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  • 1.
    Conze, Ronald
    et al.
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Lorenz, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Ulbricht, Damian
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Elger, Kirsten
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Gorgas, Thomas
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Utilizing the International Geo Sample Number Concept in Continental Scientific Drilling During ICDP Expedition COSC-12017Ingår i: Data Science Journal, ISSN 1683-1470, E-ISSN 1683-1470, Vol. 1, nr 1, 1-8 s., 16:2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The International Geo Sample Number (IGSN) is a globally unique persistent identifier (PID) for physical samples that provides discovery functionality of digital sample descriptions via the internet. In this article we describe the implementation of a registration service for IGSNs of the Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences. This includes the adaption of the metadata schema developed within the context of the System for Earth Sample Registration (SESAR1) to better describe the complex sample hierarchy of drilling cores, core sections and samples of scientific drilling projects. Our case study is the COSC-1 expedition2 (Collisional Orogeny in the Scandinavian Caledonides) supported by the International Continental Scientific Drilling Program3 (ICDP). COSC-1 prompted for the first time in ICDP’s history to assign and register IGSNs during an on-going drilling campaign preserving the original parent-child relationship of the sample objects. IGSN-associated data and metadata are distributed and shared with the world wide community through novel web portals, one of which is currently evolving as part of ICDP’s collaborative efforts within the GFZ Potsdam and researchers from ICDP’s COSC clientele. Thus, COSC-1 can be considered as a ‘Prime-Example’ for ICDP projects to further improve the quality of scientific research output through a transparent process of producing and managing large quantities of data as they are normally acquired during a typical scientific drilling operation. The IGSN is an important new player in the general publication landscape that can be cited in scholarly literature and also cross-referenced in DOI-bearing scholarly and data publications.

  • 2.
    Muhamad, Harbe
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Geophysical studies in the western part of the Siljan Ring Impact Crater2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis utilizes several geophysical methods to study the Siljan Ring impact structure, focusing on the western part of the structure. This thesis, and the three papers upon which it is based, reports on attempts to delineate the Paleozoic rocks at depth within the annular ring graben and characterize their structure. In addition, the nature of the basement, which underlies these sedimentary rocks is investigated.

    Papers I and III focus on analysis of the down-hole logging and borehole core data. As well as the acquisition, processing and interpretation of 2D high-resolution reflection seismic data from the Mora area. The borehole log responses were compared with the core lithology from the Mora 001 borehole and information from two other cores (Mora VM 2 and Mora MV 3) in order to interpret the logs. The logs reveal significant changes in the lithology between boreholes, indicating a very high level of structural complexity, which is attributed to impact tectonics. In addition, the log data revealed a high sonic velocity contrast between the Silurian and Ordovician successions and a higher apparent temperature gradient than in the northern part of the structure. The interpretation of the high-resolution 2D seismic data suggest that the Mora area has been significantly affected by the impact. Several potential faults were identified in the area and interpreted to be post depositional and related to the impact. In paper II, a 2D seismic profile from the Orsa area (12 km) located in the northwestern part of the Siljan Ring was re-processed. To compliment this seismic line, first break traveltime tomography results, vintage seismic OPAB profiles, new and pre-existing gravity data, aeromagnetic data and the bedrock geological map were used to present a geological model along the Orsa profile. Reprocessing of the seismic data resulted in improved stacked and migrated sections and better imaging of the top of the crystalline basement than the original processing. Integrated interpretation of the seismic profiles suggests that the area has been significantly affected by faulting and that the depth to the basement varies greatly along the different profiles.

    Delarbeten
    1. Analysis of borehole geophysical data from the Mora area of the Siljan Ring impact structure, central Sweden
    Öppna denna publikation i ny flik eller fönster >>Analysis of borehole geophysical data from the Mora area of the Siljan Ring impact structure, central Sweden
    Visa övriga...
    2015 (Engelska)Ingår i: Journal of Applied Geophysics, ISSN 0926-9851, Vol. 115, 183-196 s.Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The Siljan impact structure is the largest known impact structure in Europe, the result of a Late Devonian meteorite impact (380.9 +/- 4.6 Ma). It is outlined mainly by a ring of lakes and Palaeozoic sedimentary rocks of Ordovician to Devonian age. The Palaeozoic successions are generally poorly exposed, but often well preserved with clear stratigraphy. At some locations they are strongly tectonised with sharply inclined or nearly overturned packages of crystalline basement and/or sediments. Down-hole logging data were acquired in the western part of the Siljan impact structure to determine some of the physical properties of the Palaeozoic sedimentary rocks in the area. Boreholes Mora 001 (356 m logged depth), Vattumyra Production (420 m logged depth), Mora VM 2 (94 m logged depth) and Mobillyft (437 m logged depth) were logged for temperature, sonic velocity and electrical resistivity. Logging data were compared to the lithology in the Mora 001 core, which had been mapped in detail, and information from other cores in the area. Good agreement between the natural gamma log and the core lithology was found. The sonic log shows a marked difference in velocity for the more clastic Silurian succession compared to the Ordovician succession and the Precambrian basement. A synthetic seismogram shows that a high amplitude reflection is expected at the Silurian-Ordovician boundary, raising some questions concerning interpretation of a seismic profile located about 6-7 km north of the study area. Correlation of the borehole logs shows that the thickness of the Silurian succession varies rapidly in the area and that its composition differs over distances of less than 1 km. These rapid variations suggest that the study area may be located in a megablock zone that was highly influenced by the impact Caledonian tectonics and changing depositional environments may also play a role in explaining the present-day borehole lithologies. Even though the boreholes are relatively far from the seismic profile and the geology is complex, the new data confirm that the Silurian has significant thickness along parts of the seismic profile. Potentially, the Silurian can be up to 450 m thick on parts of the profile. Further geophysical investigations in the area, including seismic surveying and gravity measurements, may help in mapping the complex structures away from the boreholes and discriminating between possible geological models.

