retrieving the stress field within the campi flegrei caldera southern italy through an integrated geodetical and seismological approach we investigated the campi flegrei caldera using a quantitative approach to retrieve the spatial and temporal variations of the stress field for this aim we applied a joint inversion of geodetic and seismological data to a dataset of 1 100 optical levelling measurements and 222 focal mechanisms recorded during the bradyseismic crisis of 1982 1984 the inversion of the geodetic dataset alone shows that the observed ground deformation is compatible with a source consisting of a planar crack located at the centre of the caldera at a depth of about 2 56 km and a size of about 4 4 km inversion of focal mechanisms using both analytical and graphical approaches has shown that the key features of the stress field in the area are a nearly subvertical 1 and a sub horizontal roughly nne ssw trending 3 unfortunately the modelling of the stress fields based only upon the retrieved ground deformation source is not able to fully account for the stress pattern delineated by focal mechanism inversion the introduction of an additional regional background field has been necessary this field has been determined by minimizing the difference between observed slip vectors for each focal mechanism and the theoretical maximum shear stress deriving from both the volcanic time varying and the regional constant field the latter is responsible for a weak nne ssw extension which is consistent with the field determined for the nearby mt vesuvius volcano the proposed approach accurately models observations and provides interesting hints to better understand the dynamics of the volcanic unrest and seismogenic processes at campi flegrei caldera this procedure could be applied to other volcanoes experiencing active ground deformation and seismicity

creep along the imperial fault southern california from gps measurements 1 in may of 1999 and 2000 we surveyed with global positioning system gps 46 geodetic monuments established by imperial college london in a dense grid half mile spacing along the imperial fault with three additional national geodetic survey sites serving as base stations these stations were previously surveyed in 1991 and 1993 the imperial college sites were surveyed in rapid static mode 15 20 min occupations while the ngs sites continuously received data for 10 h d 1 site locations were calculated using the method of instantaneous positioning and velocities were determined relative to one of the ngs base stations combining our results with far field velocities from the southern california earthquake center scec we fit the data to a simple elastic dislocation model with 35 mm yr 1 of right lateral slip below 10 km and 9 mm yr 1 of creep from the surface down to 3 km the velocity field is asymmetrical across the fault and could indicate a dipping fault plane to the northeast or a viscosity contrast across the fault

coherent change detection using insar temporal decorrelation model a case study for volcanic ash detection detection of changes caused by major events such as earthquakes volcanic eruptions and floods from interferometric synthetic aperture radar sar data is challenging because of the coupled effects with temporal decorrelation caused by natural phenomena including rain snow wind and seasonal changes the coupled effect of major events and natural phenomena sometimes leads to misinterpretation of interferometric coherence maps and often degrades the performance of change detection algorithms to differentiate decorrelation sources caused by natural changes from those caused by an event of interest we formulated a temporal decorrelation model that accounts for the random motion of canopy elements temporally correlated dielectric changes and temporally uncorrelated dielectric changes of canopy and ground the model parameters are extracted from the interferometric pairs associated with natural changes in canopy and ground using the proposed temporal decorrelation model in addition the cumulative distribution functions of the temporally uncorrelated model parameters which are associated with natural changes in canopy and ground are estimated from interferometric pairs acquired before the event model parameters are also extracted from interferometric sar data acquired across the event and compared with the cumulative probabilities of natural changes in order to calculate the probability of a major event subsequently pixels with cumulative probabilities greater than 75 are marked as changed due to the event a case study for detecting volcanic ash during the eruption of the shinmoedake volcano in january 2011 was carried out using l band advanced land observation satellite palsar data

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

neural forecasting of seismicity and ground displacements in different volcanic areas abstract volcanic events have been up to now traditionally predicted through deterministic or probabilistic linear methods here a new non linear approach is carried out based on artificial neural networks ann a non linear physical mathematical model to interconnect data emulating animal brain behaviour being an artificial intelligence system this model is able once both the observed data records and starting values of the network s parameters have been entered to self guide itself and supply the best outputs with respect to the input parameters on varying the starting values the exit values change too the degree of improvement being measurable quantitatively this model has been applied to four different volcanoes vesuvius phlegraean fields etna hawaii with different volcanic characteristics in order to measure the effectiveness of the method as a general one for this purpose data regarding seismicity or ground displacements vertical radial tangential components were processed and predicted by means of ann the results are encouraging and in many cases in very fair agreement with the observed data

interseismic deformation and creep along the central section of the north anatolian fault turkey insar observations and implications for rate and state friction properties 1 we present high resolution measurements of interseismic deformation along the central section of the north anatolian fault naf in turkey using interferometric synthetic aperture radar data from the advanced land observing satellite and envisat missions we generated maps of satellite line of sight velocity using five ascending advanced land observing satellite tracks and one descending envisat track covering the naf between 31 2 e and 34 3 e the line of sight velocity reveals discontinuities of up to 5 mm yr across the ismetpasa segment of the naf implying surface creep at a rate of 9 mm yr this is a large fraction of the inferred slip rate of the naf 21 25 mm yr the lateral extent of significant surface creep is about 75 km we model the inferred surface velocity and shallow fault creep using numerical simulations of spontaneous earthquake sequences that incorporate laboratory derived rate and state friction our results indicate that frictional behavior in the ismetpasa segment is velocity strengthening at shallow depths and transitions to velocity weakening at a depth of 3 6 km the inferred depth extent of shallow fault creep is 5 5 7 km suggesting that the deeper locked portion of the partially creeping segment is characterized by a higher stressing rate smaller events and shorter recurrence interval we also reproduce surface velocity in a locked segment of the naf by fault models with velocity weakening conditions at shallow depth our results imply that frictional behavior in a shallow portion of major active faults with little or no shallow creep is mostly velocity weakening

the potential of alos palsar backscatter and insar coherence for forest growing stock volume estimation in central siberia abstract the full potential of alos palsar l band interferometric insar coherence data for the estimation of forest growing stock volume gsv in the boreal forest has rarely been investigated moreover alos palsar backscatter and insar coherence have yet to be used together to delineate gsv due to the observation strategy and the high acquisition success rate over eurasia a large amount of high quality alos palsar l band data is available over siberia consequently this paper investigates the capability of alos palsar backscatter and insar coherence for the estimation of gsv in central siberia russia the potential of backscatter and coherence are directly compared using the same inventory data altogether 87 palsar images are used and eleven forest inventory sites are investigated based on this large dataset it was observed that insar coherence acquired in frozen conditions offers the highest potential for gsv estimation the saturation level for single coherence images was on average 230 m 3 ha with an average r 2 between coherence and gsv of 0 58 palsar backscatter acquired in unfrozen conditions could also estimate gsv however the saturation levels 75 100 m 3 ha and the average r 2 0 42 0 48 were lower hv backscatter offered only a slightly greater potential than hh backscatter a simple inversion approach aiming at the delineation of forest gsv maps based on the multitemporal sar data was developed and applied to five forest inventory sites this approach combines hv backscatter data acquired in unfrozen conditions and insar coherence data acquired in frozen conditions in general the produced maps feature a corrected relative rmse corr of 2 between inventory data and sar data based maps varied between 0 54 and 0 83

