structural styles and regional tectonic setting of the gela nappe and frontal part of the maghrebian thrust belt in sicily the gela nappe of south central sicily provides an example of a curved segment of an orogenic front that can be examined both onshore and offshore for deformational style and amount of shortening synorogenic sediments allow the deformation to be dated two distinct structural styles are observed in the gela nappe the central salient part of the nappe caltanissetta basin consists of a single thrust sheet containing a train of continuously tightening folds and the reentrant margins of the nappe sciacca and monte judica consist of a stack of several thrust sheets these different structural styles correspond to the pretectonic mesozoic stratigraphy of the foreland plate carbonate platforms exist on the adventure bank and hyblean plateau ahead of sciacca and monte judica respectively while the caltanissetta basin region appears to have accumulated basinal clay facies where the resistant carbonate stratigraphy provides a buttress to the propagation of the thrust front deformation is taken up by imbrication on steep ramps through the carbonates generating a relatively thick orogenic wedge in the basinal setting where no strong rheology exists the low angle of friction on the clay detachment levels requires the growing thrust wedge to be much thinner with a very low foreland dip hence the thrust front propagates much farther forward into the basin than it does in the adjacent platformal areas producing a nonlinear thrust front in the basinal region accretion of foreland material to the nappe by imbrication was only prominent during the messinian when subaerial exposure prevented low friction transport of the nappe across the highest levels of the stratigraphy a steady thickening of the nappe by internal folding suggests an increase in friction along the basal detachment possibly due to progressive compaction of the clays

mud volcano eruptions and earthquakes in the northern apennines and sicily italy abstract the relations between earthquakes and the eruption of mud volcanoes have been investigated at the pede apennine margin of the northern apennines and in sicily some of these volcanoes experienced eruptions or increased activity in connection with historical seismic events showing a good correlation with established thresholds of hydrological response liquefaction to earthquakes however the majority of eruptions have been documented to be independent of seismic activity being mud volcanoes often not activated even when the earthquakes were of suitable magnitude and the epicentre at the proper distance for the triggering this behaviour suggests that paroxysmal activity of mud volcanoes depends upon the reaching of a specific critical state dictated by internal fluid pressure and implies that the strain caused by the passage of seismic waves can activate only mud volcanoes in near critical conditions i e close to the eruption seismogenic faults such as the pede apennine thrust often structurally control the fluid reservoirs of mud volcanoes which are frequently located at the core of thrust related folds such an intimate link enables mud volcanoes to represent features potentially suitable for recording perturbations associated with the past and ongoing tectonic activity of the controlling fault system

ascent velocity and dynamics of the fiumicino mud eruption rome italy author s vona a giordano g de benedetti aa d ambrosio r romano c manga m abstract 2015 american geophysical union all rights reserved in august 2013 drilling triggered the eruption of mud near the international airport of fiumicino rome italy we monitored the evolution of the eruption and collected samples for laboratory characterization of physicochemical and rheological properties over time muds show a progressive dilution with water the rheology is typical of pseudoplastic fluids with a small yield stress that decreases as mud density decreases the eruption while not naturally triggered shares several similarities with natural mud volcanoes including mud componentry grain size distribution gas discharge and mud rheology we use the size of large ballistic fragments ejected from the vent along with mud rheology to compute a minimum ascent velocity of the mud computed values are consistent with in situ measurements of gas phase velocities confirming that the stratigraphic record of mud eruptions can be quantitatively used to infer eruption history and ascent rates and hence to assess or reassess mud eruption hazards

triggering and dynamic evolution of the lusi mud volcano indonesia abstract mud volcanoes are geologically important manifestations of vertical fluid flow and mud eruption in sedimentary basins worldwide their formation is predominantly ascribed to release of overpressure from clay and organic rich sediments leading to impressive build up of mud mountains in submarine and subaerial settings here we report on a newly born mud volcano appearing close to an active magmatic complex in a backarc sedimentary basin in indonesia the location of the mud volcano close to magmatic volcanoes results in a high background temperature gradient that triggers mineralogical transformations and geochemical reactions at shallow depth the eruption of 100 c mud and gas that started the 29th of may 2006 flooded a large area within the sidoarjo village in northeast java thousands of people have so far been evacuated due to the mud flood hazards from the eruption since the initial eruption the flow rate escalated from 5000 to 120 000 m 3 d during the first eleven weeks then the erupted volume started to pulsate between almost zero and 120 000 m 3 d in the period august 14 to september 10 whereas it increased dramatically following swarms of earthquakes in september before reaching almost 180 000 m 3 d in december 2006 sampling and observations were completed during two fieldwork campaigns on the site the eruption of boiling water is accompanied by mud aqueous vapour co 2 and ch 4 based on geochemical and field results we propose a mechanism where the eruptions started following the 27th of may earthquake due to fracturing and accompanied depressurization of 100 c pore fluids from 1700 m depth this resulted in the formation of a quasi hydrothermal system with a geyser like surface expression and with an activity influenced by the regional seismicity

