the measurement technique and its accompanying assumptions

well bore breakouts and in situ stress the detailed cross sectional shape of stress induced well bore breakouts has been studied using specially processed ultrasonic borehole televiewer data we show breakout shapes for a variety of rock types and introduce a simple elastic failure model which explains many features of the observations both the observations and calculations indicate that the breakouts define relatively broad and flat curvilinear surfaces which enlarge the borehole in the direction of minimum horizontal compression this work supports the hypothesis that breakouts result from shear failure of the rock where the compressive stress concentration around the well bore is greatest and that breakouts can be used to determine the orientation of the horizontal principal stresses in situ

estimation of source parameters quality factor qs and site characteristics using accelerograms uttarakhand himalaya region abstract a study of source path and site characteristics was conducted for the uttarakhand himalaya region using accelerogram data from 15 earthquakes m l 3 5 these earthquakes were recorded at the 16 station accelerograph network operated by the indian institute of technology roorkee during 2005 2011 the average seismic moment m 0 of the studied earthquakes ranges between 1 20 10 22 and 1 02 10 24 dyn cm and the average moment magnitude m w is between 4 0 and 5 3 the estimated corner frequency f c varies from 1 1 to 3 3 hz radius of rupture r d from 0 5 to 1 4 km and stress drop from 6 to 172 bars indicating continuous seismic energy release in the uttarakhand region the interdependence between estimated source parameters is shown by determining scaling laws for the studied region the constant q 0 of the shear wave quality factor q s q 0 f n varies between 40 and 300 and exponent n varies between 0 85 and 1 5 providing an average relation of q s 174 f 1 27 however least square fitting of the observed data set in the frequency range 0 1 20 hz gives q s as 159 f 1 16 the value of q s demonstrates that the region is heterogeneous seismically active and attenuative the high frequency spectral fall off factor varies from 1 3 to 2 1 and the upper crustal attenuation factor from 0 023 to 0 07 s at different sites with an average of 0 044 s the site response characteristics are estimated by horizontal to vertical spectral ratio hvsr and generalized inversion ginv techniques results obtained from both the techniques show 1 1 correspondence the site amplification factor varies between 2 3 and 9 4 using hvsr and between 2 6 and 10 9 using ginv among different stations the predominant frequency ranges from 1 3 to 8 3 hz with hvsr and from 1 3 to and 9 0 hz with ginv online material tables of source path and site parameters with associated errors at different sites for the earthquakes recorded from december 2005 to march 2011 figures represent accelerogram records source spectra matching and site amplification patterns

anisotropy in the oceanic lithosphere theory and observations from the ngendei seismic refraction experiment in the south west pacific summary p wave travel time data from a seismic refraction experiment on the 1983 ngendei expedition to the south pacific indicate anisotropy at two levels in the oceanic lithosphere in the upper mantle p wave velocities vary between 8 0 and 8 5 km s 1 with the fast direction at n30 e crustal anisotropy within layer 2 is characterized by azimuthal p wave velocity differences of about 0 2 0 4 km s 1 with the fast direction at n120 e orthogonal to the upper mantle anisotropy the observed anisotropy is consistent with a model in which aligned olivine crystals cause anisotropy in the upper mantle and aligned cracks within layer 2 cause anisotropy in the crust we examine a model of p wave propagation from a point source in an isotropic layer above an anisotropic half space and show that under these conditions anisotropy can cause seismic ray paths to deviate from the vertical plane connecting source and receiver this deviation has a negligible effect on seismic travel times but must be taken into account in modelling p wave polarization anomalies p wave polarization anomalies within the anisotropic half space are the sum of the particle motion deviation from the ray path and ray path deviation from the source receiver azimuth and are typically range dependent p wave polarization anomalies will also occur in the overlying isotropic layer purely as a result of the ray path deviation with greater deviations at long ranges a simple model of upper mantle anisotropy 6kms 1 crust above 8 0 8 6 km s 1 anisotropic mantle produces surface polarization anomalies of 1 5 3 5 in practice p wave polarization anomalies are difficult to observe because they are small compared to observed scatter in polarization data and are sensitive to differences in horizontal seismometer gain levels we examine the implications of anisotropic ray path deviations on travel times and p wave polarizations for the ngendei data as well as some previous marine seismic refraction experiments

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

effects of viewing geometry on avhrr observations of volcanic thermal anomalies abstract we investigate the influence of viewing geometry and dynamic range of the advanced very high resolution radiometer avhrr sensor on detecting eruptions on poorly monitored volcanoes numerical models of sunwarmed flows and typical active features associated with hawaiian eruptions overturning lava lakes surface flows of three different sizes and lava tubes with skylights show that new lava flows at 1000 c can be identified at all scan angles if the area of the activity exceeds 60 m 2 given a background temperature of 20 c more difficult is the detection of small breakouts of lava flows or tube fed flows when these features lie towards the edge of the swath because of the dynamic range and gain setting of the sensor bands 3 4 and 5 saturate at 49 c it is possible that similar thermal signatures may be produced when inactive flows are heated by the sun the ability of the avhrr to detect on going activity in hawaii in july 1991 is tested by comparing landsat thematic mapper and nadir avhrr scenes obtained within 3 5 hours of each other for an active pahoehoe flow field with a well developed tube system this comparison shows that within the area of thermally alarmed avhrr pixels