    Nyckelord
    Siljan impact structure, Sweden, Down-hole logging, Palaeozoic rocks
    Nationell ämneskategori
    Geofysik
    Identifikatorer
    urn:nbn:se:uu:diva-258831 (URN)10.1016/j.jappgeo.2015.02.019 (DOI)000351646900018 ()
    Tillgänglig från: 2015-07-23 Skapad: 2015-07-20 Senast uppdaterad: 2017-01-25Bibliografiskt granskad
    2. Integrated interpretation of geophysical data of the Paleozoic structure in the northwestern part of the Siljan Ring impact crater, central Sweden
    Öppna denna publikation i ny flik eller fönster >>Integrated interpretation of geophysical data of the Paleozoic structure in the northwestern part of the Siljan Ring impact crater, central Sweden
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Geofysik
    Identifikatorer
    urn:nbn:se:uu:diva-311546 (URN)
    Tillgänglig från: 2016-12-28 Skapad: 2016-12-28 Senast uppdaterad: 2017-01-04
    3. High-resolution seismic imaging of Paleozoic rocks in the Mora area, Siljan Ring structure, central Sweden
    Öppna denna publikation i ny flik eller fönster >>High-resolution seismic imaging of Paleozoic rocks in the Mora area, Siljan Ring structure, central Sweden
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Geofysik
    Identifikatorer
    urn:nbn:se:uu:diva-312020 (URN)
    Tillgänglig från: 2017-01-04 Skapad: 2017-01-04 Senast uppdaterad: 2017-01-04
  • 3.
    Shirzad, Taghi
    et al.
    Islamic Azad Univ, Dept Phys, Damavand Branch, Damavand 39715194, Iran..
    Shomali, Zaher-Hossein
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik. Univ Tehran, Inst Geophys, Tehran 141556466, Iran..
    Riahi, Mohammad-Ali
    Univ Tehran, Inst Geophys, Tehran 141556466, Iran..
    Jarrahi, Maziar
    Pars Petro Zagros Geophys Co PPZG, Tehran, Iran..
    Near surface radial anisotropy in the Rigan area/SE Iran2017Ingår i: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 694, 23-34 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By analyzing Rayleigh and Love wave empirical Green's functions extracted from ambient seismic noise and earthquake data, we obtained near surface radial anisotropy structure beneath the hidden part of the Kahurak fault in the Rigan region, in the southeast oilcan. The deduced seismic radial anisotropy within the hidden part of the Kahurak fault can reveal record of shallow crustal deformation caused by the Rigan earthquake (M-W 6.5) occurred on 20 December 2010. Significant radial anisotropy with positive magnitude (V-SH > V-SV) appears in the shallow subsurface of the upper part of the crust. The magnitude of radial anisotropy varies from predominantly positive (V-SH > V-SV) to mostly negative (V-SH < V-SV) values with increasing depth which is correlated with a known sedimentary layer. The sedimentary layer is observed with prominent positive radial anisotropy (V-SH > V-SV). The thickness of the sedimentary layer varies between 1 and 3 km from the south to the north beneath the study area with an average radial anisotropy of about 5%. However, cross-section profiles indicate that negative ahomaly stretches inside a thick sedimentary layer where the aftershocks occurred. Also, the investigation of cross-section profiles reveals that a dipping angle of the hidden part of Kahurak fault is resolved at approximately 85 using the anisotropy pattern. Moreover, the aftershocks generally occurred in the transitional zones where signs of radial anisotropy anomalies change. Our study indicates that the influence of different resolving powers and path coverage density of Rayleigh and Love waves, which can be artificially interpreted as radial anisotropy, have minor effect on calculated radial anisotropy and they are estimated in the range of -2% to +2%.

  • 4.
    Marti, J.
    et al.
    CSIC, Inst Earth Sci Jaume Almera, ICTJA, Barcelona, Spain..
    Villasenor, A.
    CSIC, Inst Earth Sci Jaume Almera, ICTJA, Barcelona, Spain..
    Geyer, A.
    CSIC, Inst Earth Sci Jaume Almera, ICTJA, Barcelona, Spain..
    Lopez, C.
    IGN, Observ Geofis Cent, Madrid, Spain..
    Tryggvason, Ari
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Stress barriers controlling lateral migration of magma revealed by seismic tomography2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 40757Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding how monogenetic volcanic systems work requires full comprehension of the local and regional stresses that govern magma migration inside them and why/how they seem to change from one eruption to another. During the 2011-2012 El Hierro eruption (Canary Islands) the characteristics of unrest, including a continuous change in the location of seismicity, made the location of the future vent unpredictable, so short term hazard assessment was highly imprecise. A 3D P-wave velocity model is obtained using arrival times of the earthquakes occurred during that pre-eruptive unrest and several latter post-eruptive seismic crises not related to further eruptions. This model reveals the rheological and structural complexity of the interior of El Hierro volcanic island. It shows a number of stress barriers corresponding to regional tectonic structures and blocked pathways from previous eruptions, which controlled ascent and lateral migration of magma and, together with the existence of N-S regional compression, reduced its options to find a suitable path to reach the surface and erupt.

