Christian Weidle

Christian-Albrechts-Universität zu Kiel | CAU · Institute of Geosciences

Ambient seismic noise tomography has, over the last two decades, developed into a well-established tool for imaging seismic properties of the Earth’s crust. Fundamental mode Rayleigh and Love wave phase velocity dispersion curves can be measured from ambient noise cross-correlation functions (CCF) either using a high-frequency approximation theory,...

The Semail Ophiolite in eastern Arabia is the largest and best-exposed slice of oceanic lithosphere on land. Detailed knowledge of the tectonic evolution of the shallow crust, in particular during and after ophiolite obduction in Late Cretaceous times is contrasted by few constraints on physical and compositional properties of the middle and lower...

The northern Oman margin is a key area for understanding the emplacement of the Semail Ophiolite and obduction processes in general. This study uses a grid of 2D‐multichannel seismic lines tied to well data to characterize the offshore domain of the Semail Ophiolite and reappraises the obduction and post‐obduction history of the Oman margin. West o...

The Oman ophiolite is one of the best preserved and studied ophiolites, where oceanic lithosphere was obducted on top of a continent. It covers an area of about 700 x 140 km² but its 3D geometry, as well as the properties of the underlying continental lithosphere are largely unknown. We operated a temporary broadband seismic network with 40 instrum...

Frontal ablation contributes significantly to the mass balance of tidewater glaciers in Svalbard and can be recovered with high temporal resolution using continuous seismic records. Determination of the relative contribution of dynamic ice loss through calving to frontal ablation requires precise estimates of calving volumes at the same temporal re...

This is the appendix to the Scharf et al. (2019) Tectonics article

The Semail Gap/Semail Gap Fault Zone is one of the most prominent tectonic features in the Oman Mountains and is located between the Jabal Akhdar Dome in the west and the Saih Hatat Dome to the east. The two domes were uplifted during the Late Eocene to Early Miocene. Uplift led to monoclinal bending with a “fold axis” parallel to the Semail Gap. S...

Frontal ablation contributes significantly to the mass balance of tidewater glaciers in Svalbard and can be recovered with high temporal resolution using continuous seismic records. Determination of the relative contribution of dynamic ice loss through calving to frontal ablation requires precise estimates of calving volumes at the same temporal re...

Tectonics of the Semail Gap Fault Zone

Glacier flow instabilities can rapidly increase sea level through enhanced ice discharge. Surge-type glacier accelerations often occur with a decadal to centennial cyclicity suggesting internal mechanisms responsible. Recently, many surging tidewater glaciers around the Arctic Barents Sea region question whether external forces such as climate can...

The international research project ScanArray with the German contribution LITHOS-CAPP operated 98 broad band seismic stations in Norway, Sweden and Finland. Recordings from these stations and additionally from permanent stations and broadband sensors of previous studies in different areas of Fennoscandinavia are used to compute a 3D-absolute shear...

Time-lapse monitoring of the subsurface using ambient seismic noise is a popular method in environmental seismology. We assess the reliability of the horizontal-to-vertical spectral ratio (HVSR) method for monitoring seasonal permafrost active layer variability in northwest Svalbard. We observe complex HVSR variability between 1 and 50Hz in the rec...

Time-lapse monitoring of the sub-surface using ambient seismic noise is a popular method in environmental seismology. We assess the reliability of the Horizontal-to-Vertical Spectral Ratio (HVSR) method for monitoring seasonal permafrost active layer variability in northwest Svalbard. We observe complex HVSR variability between 1 and 50Hz in the re...

A large data set of surface-wave phase-velocity measurements is compiled to study the structures of the crust and upper mantle underneath the Alpine continental collision zone. Records from both ambient-noise and earthquake-based methods are combined to obtain a high-resolution 3-D model of seismic shear velocity. The applied techniques allow us to...

We present a unique time series of continuous glacier frontal ablation rates with weekly resolution over 15 years estimated from seismic calving observations at Kronebreen, Svalbard. Using linear statistical models, we calibrate the seismic record with seven years of satellite derived frontal ablation measurements. The two basic input parameters re...

P-wave polarization at the Gräfenberg array (GRF) in southern Germany is analyzed in terms of azimuthal deviations and deviations in the vertical polarization using 20 years of broad band recordings. An automated procedure for estimating P-wave polarization parameters is suggested, based on the definition of a characteristic function, which evaluat...

The upper crust of central Europe preserves a mosaic of tectonic blocks brought together by the Caledonian and Variscan Orogenies. The lower crust, in contrast, appears to have undergone extensive reworking: the flat Moho across broad areas and the absence of contrasts in seismic properties across tectonic boundaries suggest that the Moho and lower...

