the macolod corridor a rift crossing the philippine island arc abstract the macolod corridor in southwestern luzon is an approximately 40 km wide zone of still active intense quarternary volcanism which perpendicularly crosses the island in a ne sw direction the tectonic setting of the corridor is still somewhat questionable due to several not yet well understood major structural elements affecting southwestern luzon based on the presently available information we believe that the corridor is a pull apart zone formed by a diffuse system of nw se oriented shearing

time space modeling of the dynamics of santorini volcano greece during the 2011 2012 unrest the 2011 2012 unrest of santorini thera volcano aegean sea greece was associated with microseismicity confined to the kameni line kl a major tectonovolcanic lineament and has been regarded as a single magmatic episode produced by a spherical source derived from inversion of gps data however such a source is a few kilometers away from the kl and cannot explain observed microseismicity for this reason we divided the unrest episode into five periods based on the fluctuations of seismicity and deformation rates and investigated the connection between seismicity and two spherical magmatic point sources for each period based on a new inversion algorithm and consistent gps data we recognized during the volcano unrest episode an unstable pattern of intrusions correlating with both the kl and columbo line cl a second major tectonovolcanic lineament intrusions correlating with cl appear relatively persistent aseismic small and shallow which is consistent with marine geophysical evidence for arrested shallow dykes and geodetic evidence from a previous inflation episode during the two periods of intense seismicity sources close to the kl explaining seismicity were obtained this unstable pattern of intrusions explains both the well observed location and timing of seismicity as well as ground deformation and is consistent with results of an okada type inversion for a sill and a dyke the stress interactions between the two sources agree with coulomb failure stress models santorini appears to be affected by concurrent offset magma pulses and only recent activity from a magma pulse below the kl produced microseismic swarms

geochemistry of silicic magmas in the macolod corridor sw luzon philippines evidence of distinct mantle derived crustal sources for silicic magmas silicic volcanic deposits 65 wt sio2 which occur as domes lavas and pyroclastic deposits are relatively abundant in the macolod corridor sw luzon philippines at makiling stratovolcano silicic domes occur along the margins of the volcano and are chemically similar to the silicic lavas that comprise part of the volcano pyroclastic flows are associated with the laguna de bay caldera and these are chemically distinct from the domes and lavas at makiling stratovolcano as a whole samples from the laguna de bay caldera contain lower concentrations of mgo and higher concentrations of fe2o3 t than the samples from domes and lavas the laguna de bay samples are more enriched in incompatible trace elements the silicic rocks from the domes makiling volcano and laguna de bay caldera all contain high alkalis and high k2o na2o ratios melting experiments of primitive basalts and andesites demonstrate that it is difficult to produce high k2o na2o silicic magmas by fractional crystallization or partial melting of a low k2o na2o source however recent melting experiments sisson et al contrib mineral petrol 148 635 661 2005 demonstrate that extreme fractional crystallization or partial melting of k rich basalts can produce these silicic magmas our model for the generation of the silicic magmas in the macolod corridor requires partial melting of mantle derived evolved moderate to k rich crystallized calc alkaline magmas that ponded and crystallized in the mid crust major and trace element variations along with oxygen isotopes and ages of the deposits are consistent with this model

combined electromagnetic geochemical and thermal surveys of taal volcano philippines during the period 2005 2006 since 1572 33 phreatic to phreatomagmatic eruptions have occurred on taal volcano philippines some of them causing several hundred casualties considering the time delay between two consecutive eruptions there is an 88 probability that taal volcano should have already erupted since 1992 several phases of seismic activity have been recorded accompanied by ground deformation opening of fissures and surface activity the volcanic activity of taal appears to be controlled by dike injections and magma supply buffered by a hydrothermal system that releases fluids and heat through boiling and subsequent steaming in early 2005 a multidisciplinary project was launched for studying the hydrothermal activity to map the hydrothermal system combined surveys were carried out to investigate self potential total magnetic field ground temperature and carbon dioxide soil degassing along with satellite thermal imaging of the main crater lake the elevated temperatures and high concentrations of carbon dioxide as well as electromagnetic anomalies indicate large scale hydrothermal degassing this process is enhanced along the tectonic features e g crater rim and faults of the volcano while active fissures opened along the e w northern flank during the 1992 1994 seismic activity heat and fluids from the hydrothermal system are essentially released in the northern part of the crater which is bounded to the south by a suspected nw se fault along which seismicity seems to take place and dikes are thought to be intruded during the january 2005 surveys a new seismic crisis started and the felt earthquakes prompted spontaneous evacuation of hundreds of inhabitants living on the volcano repeated surveys show changes of self potential total magnetic field and ground temperature with time without any noticeable spatial enlargement these observations suggest that the northern flank located between the crater rim and the 1992 1994 fissures is connected with a deep thermal source in main crater and is reactivated during seismic crises this sector could be subjected to flank failure