  • 5.
    Moros, Matthias
    et al.
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Andersen, Thorbjorn J.
    Univ Copenhagen, Dept Geosci & Nat Resource Management, Oster Voldgade 10, DK-1350 Copenhagen, Denmark..
    Schulz-Bull, Detlef
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Haeusler, Katharina
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Bunke, Dennis
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Snowball, Ian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Kotilainen, Aarno
    Geol Survey Finland, PL 96,Betonimiehenkuja 4, Espoo 02151, Finland..
    Zillen, Lovisa
    Geol Survey Sweden, Dept Marine Geol, Box 670, S-75128 Uppsala, Sweden..
    Jensen, Jorn B.
    Geol Survey Denmark & Greenland, Oster Voldgade 10, DK-1350 Copenhagen, Denmark..
    Kabel, Karoline
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Hand, Ines
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Leipe, Thomas
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Lougheed, Bryan C.
    Uppsala Univ, Dept Earth Sci, Villavagen 16, S-75236 Uppsala, Sweden.;Vrije Univ Amsterdam, Dept Earth Sci, De Boelelaan 1085, NL-1081 HV Amsterdam, Netherlands..
    Wagner, Bernd
    Univ Cologne, Zulpicher Str 49a, D-50674 Cologne, Germany..
    Arz, Helge W.
    Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany..
    Towards an event stratigraphy for Baltic Sea sediments deposited since AD 1900: approaches and challenges2017Ingår i: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 46, nr 1, 129-142 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reconstructions of environmental changes at sub-decadal to decadal resolution based on central Baltic Sea sediments rely on accurate and precise high-resolution sediment depth/age relationships. A model chronology for Baltic Sea sediments is presented here based on established historical records of anthropogenic radionuclides (Cs-137/Am-241/bomb(14)C), polychlorinated biphenyls (PCBs), lead (Pb) and stable lead isotope (Pb-206/207 ratios), and radionuclide Pb-210 and C-14 decay dating methods. Marker horizons consisting of chemical precipitates formed by documented Major Baltic Inflow (MBIs) events and an extended diatom bloom period were also integrated into the model. The main time markers in Baltic Sea sediments that formed during the last 120years were the following: (i) the deepest observation of Pb-210(unsupp.) (marking the Pb-210 dating horizon) and departure of Hg from natural background levels at c.AD 1900; (ii) first detectable presence of PCBs at AD 1935; (iii) radionuclide production (i.e. Am-241) due to nuclear weapons testing between AD 1954 and AD 1975, with a peak in AD 1963; (iv) maximum heavy metal and PCB concentrations in the AD 1960s/1970s; (v) the Chernobyl nuclear accident in AD 1986 as a sharp Cs-137 increase; (vi) exceptionally strong diatom blooms with a massive diatom layer found in the Eastern Gotland Basin in AD 1988-1990; and (vii) characteristic manganese-carbonate layers in the deeper central basins formed by MBIs in AD 1993 and AD 2003. A precise and accurate sediment depth/age relationship can only be achieved in restricted areas of the Baltic Sea where continuous sedimentation has prevailed and there has been limited postdepositional disturbance. We demonstrate that parallel Hg and Cs-137 measurements can be used to assess the quality of sediment sequences for high-resolution environmental reconstructions. We show examples of sediment profiles that conform to the historical record, and examples from Western Baltic Sea areas where it appears to be impossible to establish accurate geochronologies.

  • 6.
    Gee, David G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Andreasson, Per-Gunnar
    Lund Univ, Dept Geol, Lund, Sweden..
    Li, Yuan
    MLR Inst Geol, Beijing, Peoples R China..
    Krill, Allan
    Norwegian Univ Sci & Technol, Dept Geol & Mineral Resources, Trondheim, Norway..
    Baltoscandian margin, Sveconorwegian crust lost by subduction during Caledonian collisional orogeny2017Ingår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 139, nr 1, 36-51 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Underthrusting of Laurentia by the continental margin of Baltica during Caledonian orogeny resulted in the lateral emplacement of Iapetus Ocean-related terranes of the Upper Allochthon at least 500 km onto Baltica. The underlying Lower and Middle allochthons of the Baltoscandian margin mostly comprise Cryogenian, Ediacaran and Cambro-Silurian sedimentary successions; basement to these formations are present only as minor, isolated fragments, except at the base of the Middle Allochthon and within the underlying windows. The upper parts of the Middle Allochthon are notable for the presence of early Ediacaran dyke-swarms and other components of the Baltoscandian continent-ocean transition zone (COT). New data are presented here on the c. 610 Ma age of the COT-related dolerites in the Kalak Nappe Complex in Northern Norway and also on detrital zircons in the underlying Laksefjord and Gaissa nappes. The former confirms that the Baltoscandian COT has a similar age along the length of the orogen; the latter shows that the detrital zircon signatures in the Lower and Middle allochthons are comparable throughout the orogen. These sedimentary rocks have dominating populations of Mesoproterozoic to latest Palaeoproterozoic zircons similar to those from southern parts of the orogen, where Sveconorwegian complexes comprise the basement to the Caledonides. Thus, they help define the probable character and age of the crystalline basement that existed along this outer margin of Baltica during the Neoproterozoic, continental lower crust that was partly subducted during Ordovician continent-arc collision and subsequently lost beneath Laurentia during the 50 million years of Scandian collisional orogeny.