the nature and hydrogeologic significance of mud diapirs and diatremes for accretionary systems in accretionary wedges often morphologically similar sedimentary intrusions when observed by remote geophysical means may have one of two quite different driving mechanisms and a highly variable significance for the regional hydrogeologic picture for example mud diapirs are driven by buoyancy forces that arise from bulk density contrasts in them mud and pore fluid upwell en masse and fluid migration is a related sometimes important but generally subsidiary process in contrast diatremes contain sediments fluidized during rapid fluid advection and are forcibly and directly driven by the hydrogeologic system the nature of fluid input from local and exotic source regions can therefore strongly affect sedimentary intrusive processes and vice versa this complicates the process of defining the main features of the hydrogeological systems operating in accretionary wedges focused vertical advection through steep sided piercement mud diapirs requires conduit systems otherwise flow will be diffuse and directed more horizontally out of the low permeability mud mass however where the permeability of the overburden is less than that of the diapir the whole diapir may act as a conduit apart from this special case conduits will be associated with highly anisotropic scaly fabrics that can sometimes develop in the marginal shear zone of diapirs scaly fabrics form during deformation and compaction of a mud matrix under conditions of constant or increasing effective stress however the effective stress path can be complex as it is both controlled by the relative rates of upward intrusion and burial by sedimentation and or structural thickening and the hydrogeologic system due to this it appears likely that even in a geographically related group of diapirs effective stress histories will vary widely between intrusions so that some can form advective pathways for fluids and some cannot mixed systems of behavior may also be present with local diatremes developing within diapirs above the terminations of conduit systems and rapidly expanding methane gas pockets the potentially heterogeneous near surface behavior may be why the surface manifestations of sedimentary intrusions are so variable when observed in the field diatremes can also form separately as large primary features above any structural or stratigraphic conduit that rapidly expels water or gas into the base of an unlithified sediment column when active large diatremes require enormous quantities of fluid water or gas to drive them particularly if they are long lived features and hence are a direct indication of at least an episodically vigorous hydrogeologic system

considerations on the seismotectonics of the northern apennines abstract the northern apennines have been subdivided into homogeneous zones on the basis of recent structural evolution and crustal structure in which the earthquake distribution can find a coherent framework these zones whose physiography is in strict connection with their structure are the internal peri tyrrhenian belt the external or main belt the buried belt and the pede alpine homocline earthquake activity has a tendency to cluster along well defined bands particularly in the easternmost border of the peri tyrrhenian belt as well as along the zone between the external belt and the buried belt i e along the padanian margin of the northern apennines a minimum of seismic activity seems to be correlated with some zones of the external belt as well as with the late tertiary and quaternary magmatic province of tyrrhenian southern tuscany the fault plane solutions are coherent with the structural picture a tentative seismotectonic model of the northern apennines is discussed

sedimentary response of arctic coastal wetlands to sea level rise abstract arctic coastal wetlands are of international importance providing a range of ecosystem services they differ markedly from atlantic saltmarshes in the limited development of the creek network associated plant species and the influence of the rapid influx of sediment during the spring thaw this study presents the findings of research conducted in five arctic coastal wetlands in northern norway utilising 210pb and 137cs radionuclide dating techniques to investigate the recent sedimentary responses of these wetlands to alterations in sea level rise historically coastal wetland evolution has been driven by glacio isostatic adjustment gia with rates between 0 5 and 1 mm yr similar to sites in scotland and the northern and eastern baltic resulting in wetland progradation dating of the sedimentary horizons suggests broad agreement between sediment accretion rates derived from both the 210pb methods and 137cs impulse dating methods with average rates of sediment accretion being between 0 3 and 1 9 mm yr dependent on site and zonation sea level rise in the region is between 2 2 and 2 8 mm yr accounting for gia meaning that at present sea level rise appears to be outpacing sediment accretion resulting in negative elevation capital the results of this study indicate that recent increases in sea level as a result of climate change are likely to have reversed the historical trend of progradation driven by isostatic uplift coupled with sediment accretion suggesting that there may be losses of arctic coastal wetland extent and associated ecosystem services in some areas

