98 research outputs found
Point Cloud Data Ikka Fjord Greenland 2019
No full textPoint Cloud Data from the Ikka Fjord in Greenland 201
Deflation of the Askja volcanic system: Constraints on the deformation source from combined inversion of satellite radar interferograms and GPS measurements
No full textThe Askja central volcano in northern Iceland has been continuously subsiding at least since 1983. GPS and optical leveling tilt measurements show subsidence of at least 75 cm from 1983 to 1998 in the center of the Askja caldera, without any eruptive activity. We have performed an interferometric analysis of Synthetic Aperture Radar images (InSAR) of the area, utilizing data from the ERS satellites. We observe subsidence of the Askja caldera and its fissure swarm, up to a distance of 25 km from the volcano. We evaluate the geometry of the magma chamber at Askja, from a combined inversion of satellite radar interferograms and GPS measurements. Several models were tested, including a Mogi point source as well as an ellipsoidal source. The use of an ellipsoidal source instead of a Mogi source gives an estimate of the dimensions of the magma chamber and its deflating pressure, whereas these parameters are not independently resolved if a Mogi source is used. Two-source models were also considered in order to explain the additional subsidence observed along the Askja fissure swarm. We tested a model using two Mogi sources at different depths, a shallow ellipsoidal cavity with a deeper Mogi source, and then a shallow Mogi source with a deeper elongated ellipsoid, oriented along the fissure swarm. Results indicate that an ellipsoidal source at about 3 km depth can accommodate most of the deflation occurring in the caldera. Residual subsidence occurs along the Askja fissure swarm suggesting the existence of a deeper source of contraction. We interpret this signal in terms of subsidence of the plate boundary
A new interpretation of the sedimentary cover in the western Siljan Ring area, central Sweden, based on seismic data
No full textAbstractTwo new reflection seismic profiles over the Paleozoic successions of the western part of the Siljan Ring impact structure show a contrasting seismic signature. The more southerly c. 10km long Mora profile reveals a highly disturbed structure, with only a few kilometers of relatively horizontally layered structures observed. However, interpretations of refracted arrivals in the data, that can be correlated to reflections, indicate the Silurian clastic rocks to be about 200m thick in the central part of the profile. Weak reflections from about 600m depth suggest a 400m thick Ordovician limestone sequence to be present. Cores from the area show a mainly shale lithology for the Silurian and only a thin sequence of Ordovician strata, suggesting a rapid thickening of the Ordovician towards the north. On the more northern c. 12km Orsa profile clear reflections from the Paleozoic successions are seen along the entire profile, except on the southernmost few kilometers. Based on interpretations of refracted arrivals, the Silurian succession appears to be considerably thinner here, and possibly absent at some locations. The Ordovician is also interpreted to be thinner in this area, with a maximum thickness of about 200–300m along most of the profile. A deeper reflection from about 2km within the crystalline basement may represent a dolerite sill. The lack of clear basement reflections on the Mora profile can be attributed to near-surface conditions and the acquisition geometry. The seismic data and recent coring in the area suggest the presence of a deeper paleo-basin towards the southwest with significantly more shales being deposited and the Paleozoic successions being severely disturbed. The shallow coring and seismic data will help form the basis for locating future boreholes for deeper drilling to study impact processes and the Paleozoic evolution of central Sweden
Glacio-isostatic deformation around the Vatnajokull ice cap, Iceland, induced by recent climate warming: GPS observations and finite element modeling
No full textGlaciers in Iceland began retreating around 1890, and since then the Vatnajökull ice cap has lost over 400 km3 of ice. The associated unloading of the crust induces a glacio‐isostatic response. From 1996 to 2004 a GPS network was measured around the southern edge of Vatnajökull. These measurements, together with more extended time series at several other GPS sites, indicate vertical velocities around the ice cap ranging from 9 to 25 mm/yr, and horizontal velocities in the range 3 to 4 mm/yr. The vertical velocities have been modeled using the finite element method (FEM) in order to constrain the viscosity structure beneath Vatnajökull. We use an axisymmetric Earth model with an elastic plate over a uniform viscoelastic half‐space. The observations are consistent with predictions based on an Earth model made up of an elastic plate with a thickness of 10–20 km and an underlying viscosity in the range 4–10 × 1018 Pa s. Knowledge of the Earth structure allows us to predict uplift around Vatnajökull in the next decades. According to our estimates of the rheological parameters, and assuming that ice thinning will continue at a similar rate during this century (about 4 km3/year), a minimum uplift of 2.5 meters between 2000 to 2100 is expected near the current ice cap edge. If the thinning rates were to double in response to global warming (about 8 km3/year), then the minimum uplift between 2000 to 2100 near the current ice cap edge is expected to be 3.7 meters
”Jag känner mig inte lika ensam” - Socialmedicinsk samverkan mellan huvudmän, för personer med missbruks- och beroendeproblem i Götene kommun
No full textSyftet med denna studie är att undersöka den socialmedicinska samverkan mellan huvudmän för personer med missbruks- och/eller beroendeproblem i Götene kommun. Avtalet och samverkansgruppen har varit aktiva sedan hösten 2010. Under de år som har passerat har de upprättat individuella vårdplaner för ca 40 personer.
Frågeställningarna i denna studie är inriktade på att se hur samverkan har utvecklat sig över tid; vilka förutsättningarna har varit för att få till en fungerande samverkan; hur de professionella rollerna har utvecklats och vilken nivå av samverkan man har nått samt vilket resultatet har varit för brukarna.