  • 7.
    Almqvist, Bjarne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Mainprice, David
    Seismic properties and anisotropy of the continental crust: Predictions based on mineral texture and rock microstructure2017Ingår i: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208Artikel i tidskrift (Refereegranskat)
  • 8.
    Ren, Zhengyong
    et al.
    Cent S Univ, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha, Hunan, Peoples R China.;Key Lab Nonferrous Resources & Geol Hazard Detect, Changsha, Hunan, Peoples R China.;Cent S Univ, Sch Geosci & Infophys, Changsha, Hunan, Peoples R China..
    Tang, Jingtian
    Cent S Univ, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha, Hunan, Peoples R China.;Key Lab Nonferrous Resources & Geol Hazard Detect, Changsha, Hunan, Peoples R China.;Cent S Univ, Sch Geosci & Infophys, Changsha, Hunan, Peoples R China..
    Kalscheuer, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Maurer, Hansruedi
    Swiss Fed Inst Technol, Inst Geophys, Dept Earth Sci, Zurich, Switzerland..
    Fast 3-D large-scale gravity and magnetic modeling using unstructured grids and an adaptive multilevel fast multipole method2017Ingår i: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 122, nr 1, 79-109 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel fast and accurate algorithm is developed for large-scale 3-D gravity and magnetic modeling problems. An unstructured grid discretization is used to approximate sources with arbitrary mass and magnetization distributions. A novel adaptive multilevel fast multipole (AMFM) method is developed to reduce the modeling time. An observation octree is constructed on a set of arbitrarily distributed observation sites, while a source octree is constructed on a source tetrahedral grid. A novel characteristic is the independence between the observation octree and the source octree, which simplifies the implementation of different survey configurations such as airborne and ground surveys. Two synthetic models, a cubic model and a half-space model with mountain-valley topography, are tested. As compared to analytical solutions of gravity and magnetic signals, excellent agreements of the solutions verify the accuracy of our AMFM algorithm. Finally, our AMFM method is used to calculate the terrain effect on an airborne gravity data set for a realistic topography model represented by a triangular surface retrieved from a digital elevation model. Using 16 threads, more than 5800 billion interactions between 1,002,001 observation points and 5,839,830 tetrahedral elements are computed in 453.6s. A traditional first-order Gaussian quadrature approach requires 3.77days. Hence, our new AMFM algorithm not only can quickly compute the gravity and magnetic signals for complicated problems but also can substantially accelerate the solution of 3-D inversion problems.

  • 9.
    Zardari, Muhammad Auchar
    et al.
    Quaid E Awam Univ Engn Sci & Technol, Dept Civil Engn, Nawabshah, Sindh, Pakistan..
    Mattsson, Hans
    Lulea Univ Technol, Dept Civil Environm & Nat Resources Engn, S-97187 Lulea, Sweden..
    Knutsson, Sven
    Lulea Univ Technol, Dept Civil Environm & Nat Resources Engn, S-97187 Lulea, Sweden..
    Khalid, Muhammad Shehzad
    Kyoto Univ, Dept Urban Management, Kyoto, Japan..
    Ask, Maria V. S.
    Lulea Univ Technol, Dept Civil Environm & Nat Resources Engn, S-97187 Lulea, Sweden..
    Lund, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Numerical Analyses of Earthquake Induced Liquefaction and Deformation Behaviour of an Upstream Tailings Dam2017Ingår i: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, 5389308Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Much of the seismic activity of northern Sweden consists of micro-earthquakes occurring near postglacial faults. However, larger magnitude earthquakes do occur in Sweden, and earthquake statistics indicate that a magnitude 5 event is likely to occur once every century. This paper presents dynamic analyses of the effects of larger earthquakes on an upstream tailings dam at the Aitik copper mine in northern Sweden. The analyses were performed to evaluate the potential for liquefaction and to assess stability of the dam under two specific earthquakes: a commonly occurring magnitude 3.6 event and a more extreme earthquake of magnitude 5.8. The dynamic analyses were carried out with the finite element program PLAXIS using a recently implemented constitutive model called UBCSAND. The results indicate that the magnitude 5.8 earthquake would likely induce liquefaction in a limited zone located below the ground surface near the embankment dikes. It is interpreted that stability of the dam may not be affected due to the limited extent of the liquefied zone. Both types of earthquakes are predicted to induce tolerable magnitudes of displacements. The results of the postseismic slope stability analysis, performed for a state after a seismic event, suggest that the dam is stable during both the earthquakes.