fluid migration and origin of a mud volcano in the northern apennines italy the role of deeply rooted normal faults introductionsurface seeps of gas oil and salinewaters areconsideredtobeindicatorsof deep seated hydrocarbon accumu lationandhavebeenused forover60years as a guide to hydrocarbonprospectivity a wide spectrum ofseepages belongs to di erent geologi cal settings e g camerlenghi etal 1992 1995 thrasher etal 1996 schulz etal 1997 kopf etal 1998 graue 2000 spectacular seepagescan be found in basins with highsedimentation rates that generateoverpressureandmuddiapirism gu liev and feyzullayev 1996 up dipcarrier beds and active tectonic fea tures act as channels for subsurface uidandlocalizesurfaceemissionsuptotens orevenahundred kilometresfrom the reservoir thrasher etal 1996 during migration the domi nant mechanism that changeshydrocarbon composition is phasepartitioning migration of hydrocar bons is then largely the result ofbuoyancy of the free phase formedduringthisprocess matthews 1996 eventually thegeologyofthebasinisthe key to interpreting complicated uidmigrationpathways manystud ies simply focus on the oil and gascomponents of the migrating uidrather than on the characteristics ofthewaterandmudthatareassociatedwithhydrocarbonmigrationandalsoextruded by spontaneous seeps eventhough water is invoked as beingresponsibleforatleastlighthydrocar bon removal klusman and saaed 1996 watersofdi erentprovenancecontributetotheascending uidsandtheir geochemical characteristics canhelp in understanding their evolutionduring diagenesis and migration e g white 1965 hanor 1987 holyshandto th 1996 thispaperpresentssomeanalytical data from a spontaneoussurface seep bearing saline water mud gas and oil at the foothills ofthe northern apennines the aimsare i to provide some insight intothedepthandoriginofthe uidsandthe nature of the seepage pathway and ii tode nethelossofsubsurface uids accumulation related to thegeologicalpattern geological setting and structuralcontrol of the regnano mudvolcanoin the external portion of the nor thern apennines spontaneous uidemissions are distributed along twobelts borgia etal 1986 nanni andvivalda 1999 minissaleetal 2000 the rst belt stretches along the poplainfoothills whilethesecondoneisinternal and runs nearly parallel tothe main apenninic divide fig 1 theregnanomudvolcanoconsistsofmud breccias and mud ows spread ing over an area of 0 5km

active thrust tectonics in western sicily southern italy the 1968 belice earthquake sequence the 1968 belice earthquake sequence characterized by six main shocks with 5 m 5 4 represents the strongest seismic event recorded in western sicily in historical times the epicentral area is located in the belice valley a region lacking any topographic lineament likely to result from a fault with significant offsets of any kind instrumental data show that hypocentres of the major shocks are distributed along a roughly n dipping plane extending from about 36 km to 1 km depth fault plane solutions show pure thrusting mechanisms on n dipping ene trending planes or oblique slip with a right lateral component of motion along steep wsw dipping planes both as a result of approximate n s shortening the observed destruction indicates that isoseismal areas are elongated in an ene direction similarly the epiccntral distribution of events with m 4 outlines a roughly elliptical ene elongated area located 20 km nw of the sciacca rocca ficuzza thrust front this ene striking structure representing the regional morphotectonic feature closest to the epicentral area consists of two main imbricate fan systems in the southernmost system quaternary deposits tentatively dated as 1 0 0 7 myr old are involved in a large ramp anticline uplifting them to a maximum altitude of 346 m the occurrence of holocene lacustrine piggy back basins on the rear of this structure also indicates late quaternary activity of the underlying thrust seismological structural and morphotectonic observations suggest that multiple ruptures might have occurred during the 1968 sequence on a blind crustal thrust ramp located beneath the epicentral area slip propagated southwards along the shallow ramp flat system characterizing the thin skinned foreland fold and thrust belt of southwestern sicily being dispersed in flexural folding processes and diffuse strain along this path

the mw 5 4 reggio emilia 1996 earthquake active compressional tectonics in the po plain italy summary we have analysed the seismic sequence that occurred in october 1996 near the town of reggio emilia on the southern edge of the po plain the onset of the sequence was marked by a 5 4 moment magnitude main shock located at 15 km depth the main shock focal mechanism is a reverse solution with a strike slip component and the scalar moment is 1 46 1017 n m we used broad band digital recordings from a borehole station located at about 70 km from the epicentre for a spectral analysis in order to estimate attenuation and source parameters for the main shock in addition the empirical green s function method has been applied to evaluate the source time function in terms of both moment rate and stress rate we infer an asperity like rupture process for the main shock as suggested by the short duration of the stress release with respect to the overall duration of the moment rate function this analysis also allows us to estimate the average dynamic stress drop of the main shock 600 bar we analysed the digital recordings of the temporary local seismic network deployed after the main shock and of a permanent local network maintained by the italian petroleum agency agip during 15 days of field experiments we recorded more than 800 aftershocks which delineate a 9 km long ne elongated distribution confined between 12 and 15 km depth suggesting that the basement is involved in the deformation processes 102 focal mechanism of aftershocks have been computed from p wave polarities showing mainly pure reverse solutions we calculate the principal stress axes from a selected population of earthquakes providing a constraint on the stress regime of this part of the po plain the focal mechanisms are consistent with a n s subhorizontal 1 all the seismological data we have analysed confirm that this region is undergoing active compressional tectonics as already inferred from recent earthquakes geomorphological data and other stress indicators moreover the elongation of the reggio emilia aftershock sequence is consistent with the regional direction of the thrust fronts cropping out in the area suggesting that they are still active