surface deformation and coherence measurements of kilauea volcano hawaii from sir c radar interferometry the shuttle imaging radar c x synthetic aperture radar sir c x sar radar on board the space shuttle endeavor imaged kilauea volcano hawaii in april and october 1994 for the purpose of measuring active surface deformation by the methods of repeat pass differential radar interferometry observations at 24 cm l band and 5 6 cm c band wavelengths were reduced to interferograms showing apparent surface deformation over the 6 month interval and over a succession of 1 day intervals in october a statistically significant local phase signature in the 6 month interferogram is coincident with the pu u o o lava vent interpreted as deformation the signal implies centimeter scale deflation in an area several kilometers wide surrounding the vent peak deflation is roughly 14 cm if the deformation is purely vertical centered southward of the pu u o o caldera delays in the radar signal phase induced by atmospheric refractivity anomalies introduce spurious apparent deformation signatures at the level of 12 cm peak to peak in the radar line of sight direction though the phase observations are suggestive of the wide area deformation measured by global positioning system gps methods the atmospheric effects are large enough to limit the interpretation of the result it is difficult to characterize centimeter scale deformations spatially distributed over tens of kilometers using differential interferometry without supporting simultaneous spatially distributed measurements of refractivity along the radar line of sight studies of the interferometric correlation of images acquired at different times show that l band is far superior to c band in the vegetated areas even when the observations are separated by only 1 day these results imply longer wavelength instruments are more appropriate for studying surfaces by repeat pass observations

thirty five year creep rates for the creeping segment of the san andreas fault and the effects of the 2004 parkfield earthquake constraints from alignment arrays continuous global positioning system and creepmeters we present results from differential global positioning system gps surveys of seven alignment arrays and four continuous gps sites along the creeping segment of the san andreas fault surveys of four alignment arrays from the central creeping segment yield 33 to 36 year average minimum slip rates of 21 26 mm yr these rates are consistent with previous alignment array surveys spanning a 10 year period and with rates determined by creepmeters indicating approximate steady state creep along the central creeping segment for at least 35 years motion between continuous gps sites that span the central creeping segment is 28 2 0 5 mm yr for two sites that are 1 km apart and 33 6 1 mm yr for two sites that are 70 km apart slip rates therefore increase with distance from the creeping segment of the san andreas fault all rates reported here are significantly slower than the 39 2 mm yr rate predicted for motion between the sierra nevada great valley block and the pacific plate repeat surveys of three alignment arrays following the 2004 parkfield earthquake demonstrate that its coseismic and short term postseismic offsets decrease rapidly with distance from the epicenter from 150 mm to 15 mm to 5 mm at respective distances of 9 36 and 54 km to the northwest continuous gps data confirm that little coseismic and postseismic slip occurred along the central creeping segment geodetic and geologic slip rates are compared and different models for the accommodation of transcurrent deformation across the creeping segment are discussed

sbas interferometric analysis for volcanic eruption of hawaii island abstract the kilauea volcano on the hawaii island started erupting on 3rd may 2018 after an earthquake of magnitude 5 0 the initial volcano eruption and the subsequent earthquakes resulted in the opening of new volcanic fissures continuous lava flow at the lower east rift zone and the collapse of the summit caldera floor all these activities continued until the 1st week of august 2018 the small baseline subset sbas technique is an advanced form of differential interferometry dinsar which is capable of monitoring surface deformations with millimetre level accuracy sbas technique was utilised here for estimating the surface deformation on hawaii island due to the volcanic episode insar coherence technique was also utilised in this study for localised analysis at the summit and at the lower east rift zone to detect the time series deformation information and lava flow patterns 14 interferometric datasets acquired by the esa s sentinel 1 c band satellite from april 2018 to september 2018 were used in this study the data acquired by the seismometers installed at kilauea by hawaii volcano observatory the swir band of sentinel 2 and the thermal band of landsat 8 were used to correlate and verify the results obtained through the sbas and insar coherence analysis the combined interpretation of results obtained from all the sources gave insights about the underground magma conduit system surface deformations lava flow channels and the correlation between the magmatic and seismic activity happened there which are discussed in detail in this paper

surface creep rate and moment accumulation rate along the aceh segment of the sumatran fault from l band alos 1 palsar 1 observations

fault plane solutions and seismicity of the italian peninsula abstract a new fault plane solution map of the italian peninsula is presented in this paper the earthquakes analyzed are included in the period 1905 1980 with magnitudes ranging 4 7 75 earthquakes are located in the crust while 31 are related to the deep and intermediate zone of the calabrian arc the large seismic events of the italian peninsula are generally associated with normal faulting while strike slip motion is mostly related to small earthquakes located along lateral segments of the mountain chain the deep and intermediate earthquakes of the tyrrhenian sea indicate predominant down dip compression and strike slip motion at the boundaries of this benioff zone this last is interpreted as a remnant of a subduction zone active since oligocene extending to 500 km depth with a very small lateral size about 300 km the present tectonics of this benioff zone is strongly conditioned by the lateral bending more so than the gravitational sinking process the coexistence of thrust and normal faulting motion associated to the earthquakes within a few tens of kilometers of each other seems to be explained by the strong lateral inhomogeneities of the crustal rocks present in this region more so than to the depth of the seismogenetic zone and the nature of the faulting process

accurate fault mechanism determinations for a 1984 earthquake swarm at campi flegrei caldera italy during an unrest episode implications for volcanological research we have analyzed 42 microearthquakes 1 ml 3 that occurred at campi flegrei volcanic area during an intense swarm like activity more than 500 events in half a day in the last period of strong ground uplift 1982 1984 focal mechanisms of these earthquakes have been computed by a probability method which uses p wave polarity and s wave polarization data composite focal mechanisms for different groups of earthquakes have also been computed by the same technique results show a well defined fault plane in agreement with the elongation of the epicentral pattern the orientation and dip of this fault plane together with other observations about hypocenter locations and focal mechanisms of the whole seismicity accompanying the ground uplift episode suggest the presence of an elliptical fracture system at the caldera center this fracture system dipping toward the center of the caldera should represent the limit of the most recent caldera collapse which is also indicated by a negative bouguer gravity anomaly moreover an important differential feature among various groups of earthquakes has been shown namely a rotation up to about 30 of the strike of the compressive stress axis between the easternmost and the westernmost events the resulting pattern indicates that the axis is always oriented towards the town of pozzuoli which roughly represents the very center of the caldera and also the center of symmetry of the ground deformation these observations strongly suggest that earthquakes are generated by the variation of the stress field associated with the deformation along prefractured zones because of their greater weakeness this study provides then the first direct evidence that both seismicity and ground deformations have a common origin