  • 10. Wenning, Quinn
    et al.
    Berthet, Théo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Ask, Maria
    Zappone, Alba
    Rosberg, Jan-Erik
    Almqvist, Bjarne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Image log analysis of in-situ stress orientation, breakout growth, and natural geologic structures to 2.5 km depth in central Scandinavian Caledonides: Results from the COSC-1 borehole2017Ingår i: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356Artikel i tidskrift (Refereegranskat)
  • 11.
    Malehmir, Alireza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Heinonen, Suvi
    Geol Survey Finland GTK, Espoo, Finland..
    Dehghannejad, Mahdieh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Heino, Pasi
    Yara Suomi Oy, Siilinjarvi, Finland..
    Maries, Georgiana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Karell, Fredrik
    Geol Survey Finland GTK, Espoo, Finland..
    Suikkanen, Mikko
    Yara Suomi Oy, Siilinjarvi, Finland..
    Salo, Aleksi
    Yara Suomi Oy, Siilinjarvi, Finland..
    Landstreamer seismics and physical property measurements in the Siilinjarvi open-pit apatite (phosphate) mine, central Finland2017Ingår i: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 82, nr 2, B29-B48 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We tested the applicability of a newly developed broadband (0-800 Hz) digital-based seismic landstreamer for open-pit mine planning in the apatite-bearing Siilinjarvi mine in central Finland. Four seismic profiles, in total approximately 2.5 km long (2-4 m source and landstreamer receiver spacing), two inside the pit and two on its margins, were acquired in combination with wireless recorders connected to 10 Hz geophones and fixed at every 10 m spacing along the seismic profiles while the streamer data were being acquired. Downhole logging and laboratory physical property measurements on core and rock samples were carried out to not only support the seismic interpretations but also to provide information about the possible geophysical signature of these unique types of deposits. In spite of a highly noisy mining environment, seismic data of high quality were acquired; however, reflection processing and interpretations were challenged by the geologic complexities of several generations of basic and carbonatite dikes. To complement the reflection data imaging and to account for the steep elevation changes and crookedness of some of the seismic profiles, 3D first-arrival traveltime tomography and 3D swath reflection imaging were also carried out. Clear refracted arrivals from the open-pit profiles suggest the possibility of low-velocity zones associated with either blasting or several shear zones intersecting the seismic profiles. In terms of reflectivity, reflections have a different appearance from short and flat to longer and steep ones. The downhole-and borehole logging data suggest that some of these reflections are associated with diabase dikes and some are likely from zones of weaknesses in the alkaline- carbonatite complex. We determine the potential of using seismic streamers for cost-and time-effective open-pit mine planning and encourage further testing in simpler geologic settings to be established.

  • 12.
    Vachon, Remi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Hieronymus, Christoph F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Effect of host-rock rheology on dyke shape, thickness and magma overpressure2017Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 208, nr 3, 1414-1429 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The size and thickness of dykes is of fundamental importance for volcano dynamics because dykes are the primary path for magma transport, and because large numbers of dykes often comprise a major proportion of the volcanic edifice and of the underlying crust. Standard elastic models predict dyke geometry to be elliptic in cross-section for constant overpressure and uniform host-rock properties, whereas observations show that dyke thickness is typically more nearly constant with a sharp taper at the ends. Moreover, the predicted overpressures required to inflate dykes in a purely elastic medium are often significantly higher (> 150 MPa and up to 2 GPa) than those estimated by other means (about 1-50 MPa). In this study, we use 2-D finite element models to test whether other host-rock rheologies lead to more realistic dyke shapes and overpressures. We examine three different rheologies, each of which is affected by the presence of the dyke itself: (1) elasticity with reduced moduli in regions of low pressure or tension; (2) elastoplasticity with plastic failure in the high-stress regions surrounding the dyke tips; (3) viscoelasticity with a viscosity decrease due to heating by the dyke. We use rheological parameters obtained from laboratory experiments whenever possible, and assume static conditions for the final dyke shape. We find that all three rheologies tend to make the dyke more rectangular relative to the elliptical dykes of the linearly elastic models. The change in shape is due to enhanced deformation in the high-stress zone surrounding the dyke tip. We also find that the overpressure required to inflate an initially thin dyke to a given thickness is reduced for all three rheologies. The greatest decrease in overpressure by a factor of about 0.1 is observed for the elastoplastic model, and for the viscoelastic model if the dyke intrudes into moderately pre-heated host-rock. We discuss our results with respect to dyke observations from Rum Island (Scotland) and use these as a guide to evaluate our models.

  • 13.
    Doughty, Christine
    et al.
    Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Tsang, Chin-Fu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Rosberg, Jan-Erik
    Lund Univ, Lund, Sweden..
    Juhlin, Christopher
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Dobson, Patrick F.
    Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Birkholzer, Jens T.
    Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA..
    Flowing fluid electrical conductivity logging of a deep borehole during and following drilling: estimation of transmissivity, water salinity and hydraulic head of conductive zones2017Ingår i: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157, Vol. 25, nr 2, 501-517 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Flowing fluid electrical conductivity (FFEC) logging is a hydrogeologic testing method that is usually conducted in an existing borehole. However, for the 2,500-m deep COSC-1 borehole, drilled at re, central Sweden, it was done within the drilling period during a scheduled 1-day break, thus having a negligible impact on the drilling schedule, yet providing important information on depths of hydraulically conductive zones and their transmissivities and salinities. This paper presents a reanalysis of this set of data together with a new FFEC logging data set obtained soon after drilling was completed, also over a period of 1 day, but with a different pumping rate and water-level drawdown. Their joint analysis not only results in better estimates of transmissivity and salinity in the conducting fractures intercepted by the borehole, but also yields the hydraulic head values of these fractures, an important piece of information for the understanding of hydraulic structure of the subsurface. Two additional FFEC logging tests were done about 1 year later, and are used to confirm and refine this analysis. Results show that from 250 to 2,000 m depths, there are seven distinct hydraulically conductive zones with different hydraulic heads and low transmissivity values. For the final test, conducted with a much smaller water-level drawdown, inflow ceased from some of the conductive zones, confirming that their hydraulic heads are below the hydraulic head measured in the wellbore under non-pumped conditions. The challenges accompanying 1-day FFEC logging are summarized, along with lessons learned in addressing them.