influence of seismicity on the lusi mud eruption earthquakes trigger the eruption of mud and magmatic volcanoes and influence ongoing eruptive activity one mechanism that could trigger an eruption is clay liquefaction here we model the propagation of seismic waves beneath the lusi mud eruption east java indonesia using available seismic velocity and density models to assess the effect of subsurface structure on the amplification of incident seismic waves we find that using an updated subsurface density and velocity structure there is no significant amplification of incident seismic energy in the upper kalibeng formation the source of the erupting solids hence the hypothesis that the lusi eruption was triggered by clay liquefaction appears unlikely to be correct independent constraints from gas chemistry as well as analyses of drilling activities at the nearby banjar panji 1 gas exploration well and an analysis of the effects of other earthquakes all favor a drilling trigger

when mud volcanoes sleep insight from seep geochemistry at the dashgil mud volcano azerbaijan the worlds 1500 mud volcanoes are normally in a dormant stage due to the short duration of eruptions their dormant stage activity is often characterized by vigorous seepage of water gas and petroleum however the source of the fluids and the fluid rock interactions within the mud volcano conduit remain poorly understood in order to investigate this type of activity we have combined satellite images with fieldwork and extensive sampling of water and gas at seeping gryphons pools and salsa lakes at the dashgil mud volcano in azerbaijan we find that caldera collapse faults and e w oriented faults determine the location of the seeps the seeping gas is dominated by methane 94 9 99 6 with a 13c v pdb in the 43 9 to 40 4 range consistent throughout the 12 analysed seeps ethane and carbon dioxide occur in minor amounts seventeen samples of seeping water show a wide range in solute content and isotopic composition pools and salsa lakes have the highest salinities up to 101 043 ppm cl and the lowest 18o v smow values 1 4 the mud rich gryphons have low salinities 18 000 ppm cl and are enriched in 18o 18o 4 6 the gas geochemistry suggests that the gases migrate to the surface from continuously leaking deep seated reservoirs underneath the mud volcano with minimal oxidation during migration however variations in gas wetness can be ascribed to molecular fractionation during the gas rise in contrast the water shows seasonal variations in isotopic composition and surface evaporation is proposed as a mechanism to explain high water salinities in salsa lakes by contrast gryphons have geochemical signals suggesting a deep seated water source these results demonstrate that the plumbing system of dormant mud volcanoes is continuously recharged from deeper sedimentary reservoirs and that a branched system of conduits exists in the shallow subsurface while the gas composition is consistently similar throughout the crater the large assortment of water present reflects the type of seep i e gryphons versus pools and salsa lakes and their location within the volcano our data highlight the importance of a carefully planned sampling strategy when the target is water geochemistry whereas the methane content and isotopic composition is relatively independent of the particular seep morphology

erroneous sea ice concentration retrieval in the east antarctic large discrepancies have been observed between satellite derived sea ice concentrations ic from passive microwave remote sensing and those derived from optical images at several locations in the east antarctic between february and april 2014 these artefacts that resemble polynyas in the ic maps appear in areas where optical satellite data show that there is landfast sea ice the ic datasets and the corresponding retrieval algorithms are investigated together with microwave brightness temperature air temperature snowfall and bathymetry to understand the failure of the ic retrieval the artefacts are the result of the application of weather filters in retrieval algorithms these filters use the 37 and 19 ghz channels to correct for atmospheric effects on the retrieval these channels show significant departures from typical ranges when the artefacts occur a melt refreeze cycle with associated snow metamorphism is proposed as the most likely cause together the areas of the artefacts account for up to 0 5 of the antarctic sea ice area and thus cause a bias in sea ic time series in addition erroneous sea ics can adversely affect shipping operations

radon emissions from mud volcanoes in northern italy possible connection with local seismicity data concerning radon emission in waters filling mud volcanoes of northern apennines northern italy sampled from 1986 until 1989 have been analyzed possible connections between shallow environmental conditions and rn emission from mud volcanoes have been explored a linear relationship between air temperature and rn count rates has been determined after the removal of temperature related rn variations a significant correlation has been pointed out between anomalous spike like rn emissions at one of the station considered and the occurrence of low magnitude m 4 5 local earthquakes

triggering of volcanic eruptions although earthquakes and volcanic eruptions are each manifestations of large scale tectonic plate and mantle motions it is usually thought that the occurrences of these events are not directly related there have been some studies however in which triggering of volcanic eruptions by earthquakes remote from the volcano has been proposed1 2 the 1992 landers southern california earthquake caused triggered seismicity at very large distances3 including the magmatically active4 long valley caldera region which also experienced a significant coincident deformation transient5 motivated by this demonstration of the ability of a distant earthquake to disturb a volcanic system and the earlier studies of specific cases of eruption triggering we examine here the historical record of eruptions and earthquakes to see if there are indeed significantly more eruptions immediately following large earthquakes we find that within a day or two of large earthquakes there are many more eruptions within a range of 750 km than would otherwise be expected additionally it is well known6 that volcanoes separated by hundreds of kilometres frequently erupt in unison the characteristics of such eruption pairs are also consistent with the hypothesis that the second eruption is triggered by earthquakes associated with the first