synthesizing multi sensor multi satellite multi decadal datasets for global volcano monitoring abstract owing to practical limitations less than half of earth s 1400 subaerial volcanoes have no ground monitoring and few are monitored consistently earth observing satellite missions provide global and frequent measurements of volcanic activity that are closing these gaps in coverage we compare databases of global satellite detections of ground deformation 1992 2016 so2 emissions 1978 2016 and thermal features 2000 2016 that together include 306 volcanoes each database has limitations in terms of spatial and temporal resolution but each technique contributed 45 86 unique detections of activity that were not detected by other techniques integration of these three databases shows that satellites detected 102 volcanic activities per year before the year 2000 and 103 activities per year after the year 2000 we find that most of the 54 erupting volcanoes without satellite detections are associated with low volcano explosivity index eruptions and note that many of these eruptions 71 97 135 occurred in the earliest decades of remote sensing pre 2000 when detection thresholds were high from 1978 to 2016 we conduct a preliminary analysis of the timing between the onset of satellite detections of deformation n 154 episodes n 71 volcanoes thermal features n 16 544 episodes n 99 volcanoes and so2 emissions n 1495 episodes n 116 volcanoes to eruption start dates we analyze these data in two ways first including all satellite detected volcanic activities associated with an eruption and second by considering only the first satellite detected activity related to eruption in both scenarios we find that deformation is dominantly pre eruptive 47 and 57 whereas available databases of thermal features and so2 emissions utilizing mainly low resolution sensors are dominantly co eruptive 88 and 76 for thermal features 97 and 96 for so2 emissions

spatial and temporal variations in creep rate along the el pilar fault at the caribbean south american plate boundary venezuela from insar in eastern venezuela the caribbean south american plate boundary follows the el pilar fault system previous studies based on three gps campaigns 2003 2005 2013 demonstrated that the el pilar fault accommodates the whole relative displacement between the two tectonic plates 20 mm yr and proposed that 50 60 of the slip is aseismic jouanne et al 2011 reinoza et al 2015 in order to quantify the possible variations of the aseismic creep in time and space we conducted an insar time series analysis using the nsbas method on 18 images from the alos 1 satellite spanning the 2007 2011 period during this 3 5 year period insar observations show that aseismic slip decreases eastwards along the fault the creep rate of the western segment reaches 25 3 9 4 mm yr on average compared to 13 4 6 9 mm yr on average for the eastern segment this is interpreted through slip distribution models as being related to coupled and un coupled areas between the surface and ca 20 km in depth insar observations also show significant temporal creep rate variations accelerations during the considered time span along the western segment the transient behavior of the creep is not consistent with typical postseismic afterslip following the 1997 ms 6 8 earthquake the creep is thus interpreted as persistent aseismic slip during an interseismic period which have a pulse or transient like behavior

creep and quakes on the northern transition zone of the san andreas fault from gps and insar data 1 the san juan bautista sjb segment forms the northern transition zone of the creeping section of the san andreas fault it is an area of moderate seismicity the largest instrumentally recorded earthquakes have been m5 5 however historic records suggest six m 6 earthquakes occurred near the sjb segment between 1840 and 1899 it is also an area that has experienced several slow earthquakes we perform a joint inversion of gps and insar data to determine the current rate and distribution of interseismic creep we find two low slip locked segments at mid seismogenic depths that may represent source regions for the 19th century earthquakes we find that the sjb segment is currently accumulating strain energy at the rate of one m6 3 6 7 earthquake per century at this rate the 1840 1899 sequence released 135 510 years of accumulated moment deficit

travel time residuals and three dimensional velocity structure of italy jeffreys bullen p and pkp travel time residuals observed at more than 50 seismic stations distributed along italy and surrounding areas in the time interval 1962 1979 indicate the complex velocity pattern of this region strong lateral velocity inhomogeneities and low velocity zones are required to explain the observed pattern of residuals in particular late arrivals of about 1 sec are observed in the apenninic mountain range requiring both greater crustal thickness and low velocity layers coherent with seismic refraction data and surface wave dispersion measurements the seismic stations located in the western and eastern alps indicate the presence of high velocities in the western alps the strong azimuthal variation of residuals and the high values of early arrivals have a close relationship to the ivrea body an intrusive crustal complex characterized by a velocity as high as 7 7 2 km sec a travel time inversion performed with theaki et al 1977 block model confirms the peculiar characteristics and the sharp variations in the lithosphere of the whole italian region with values of velocity perturbations between many adjacent blocks ranging in size from 50 to 100 km and independent from the earth parametrization chosen reaching values up to 10 in the lithospheric part and 5 in the asthenosphere 3 d inversion requires also high velocity along the tyrrhenian coastal margin equivalent to an uprise of major crustal and lithospheric discontinuities along this part of the italian peninsula moreover low velocity material must be present in the northern part of the adriatic foreland in the lithosphere asthenosphere system closely related to the stress and seismicity pattern and the lateral bending of the lithosphere in the same region

seismotectonics of the calabrian arc abstract relocation of intermediate and deep earthquakes of tyrrhenian sea area through joint hypocenter determination for the period 1962 1979 has allowed a more detailed definition of the geometry of this peculiar benioff zone earthquakes dip along a quasi vertical plane to 250 km depth there is a 50 dip in the 250 340 km depth range and a low dip angle to 480 km depth the structure sketched from the hypocenters is almost continuous but most energy has been released in the 230 340 km depth interval an evaluation of fault plane solutions of intermediate earthquakes in this area indicates predominance of down dip compressions in the central part of the slab at the border strike slip motion occurs independent of depth some earthquakes that occurred at intermediate depth less than 100 km along the ionian margin of calabria show predominance of reverse faulting with the p axis oriented se nw however shallow earthquakes in the calabria sicily region indicate a more complex motion with predominance of normal faulting a possible interpretation of these features according to the available geological history which involves subduction of continental lithosphere is discussed

use of c band ground penetrating radar to determine backscatter sources within glaciers the question of penetration of synthetic aperture radar sar signals at c band frequency into polar glaciers is addressed by comparing ground penetrating radar gpr and sar backscatter signatures profiles of the kongsvegen glacier svalbard were obtained with a c band gpr the received signal is converted to the equivalent radar cross section using the standard radar equation thus mapping the effective scattering sources within the glacier at this frequency the depth of the observed scattering sources is greatest in the superimposed ice where layers are clearly seen to a depth of approximately 14 m the very high scattering properties of the upper firn layers preclude layers deeper than approximately 6 m from being imaged integrating the radar cross sections over the depth gives a single backscatter value that we compare with the backscatter coefficient scattering cross section per unit area of the processed sar data for the same profile the comparison indicates that for coincidentally acquired gpr and sar data the radar cross section measured by the gpr does represent the features that contribute to the sar signal

quantification of l band insar coherence over volcanic areas using lidar and in situ measurements abstract interferometric synthetic aperture radar insar is a powerful tool to monitor large scale ground deformation at active volcanoes however vegetation and pyroclastic deposits degrade the radar coherence and therefore the measurement of 3 d surface displacements in this article we explore the complementarity between alos palsar coherence images airborne lidar data and in situ measurements acquired over the piton de la fournaise volcano reunion island france to determine the sources of errors that may affect repeat pass insar measurements we investigate three types of surfaces terrains covered with vegetation lava flows a a pahoehoe or slabby pahoehoe lava flows and pyroclastic deposits lapilli to explain the loss of coherence observed over the dolomieu crater between 2008 and 2009 we first use laser altimetry data to map topographic variations the lidar intensity which depends on surface reflectance also provides ancillary information about the potential sources of coherence loss in addition surface roughness and rock dielectric properties of each terrain have been determined in situ to better understand how electromagnetic waves interact with such media rough and porous surfaces such as the a a lava flows produce a higher coherence loss than smoother surfaces such as the pahoehoe lava flows variations in dielectric properties suggest a higher penetration depth in pyroclasts than in lava flows at l band frequency decorrelation over the lapilli is hence mainly caused by volumetric effects finally a map of lai leaf area index produced using spot 5 imagery allows us to quantify the effect of vegetation density radar coherence is negatively correlated with lai and is unreliable for values higher than 7 5