The increasingly dense coverage of Europe with broad-band seismic stations makes it possible to image its lithospheric structure in great detail, provided that structural information can be extracted effectively from the very large volumes of data. We develop an automated technique for the measurement of interstation phase velocities of (earthquake...

Global glaciers and ice caps loose mass through calving, while existing models are currently not equipped to realistically predict dynamic ice loss. This is mainly because long-term continuous calving records, that would help to better understand fine scale processes and key climatic-dynamic feedbacks between calving, climate, terminus evolution an...

Dynamic glacier activity is increasingly observed through passive seismic monitoring. We analysed near-regional-scale seismicity on the Arctic archipelago of Svalbard to identify seismic icequake signals and to study their spatial–temporal distribution within the 14-year period from 2000 until 2013. This is the first study that uses seismic data re...

Broad-band phase velocity measurements of fundamental mode surface waves yield information on the isotropic as well as anisotropic structure of the crust and the upper mantle. Dispersion curves may be determined by cross correlating direct and coda fundamental mode waveforms recorded at two stations on the great circle path. In many cases the cross...

We apply automated two-station broadband phase velocity dispersion measurements to all available broadband data from permanent seismic stations in Europe, as available through the European Integrated Data Archive (EIDA, http://www.orfeus-eu.org/eida/) infrastructure. As part of our quality control we detect several typical patterns in our measureme...

We use ambient seismic noise and earthquake recordings on a temporary regional network in southern Norway to produce Rayleigh and Love wave phase velocity maps from 3 to 67 s period. Local dispersion curves are then jointly inverted for a 3-D shear wave velocity model of the region. We perform a two-step inversion approach. First, a direct search,...

This study images upper-mantle structure beneath different tectonic and geomorphological provinces in southern Scandinavia by P-wave traveltime tomography based on teleseismic events. We present results using integrated data from several individual projects (CALAS, MAGNUS, SCANLIPS, CENMOVE and Tor) with a total of 202 temporary seismological stati...

In this review we give an overview of geophysical data and models available for the Scandinavian mountains and adjacent areas, as they are of relevance to the debate about the existence and cause of Neogene uplift. Emphasis is given to potential field and petrophysical data of which the earth science communities of Norway and Sweden have a long tra...

The origin of the Scandinavian mountains, located far away from any presently active plate margin, is still not well understood. In particular, it is not clear if the mountains are sustained isostatically either by crustal thickening or by light upper mantle material. Within the TopoScandiaDeep project (a collaborative research project within the E...

This study images upper mantle structure beneath different tectonic and geomorphological provinces in southern Scandinavia by P-wave travel time tomography based on teleseismic events. We present integrated results using data from several projects (CALAS, MAGNUS, SCANLIPS, CENMOVE and Tor) with a total of 202 temporary seismological stations deploy...

Polarization analysis of P-waves has been applied for identification of seismic phases (Earle, 1999), for earthquake location (Dyer et al., 1999), measurements of seismic anisotropy (Schulte-Pelkum, 2001), and determination of velocity models. In isotropic, lateral homogeneous media, P-wave polarization is confined to the vertical-radial plane; de...

Due to the increasing popularity of using empirical Green's functions obtained from ambient seismic noise, more and more regional tomographical studies based on short-periods surface waves are published. Results could potentially be biased in mountainous regions where topography is not small compared to the wavelength and penetration depth of the c...

We detect and cluster waveforms of seismic signals recorded close to the calving front of Kronebreen, Svalbard, to identify glacier-related seismic events and to investigate their relation to calving processes. Single-channel geophone data recorded over several months in 2009 and 2010 are combined with eleven days of direct visual observations of t...

We detect and cluster waveforms of seismic signals recorded close to the calving front of Kronebreen, Svalbard, to identify glacier-induced seismic events and to investigate their relation to calving processes. Single-channel geophone data recorded over several months in 2009 and 2010 are combined with eleven days of direct visual observations of t...

Availability of spatially dense broadband observations of seismic surface wave fields allows to derive phase velocity maps on regional scale by non-tomographic means. I present a multiscale interpolation scheme for surface wave fields where for each observed wave field, a multiscale phase velocity map and its standard deviation are calculated from...

Due to the increasing popularity of analyzing empirical Green’s functions obtained from ambient seismic noise, more and more regional tomographical studies based on short-period surface waves are published. Results could potentially be biased in mountainous regions where topography is not small compared to the wavelength and penetration depth of th...

We process seismic broad-band data from southern Norway by cross correlation of ambient seismic noise in view of getting a better image of the crustal structure in the area. The main data set sterns from the temporary MAGNUS network which operated continuously from 2006 September to 2008 June. Additionally, data from permanent stations of the Natio...

The noise cross-correlation technique is especially useful in regions like southern Norway since local seismicity is rare and teleseismic records are not able to resolve the upper crust. Within the TopoScandiaDeep project, which aims to investigate the relation between surface topography and lithosphere-asthenosphere structure, we process seismic b...