methane emission from the mud volcanoes of sicily italy 1 mud volcanoes represent the largest expression of natural methane release into the atmosphere however the gas flux has never been investigated in detail methane output from vents and diffuse soil degassing is herewith reported for the first time measurements were carried out at 5 mud volcano fields around sicily italy each mud volcano is characterized by tens of vents and bubbling pools in the quiescent phase methane emission from single vents ranges between 0 01 and 6 8 kg day diffuse soil leakage around the vents is in the order of 102 104 mg m 2 d 1 an exceptional flux of 106 mg m 2 d 1 was recorded close to an everlasting fire soil ch4 flux is positive even at large distances from the mud volcano fields suggesting a diffuse microseepage over wider areas a total of at least 400 tons ch4 per year can be estimated over the area investigated alone 1 5 km2

interrelations of mud volcanism fluid venting and thrust anticline folding examples from the external northern apennines emilia romagna italy 1 the present work aims to provide an example of connection between fluid seepage and fault fracture zones associated with compressional thrust folds surface fluid seepage along the pede apennine margin consists of mud volcanism and methane rich emissions showing an intimate link with thrust related folds dominant gaseous or ch4 bearing fluid emissions characterize thrust fold settings in which fluid escape from the main reservoir and source rock i e the marnoso arenacea flysch is not impeded by a seal layer conversely remarkable mud volcanism is closely linked to the presence of the impermeable ligurian units sealing the marnoso arenacea reservoir structural analyses focused on selected thrust folds exhibiting clear relations between surface seepage and brittle elements associated with the fold various scenarios potentially explaining mud volcanism and venting over the crestal region of the thrust related folds are discussed with respect to fluid pressure state and the development of second order fault and fracture sets that are observed to control surface fluid expulsion it is proposed that mud volcanism can be potentially triggered by first order fault failure cycles during which the overpressured fluid is released during faulting events past anomalous eruptions associated with strong earthquakes seem to support this hypothesis the relatively quiescent but continuous activity of the current pede apennine mud volcanoes could instead reflect a short lived leakage of overpressured fluids along permeable fractures faults expansion of methane contained in the rising mud may assist this process fundamentally

geochemistry of gases and waters discharged by the mud volcanoes at paterno mt etna italy approximately 20 km south of mt etna craters at the contact between volcanic and sedimentary formations three mud volcanoes discharge co2 rich gases and na cl brines the compositions of gas and liquid phases indicate that they are fed by a hydrothermal system for which temperatures of 100 150 c were estimated by means of both gas and solute geothermometry the hydrothermal system may be associated with co2 rich groundwaters over a large area extending from the central part of etna to the mud volcanoes numerous data on the he ch4 co2 composition of the gases of the three manifestations sampled over the past 5 years indicate clearly that variations are due to separation processes of a co2 rich gas phase from the liquid the effects of these processes have to be taken into account in the interpretation of the monitoring data collected for the geochemical surveillance of etna volcano

origin of light hydrocarbons in gases from mud volcanoes and ch4 rich emissions abstract this paper presents new chemical data of hydrocarbon rich gases discharged from mud volcanoes and ch4 rich emissions located in different areas of italy northern apennines and sicily the determination of c5 c10 alkanes cyclics and aromatics was carried out by gc ms while the main gas species and c1 c4 hydrocarbons were analyzed by gc tdc and gc fid respectively methane is by far the most abundant component of all the investigated gas emissions with the exception of part of those discharging close to mt etna volcano which are co2 rich the gas samples collected from the emilia apennine and sicily show d ch4 and 13c ch4 values typical of thermogenic gases most gases from the romagna apennine discharge methane with a biogenic isotopic signature non methane hydrocarbons of biogenic gases are almost exclusively c2 c4 alkanes with minor amounts fraction of mol mol of c4 compounds including few aromatics and cyclics likely deriving from minor thermogenic contribution not evidenced by the 13c ch4 and d ch4 values the etnean gases whose r ra and 13c co2 values indicate a strong contribution from a hydrothermal fluid source related to the nearby volcanic system show a significant enrichment of aromatics compounds up to 36 of the non methane organic gas fraction which is likely produced by catalytic reforming processes such as dehydrocyclization of alkanes the thermogenic gases from the apennines and southwestern sicily are characterized by the presence of more than 20 different cyclic compounds with concentrations up to several mol mol cyclic compounds are likely formed by i thermal cracking and ii uncompleted aromatization of alkanes occurring at depth 3 km and temperatures not exceeding 120 150 c

evidence of late holocene mud volcanic eruptions in the modena foothills northern italy among natural hazards mud volcanoes can damage property and infrastructures and affect hillslope evolution at different spatial and temporal scales the results of 10 year long multidisciplinary i