  • 14.
    Yan, Ping
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Garcı́a Juanatey, Marı́a A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Kalscheuer, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Juhlin, Christopher
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Hedin, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Savvaidis, Alexandros
    Univ Texas Austin, Bur Econ Geol, Jackson Sch Geosci, Austin, TX 78712 USA..
    Lorenz, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Kück, Jochem
    GFZ German Res Ctr Geosci, Helmholtz Ctr Potsdam, Ctr Sci Drilling, Potsdam, Germany..
    A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information2017Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 208, nr 3, 1465-1489 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In connection with the Collisional Orogeny in the Scandinavian Caledonides (COSC) project, broad-band magnetotelluric (MT) data were acquired at 78 stations along a recent ca. 55km- long NW-SE directed reflection seismic profile (referred to as the COSC Seismic Profile; CSP), with the eastern end located similar to 30 km to the west of the orogenic Caledonian front. The MT component of the project aims at (i) delineating the highly conductive (similar to 0.1 Omega . m) alum shales that are associated with an underlying main decollement and (ii) calibrating the MT model to borehole logs. Strike and distortion analyses of the MT data show a 3-D structure in the western 10 km of the profile around the 2.5 km deep COSC-1 borehole (IGSN: ICDP5054EHW1001) and a preferred strike angle of N34 degrees E in the central and eastern parts of the profile. 2-D modelling of MT impedances was tested using different inversion schemes and parameters. To adjust the resistivity structure locally around the borehole, resistivity logging data from COSC-1 were successfully employed as prior constraints in the 2-D MT inversions. Compared with the CSP, the model inverted from the determinant impedances shows the highest level of structural similarity. A shallow resistor (> 1000 Omega . m) in the top 2-3 km depth underneath the western most 10 km of the profile around COSC-1 corresponds to a zone of high seismic reflectivity, and a boundary at less than 1 km depth where the resistivity decreases rapidly from > 100 to < 1 Omega . m in the central and eastern parts of the profile coincides with the first seismic reflections. The depth to this boundary is well constrained as shown by 1-D inversions of the MT data from five selected sites and it decreases towards the Caledonian front in the east. Underneath the easternmost part of the profile, the MT data show evidence of a second deeper conductor (resistivity < 1 Omega . m) at > 3 km depth. Based upon the COSC-1 borehole logs, the CSP reflection seismic image, and the surface geologic map, the MT resistivity models were interpreted geologically. In the vicinity of COSC-1, the resistor down to 2-3 km depth pertains to the metamorphic Middle Allochthon. The up to 1000-m-thick shallow resistor in the central and eastern parts of the profile is interpreted to overly an imbricated unit at the bottom of the Lower Allochthon that includes the alum shales. In the MT resistivity model, the 300-500 m thick imbricated unit masks the main Caledonian decollement at its bottom. A second possible interpretation, though not favoured here, is that the decollement occurs along a much deeper seismic reflection shallowing from 4.5 km depth in the west to similar to 600 m depth in the east. An additional borehole (COSC-2) is planned to penetrate the Lower Allochthon and the main decollement surface in the central part of the profile and can provide information to overcome this interpretational ambiguity. Using a synthetic study, we evaluate how resistivity logs from COSC-2 can improve the 2-D inversion model.

  • 15.
    Raeesi, Mohammad
    et al.
    Bergen, Norway..
    Zarifi, Zoya
    Department of Earth Sciences, University of Western Ontario, London, Canada..
    Nilfouroushan, Faramarz
    Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden.; Lantmateriet, Gavle, Sweden..
    Boroujeni, Samar Amini
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Tiampo, Kristy
    Univ Colorado, CIRES, Boulder, CO USA.; Univ Colorado, Dept Geol Sci, Boulder, CO USA..
    Quantitative Analysis of Seismicity in Iran2017Ingår i: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 174, nr 3, 793-833 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use historical and recent major earthquakes and GPS geodetic data to compute seismic strain rate, geodetic slip deficit, static stress drop, the parameters of the magnitude-frequency distribution and geodetic strain rate in the Iranian Plateau to identify seismically mature fault segments and regions. Our analysis suggests that 11 fault segments are in the mature stage of the earthquake cycle, with the possibility of generating major earthquakes. These faults primarily are located in the north and the east of Iran. Four seismically mature regions in southern Iran with the potential for damaging strong earthquakes are also identified. We also delineate four additional fault segments in Iran that can generate major earthquakes without robust clues to their maturity. The most important fault segment in this study is the strike-slip system near the capital city of Tehran, with the potential to cause more than one million fatalities.