effects of mechanical layering on volcano deformation summary the migration and accumulation of magma beneath volcanoes often causes surface displacements that can be measured by geodetic techniques usually deformation signals are explained using models with uniform mechanical properties in this paper we study surface displacements due to magma chamber inflation using heterogeneous finite element models we first present a systematic analysis of the influence of mechanical layering showing that the stiffness contrast significantly affects the entity and the pattern of vertical and radial displacements second as an example we apply the models to interpret ground displacements at darwin volcano

catastrophic caldera forming eruptions thermomechanics and implications for eruption triggering and maximum caldera dimensions on earth abstract approximately every 100 000 years the earth experiences catastrophic caldera forming supereruptions that are considered to be one of the most hazardous natural events on earth utilizing new temperature dependent viscoelastic numerical models that incorporate a mohr coulomb failure criterion we find that eruptive failure of the largest magma chambers is a function of the geometry of the overlying roof and the location of the brittle ductile transition in particular the ductile halo created around the hot magma chamber buffers increasing overpressures and prevents pressure relief via magmatic injection from the magma chamber the numerical results indicate that as chamber volume increases the higher temperatures in the host rock and the decrease in the roof aspect ratio cause a shift from reservoir triggered eruption to an external roof triggered mechanism specifically as overpressure increases within the largest magma chambers extensive uplift in the overlying roof promotes the development of through going faults that may trigger eruption and caldera collapse from above we find that for magma chamber volumes 103 km3 and roof aspect ratios depth width

estimating source parameters from deformation data with an application to the march 1997 earthquake swarm off the izu peninsula japan we have applied two monte carlo optimization techniques simulated annealing and random cost to the inversion of deformation data for fault and magma chamber geometry these techniques involve an element of randomness that permits them to escape local minima and ultimately converge to the global minimum of misfit space we have tested the monte carlo algorithms on two synthetic data sets we have also compared them to one another in terms of their efficiency and reliability we have applied the bootstrap method to estimate confidence intervals for the source parameters including the correlations inherent in the data additionally we present methods that use the information from the bootstrapping procedure to visualize the correlations between the different model parameters we have applied these techniques to gps tilt and leveling data from the march 1997 earthquake swarm off of the izu peninsula japan using the two monte carlo algorithms we have inferred two sources a dike and a fault that fit the deformation data and the patterns of seismicity and that are consistent with the regional stress field

calderas and caldera structures a review abstract calderas are important features in all volcanic environments and are commonly the sites of geothermal activity and mineralisation yet it is only in the last 25 years that a thorough three dimensional study of calderas has been carried out utilising studies of eroded calderas geophysical analysis of their structures and analogue modelling of caldera formation as more data has become available on calderas their individuality has become apparent a distinction between caldera caldera complex cauldron and ring structure is necessary and new definitions are given in this paper descriptions of calderas based on dominant composition of eruptives basaltic peralkaline andesitic dacitic rhyolitic can be used and characteristics of each broad group are given styles of eruption may be effusive or explosive with the former dominant in basaltic calderas and the latter dominant in andesitic dacitic rhyolitic and peralkaline calderas four end member collapse styles occur plate or piston piecemeal trapdoor and downsag but many calderas have multiple styles features of so called funnel and chaotic calderas proposed in the literature can be explained by other collapse styles and the terms are considered unnecessary ground deformation comprises subsidence or collapse essential characteristics of a caldera and uplifting doming and fracturing due to tumescence and or resurgence frequent but not essential collapse may occur on pre existing structures such as regional faults or on faults created during the caldera formation and the shape of the collapse area will be influenced by depth size and shape of the magma chamber the final morphology of a caldera will depend on how the caldera floor breaks up whether collapse takes place in one event or multiple events whether vertical movement is spasmodic or continuous throughout the eruptive sequence and whether blocks subside uniformly or chaotically at one or more collapse centres a meaningful description of any caldera should therefore include number of collapse events presence or absence of resurgence caldera floor coherency caldera floor collapse geometry and dominant composition of eruptives