axi symmetric deformation of a thermo poro elastic half space inflation of a magma chamber summary the deformation observed at phlegraean fields italy during the recent 1982 1984 crisis is interpreted in terms of overpressure in a shallow magma chamber and migration of hot pressurized fluids elastic effects are studied first and previous results obtained from maruyama s strain nuclei are corrected poro elastic and thermo elastic effects are found to be as important as the elastic ones in a semi pervious medium the three terms are typically of the same magnitude results are applied to interpreting the bradyseismic crisis of 1982 84 at phlegraean fields pf near naples italy the concave shape of the first phase of the deformation history at pf can be reproduced by linearly increasing fluid pressure and or temperature at the boundary of a spherical cavity the convex shape of the second phase is interpreted in terms of a gradual return to normal conditions the late phase of slow subsidence is interpreted as the effect of diffusional dissipation of temperature and pressure excess the deconvolution of the real source time history at pf is largely non unique but in any case the importance of fluids in the deformation history is assessed furthermore the inclusion of fluid migration in the deformation model allows simple explanations of several geochemical and geophysical observations made during the bradyseismic crisis

stress pattern at campi flegrei from focal mechanisms of the 1982 1984 earthquakes southern italy abstract campi flegrei is a holocene volcanic area in the campanian plain southern italy within the apennine chain a neogenic thrust belt built up since the middle miocene the volcanic complex consists of a c 12 km diameter caldera containing several monogenetic volcanoes the youngest of which monte nuovo erupted in 1538 since at least roman times the area has also been affected by slow vertical movements bradiseismic activity between 1982 and 1985 this slow motion was interrupted by a period of more rapid displacement which caused a maximum uplift of 180 cm in the town of pozzuoli to model the local stress field associated with the uplift the angelier inversion technique has been applied using the focal mechanisms of forty nine earthquakes which occurred between april 1982 and december 1984 the results show that doming coupled with a regional extensional strain can account for the seismic phenomena that affected the area

the eruptive activity of vesuvius and its neural architecture the vesuvius volcano is a complex system that shows fractal and turbulent behaviours on short time scales to capture the intrinsic non linear dynamic processes of the volcano on longer time scales a hybrid system consisting of an artificial neural network and an evolutionary algorithm was applied to the well documented eruptive activity occurring from 1631 onward an important result of such an investigation is that the next volcanic activity is very unlikely to occur before 2020

focal mechanisms of recent seismicity at campi flegrei italy abstract the present study analysed volcano tectonic earthquakes that occurred in the caldera of campi flegrei italy from 2000 to 2019 to compute source focal mechanisms we used data from a large number of seismic stations to estimate reliable fault plane solutions for 71 events of a maximum duration magnitude md ranging between 0 5 md 2 5 we found that most solutions were of a normal type and were rake angle negative focal mechanisms in 86 of the cases only a few earthquakes occurred on normal dip slip faults the majority occurred on varying degrees of oblique slip only one event had a pure reverse mechanism and it was located far from the caldera centre the spatial distribution of the computed mechanisms exhibited a remarkable mix of fault orientations without any relationship to the location area or source depth the predominance of normal kinematics on high angle and nearly vertical faults and the very shallow source depth exhibited good agreement with the fact that seismicity at campi flegrei occurred during periods of ground uplift in fact ground uplift elongated the shallowest crust thus reducing the normal stress on existing locked faults this facilitated earthquakes particularly those characterised by normal dip slip and strike slip mechanisms in contrast ground subsidence produced a horizontal shortening of the upper crust which increased the normal stress on high angle faults and reduced earthquake occurrence our results indicate that the driving force of the recent volcano tectonic seismicity in the study region is the ongoing ground uplift

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

evidences for higher nocturnal seismic activity at the mt vesuvius abstract we analyze hourly seismic data measured at the osservatorio vesuviano ovest ovo 1972 2014 and at the bunker est bke 1999 2014 stations on the mt vesuvius the ovo record is complete for seismic events with magnitude m 1 9 we demonstrate that before 1996 this record presents a daily oscillation that nearly vanishes afterwards to determine whether a daily oscillation exists in the seismic activity of the mt vesuvius we use the higher quality bke record that is complete for seismic events with magnitude m 0 2 we demonstrate that bke confirms that the seismic activity at the mt vesuvius is higher during nighttime than during daytime the amplitude of the daily oscillation is enhanced during summer and damped during winter we speculate possible links with the cooling warming diurnal cycle of the volcanic edifice with external geomagnetic field and with magnetostriction which stress the rocks we find that the amplitude of the seismic daily cycle changes in time and has been increasing since 2008 finally we propose a seismic activity index to monitor the 24 hour oscillation that could be used to complement other methodologies currently adopted to determine the seismic status of the volcano to prevent the relative hazard

evidences of surface rupture associated with a low magnitude mw5 0 shallow earthquake in the ecuadorian andes this study analyzes surface displacements generated by a low magnitude crustal earthquake in the ecuadorian andes by combining analysis of sar interferometry geological field investigations and seismological data in march 2010 a significant surface faulting event occurred in the pisayambo area eastern cordillera along the major dextral fault zone bounding the north andean sliver and the south america plate interferograms were inverted to determine fault plane geometry and slip displacement distribution the event affected a 9 km long previously unknown fault referred as the laguna pisayambo fault lpf with purely dextral movement reaching 45 cm and concentrated in the top 3 km of the crust geological investigations confirm both the fault mechanism and the amplitude of displacements while these large displacements would be related to an event with a magnitude of 5 44 if using a standard crustal rigidity we show that they can be convincingly associated with an mw5 0 earthquake that occurred on 2010 03 26 reconciling the apparent differences in magnitude requires the existence of a low rigidity medium at shallow depths and or postseismic activity of the fault however considering only the latter hypothesis would imply an unusually active postseismic process in which 400 500 of the coseismic moment is released in the 6 days following the earthquake our observations highlight that the scaling laws relating surface observations to earthquake magnitude classically used for seismic hazard assessment should be carefully used this study also illustrates how systematic insar analysis even in places where no clues of ground deformation are present can reveal tectonic processes