  • 16.
    Ren, Zhengyong
    et al.
    Cent S Univ, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha 410083, Hunan, Peoples R China.;Cent S Univ, Sch Geosci & Infophys, Changsha 410083, Hunan, Peoples R China..
    Chen, Chaojian
    Cent S Univ, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha 410083, Hunan, Peoples R China.;Cent S Univ, Sch Geosci & Infophys, Changsha 410083, Hunan, Peoples R China..
    Pan, Kejia
    Cent S Univ, Sch Math & Stat, Changsha 410083, Hunan, Peoples R China..
    Kalscheuer, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Maurer, Hansruedi
    Swiss Fed Inst Technol, Inst Geophys, Dept Earth Sci, CH-8092 Zurich, Switzerland..
    Tang, Jingtian
    Cent S Univ, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha 410083, Hunan, Peoples R China.;Cent S Univ, Sch Geosci & Infophys, Changsha 410083, Hunan, Peoples R China..
    Gravity Anomalies of Arbitrary 3D Polyhedral Bodies with Horizontal and Vertical Mass Contrasts2017Ingår i: Surveys in geophysics, ISSN 0169-3298, E-ISSN 1573-0956, Vol. 38, nr 2, 479-502 s.Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    During the last 15 years, more attention has been paid to derive analytic formulae for the gravitational potential and field of polyhedral mass bodies with complicated polynomial density contrasts, because such formulae can be more suitable to approximate the true mass density variations of the earth (e.g., sedimentary basins and bedrock topography) than methods that use finer volume discretization and constant density contrasts. In this study, we derive analytic formulae for gravity anomalies of arbitrary polyhedral bodies with complicated polynomial density contrasts in 3D space. The anomalous mass density is allowed to vary in both horizontal and vertical directions in a polynomial form of , where m, n, t are nonnegative integers and a, b, c are coefficients of mass density. First, the singular volume integrals of the gravity anomalies are transformed to regular or weakly singular surface integrals over each polygon of the polyhedral body. Then, in terms of the derived singularity-free analytic formulae of these surface integrals, singularity-free analytic formulae for gravity anomalies of arbitrary polyhedral bodies with horizontal and vertical polynomial density contrasts are obtained. For an arbitrary polyhedron, we successfully derived analytic formulae of the gravity potential and the gravity field in the case of , , , and an analytic formula of the gravity potential in the case of . For a rectangular prism, we derive an analytic formula of the gravity potential for , and and closed forms of the gravity field are presented for , and . Besides generalizing previously published closed-form solutions for cases of constant and linear mass density contrasts to higher polynomial order, to our best knowledge, this is the first time that closed-form solutions are presented for the gravitational potential of a general polyhedral body with quadratic density contrast in all spatial directions and for the vertical gravitational field of a prismatic body with quartic density contrast along the vertical direction. To verify our new analytic formulae, a prismatic model with depth-dependent polynomial density contrast and a polyhedral body in the form of a triangular prism with constant contrast are tested. Excellent agreements between results of published analytic formulae and our results are achieved. Our new analytic formulae are useful tools to compute gravity anomalies of complicated mass density contrasts in the earth, when the observation sites are close to the surface or within mass bodies.

  • 17.
    Sadeghisorkhani, Hamzeh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Analyses and Application of Ambient Seismic Noise in Sweden: Source, Interferometry, Tomography2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Ambient seismic noise from generation to its application for determination of sub-surface velocity structures is analyzed using continuous data recordings from the Swedish National Seismic Network (SNSN). The fundamental aim of the thesis is to investigate the applicability of precise velocity measurements from ambient noise data. In the ambient noise method, a form of interferometry, the seismic signal is constructed from long-term cross correlation of a random noise field. Anisotropy of the source distribution causes apparent time shifts (velocity bias) in the interferometric signals. The velocity bias can be important for the study area (Sweden) which has relatively small velocity variations. This work explores the entire data path, from investigating the noise-source distribution to a tomographic study of southern Sweden.

    A new method to invert for the azimuthal source distribution from cross-correlation envelopes is introduced. The method provides quantitative estimates of the azimuthal source distribution which can be used for detailed studies of source generation processes. An advantage of the method is that it uses few stations to constrain azimuthal source distributions. The results show that the source distribution is inhomogeneous, with sources concentrated along the western coast of Norway. This leads to an anisotropic noise field, especially for the secondary microseisms. The primary microseismic energy comes mainly from the northeast.

    The deduced azimuthal source distributions are used to study the level of expected bias invelocity estimates within the SNSN. The results indicate that the phase-velocity bias is less than 1% for most station pairs but can be larger for small values of the ratio of inter-station distance over wavelength. In addition, the nature of velocity bias due to a heterogeneous source field is investigated in terms of high and finite-frequency regimes.

    Graphical software for phase-velocity dispersion measurements based on new algorithms is presented and validated with synthetic data and by comparisons to other methods. The software is used for phase-velocity measurements, and deduced azimuthal source distributions are used for velocity-bias correction. Derived phase-velocity dispersion curves are used to construct two-dimensional velocity maps of southern Sweden at different periods based on travel-time tomography. The effect of the bias correction is investigated, and velocity maps are interpreted in comparison to previous geological and geophysical information.