spherical and ellipsoidal volcanic sources at long valley caldera california using a genetic algorithm inversion technique abstract we model the second inflation period at long valley caldera california using a genetic algorithm technique and high quality geodetic measurements of elevation changes and baseline extensions we compare two source inversions for both spherical mogi point sources and the finite prolate ellipsoid of yang and davis a sensitivity analysis for the genetic algorithm is performed based upon synthetic data set inversions on similar sources in order to better constrain the areal location orientation and volume of the potential sources the spherical sources are well constrained the larger located at 9 9 km beneath the resurgent dome with a volume of 0 036 km 3 while the second at only 0 008 km 3 is located at a depth of 7 3 km beneath the south moat the depths to the ellipsoidal sources are switched with the larger source at a depth of 9 6 km and the smaller at 11 8 km with volumes of 0 037 and 0 002 km 3 respectively

modelling ground deformation patterns associated with volcanic processes at the okataina volcanic centre abstract the okataina volcanic centre ovc is one of two large active rhyolite centres in the modern taupo volcanic zone tvz in the north island of new zealand it is located in a complex section of the taupo rift a tectonically active section of the tvz the most recent volcanic unrest at the ovc includes the 1315 ce kaharoa and 1886 tarawera eruptions current monitoring activity at the ovc includes the use of continuous gps receivers cgps lake levelling and seismographs the ground deformation patterns preceding volcanic activity the ovc are poorly constrained and restricted to predictions from basic modelling and comparison to other volcanoes worldwide a better understanding of the deformation patterns preceding renewed volcanic activity is essential to determine if observed deformation is related to volcanic tectonic or hydrothermal processes such an understanding also means that the ability of the present day cgps network to detect these deformation patterns can also be assessed the research presented here uses the finite element fe modelling technique to investigate ground deformation patterns associated with magma accumulation and diking processes at the ovc in greater detail a number of fe models are produced and tested using pylith software and incorporate characteristics of the 1315 ce kaharoa and 1886 tarawera eruptions summarised from the existing body of research literature the influence of a simple ring fault structure at the ovc on the modelled deformation is evaluated the ability of the present day continuous gps cgps geonet monitoring network to detect or observe the modelled deformation is also considered the results show the modelled horizontal and vertical displacement fields have a number of key features which include prominent lobe based regions extending northwest and southeast of the ovc the results also show that the ring fault structure increases the magnitude of the displacements inside the caldera in particular in the vicinity of the southern margin as a result some of the cgps stations in the vicinity of the ovc are more important for measuring deformation related to volcanic processes than others the results have important implications for how any future observed deformation at the ovc is observed and interpreted