geomorphic evidence for an emergent active thrust along the edge of the po plain the broni stradella fault 1 we present here geomorphic evidence for an emergent active thrust along the northwestern apennine front about 50 km south of milano fieldwork combined with spot image analysis attests to the presence of a 35 km long en echelon cumulative fault scarp that cuts e w across quaternary surface deposits from casteggio to sarmato the scarp offsets vertically alluvial fans and terraces emplaced by tributaries of the po river that flow northward from the apennines incision by such tributaries occurs only south of the scarp valleys of smaller streams stand in hanging position to the northeast the buried east dipping pavia lateral ramp bounds the san colombano anticline we interpret the montebello sarmato scarp to result from the emergence of an active thrust fault dipping south the stradella thrust which splays eastward from that ramp total station profiles leveled perpendicular to the stradella thrust show variable cumulative surface throws ranging from 2 to 25 m scarp degradation analysis indicates fairly recent offset of the terrace surfaces 10 100 kyr suggesting a minimum uplift rate of 0 3 mm yr the underlying fault might thus be one of the most active thrust ramps along this segment of the apennines n s to n15 w shortening is consistent with both the e w strike of this thrust ramp and with coeval oblique sinistral motion on the nne ssw trending pavia lateral ramp the vogherese bobbiese earthquake of 1828 i ix south of casteggio and broni may have activated one segment of this lateral ramp rather than the stradella thrust other historical events i 7 that caused damage in pavia piacenza lodi and milano in the last 2000 years 290 a d 1249 a d 1276 a d 1473 a d may have occurred on the broni stradella thrust or on the blind san colombano and lodi thrusts farther north this makes detailed paleoseismological studies and trenching across its trace mandatory

fluid seepage variability across the external northern apennines italy structural controls with seismotectonic and geodynamic implications abstract the relations between fluid seeps and tectonic structures have been targeted in some key areas of the axial sector and partly at the edge of the exposed northern apennines pede apennine margin in the axial zone fluid seepage is dominated by methane venting which may occur in the form of dry seeps or associated with mineral springs surface venting is linked to the presence of foreland dipping normal faults or related to reservoirs localised at inactive anticlines the pede apennine margin is instead dominated by thrusting and mud volcanism the two different categories of fluid seepage appear strongly coupled to the dissimilar stress fields compressional or extensional operating in these sectors pressure data inferred from deep wells delineate an overall fluid pressure increase from the axial zone toward the pede apennine margin possibly as a result of the growth of tectonic compaction in this direction the increase of fluid pressure at the pede apennine margin is thus interpreted as the primary control on the transition from dry vents to mud volcanism the intimate association between seepage modes and distinct tectonic structures involves relevant consequences on fluid fault interactions and seismotectonics and also shows connections with processes dictating the internal deformation of evolving fold and thrust belts

tomographic models and seismotectonics of the reggio emilia region italy the aim of this study is to define the vp and vp vs structure of the fault zone ruptured by the ml 5 1 earthquake of october 15 1996 which occurred near reggio emilia central northern italy a 1 month long seismic sequence followed the mainshock and occurred in a small region along the outer border of the northern apenninic belt at depth ranging between 10 and 17 km p and s wave arrival times from 304 aftershocks recorded by two local dense seismic arrays installed in the epicentral region have been inverted to obtain one and three dimensional velocity models by using state of the art local earthquake tomographic techniques velocity models and aftershock relocation help us to infer the seismotectonic of the region earthquakes originated along a nw dipping backthrust of a ne trending main thrust composing the western part of the broad ferrara arc a main high vp and high vp vs region delineates a pop up structure in the center of the area the high vp vs within the pop up structure supports the presence of a zone with increased pore pressure the hypocentral depth of both mainshock and aftershocks is greater than those usually found for the main seismogenic regions of the apenninic belt p wave velocity values in the seismogenic area obtained by tomography are compatible with rocks of the mesozoic cover and suggest that seismicity occurred within the mesozoic units stack at present by compressional tectonics

the east java mud volcano 2006 to present an earthquake or drilling trigger abstract on may 29th 2006 a mud volcano later to be named lusi started to form in east java it is still active and has displaced 30 000 people the trigger mechanism for this the world s largest and best known active mud volcano is still the subject of debate trigger mechanisms considered here are a the may 27th 2006 yogyakarta earthquake b the drilling of the nearby banjar panji 1 gas exploration well 150 m away and c a combination of the earthquake and drilling operations we compare the distance and magnitude of the earthquake with the relationship between the distance and magnitude of historical earthquakes that have caused sediment liquefaction or triggered the eruption of mud volcanoes or caused other hydrological responses based on this comparison an earthquake trigger is not expected the static stress changes caused by the rupture of the fault that created the yogyakarta earthquake are a few tens of pascals much smaller than changes in stress caused by tides or variations in barometric pressure at least 22 earthquakes and possibly hundreds likely caused stronger ground shaking at the site of lusi in the past 30 years without causing an eruption the period immediately preceding the eruption was seismically quieter than average and thus there is no evidence that lusi was primed by previous earthquakes we thus rule out an earthquake only trigger the day before the eruption started may 28th 2006 as a result of pulling the drill bit and drill pipe out of the hole there was a significant influx of formation fluid and gas the monitored pressure after the influx in the drill pipe and annulus showed variations typical of the leakage of drilling fluid into the surrounding sedimentary rock strata furthermore we calculate that the pressure at a depth of 1091 m the shallowest depth without any protective steel casing exceeded a critical level after the influx occurred fractures formed due to the excess pressure allowing a fluid gas mud mix to flow to the surface with detailed data from the exploration well we can now identify the specific drilling induced phenomena that caused this man made disaster