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

accuracy and resolution of alos interferometry vector deformation maps of the father s day intrusion at kilauea we assess the spatial resolution and phase noise of interferograms made from l band advanced land observing satellite alos synthetic aperture radar sar data and compare these results with corresponding c band measurements from european space agency remote sensing satellite ers based on cross spectral analysis of phase gradients we find that the spatial resolution of alos interferograms is 1 3times better than ers interferograms the phase noise of alos i e line of sight precision in the 100 5000 m wavelength band is 1 6times worse than ers 3 3 mm versus 2 1 mm in both cases the largest source of error is tropospheric phase delay vector deformation maps associated with the june 17 2007 father s day intrusion along the east rift zone of the kilauea volcano were recovered using just four alos sar images from two look directions comparisons with deformation vectors from 19 continuous gps sites show rms line of site precision of 14 mm and rms azimuth precision flight direction of 71 mm this azimuth precision is at least 4times better than the corresponding measurements made at c band phase coherence is high even in heavily vegetated areas in agreement with previous results this improved coherence combined with similar or better accuracy and resolution suggests that l band alos will outperform c band ers in the recovery of slow crustal deformation

landslide susceptibility map refinement using psinsar data abstract landslide susceptibility maps lsm are commonly used by local authorities for land use management and planning activities representing a valuable tool used to support decision makers in urban and infrastructural planning the accuracy of a landslide susceptibility map is affected by false negative and false positive errors which can decrease the reliability of this useful product in particular false negative errors are generally worse in terms of social and economic losses with respect to the losses associated with false positives in this paper we present a new technique to improve the accuracy of landslide susceptibility maps using permanent scatterer interferometric synthetic aperture radar psinsar data the proposed approach uses two different data sets acquired in ascending and descending geometry the ps velocity measured along the line of sight is re projected into a new velocity along the steepest slope direction v slope integration between the lsm and the ground deformation velocity map along the slope was performed using an empirical contingency matrix which takes into account the average v slope and the susceptibility degree obtained using the random forests algorithm the results show that the susceptibility degree increased in 56 41 km 2 of the study area the combination of psinsar data and the landslide susceptibility map lsm improved the prediction reliability of slow moving landslides which particularly affect urbanized areas the use of this procedure can be easily applied in different areas where psi data sets are available this approach will help planning and decision making authorities produce reliable landslide susceptibility maps correcting some of the lsm errors

forest height inversion using high resolution p band pol insar data in this paper a high resolution p band pol insar data set acquired by the airborne ramses system over pine forest stands of different height is investigated a significant penetration depth in all the polarimetric channels and a wide range of polarimetric phase center heights are observed attesting of an interaction of the radar waves with different forest structural elements the main objective of this paper concerns forest height inversion at p band first forest modeling assumptions are evaluated using a priori information such as ground level and forest height measurements the full extend of the forest height is shown to be responsible of the volume decorrelation and a significant orientation effect is clearly identified over the highest stands as a consequence the oriented volume over ground model ovog is determined to be the most appropriated model for the forest height inversion at p band the ground contribution is present in all the polarimetric channels due to the important penetration at this frequency to overcome this difficulty a time frequency optimization method based on sublook decomposition is developed to separate the pure ground and canopy contributions allowing forest height estimation with ovog with an rms error on the order of 2 m in the last section of this paper a sensitivity analysis of the inversion with respect to two important system parameters the signal to noise ratio and the resolution is presented leading to a discussion on the inversion robustness in spaceborne conditions where these system parameters are the most deteriorated as compared to airborne configurations

a silent mw 4 7 slip event of october 2006 on the superstition hills fault southern california 1 during october 2006 the 20 km long superstition hills fault shf in the salton trough southern california slipped aseismically producing a maximum offset of 27 mm as recorded by a creepmeter we investigate this creep event as well as the spatial and temporal variations in slip history since 1992 using ers 1 2 and envisat satellite data during a 15 year period steady creep is punctuated by at least three events the first two events were dynamically triggered by the 1992 landers and 1999 hector mine earthquakes in contrast there is no obvious triggering mechanism for the october 2006 event field measurements of fault offset after the 1999 and 2006 events are in good agreement with the interferometric synthetic aperture radar data indicating that creep occurred along the 20 km long fault above 4 km depth with most of the slip occurring at the surface the moment released during this event is equivalent to a mw 4 7 earthquake this event produced no detectable aftershocks and was not recorded by the continuous gps stations that were 9 km away modeling of the long term creep from 1992 to 2007 creep using stacked ers 1 2 interferograms also shows a maximum creep depth of 2 4 km with slip tapering with depth considering that the sediment thickness varies between 3 km and 5 km along the shf our results are consistent with previous studies suggesting that shallow creep is controlled by sediment depth perhaps due to high pore pressures in the unconsolidated sediments

monitoring of active tectonic deformations in the longitudinal valley eastern taiwan using persistent scatterer insar method with alos palsar data abstract this paper presents new observation of the interseismic deformation along the longitudinal valley eastern taiwan that represents a major tectonic boundary of the taiwan collision zone we investigate the southern part of the valley from rueisuei to taitung latitude 23 5 n 22 7 n which is the part of the valley where interseismic surface creep has already been observed at some points of the longitudinal valley fault lvf a persistent scatterer sar interferometry approach stamps is applied using ten l band sar images from alos satellite acquired over the period 2007 2010 interferograms from l band data show a dramatic improvement of coherence in comparison to previous studies using c band ers data the density of measurement resulting from stamps processing is the highest achieved so far in the area about 40 55 points per km2 for a total of 77 000 points allowing a continuous view of the deformation along the valley and also giving information on its borders central range and coastal range the most striking feature of the resulting mean velocity map is a clear velocity discontinuity localized in a narrow band 0 1 1 km along the lvf and responsible for up to 3 cm yr velocity offset along the radar line of sight which is attributed to shallow interseismic creep insar results are in good agreement with continuous gps measurements over the same period 0 3 cm yr rms the density of measurement allows us to improve fault trace map along the creeping section of the lvf with accuracy of about 100 m and to find new field evidences of the fault activity in some places our trace differs significantly hundreds of meters from previous published traces the creep rate shows significant variations along the fault at the southern end of the valley the deformation is distributed on several structures including the luyeh strand and drops significantly south of the peinanshan however there are discrepancies with previous studies made from ers data over the period 1993 1999 that remain to be investigated the mean velocity for each point of measure and the improved faults trace are provided as supplementary data

rates of similar micro earthquakes comparison between campi flegrei southern italy and other volcanic areas abstract the precise relocation of micro earthquakes using waveform cross correlation is an efficient tool for defining the spatial characteristics of seismogenic structures in volcanic areas to be applied and to provide meaningful results the technique requires however the presence of sufficient amounts of similar events we examined about 870 earthquakes recorded at the campi flegrei cf caldera by a temporary digital network during the end of the 1982 1984 bradiseismic crisis the classification of these earthquakes indicates a surprising low amount of similar events especially according to the clustered aspect of the seismicity the relocation technique allows only to identify 3 elongated patterns that may be interpreted as small faults which are dipping inward toward the center of the caldera to determine up to which point this low similarity rate is unusual we examined the rates for several data sets coming from various volcanic areas hawaii mount pinatubo philippines and piton de la fournaise la reunion island the results show for all areas percentages of similar events significantly higher than for cf and indicate that the low rate observed there is not just a matter of low detection threshold or network characteristics at cf most of the seismicity appears to be diffused and generated along small fractures rather than along well defined fault structures the low similarity rate is in good agreement with a seismicity generated in a fractured medium by overpressure in the hydrothermal system and low deviatoric local stress

three dimensional deformation mapping of a dike intrusion event in sakurajima in 2015 by exploiting the right and left looking alos 2 insar one of the limitations of the interferometric synthetic aperture radar insar is its one dimensional measurement capability although three dimensional 3 d deformation can be studied if there are three or more measurements with different viewing geometries it has not been executed because almost all sar data are acquired using a right looking geometry for the sakurajima volcanic activity on 15 august 2015 alos 2 conducted sar observations from four different viewing directions ascending descending and right left looking enabling the retrieval of 3 d deformation data only from the insar results we have retrieved 3 d deformation with high precision and resolution by a weighted least squares approach expansive deformation of over 10 cm has been observed with standard errors of 0 8 3 4 and 0 7 cm for east west north south and up down components respectively it is inferred that a dike of 1 7 106m3 volume intruded beneath the showa crater at a depth of 0 4 1 2 km