a synthesis and review of historical eruptions at taal volcano southern luzon philippines abstract the philippines is an area of persistent volcanism being located in one of the most tectonically active regions in the world taal volcano in southern luzon is the second most frequently erupting volcano of the 24 active volcanoes in the philippines a comprehensive and critical review of published and unpublished references describing the 33 known historical eruptions of taal may provide answers to knowledge gaps on past eruptive behavior processes and products that could be utilized for hazard and risk assessment of future eruptions data on the prehistoric eruptions and evolution of taal caldera and subsequent deposits are limited only four caldera forming events were identified based on four mapped ignimbrite deposits from oldest to youngest these are the silicic alitagtag ali and caloocan cal pumice flow deposits the dacitic sambong ignimbrite sam and the basaltic andesitic taal scoria flow renamed scoria pyroclastic flow sfl except for sfl with 14c dating yielding 5380 70 to 6830 80 ky there are no age constraints or estimates of extent for the three older deposits a comprehensive review of the historical eruptions of taal volcano is the central element of this paper and includes all eruptions from ad1572 the first known historic event to ad1977 eruption styles and the interplay between processes and products for each eruption are reinterpreted based on the narrative descriptions from all available accounts a change of classification of eruption styles and eruptive products is undertaken for some events at least nine reported eruptions were deemed uncertain including the ad1605 ad1611 event more likely seismic swarms the ad1634 ad1635 and ad1645 may simply be solfataric or hydrothermal activity events and the ad1790 ad1825 ad1842 ad1873 and ad1903 events that were listed in recent published and unpublished documents but do not provide any details to describe and confirm the eruptions except for listing a default vei of 2 pyroclastic density currents brought devastating impacts to the communities around taal during the ad1749 ad1754 ad1911 and ad1965 eruptions and remain the biggest threat in the case of renewed volcanic activity significant implications for aviation are implied by the narrative of tephra fall dispersal towards manila the central gateway of international aviation operation in the philippines during the ad1754 eruptions the dispersal of tephra in the event of an explosive eruption at taal towards metro manila would have catastrophic effects to transport utilities and business activity potentially generating enormous economic losses hazards from earthquake events associated with future volcanic activity may also have localized impacts occurrences of liquefaction phenomena as a consequence of severe ground shaking are interpreted during the ad1749 ad1754 and ad1911 eruptions more work needs to be done to develop a comprehensive understanding of the hazards and risks associated with an explosive eruption at taal volcano especially related to the older quaternary caldera forming eruptions that produced large volume pyroclastic deposits that are extensively distributed and exposed we acknowledge that there may be additional prehistoric eruptions where the eruptive products have not been preserved recognized or reported events that cannot be verified or do not have sufficient details to confirm the eruption have been downgraded to uncertain eruptions that are confirmed with identified dispersal and emplacement of tephra fall and other eruptive deposits as interpreted from narrated records could provide crucial information that may be utilized in hazard assessment

dynamics of active magmatic and hydrothermal systems at taal volcano philippines from continuous gps measurements 1 a dense network of continuous single and dual frequency gps receivers at taal volcano philippines reveals four major stages of volcanogenic deformation deflation from installation in june 1998 to december 1998 inflation from january to march 1999 deflation from april 1999 to february 2000 and inflation from february to november 2000 the largest displacements occurred during the february november 2000 period of inflation which was characterized by 120 mm of uplift of the center of volcano island relative to the northern caldera rim at average rates up to 216 mm yr deformation sources were modeled using a constrained least squares inversion algorithm the source of 1999 deflation and inflation in 2000 were modeled as contractional and dilatational mogi point sources centered at 4 2 and 5 2 km depth respectively beneath volcano island the locations of the inflationary and deflationary sources are indistinguishable within the 95 confidence estimates modeling using a running 4 month time window from june 1999 to march 2001 reveals little evidence for source migration we suggest that the two periods of inflation observed at taal result from episodic intrusions of magma into a shallow reservoir centered beneath volcano island subsequent deflation may result from exsolution of magmatic fluids and or gases into an overlying unconfined hydrothermal system

very low frequency resistivity self potential and ground temperature surveys on taal volcano philippines implications for future activity abstract taal volcano is one of the most dangerous volcanoes in the philippines thirty three eruptions have occurred through historical time with several exhibiting cataclysmic phases most recent eruptions are confined to volcano island located within the prehistoric taal collapse caldera that is now filled by taal lake the last eruptive activity from 1965 to 1977 took place from mt tabaro about 2 km to the southwest of the main crater center since this time episodes of seismic activity ground deformation gas release surface fissuring fumarole activity and temperature changes are recorded periodically around the main crater but no major eruption has occurred this period of quiescence is the third longest period without eruptive activity since 1572 in march 2010 a campaign based on very low frequency vlf resistivity surveys together with repeated surveys of self potential ground temperature and fissure activity was intensified and the results compared to a large scale electrical resistivity tomography experiment this work fortunately occurred before within and after a new seismovolcanic crisis from late april 2010 to march 2011 the joint analysis of these new data together with results from previous magnetotelluric soundings allows a better description of the electrical resistivity and crustal structure beneath the main crater down to a depth of several kilometers no indication of growth of the two geothermal areas located on both sides of the northern crater rim was apparent from 2005 to march 2010 these areas appear controlled by active fissures opened during the 1992 and 1994 crises that dip downward towards the core of the hydrothermal system located at about 2 5 km depth beneath the crater older mineralized fissures at lower elevations to the north of the geothermal areas also dip downward under the crater repeated self potential and ground temperature surveys completed between 2005 and 2015 show new geothermal and hydrothermal activity in the areas of these older mineralized fissures that occurred during the april 2010 to march 2011 seismovolcanic crisis this dramatically extends the geothermal activity further to the north on the volcano the occurrence of these newly activated fissures after a long period of quiescence and indications of inflation in mid 2010 under the north rim of the main crater suggests that new eruptive activity near the north rim of the crater could occur in the future