    Delarbeten
    1. Mapping the source distribution of microseisms using noise covariogram envelopes
    Öppna denna publikation i ny flik eller fönster >>Mapping the source distribution of microseisms using noise covariogram envelopes
    2016 (Engelska)Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 205, nr 3, 1473-1491 s.Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We introduce a method for mapping the noise-source distribution of microseisms which uses information from the full length of covariograms (cross-correlations). We derive a forward calculation based on the plane-wave assumption in 2-D, to formulate an iterative, linearized inversion of covariogram envelopes in the time domain. The forward calculation involves bandpass filtering of the covariograms. The inversion exploits the well-known feature of noise cross-correlation, that is, an anomaly in the noise field that is oblique to the interstation direction appears as cross-correlation amplitude at a smaller time lag than the in-line, surface wave arrival. Therefore, the inversion extracts more information from the covariograms than that contained at the expected surface wave arrival, and this allows us to work with few stations to find the propagation directions of incoming energy. The inversion is naturally applied to data that retain physical units that are not amplitude normalized in any way. By dividing a network into groups of stations, we can constrain the source location by triangulation. We demonstrate results of the method with synthetic data and one year (2012) of data from the Swedish National Seismic Network and also look at the seasonal variation of source distribution around Scandinavia. After preprocessing and cross-correlation, the stations are divided into five groups of 9-12 stations. We invert the envelopes of each group in eight period ranges between 2 and 25 s. Results show that the noise sources at short periods (less than 12 s) lie predominantly in the North Atlantic Ocean and the Barents Sea, and at longer periods the energy appears to have a broader distribution. The strongly anisotropic source distribution in this area is estimated to cause significant biases of velocity measurements compared to the level of heterogeneity in the region. The amplitude of the primary microseisms varies little over the year, but secondary microseisms are much weaker in summer than in winter. Furthermore, the peak period of the secondary microseisms shifts from 5-6 s in winter to 4-5 s during the summer.

    Nyckelord
    Inverse theory, Interferometry, Surface waves and free oscillations, Wave propagation, Europe
    Nationell ämneskategori
    Geovetenskap och miljövetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-302233 (URN)10.1093/gji/ggw092 (DOI)000376380000011 ()
    Externt samarbete:
    Tillgänglig från: 2016-09-01 Skapad: 2016-08-31 Senast uppdaterad: 2017-04-17Bibliografiskt granskad
    2. Velocity-measurement bias of the ambient noise method due to source directivity: A case study for the Swedish National Seismic Network
    Öppna denna publikation i ny flik eller fönster >>Velocity-measurement bias of the ambient noise method due to source directivity: A case study for the Swedish National Seismic Network
    (Engelska)Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246XArtikel i tidskrift (Refereegranskat) Epub ahead of print
    Abstract [en]

    The bias of velocity measurements from ambient-noise covariograms due to an anisotropic distribution of noise sources is studied assuming that the noise field consists of planar surface waves from large distance. First, general characteristics of the bias are described in terms of their dependence on wavelength, source-anomaly amplitude and width. Second, the expected bias of measurements in Sweden based on a noise-source model for the adjacent regions is analysed. The bias is conceptually explained and described in terms of two regimes, namely a high-frequency and a finite-frequency regime and their parameter domains quantified. Basic scaling laws are established for the bias. It is generally found to be small compared to lateral heterogeneity, except in the finite-frequency regime when inter-station distance is small compared to a wavelength and in regions of low levels of heterogeneity. The potential bias, i.e., its peak-to-peak variation, is generally higher for group-velocity than phase-velocity measurements. The strongly varying noise-source distribution as seen from Sweden results in predictions of relatively strong bias in the area at relevant frequencies and inter-station distances. Levels of heterogeneity in the Baltic shield are relatively low, rendering the potential bias significant. This highlights the need for detailed studies of source anisotropy before application of ambient-noise tomography, particularly in regions with weak velocity heterogeneity. Predicted bias only partially explains deviations of phase-velocity measurements from a regional average for individual station pairs. Restricting measurements to station pairs with inter-station distance exceeding five wavelengths limits the potential velocity bias in the area to within 1%. This rather dramatic restriction can be relaxed by directional analysis of the noise-source field and application of azimuthal restrictions to the selected station pairs for measurement.

    Nationell ämneskategori
    Geofysik
    Identifikatorer
    urn:nbn:se:uu:diva-320163 (URN)10.1093/gji/ggx115 (DOI)
    Tillgänglig från: 2017-04-16 Skapad: 2017-04-16 Senast uppdaterad: 2017-04-17
    3. GSpecDisp: a Matlab GUI package for phase-velocity dispersion measurements from ambient-noise correlations
    Öppna denna publikation i ny flik eller fönster >>GSpecDisp: a Matlab GUI package for phase-velocity dispersion measurements from ambient-noise correlations
    (Engelska)Ingår i: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803Artikel i tidskrift (Refereegranskat) Submitted
    Nationell ämneskategori
    Geofysik
    Identifikatorer
    urn:nbn:se:uu:diva-320166 (URN)
    Tillgänglig från: 2017-04-16 Skapad: 2017-04-16 Senast uppdaterad: 2017-04-17
    4. Surface wave tomography of southern Sweden from ambient seismic noise
    Öppna denna publikation i ny flik eller fönster >>Surface wave tomography of southern Sweden from ambient seismic noise
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Geofysik
    Identifikatorer
    urn:nbn:se:uu:diva-320167 (URN)
    Tillgänglig från: 2017-04-16 Skapad: 2017-04-16 Senast uppdaterad: 2017-04-17
  • 18.
    Yan, Ping
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik. Zhejiang Univ, Sch Earth Sci, Hangzhou, Zhejiang, Peoples R China..
    Kalscheuer, Thomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Hedin, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Juanatey, María de los Garcia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Two-dimensional magnetotelluric inversion using reflection seismic data as constraints and application in the COSC project2017Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, nr 8, 3554-3563 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]