mechanical and thermo fluid behaviour during unrest at the campi flegrei caldera italy abstract the campi flegrei caldera cfc is a resurgent nested structure resulting from the two main collapses of the campanian ignimbrite 37 ka and the neapolitan yellow tuff 12 ka eruptions while the whole structure is affected by a broad subsidence ongoing local resurgence and unrest occur inside the young nested caldera structure the caldera has shown signs of unrest during the past 30 years with two uplift events that have generated a net displacement of 3 5 m each followed by subsidence the time evolution of both ground deformation and seismicity recorded in campi flegrei in the last 30 years since 1969 up to the present shows aspects not completely explainable by means of mechanical models in particular the occurrence of an intense seismic activity during uplift and its absence during subsidence lead us to infer that these two phases might be related to two variable mechanisms the large amount of magma and the shallow convective fluids circulation needed to explain the very high temperature gradient 100 c km measured also in marginal areas of the caldera suggest the presence of a thermo dynamical system in supercritical conditions we have carried out an analysis of the unrest episodes by means of 3d finite element method simulating the mechanical and fluid dynamical response of a two phase medium solid fluid to a sudden stepwise pressure or volume increase at a depth of 4 km according to geological and geophysical constraints in our scheme we have subdivided the caldera floor into a central and a peripheral zone the central zone represents the resurgent block and has high permeability while the peripheral zone is less permeable we have performed a parametric analysis assuming both young modulus and permeability of each zone as variables the basic test for each solution was how well it simulates the time evolution of ground deformation during the last unrest episode 1982 1984 the results obtained clearly show that fluids diffusion accounts for some peculiar features of the ground deformation such as the variable behavior between the resurgent block and the peripheral part of the caldera floor subsidence is explained in terms of lateral diffusion of fluids instead of a regression of source processes consequently no variation of shear stress occurs during this phase providing a physical explanation to the absence of seismicity

source mechanism of volcanic earthquakes a description and classification of seismic sources found in active zones of volcanism are given the main sources of seismic wave energy are caldera collapse shear fractures with comparatively low spectral corner frequencies shallow gas explosions hydraulic pressure transients and non stationary magma flew

aseismic creep along the san andreas fault northwest of parkfield ca measured by radar interferometry ers 1 radar images acquired 14 months apart studied by differential radar interferometry show the wide area distribution of aseismic creep along the fault segment northwest of parkfield california a sharp discontinuity in the interferometric phase of less than 2 cm equivalent line of sight displacement extends over 80 km in the differential interferogram coincident with the mapped trace of the active san andreas fault and consistent with the expected and measured fault motion although patterns of strain associated with the transition from locked to creeping are not clearly identifiable a decrease in creep displacement from northwest to southeast along the fault is visible the observations are in agreement with a model of elastic deformation constrained by in situ data that supports a maximum expected deformation signature of 10 mm across the image

the influence of equatorial scintillation on l band sar image quality and phase it is well known that many of the nighttime acquisitions of the l band advanced land observing satellite alos phased array type l band synthetic aperture radar palsar instrument over equatorial regions show significant distortions of the image amplitude information these distortions have the form of amplitude stripes that are roughly aligned with the local geomagnetic field while ionospheric scintillation has been identified as the source of these distortions the exact nature of the induced artifacts on synthetic aperture radar sar image quality and sar signal phase has not yet been studied in sufficient detail hence this paper provides a quantitative analysis of equatorial scintillation effects on sar image quality and sar phase we have performed a statistical analysis of alos palsar images over equatorial regions to describe the observed distortions and relate them to ionospheric parameters an ionospheric simulator was developed and validated that is capable of simulating ionospheric distortions based on ionospheric scintillation parameters using this simulator we found that ionospheric scintillation in the equatorial zone can cause significant distortions of sar image amplitudes image focus and sar signal phase we determined threshold ionospheric environmental conditions that lead to the formation of these image distortions based on these thresholds we quantified the likelihood of occurrence of ionospheric distortions for the global equatorial belt and for l band sensors alos palsar alos 2 palsar 2 and nasa isro sar nisar

decorrelation of l band and c band interferometry over vegetated areas in california temporal decorrelation is one of the main limitations for recovering interseismic deformation along the san andreas fault system using interferometric synthetic aperture radar to assess the improved correlation properties of l band with respect to c band we analyzed l band advanced land observation satellite alos interferograms with a range of temporal and spatial baselines over three vegetated areas in california and compared them with corresponding c band european remote sensing satellite ers interferograms over the highly vegetated northern california forests in the coast range area alos remains remarkably well correlated over a 2 year period whereas an ers interferogram with a similar temporal and spatial baseline lost correlation in central california near parkfield we found a similar pattern in decorrelation behavior which enabled the recovery of a fault creep and a local uplifting signal at l band that was not apparent at c band in the imperial valley in southern california both alos and ers have low correlation over farmlands alos has lower correlation over some sandy surfaces than ers probably due to low signal to noise ratio in general l band interferograms with similar seasonal acquisitions have higher correlation than those with dissimilar season for both l and c band correlation over vegetated areas decreases with time for intervals less than 1 year and then remains relatively constant at longer time intervals the decorrelation time for l band is more than 2 years in the forest in california whereas that for c band is less than 6 months overall these results suggest that l band interferograms will reveal near fault interseismic deformation once sufficient data become available

interpretation of recent alpine landscape system evolution using geomorphic mapping and l band insar analyses abstract alpine landscapes are typically characterized by inherited features of past glaciations and for the more recent past by the interplay of a multitude of types of geomorphic processes including permafrost creep rockfalls debris flows and landslides these different processes usually exhibit large spatial and temporal variations in activity and velocity the understanding of these processes in a wide alpine area is often hindered by difficulties in their surveying in this study we attempt to disentangle recent changes in an alpine landscape system using geomorphic mapping and l band dinsar analyses alos palsar in the zermatt valley swiss alps geomorphic mapping points to a preferential distribution of rock glaciers on north facing slopes whereas talus slopes are concentrated on south facing slopes field based interpretation of ground deformation in rock glaciers and movements in talus slopes correlates well with the ratio of insar images showing potential ground deformation moraines formed during the little ice age rock glaciers and talus slopes on north facing slopes are more active than landforms on south facing slopes implying that the presence of permafrost facilitates the deformation of these geomorphic units such deformations of geomorphic units prevail also at the elevation of glacier termini for rock cliffs the ratio of images indicating retreat is affected by slope orientation and elevation linkages between sediment supply from rock cliffs and sediment transport in torrents are different among tributaries affected by relative locations between sediment supply areas and the channel network we conclude that the combined use of field surveys and l band dinsar analyses can substantially improve process understanding in steep high mountain terrain