the shear wave velocity structure of the crust and uppermost mantle beneath tagaytay philippines inferred from receiver function analysis depths of the partially melted zone and the moho discontinuity are probably at 18 kilometers and 34 kilometers respectively beneath tagaytay seismic station luzon philippines this conclusion is based on the shear wave velocity structure determined in this study which indicates the presence of a low velocity zone and high velocity zone at these depths the shear wave velocity model was derived from the inversion of five receiver functions of teleseismic earthquakes recorded by the broadband seismometer at tagaytay however due to the very limited information to constrain our initial model other models with comparable waveform fit were also obtained but with deeper low velocity zone and shallower moho

downflow amplitude decrease of ground penetrating radar reflections in base surge deposits ground penetrating radar gpr data were collected parallel to a flow direction in the base surge deposits of the ubehebe hydrovolcanic field death valley california these data showed a downflow amplitude decrease of the reflections that was displayed by computing fourier transforms and the average square of the sample points of the traces this trend probably reflects some aspects of the lateral facies variation of base surge deposits and could be explained by the concomitant downflow increase in sorting and decrease in grain size with a consequent reduction of the differences between the beds which in turn causes a reduction of the reflected energy these results suggest that although the gpr profiles are traditionally used merely as 2 d images of the subsurface stratigraphy they could be useful in obtaining information about the heterogeneous distribution of subsurface physical properties the downflow decrease of the amplitude of the signal could be used as a flow direction indicator when the position of the vent is unknown although other geologic information and field constraints are probably necessary

temperature dependent viscoelastic modeling of ground deformation application to etna volcano during the 1993 1997 inflation period abstract we used the finite element method fem for modeling time dependent ground deformation due to volcanic pressure sources embedded in a viscoelastic medium especially in volcanic areas the presence of heterogeneous materials and high temperatures produce a lower effective viscosity of the earth s crust that calls for considering the thermal regime of crustal volume surrounding the magmatic sources we propose a thermo mechanical numerical model for evaluating the temperature dependency of the viscoelastic solution both temperature distributions and ground deformation are evaluated by solving an axi symmetric problem to estimate the effects of thermo viscoelastic response of the medium the thermo mechanical model permits to evidence that viscoelastic relaxation is responsible for significant time dependent variations in long term deformation these effects may be relevant for the interpretation and quantitative assessments of the pressure changes within magmatic sources with this in mind we reviewed the ground deformation observed on etna volcano during the 1993 1997 inflation period by setting up a fully 3d temperature dependent viscoelastic model since 1993 different geodetic measurements edm gps sar and leveling data identified an inflationary phase characterized by a uniform and continuous expansion of the overall volcano edifice that was not perturbed by eruptive activity the numerical model including significant viscoelastic material and reduced crustal rigidity around the magmatic source enables to produce deformation comparable with those obtained from elastic model requiring a significantly lower pressure for a purely elastic model with the same geometry and rigidity the pressure change necessary to describe the 1993 through 1997 inflation is around 320 mpa whereas for the viscoelastic model a pressure increase of about 200 mpa is required