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

thermal distributions of hot volcanic surfaces constrained using three infrared bands of remote sensing data infrared remote sensing provides a means for radiometry of hot volcanic features previously two spectral band measurements have been combined to solve simple 2 component models of lava surface temperatures however pixel dimensions often exceed the widths of lava bodies in such cases 3 component models are more realistic here a procedure for solving such a model from three infrared observations is presented it is then demonstrated using thematic mapper simulator data recorded over mount etna italy in 1991 by constraining temperatures and pixel filling fractions of the three different thermal components in this way improved estimates of radiant emittance can be obtained the techniques described could be applied to satellite data of volcanic and other hot spots including fires

a simple explanation for the space based calculation of lava eruption rates abstract knowing how lava effusion rates vary during basaltic eruptions can be of great significance when trying to provide preliminary forecasts regarding how far lava will flow however problems exist in accurately determining effusion rates using conventional field based techniques to ameliorate this problem harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 j volcanol geotherm res 102 2000 237 269 developed a method for determining effusion rates using infrared satellite data and showed how the method could be used to provide realistic estimates of effusion rates repeatedly during several eruptions at kilauea hawai i krafla iceland etna and stromboli italy harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 indicate that their method allows instantaneous lava effusion rates to be determined thermodynamically by equating the amount of heat lost by an active lava flow derived from the satellite data to the amount of heat liberated by the cooling mass of lava the purpose of this paper is to provide a simpler alternative explanation we find that rather than being used to calculate heat loss harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 j volcanol geotherm res 102 2000 237 269 actually use the satellite data to estimate the area of active lava present within the satellite s field of view at the movement of data acquisition thus changes in the effusion rates they present can only be proportional to changes in this area the active flow areas were then multiplied by a constant the value of which is obtained from a crude approximation of the lava flows heat balance crucially the absolute value of this term falls within the range of an empirically derived parameter that was found by pieri and baloga j volcanol geotherm res 30 1986 29 45 to explain strong linear correlations between eruption rate i e the time averaged effusion rate and lava flow area for 34 historic hawaiian flows as a result we find that the method of harris et al j geophys res 102 1997 7985 8003 does not yield instantaneous effusion rates but instead provides a valid and useful way to estimate average effusion rates i e the eruption rate from measurements of flow area

automated volcanic eruption detection using modis abstract the moderate resolution imaging spectroradiometer modis flown on board nasa s first earth observing system eos platform terra offers complete global data coverage every 1 2 days at spatial resolutions of 250 500 and 1000 m its ability to detect emitted radiation in the short 4 m and long 12 m wave infrared regions of the electromagnetic spectrum combined with the excellent geolocation of the image pixels 200 m makes it an ideal source of data for automatically detecting and monitoring high temperature volcanic thermal anomalies this paper describes the underlying principles of and results obtained from just such a system our algorithm interrogates the modis level 1b data stream for evidence of high temperature volcanic features once a hotspot has been identified its details location emitted spectral radiance satellite observational parameters are written to an ascii text file and transferred via file transfer protocol ftp to the hawaii institute of geophysics and planetology higp where the results are posted on the internet http modis higp hawaii edu the global distribution of volcanic hotspots can be examined visually at a variety of scales using this website which also allows easy access to the quantitative data contained in the ascii files themselves we outline how the algorithm has proven robust as a hotspot detection tool for a wide range of eruptive styles at both permanently and sporadically active volcanoes including soufriere hills montserrat popocatepetl mexico bezymianny russia and merapi java amongst others we also present case studies of how the system has allowed the onset development and cessation of discrete eruptive events to be monitored at nyamuragira congo piton de la fournaise reunion island and shiveluch russia

precursor seismicity foreshocks and aftershocks of the uttarkashi earthquake of october 20 1991 at garhwal himalaya abstract the uttarkashi earthquake m b 6 6 of october 20 1991 occurred in a complicated geological tectonic setting at the main central thrust mct zone of the himalaya the main shock was preceded by a precursory earthquake activity which continued for about eight years and then there was a quiescent period for about three years three foreshocks m 4 0 occurred 48 h before the main shock two aftershocks m 4 0 occurred within 12 h of the main shock which was then followed by another two aftershocks m 4 0 after about seven days on october 27 1991 the largest aftershock m 5 2 occurred within 12 h the aftershocks magnitude less than 4 0 continued for about two months and it decayed at a rate t 0 87 about 1000 earthquakes magnitude less than 1 0 and above were recorded by a closely spaced five station temporary microearthquake meq network out of these 124 aftershocks which occurred inside the network are located by homogeneous station method spatial variation of the aftershocks with time was observed fault plane solutions of the main shock and aftershocks indicate dominantly thrust faulting based on the hypocentral data depth estimate of the plane of detachment is made and a fault interaction model is presented the model shows that the main shock occurred at the juncture of mct zone plane of detachment and the basement thrust the north dipping uttarkashi fault a parallel fault at the mct zone has been activated by the tectonic stress generated due to relative movement of the tibetan plate over the indian plate