stratigraphic variations control deformation patterns in evaporite basins messinian examples onshore and offshore sicily italy three dimensional seismic data are increasingly resolving original compositional heterogeneity and structural complexity in evaporitic successions within sedimentary basins the relationship between basin structure evaporite composition and its influence on subsequent deformation are investigated here using messinian examples from the maghrebian thrust system of sicily and applied to the adjacent ionian sea bed by integrating outcrop and onshore subsurface data we demonstrate variations in evaporite stratigraphies deposited across thrust top basins and how these variations have controlled subsequent deformation of these basins gypsum and carbonate units develop broad single layer buckle fold trains with wavelengths reflecting layer thickness the development of deformation appears limited by bending resistance at fold hinges which can be overcome by syntectonic erosion in contrast the thick halite and k salt accumulations in growth synclines have deformed with short wavelength folds and distributed strain these structures can display rapid lateral variations on a scale of hundreds of metres similar structural styles with buckle fold trains passing laterally into more homogeneously shortened short wavelength folding are evident on seismic data from the buried messinian interval beneath the ionian sea using the sicilian outcrop as analogues the structural styles for the ionian may be used to infer evaporite type in these subsurface examples

the migration of plate boundaries in se sicily influence on the large scale kinematic model of the african promontory in southern italy abstract a detailed field mapping coupled with structural analyses and morphological investigation has been carried out along the northern and western borders of the hyblean plateau se sicily in order to define the nature and the kinematics of a major quaternary fault belt this here designed as the scicli line fault belt is composed of two n50 oriented extensional basins that linked by a regional n10 trending transfer zone originated during the early pleistocene and experienced since the late quaternary a positive tectonic inversion in both the two stages of deformation the scicli line fault belt has been characterised by displacement rate comparable with the relative velocities measured between the distinct plates composing the central mediterranean region in the period going from 1 5 1 2 to 0 85 ma the fault belt accommodated the entire divergence between adria and nubia at present the scicli line fault belt absorbs most of the nubia eurasia convergence while the western divergent margin of the adria microplate has jumped to the eastern and the southern margins of the hyblean plateau along the late quaternary siculo calabrian rift zone the off shore prolongation of the two tectonic boundaries of the hyblean plateau has been recognised in the sicily channel where they are both interrupted by a wnw ese oriented dextral fault according to our reconstruction the hyblean plateau represents an isolated lithospheric block whose evolution can be related to the propagation of the western divergent margin of the adria microplate accompanied with the southward migration of the triple junction between eurasia nubia and adria in this new large scale kinematic picture the gps velocity measured in the hyblean region at the permanent site of noto is actually representative of the local kinematics rather than of the entire african promontory of southern italy this implies a correction of previous regional kinematic models based on combination of gps vectors in particular our data constrain a new interpretation both for the kinematics along the e w oriented nubia eurasia margin dominated by prevalent dextral deformation rather than reverse motions and for the intraplate deformation in the sicily channel within the africa promontory which would be dominated by a roughly n110 oriented extension this conclusion has implication also on the mechanism and the origin of the pantelleria linosa malta rift that is here interpreted as a transtensive feature developed along a major transform fault rather than the result of passive rifting induced by the nubia eurasia collision as it is currently interpreted

earthquake forerunners in a selected area of northern italy recent developments in automatic geochemical monitoring abstract this article describes the monitoring of certain mud volcanoes in the northern apennines of italy this monitoring was carried out from a geochemical point of view and its aim was to verify the seismic precursory nature of the mud volcano fluids the operational strategy began by determining the regional character of the main physical and chemical precursors and a multidisciplinary approach to the historical research was used to achieve this the utility of such an approach in monitoring strategy has been confirmed a series of experiments was carried out to identify the physical model the main geochemical characteristics and the origin of the seismic precursory phenomena with particular reference to radon 222 the technological apparatus necessary for a reliable automatic continuous monitoring system of the geochemical parameters of mud volcanoes were then extensively tried out the first results of this monitoring system refer to dec 1988 jan 1989 in this period there were some seismic events which were preceded by certain phenomena we can call precursory an interpretative model has been created from all the information collected so that similar situations can be better understood from a physical and chemical point of view