the 1994 1995 seismicity and deformation at the hengill triple junction iceland triggering of earthquakes by minor magma injection in a zone of horizontal shear stress since july 1994 an unusually persistent swarm of earthquakes m 4 0 has been in progress at the hengill triple junction sw iceland activity is clustered around the center of the hromundartindur volcanic system geodetic measurements indicate a few centimeters uplift and expansion of the area consistent with a pressure source at 6 5 3 km depth beneath the center of the volcanic system the system is within the stress field of the south iceland transform zone and the majority of the recorded earthquakes represent strike slip faulting on subvertical planes we show that the secondary effects of a pressure source modeled as a point source in an elastic half space include horizontal shear that perturbs the regional stress near the surface shear stress is enhanced in quadrants around the direction of maximum regional horizontal stress and diminished in quadrants around the direction of minimum regional stress the recorded earthquakes show spatial correlation with areas of enhanced shear the maximum amount of shear near the surface caused by the expanding pressure source exceeds 1 strain sufficient to trigger earthquakes if the crust in the area was previously close to failure

studies of multibaseline spaceborne interferometric synthetic aperture radars the authors have utilized a set of seasat synthetic aperture radar sar data that were obtained in nearly repeat ground track orbits to demonstrate the performance of spaceborne interferometric sar insar systems an assessment of the topography measurement capability is presented a phase measurement error model is described and compared with the data obtained at various baseline separations and signal to noise ratios finally the implications of these results on future spaceborne insar design are discussed

source parameters and three dimensional attenuation structure from the inversion of microearthquake pulse width data qp imaging and inferences on the thermal state of the campi flegrei caldera southern italy the three dimensional p wave attenuation structure of the campi flegrei caldera and the estimate of source parameters for 87 local microearthquakes is obtained by the nonlinear inversion of pulse width and rise time measurements by using the method described by zollo and de lorenzo this issue source radii represent the better resolved parameters with values ranging from 70 m to 230 m the dip and strike angles defining fault orientations are usually affected by larger uncertainties and are well constrained only for 11 events the dip fault is usually confined in the range 30 60 with an average uncertainty of 12 the fault strikes mainly range between 60 and 60 and seem to define preferential directions oriented radially from the symmetry axis of the ground deformation stress drop estimates indicate rather low values 0 01 1 mpa which suggest low strength properties of the incoherent and brittle materials filling the caldera primarily yellow tuffs the three dimensional qp images obtained from the inversion of p pulse durations show two significant low qp anomalies between 0 and 1 km of depth in the north eastern sector and at 2 3 km of depth in the central eastern sector of the caldera the high degree of spatial correlation of the low qp zone and low vs as inferred by aster and meyer 1988 at 0 1 km in depth and other geophysical and geochemical observations suggest that this anomaly can be related to the presence of densely fractured porous and fluid filled rocks in the ne sector of the caldera the deeper low qp anomaly is interpreted as being related to a dominant thermal effect we used the surface and deep borehole temperature measurements available in the area to obtain a local calibration curve to convert qp in temperature at campi flegrei the retrieved t qp map shows a high thermal deep disturbance 450 500 c at depths between 2 and 3 km in the eastern sector of the caldera where the most recent eruptive activity is concentrated the present day temperature field retrieved by qp images has been interpreted by using a three dimensional thermal conduction model assuming an extended heat source initial temperature of 800 c located underneath the attenuation anomalous region the results indicate that the qp inferred temperature field can be related to the heat conduction effect of one or more molten bodies whose top should be at about 4 km depth consistent with recent seismic estimates of the magma chamber top at campi flegrei ferrucci et al 1992 this study suggests that the present thermal state and rock rheology of the inner caldera could be controlled by the cooling of molten bodies that originally intruded at depths of 1 4 1 6 km during one or more recent time of 10 kyr eruptive events

ginsar a cgps correction for enhanced insar time series earth surface displacements from interferometric synthetic aperture radar insar have long been used to study deformation from a wide range of geophysical processes whereas deformation rates can be robustly estimated from insar by averaging many individual deformation observations noise in these observations has limited their utility for generating deformation time series in this article we introduce a novel combination of insar and global positioning system gps data that align insar displacements to an absolute reference and reduces long wavelength spatial errors prior to insar time series construction we test our ginsar gps enhanced insar methodology on sentinel 1 data over the southern central valley ca usa comparing ginsar displacement velocities and time series with those from three other referencing techniques we find that the ginsar approach outperforms alternative methods yielding mm level displacement differences with respect to collocated cgps by contrast other referencing methods can overestimate peak subsidence velocities in the central valley by upwards of 10 deviate by tens of millimeters relative to cgps validation time series and contain spatial biases absent in the ginsar methodology we also present a modification to the widely used small baseline subset sbas technique for time series estimation whereby we use a temporal connectedness constraint to regularize the mathematical inversion and increase the number of insar pixels with valid time series estimates

deformation parameter estimation in low coherence areas using a multisatellite insar approach persistent scatterer ps interferometry and small baseline subset algorithms can be used to estimate time series of surface deformation with high precision in areas with low coherence and in the absence of sufficient ps the estimation of reliable phase information can be cumbersome here we report a successful approach for estimating deformation at pasture on drained peat soils using the integrated use of data from several satellite missions a parametric deformation model with a generalized least squares method and spatial averaging over statistically homogeneous pixels the developed methodology is analyzed and applied on a test site in the netherlands where we report local subsidence rates and periodic signal over the peat and pasture areas

landslide deformation monitoring with alos palsar imagery a d insar geomorphological interpretation method the objective of this work is to propose a geomorphologically guided method for the interpretation of l band alos palsar interferograms created by differential interferometric synthetic aperture radar d insar the interferograms are used to estimate the deformation pattern of two rapid and large landslides poche la valette south east france the wrapped and unwrapped phase values are interpreted for different movement types rotational translational and complex sliding and two ranges of surface displacement rates kinematic sub units are detected for both landslides and zones affected by enlargement or retrogression are identified the insar derived displacement rates are consistent with ground based measurements and with remote estimates of the displacement from c band and x band satellite sar sensors the results demonstrate the potential of l band alos palsar imagery for the monitoring of active landslides with important changes in the soil surface state and covered by vegetation

tidal signal in the recent dynamics of campi flegrei caldera italy abstract this paper presents periodicities in geophysical measurements made during recent activity in campi flegrei caldera this caldera located west of naples in southern italy is well known for the slow vertical ground movement known as bradyseism the maximum rate of movement occurrs near the city of pozzuoli near the caldera center a monitoring system of geophysical instruments has been in operation since 1970 to record activity in campi flegrei we analyze the time series and frequency spectra of vertical ground movement seismicity and gravity changes associated with a strong episode of unrest occurred between 1982 and 1984 our purpose is to investigate the influence of the earth tide on some aspects of the unrest our results reveal periodicities coincident with some tides which range from semidiurnal to annual components some of these periodicities has already been identified during an earlier episode of activity in campi flegrei

the seismicity in the southern tyrrhenian area and its neural forecasting the southern tyrrhenian basin is a region characterized by complex tectonics and large scale geodynamic deformations and its seismicity has been recently recognized as following fractal laws in its five dimensional set magnitude time and space in particular the time occurrences of earthquakes are found to follow a significant fractal clustering within the interval ranging from 16 minutes to 24 hours for longer intervals the time clustering regime was not significantly different from that of a random process an artificial neural network is applied here to the same seismicity data set and further evidence of the nonlinear dynamic process for which the fractal approach failed is obtained the monthly values of magnitude predicted by extrapolation are found to be in fair agreement with the historical data