relationship between anisotropy of p and s wave velocities and anisotropy of attenuation in serpentinite and amphibolite velocities and q values of p and s waves as functions of pressure and temperature at 100 and 600 mpa are presented for a serpentinite and an amphibolite both rocks exhibit a strong lattice preferred orientation lpo of the major mineral phases antigorite and hornblende respectively velocities and q values increase with pressure the rate of increase is different in the three orthogonal directions normal and parallel to foliation and lineation and closely related to progressive closure of microcracks increasing temperature decreases velocities and q values only slightly as long as thermal cracking is prevented by the applied confining pressure substantial anisotropy of velocities and q in p and s waves is observed in both rocks but is found to be different in origin anisotropy of p and s wave velocities is highest at low pressure and basically caused by constructive interference of effects related to oriented microcracks and to the lpo of major minerals increasing confining pressure decreases velocity anisotropy at a smaller and smaller rate the residual anisotropy of p and s wave velocities shear wave splitting at high confining pressure is mainly a result of preferred mineral orientation by contrast anisotropy of q is very low at low confining pressure and markedly enhanced as pressure is increased at high confining pressure substantial anisotropy of q in p waves is apparent but reversed from that of p wave velocities qp is highest in the direction normal to the foliation plane whereas vp and vs is lowest in this direction the generation of a pronounced anisotropy of qp by increasing pressure is due to a directionally dependent increase of contact areas on the oriented grain boundaries of the platy minerals defining the foliation the increase of q with pressure in the direction normal to foliation is mainly caused by the decrease of energy loss due to compressive strain relative to shear strain the reverse is true for the x and y directions serpentinite and x direction amphibolite parallel to the foliation plane

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

the bhuj india earthquake lessons learned for earthquake safety of dams on alluvium abstract the bhuj india earthquake of 26 january 2001 m s 7 9 caused dams built on alluvium to sustain damage ranging from cosmetic to severe major damage was caused almost entirely by soil liquefaction in the alluvium the critical factor was the level of earthquake ground motion the bhuj earthquake showed that peak horizontal accelerations phas 0 2 g were generally safe phas 0 2 g were hazardous when unconsolidated granular foundation soils were water saturated n values of 0 2 g must be evaluated over the full area beneath a new dam and all soils deemed susceptible to liquefaction must be either removed or treated for remediating an old dam reliable options are removal and replacement of liquefiable alluvium beneath upstream and downstream portions of the dam combined with building berms designed to provide stability for the dam should there be a strength loss in soils beneath the dam

an emergent strategy for volcano hazard assessment from thermal satellite monitoring to lava flow modeling abstract spaceborne remote sensing techniques and numerical simulations have been combined in a web gis framework lav hazard to evaluate lava flow hazard in real time by using the hotsat satellite thermal monitoring system to estimate time varying tadr time averaged discharge rate and the magflow physics based model to simulate lava flow paths the lav hazard platform allows timely definition of parameters and maps essential for hazard assessment including the propagation time of lava flows and the maximum run out distance we used lav hazard during the 2008 2009 lava flow forming eruption at mt etna sicily italy we measured the temporal variation in thermal emission up to four times per hour during the entire duration of the eruption using seviri and modis data the time series of radiative power allowed us to identify six diverse thermal phases each related to different dynamic volcanic processes and associated with different tadrs and lava flow emplacement conditions satellite derived estimates of lava discharge rates were computed and integrated for the whole period of the eruption almost 14 months showing that a lava volume of between 32 and 61 million cubic meters was erupted of which about 2 3 was emplaced during the first 4 months these time varying discharge rates were then used to drive magflow simulations to chart the spread of lava as a function of time tadrs were sufficiently low 3 s that no lava flows were capable of flowing any great distance so that they did not pose a hazard to vulnerable agricultural and urban areas on the flanks of etna

analysis of volcanic activity patterns using modis thermal alerts we investigate eruptive activity by analysis of thermal alert data from the modis moderate resolution imaging spectrometer thermal infrared satellite instrument detected by the modvolc modis volcano alert algorithm these data are openly available on the internet and easy to use we show how such data can plug major gaps in the conventional monitoring record of volcanoes in an otherwise generally poorly documented region melanesia including characterising the mechanism of lava effusion at pago demonstrating an earlier than realised onset of lava effusion at lopevi extending the known period of lava lake activity at ambrym and confirming ongoing activity at bagana langila and tinakula we also add to the record of activity even at some generally better monitored volcanoes in indonesia but point out that care must be taken to recognise and exclude fires