elliptical mud volcano caldera as stress indicator in an active compressional setting nirano pede apennine margin northern italy the relations between mud volcanism and active tectonic strain were investigated at the nirano mud volcano field nmvf near the active pede apennine thrust front of the northern apennines thrust and fold belt italy active fluid release occurs through numerous vents within an elliptical depression developed over the crest of a thrust related anticline this depression is interpreted as a caldera collapse like structure that may have developed in response to the deflation of a shallow mud chamber triggered by eruption and sediment fluid evacuation events like many volcanic calderas the nmvf caldera is elongated nearly parallel to the direction of least horizontal compressive stress s h and is thus deduced to reflect the regional tectonic stress axes it is concluded that mud volcano calderas exhibit mechanical similarities to the igneous analogs and that the methods used in this first test could be applied to other calderas imaged by seismic data and in the field

geochemical characterization of the nirano mud volcano italy abstract the nirano mud volcano is located in the western sector of the modena apennine margin italy it represents one of the most spectacular phenomena of sedimentary volcanism in the entire italian territory and is among the largest in europe here numerous aligned gryphon clusters and seeping pools constantly burst gas and mud inside a morphological depression besides the obvious surface expressions of these emission spots until now the type and amount of gas released in the rest of the large nirano caldera zone remained unknown an extensive geochemical soil gas survey o2 n2 co2 ch4 222rn he h2 and light hydrocarbons and exhalation fluxes co2 and ch4 was carried out inside the mud volcano field with the aim of identifying soil degassing distribution and to estimate the micro and macro seepage budget for both co2 and ch4 soil gas data highlight the presence of two zones characterized by high concentrations and flux values these enhanced seepage zones are located in the sw and ne sectors of the mud volcano suggesting that the enhanced gas emissions present in the peripheral zones are controlled by caldera collapse structures the most significant co2 flux up to 91 g m 2 d 1 and 222rn anomalies are located in the central part of the crater in correspondence of a morphological escarpment here we infer the presence of a buried tectonic system of collapsed terraces that facilitate fluids degassing in contrast ch4 fluxes show a scattered distribution and low values mean 221 mg m 2 d 1 overall the ch4 degassing budget is low 27 09 t km 2 y 1 when compared with other italian mud volcanoes this could be related to a relative low emission activity during the period of the geochemical survey and to a more homogeneous dilution of surface distribution of the emission point s chemical and isotopical composition of the gas discharged from the active gryphons is methane dominated and the thermogenic signature ranging from 41 to 47 suggests a deep reservoir source this conclusion is supported by noble gas measurements he ne ar kr xe conducted in the pore water phase of the emitted mud indicating a secondary gas exchange occurring at a depth of a few kilometers the geochemical anomalies found in this study successfully predicted the occurrence of new degassing phenomena towards the ne sector of the caldera indeed recently i e after the survey data acquisition new manifestations of mud and gas emissions appeared in the north eastern edge of the caldera

liquefaction limit during earthquakes and underground explosions implications on ground motion attenuation liquefaction of saturated soils and sediments documented during earthquakes shows an empirical relation log r max 2 05 0 10 0 45 m where r max is the liquefaction limit in meters i e the maximum distance from liquefaction site to the hypocenter and m is the earthquake magnitude combining this with an empirical relation between m and the seismic energy of an earthquake we obtain a relation between the liquefaction limit and the seismic energy e a r max the prefactor corresponds to a threshold energy for liquefaction ranging from 0 004 to 0 1 j m3 the exponent ranging from 3 2 to 3 3 implies that the energy density of ground motion attenuates with distance according to 1 r 3 2 3 3 where r is the distance from the hypocenter the value of the threshold energy suggests a preliquefaction degradation of the shear modulus of soils by more than 3 orders of magnitude liquefaction documented during underground explosions is characterized by a threshold energy several orders of magnitude greater than that for liquefaction during earthquakes but shows a similar functional relation between e and r max as that for liquefaction during earthquakes and implies a similar attenuation relation between ground motion energy density and distance

a geochemical approach to earthquake reconnaissance at the baratang mud volcano andaman and nicobar islands abstract variations in the relative composition of constituent gases coming out of the mud volcano near jarwa creek in baratang island middle andaman are discussed on the basis of regional tectonic settings and seismo geochemical features the most abundant gas is ch4 55 7 vol followed by n2 32 2 o2 ar 9 9 co2 2 0 and he 0 2 concentration of the radioactive gas 222rn is relatively high 7500 bq m3 this paper discusses the experimental methods adopted to continuously monitor he ch4 co2 and 222rn with a view to identify pre seismic gas concentration anomalies associated with regional seismic occurrences results related to this gas geochemical monitoring are presented with a purpose to develop ability in ascribing a distinct geochemical anomaly to a particular seismic activity in the region