seasonal cycle of orographic gravity wave occurrence above small islands in the southern hemisphere implications for effects on the general circulation 1 orographic gravity waves generated by flow over the topography of small islands in the southern oceans have been observed from orbit with the atmospheric infrared sounder on the aqua satellite we examine the occurrence frequencies of these waves in the stratosphere at 40km above 14 islands and examine geographical and seasonal changes our results show that these small island mountain waves occur commonly in the stratosphere in the may september season though not every day differing seasonal variations are evident at different islands and the seasonal variations are closely related to latitude and prevailing wind patterns we also examine interannual variability in 2years of data and the relationships between occurrence frequencies momentum fluxes and stratospheric and surface winds the results suggest that stratospheric winds have a first order limiting effect on the observations of these island mountain waves in atmospheric infrared sounder airs data surface wind direction and island orographic relief have an additional but secondary influence on the island mountain wave occurrence frequencies in airs data the implications are that these wave events are extremely common and that on many days when the waves are not observed in airs data they have likely dissipated and induced a drag force on the atmosphere below the 40km observation level observations of momentum flux during these wave events also permit a first estimate of their importance to the general circulation of the southern hemisphere

correction to transient creep of a composite lower crust 2 a polymineralic basis for rapidly evolving postseismic deformation modes by erik r ivins

towards more realistic values of elastic moduli for volcano modelling abstract the accuracy of elastic analytical solutions and numerical models widely used in volcanology to interpret surface ground deformation depends heavily on the young s modulus chosen to represent the medium the paucity of laboratory studies that provide young s moduli for volcanic rocks and studies that tackle the topic of upscaling these values to the relevant lengthscale has left volcano modellers ill equipped to select appropriate young s moduli for their models here we present a wealth of laboratory data and suggest tools widely used in geotechnics but adapted here to better suit volcanic rocks to upscale these values to the scale of a volcanic rock mass we provide the means to estimate upscaled values of young s modulus poisson s ratio shear modulus and bulk modulus for a volcanic rock mass that can be improved with laboratory measurements and or structural assessments of the studied area but do not rely on them in the absence of information we estimate upscaled values of young s modulus poisson s ratio shear modulus and bulk modulus for volcanic rock with an average porosity and an average fracture density quality to be 5 4 gpa 0 3 2 1 gpa and 4 5 gpa respectively the proposed young s modulus for a typical volcanic rock mass of 5 4 gpa is much lower than the values typically used in volcano modelling we also offer two methods to estimate depth dependent rock mass young s moduli and provide two examples using published data from boreholes within k lauea volcano usa and mt unzen japan to demonstrate how to apply our approach to real datasets it is our hope that the data and analysis presented herein will assist in the selection of elastic moduli for volcano modelling to this end we provide a microsoft excel spreadsheet containing the data and necessary equations to calculate rock mass elastic moduli that can be updated when new data become available the selection of the most appropriate elastic moduli will provide the most accurate model predictions and therefore the most reliable information regarding the unrest of a particular volcano or volcanic terrain

experimental study of caldera formation scaled experiments have been carried out on caldera collapse mechanisms using silicone as analogue magma and dry sand as analogue rock experiments were carried out in two and three dimensions using a range of roof aspect ratios thickness width 0 2 to 4 5 appropriate for caldera collapse they reveal a general mechanism of collapse only weakly dependent on the shape of the reservoir for low roof aspect ratios 1 subsidence starts by flexure of the roof and the formation of outward dipping reverse ring faults which in turn trigger formation of peripheral inward dipping normal ring faults the subsidence always occurs asymmetrically in cross section the reverse faults delimit a coherent piston bounded on each side by an annular zone of inwardly tilted strata located between the reverse and normal ring fault sets the surface depression consists of a nondeformed area piston surrounded by an annular extensional zone tilted strata for high aspect ratios 1 multiple reverse faults break up the roof into large pieces and subsidence occurred as a series of nested wedges 2 d or cones 3 d the extensional zone dominates the surface depression in the case where preexisting regional faults do not play a major role the collapse mechanics of calderas probably depends strongly on the roof aspect ratio calderas with low roof aspect ratios are predicted to collapse as coherent pistons along reverse faults the annular extensional zone might be the source of the large landslides that generate intracaldera megabreccias collapse into magma reservoirs with high roof aspect ratios may be the origin of some funnel calderas where explosive reaming is not dominant