En kvalitativ metod har använts för att besvara studiens frågeställningar. Det har genom-förts en fokusgruppsintervju med deltagarna i samverkansgruppen samt en kompletterande individuell intervju, sammanlagt åtta intervjupersoner. Enskilda intervjuer har genomförts med deras respektive enhetschefer som var sex personer sammanlagt. Möjligheten att även intervjua brukare har övervägts men valts bort av olika anledning, främst på grund av tidsbrist.
Resultaten i studien visar att samverkansgruppen i Götene har uppnått en hög nivå av samverkan och att de trivs bra med varandra i gruppen. Samverkan har blivit ett stöd för dem i deras dagliga arbete, såväl som en källa till kunskap och ett gott rykte för Götene kommun. Enhetscheferna och samverkansgruppen är mer eller mindre överens kring vilka de positiva effekterna är för brukarna. Den har lett till en mer effektiv och bättre planerad vård. Den har även sparat resurser och förbättrat relationen mellan medlemmarna i samverkansgruppen. Svårigheterna som har identifierats har handlat om bristande resurser inom öppenvårds-psykiatrin, vilket har lett till att de inte alltid har kunnat delta i samverkan fullt ut.
Slutsatserna i studien är att samverkansgruppen i Götene fungerar bra, mycket på grund av att de har en väl inarbetad samverkansrutin samt att deltagarna i samverkansgruppen trivs bra med varandra. Viktiga faktorer för samverkan har varit att ha ett väl etablerat samverkansavtal, att deltagarna i samverkan har tillräckliga mandat samt att organisationerna har tillräckliga resurser för att utföra sina olika uppdrag
Pressure sources versus surface loads: Analyzing volcano deformation signal composition with an application to Hekla volcano, Iceland
No full textThe load of lava emplaced over periods of decades to centuries induces a gradual viscous response of the Earth resulting in measurable deformation. This effect should be considered in source model inversions for volcanic areas with large lava production and flow emplacement in small centralized regions. If deformation data remain uncorrected, constructive load and pressure source interference may result in an overestimate of depth and volume of a magma reservoir whereas destructive signal interference may cause these values to be underestimated. In both cases the source geometry preference could be biased. The ratio of horizontal and vertical displacements aids the identification of composite signals. We provide a method to quantify and remove the lava load deformation signals, using deformation at Hekla volcano, Iceland as an example.Remote SensingAerospace Engineerin
Paradiset som försvann (The lost paradise)
No full textGeodynamics geophysics and tectonics; Petrology igneous metamorphic and volcanic studies
Paradiset som försvann (The lost paradise)
No full textGeodynamics geophysics and tectonics; Petrology igneous metamorphic and volcanic studies
Oxygen isotopes and implications for the cavity-grown quartz crystals in the Lockne impact structure, Sweden
No full textWell-developed quartz crystals are found in open cavities in the intensely fractured crystalline basement of the marine-target impact structure at Lockne in central Sweden. The 458 Ma impact structure has a well-preserved crater in Precambrian granitic basement rock that is covered by resurge deposits composed of breccias and fine-grained sedimentary units of mixed Ordovician limestone, Cambrian black bituminous shales and the basement granite. Directly after the impact, the resurge deposits formed when the seawater rushed back into the crater. The residual heat from the impact facilitated a short-lived hydrothermal system accompanied by the inflowing seawater, which resulted in mineral growth in fractures and open cavities of the granite basement. The oxygen isotope values of the first-precipitated minerals, the cavity-grown quartz crystals, range from +15.2 to +16.2‰ (Vienna Standard Mean Ocean Water) and differ from those of the hosting granite basement rock with δ18O quartz between +10.1 and +11.7‰. The δ18O values of the quartz are more consistent with derivation from a fluid of relatively high δ18O probably attributable to oxygen isotope exchange during seawater–rock interactions in the resurge deposits. The occurrence of organic matter in association with the cavity-grown quartz strongly indicates a relationship to the black bituminous shale in the matrix of the breccia that rests on the crater floor. Comparing the results with previously obtained oxygen data on fracture-grown calcite from Lockne shows that oxygen isotope composition of the cavity-grown quartz crystals is less variable and probably more accurately reflects the original fluid source
Temperature-Dependent Newtonian Rheology in Advection-Convection Geodynamical Model for Plate Spreading in Eastern Volcanic Zone, Iceland
No full textGeodynamic process as advection-convection of the Mid-Atlantic Ocean Ridge (MAR), that is exposed on land in Iceland is investigated. Advection is considered for the plate spreading velocity. Geodetic GPS data during 2000-2010 is used to estimate plate spreading velocity along a profile in the Eastern Volcanic Zone (EVZ), Iceland striking N102˚E, approximately parallel to the NUVEL-1A spreading direction between the Eurasian and North American plates. To predict subsurface mass flow patterns, temperature-dependent Newtonian rheology is considered in the finite-element models (FEM). All models are considered 2-D with steady-state, incompressible rheology whose viscosity depends on the subsurface temperature distribution. The thickness of lithosphere along the profile in the EVZ is identified by 700˚C isotherm and 1022 Pa s iso-viscosity, those reach 50 ± 3 km depth at distance of 100 km from rift axis. Geodetic observation and model prediction results show the ~90% of spreading is accommodated within ~45 km of the rift axis in each direction. Model predicts ~8.5 mm∙yr−1 subsidence at the surface of rift center when magmatic plumbing is inactive. The rift center (the highest magmatic influx is ~11 mm∙yr−1) in model shifts ~10 - 20 km west to generate observed style surface deformation. The spreading velocity, isotherm and depth of isotherm are the driving forces resulting in the surface deformation. These three parameters have more or less equal weight. However, as the center of deformation in the EVZ shifts and most of the subsidence takes place in the volcanic system that is currently the active which is the located of plate axis
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