Structure and dynamics of the upper mantle is important in understanding timing and mechanisms shaping prensent day topography and near surface geology. Debate persists regarding the geological age of the Scandes Mountains. We contribute by imaging upper mantle structure beneath southern Scandinavia using teleseismic P-wave travel time tomography (...

While temporary deployments some 10 years ago were largely based on short-period seismometers, the availability of broadband instruments in instrument pools increased strongly in recent years and as such modern temporary deployments for passive seismological recordings often consist to a large extent, if not exclusively, of broadband instruments. T...

The 4-D evolution of topography is a complex scientific topic in geosciences that requires interdisciplinary efforts. In Europe, increased attention toward this research topic was originally coordinated by the TOPO-EUROPE initiative (Cloetingh et al. 2007), which has led to a continent-wide research program under the auspices of the European Scienc...

A recent regional surface wave tomography for Northern Europe revealed unprecedented images of the upper mantle beneath the (Tertiary) North Atlantic and the bordering Fennoscandian craton of Archean-Proterozoic age. With respect to the circum-Atlantic regions of uplift, no common mantle pattern supporting the uplift of these regions is observed. T...

We investigate whether high topography in southern Norway is associated with an anomalous upper mantle and we identify the western boundary of thick shield lithosphere. Several studies describe crustal structure in southern Scandinavia, whereas high-resolution information on upper mantle structures is sparse. We present relative P-wave travel time...

SUMMARYA model of upper-mantle S-wave velocity and transverse anisotropy beneath northwestern Europe is presented, based on regional surface wave observations. Group velocities for both Love and Rayleigh surface waves are measured on waveform data from international and regional data archives (including temporary deployments) and then inverted for...

A model of upper mantle S-wave velocity beneath northwestern Europe is presented, based on a tomography of regional surface wave observations. Data from international and, more importantly, regional data archives (including temporary deployments) were used to measure group velocities for both Love and Rayleigh surface waves. The procedure for data...

Investigation of teleseismic P-wave recordings at a temporary network in the Eastern Carpathians, equipped with predominantly short-period sensors, is compared with synthetic modelling of anelastic attenuation of teleseismic waves in the upper mantle. Using the t* approach, we examine variations of amplitude decrease over frequency for teleseismic...

The goal of this study is to refine knowledge of the structure and tectonic history of the European Arctic using the combination of all available seismological surface wave data, including historical data that were not used before for this purpose. We demonstrate how the improved data coverage leads to better depth and spatial resolution of the sei...

The Eastern Barents Sea is underlain by a wide (300-400 km) and deep (15-20 km) sedimentary basin that extends for more than 1000 km in a north-south direction. The basin formed by rapid subsidence in Late Permian-Early Triassic times. There are few signs of faulting associated with basin formation and it does not look like typical rift basins. Dee...

A new dataset of surface-wave observations from more than 150 local and regional events with travel paths through the greater Barents Sea region was compiled and group-velocity dispersion curves were measured for Love and Rayleigh waves in the period range 14-160 s (c.f. Part I: Levshin et al., 2005). This large amount of new group-velocity measure...

Existing global and regional tomographic models have limited resolution in the European Arctic due to the small number of seismic stations, relatively low regional seismicity, and poor knowledge of the crustal structure. During the last decades, new seismic stations were permanently or temporarily installed in and around this region. However, many...

We have compiled a 3D seismic velocity model for the crust and upper mantle in the greater Barents Sea region including northern Scandinavia, Svalbard, Novaya Zemlya, the Kara Sea, and the Kola-Karelia regions. While the general motivation for developing this model is basic geophysical research, a more specific goal is to create a model for researc...

Over the years, teleseismic tomography has developed to be a sophisticated method to study the Earth's upper mantle on a regional scale. Using data from tomographic experiments with temporary station networks, one faces some inherent problems, which include limited resolution at depth and artefacts due to a plane-wave approximation at the bottom of...

Existing global and regional tomographic models have limited resolution in the European Arctic due to the small number of seismic stations, relatively low regional seismicity, and limited knowledge of the crustal structure. During the last decades, new seismic stations were permanently or temporarily installed in and around this region. However, ma...

One of the seismically most active regions in Europe is situated at the southeastern bend of the Carpathian Arc (Vrancea region). Seismologically it is intriguing that the seismicity pattern is dominated by an intermediate-depth, finger-shaped volume with recurring strong earthquakes. From the tectonic evolution of the Pannonian-Carpathian subducti...

Many seismological tomography experiments with mobile stations and a local or regional focus have been carried out over the past 20 years. These experiments provided data sets which allow for a regional inversion of the seismic velocities in the upper mantle. Usually this inversion was done using a linearized inversion scheme where the resulting ve...