geodetic observations and modeling of time varying deformation at taal volcano philippines abstract we investigate active crustal deformation patterns associated with magmatic activity at taal volcano an active tholeiitic volcano located in southwestern luzon philippines we present comparisons of elastic and combined elastic viscoelastic modeling results with deformation observed by continuous gps measurements on and near the volcano continuous dual frequency and single frequency l1 gps data between 1998 and 2005 provide evidence for smoothly transitioning periods of inflation and deflation centered under the volcano within deformation phases that typically last 3 9 months with rates exceeding 200 mm yr 1 prominent inflationary phases were observed in february november 2000 and june 2004 march 2005 the 2000 period of inflation was characterized by up to 145 mm yr 1 surface extension and 220 mm yr 1 of uplift of the center of volcano island relative to the northern caldera rim while the 2005 inflation was characterized by as much as 116 mm yr 1 horizontal extension of the volcanic edifice and 180 mm yr 1 uplift inversions of observed surface deformation to determine the source location points to a relatively stable spherical source situated under volcano island s central crater at depths of 5 km based on the preferred mogi model using this source geometry we develop axisymmetric finite element models with annuli of concentric shells around the magma reservoir embedded within a multi layered elastic lithosphere using simply varying pressure histories as input a variety of forward models are fit to the time history of continuously observed deformation for gps stations located on volcano island though the inferred source geometry volume and near source rheological properties are non unique they represent more physically appropriate material properties than those assumed in simple elastic half space models the sources inferred using viscoelastic shell models suggest simpler pressure histories and reduced overall pressure changes relative to equivalent elastic half space models

water and the viscosity of andesite melts the viscosity of a synthetic andesite like melt has been measured between 1010 and 1014 p for water contents in the range 0 3 5 wt the very slow kinetics of water exsolution over this viscosity range allowed the measurements to be made at 1 bar with a high precision after a steep viscosity decrease of 5 orders of magnitude for 1 wt h2o an additional 2 5 wt h2o causes a further viscosity decrease of only 2 orders of magnitude these viscosity decreases are qualitatively similar to those observed previously for more silica rich compositions the new data join smoothly with available high temperature measurements made at high pressures on water bearing andesite melts because the intrinsic effects of pressure are as small for water bearing as for water free samples the depressing effect of water on the viscosity of natural andesite melts can be estimated changes in water speciation as a function of either temperature or pressure do not seem to have marked effects on the viscosity although quantitative applications are not yet possible the configurational entropy theory accounts qualitatively for these features

on the effects of 3 d mechanical heterogeneities at campi flegrei caldera southern italy 1 campi flegrei caldera located near the highly populated city of naples southern italy is characterized by long term subsidence punctuated by fast uplift phases most of the interpretations of the ground deformation are still based on standard models that assume the lithosphere to behave as a homogeneous half space however several geophysical investigations show the presence of vertical and lateral heterogeneities especially in the shallow subsurface which might have an effect on the interpretation of the surface displacements our 3 d finite element models constrained by seismic tomography to take into account the realistic distribution of mechanical heterogeneities demonstrate that at campi flegrei the assessment of the source location is independent of the consideration of 3 d heterogeneities while the evaluation of its strength is overestimated thus we propose an approach that still allows use of standard homogeneous half space models but accounts for 3 d heterogeneity effects this procedure applied to the deformation field revealed by differential synthetic aperture radar interferometry dinsar over the past 16 years provides new insights for the understanding of the ground displacements observed at campi flegrei caldera this work provides an approach for a quantitative evaluation of the effects of mechanical heterogeneities on surface deformation analogous procedures can be also applied in other volcanic areas where similar to campi flegrei caldera a priori information on the mechanical heterogeneities distribution is available