shallow hydrothermal pressurization before the 2010 eruption of mount sinabung volcano indonesia observed by use of alos satellite radar interferometry ground deformation in volcanic regions can be a precursor to resumption of activity volcanic eruptions are typically brief periods of activity punctuating very long inter eruptive periods this makes hazard evaluation a difficult task for volcanoes with low recurrence eruptive activity which often are poorly monitored as a result analysis of inter eruptive periods by use of remote sensing techniques can provide important information on precursory activity and improve volcano hazard assessment in august september 2010 mt sinabung indonesia reawakened after at least 400 years of dormancy the ground deformation before this eruption was investigated by use of differential interferometric synthetic aperture radar data obtained from japanese alos palsar radar imagery between 05 january 2007 and 31 august 2010 results from insar time series processing detected significant ground deformation subsidence at several locations on the karo plateau and uplift in the summit area of mt sinabung the persistent scatterers density obtained by use of alos data is sufficient to enable extraction of temporal and spatial patterns of the deformation the surface deformation at the summit can be modeled by using a spherical point source model source data are consistent with a very shallow hydrothermal reservoir with a linear increase in overpressure before the 2010 mt sinabung eruption hydrothermal origin is consistent with seismicity tiltmeters and analysis of ash products collected during and after the 2010 eruption these results support the potential of l band interferometry for hazard assessment in poorly monitored and highly vegetated volcanic areas and also indicate that hazard assessment for indonesian volcanoes could potentially be improved by identification of precursory inter eruptive uplift periods

tectonic and anthropogenic deformation at the cerro prieto geothermal step over revealed by sentinel 1a insar the cerro prieto geothermal field cpgf lies at the step over between the imperial and the cerro prieto faults in northern baja california mexico while tectonically this is the most active section of the southern san andreas fault system the spatial and temporal deformation in the area is poorly resolved by the sparse global positioning system gps network coverage moreover interferograms from satellite observations spanning more than a few months are decorrelated due to the extensive agricultural activity in this region here we investigate the use of frequent short temporal baseline interferograms offered by the new sentinel 1a satellite to recover two components of deformation time series across these faults following previous studies we developed a purely geometric approach for image alignment that achieves better than 1 200 pixel alignment needed for accurate phase recovery we construct interferometric synthetic aperture radar time series using a coherence based small baseline subset method with atmospheric corrections by means of common point stacking we did not apply enhanced spectral diversity because the burst discontinuities are generally small 1 4 mm and can be effectively captured during the atmospheric corrections with these algorithms the subsidence at cpgf is clearly resolved the maximum subsidence rate of 160 mm yr due to extraction of geothermal fluids and heat dominates the 40 mm yr deformation across the proximal ends of the imperial the cerro prieto and the indiviso faults

a preliminary study of stress pattern at phlegraean fields as inferred from focal mechanisms thirty seven selected earthquakes which occurred in phlegraean fields from april to december 1983 are investigated from the focal mechanism point of view in order to attempt a preliminary representation of the stress pattern in the area from 37 earthquakes 15 reliable solutions were obtained ten mechanisms for events located around the solfatara crater are of tensional type 2 located in the gulf of pozzuoli seem to be compressive no predominant orientation ofp andt axes seem to occur evidently a more accurate analysis with a greater number of data in particular for compressive events is necessary in order to resolve a detailed map of stress pattern

on the self organized critical state of vesuvio volcano abstract the catalogue of volcanic earthquakes recorded at vesuvio 1972 1993 is shown to be complete for events with magnitude enclosed between 1 8 and 3 0 such a result is converted in significant fractal laws power laws relating the distribution of earthquakes to the distribution of energy release seismic moment size of fractured zone and linear dimension of faults the application of the cantor dust model to time sequence of vesuvio seismic and eruptive events allows the determination of significant time clustering fractal structures in particular the vesuvio eruptive activity shows a double regime process with a stronger clustering on short time scales than on long time scales the complexity of the vesuvio system does not depend on the number of geological geophysical and geochemical factors that govern it but mainly on the number of their interconnections on the intensity of such linkages and on the feed back processes so all the identified fractal features are taken as evidence that the vesuvio system is in a self organized critical state i e in a marginally stable state in which a small perturbation can start a chain reaction that can lead to catastrophe after the catatrophe the system regulates itself and begins a new cycle not necessarily periodic that will end with a successive catastrophe the variations of the fractal dimension and of the specific scale ranges in which the fractal behaviour is found to hold serve as possible volcanic predictors reflecting changes of the same volcanic process

penetration depths inferred from interferometric volume decorrelation observed over the greenland ice sheet radar interferometry provides a novel way to study the subsurface of glaciers interferometric correlation since the two complex images that comprise the interferogram have slightly different incidence angles at each point on the ground a decorrelating phase noise with statistics related to the scattering medium is present in the interferogram the amount of surface decorrelation is increased by volume scatter the larger the vertical extent of the scatterers contributing to the radar echo the greater the decorrelation will be by modeling this effect the authors can estimate radio wave penetration depths within the upper layers of the glacier or ice sheet observations of the greenland ice sheet using ers data yield penetration depths one way 1 e point for power that range from 12 to 35 m due to the contribution of volume scatter the critical interferometer baseline is decreased and the authors find for the greenland data the baseline must be restricted to be less than 300 m the authors also compare penetration depths measured within the dry snow zone with those found in the percolation zone and coastal areas they find that as expected the rocky coastal areas evidence minimal penetration interestingly the penetration depths that the authors measure in the percolation zone spl sim 23 m indicate a large degree of volume scatter which is contrary to earlier results that found the scattering in the percolation zone dominated by structures in the first few meters this discrepancy may be due to unmodeled scattering behavior or the radar return may indeed include significant contributions from scatterers far beneath the surface

paleomagnetic evidence for counter clockwise rotations in the southern apennines fold and thrust belt during the late pliocene and middle pleistocene abstract marine and continental clay silt sediments from late miocene to middle late pleistocene age have been sampled in the southern apennines fold and thrust belt to detect the spatial and temporal aspects of tectonic rotations we sampled different parts of the tectonic system sites from both the internal western and the external eastern part the characteristic remanent magnetisation chrm component for the sediments is generally removed from 320 340 up to 450 480 c a counter clockwise rotation is observed for nearly all sites all data indicate that the main tectonic rotations in the southern apennines fold and thrust belt occurred in the middle pleistocene the late miocene to middle pliocene sediments reveal a 39 counter clockwise rotation which is similar to the rotation of the cretaceous carbonate rocks this indicates at least two phases of counter clockwise rotation a first rotation through approximately 15 during the late pliocene possibly contemporaneous with clockwise rotations in sicily 3 05 ma and a second rotation through at least 15 during the middle pleistocene there was also a third smaller rotation through about 9 since the middle pleistocene the results imply that there were no tectonic rotations in the southern apennines fold and thrust belt during the period of major shortening that took place in the early middle miocene nor during the opening of the southern part of the tyrrhenian basin in the latest pliocene earliest pleistocene our data further support the hypothesis that the late oroclinal rotations in the tyrrhenian arc were confined to distinct phases of regional compression