an unusual sauropod turning trackway from the early cretaceous of shandong province china an unusual turning and a regular straight sauropod trackway both left by small trackmakers as well as additional isolated medium sized to large sauropod tracks are described from the early cretaceous dasheng group of the zhucheng basin shandong province china based mainly on well preserved tracks exhibiting three forwardly directed digit claw impressions and a pronounced heteropody and to a lesser degree due to a predominantly narrow to medium trackway gauge the two small trackways are assigned to the parabrontopodus ichnotaxon as there is no clear trackway and no well preserved tracks amongst the medium sized to large sauropod tracks these tracks can only be identified as of sauropod origin but they cannot be assigned to an ichnotaxon the unusual turning trackway is characterized by a highly variable trackway configuration pes and manus outward rotation gauge pace stride and pattern different degree of manus overprinting by pes tracks along its course evidently related to the narrow semicircular turn to the left that the animal made this is also associated with a pronounced change from a narrow medium in the straight part at the beginning to a very wide within the turn gauge this demonstrates that these two stances could have been used by one and the same sauropod trackmaker even if in the present case associated with turning and not simply during straight progression as it was already reported from a late jurassic tracksite from nw switzerland and an early cretaceous tracksite from spain such untypical trackways provide important constraints for the reconstruction of locomotor characteristics of sauropods such as unsteady locomotion and changes in locomotor behavior and they will be of particular interest in the future to model and understand the different locomotor styles capabilities sauropods were engaged in

philippine fault a key for philippine kinematics on the basis of new geologic data and a kinematic analysis we establish a simple kinematic model in which the motion between the philippine sea plate and eurasia is distributed on two boundaries the philippine trench and the philippine fault this model predicts a velocity of 2 to 2 5 cm yr along the fault geologic data from the visayas provide an age of 2 to 4 ma for the fault an age in good agreement with the date of the beginning of subduction in the philippine trench the origin of the philippine fault would thus be the flip of subduction from west to east after the locking of convergence to the west by the collision of the philippine mobile belt with the eurasian margin

analysis of crustal deformation in luzon philippines using geodetic observations and earthquake focal mechanisms we utilize regional gps velocities from luzon philippines with focal mechanism data from the harvard centroid moment tensor cmt catalog to constrain tectonic deformation in the complex plate boundary zone between the philippine sea plate and eurasia the sundaland block processed satellite imagery and digital elevation models are used with existing gravity anomaly seismicity and geologic maps to define a suite of six elastic blocks geodetic and focal mechanism data are inverted simultaneously to estimate plate rotations and fault locking parameters for each of the tectonic blocks and faults comprising luzon major tectonic structures that were found to absorb the plate convergence include the manila trench 20 100 mm yr 1 and east luzon trough 9 15 mm yr 1 philippine trench 29 34 mm yr 1 which accommodate eastward and westward subduction beneath luzon respectively the left lateral strike slip philippine fault 20 40 mm yr 1 and its northward extensions the northern cordillera fault 17 37 mm yr 1 transtension and the digdig fault 17 27 mm yr 1 transpression the macolod corridor a zone of active volcanism crustal thinning extension and extensive normal and strike slip faulting in southwestern luzon is associated with left lateral transtensional slip of 5 10 mm yr 1 the marikina fault which separates the central luzon block from the southwestern luzon block reveals 10 12 mm yr 1 of left lateral transpression our analysis suggests that much of the philippine fault and associated splays are locked to partly coupled while the manila and philippine trenches appear to be poorly coupled luzon is best characterized as a tectonically active plate boundary zone comprising six mobile elastic tectonic blocks between two active subduction zones the philippine fault and associated intra arc faults accommodate much of the trenchparallel component of relative plate motion 2006 elsevier b v all rights reserved

structural and rheological constraints on source depth and overpressure estimates at the campi flegrei caldera italy ingv gruppo nazionale per la vulcanologia ministero dell istruzione universita e ricerca firb project

january 30 1997 eruptive event on kilauea volcano hawaii as monitored by continuous gps a continuous global positioning system gps network on kilauea volcano captured the most recent fissure eruption in kilauea s east rift zone erz in unprecedented spatial and temporal detail the short eruption drained the lava pond at pueu oeo leading to a two month long pause in its on going eruption models of the gps data indicate that the intrusion s bottom edge extended to only 2 4 km continuous gps data reveal rift opening 8 hours prior to the eruption absence of precursory summit inflation rules out magma storage overpressurization as the eruption s cause we infer that stresses in the shallow rift created by the continued deep rift dilation and slip on the south flank decollement caused the rift intrusion