TY - JOUR A1 - Rößler, Dirk A1 - Rumpker, Georg A1 - Krüger, Frank T1 - Ambiguous moment tensors and radiation patterns in anisotropic media with applications to the modeling of earthquake mechanisms in W-Bohemia N2 - Anisotropic material properties are usually neglected during inversions for source parameters of earthquakes. In general anisotropic media, however, moment tensors for pure-shear sources can exhibit significant non-double-couple components. Such effects may be erroneously interpreted as an indication for volumetric changes at the source. Here we investigate effects of anisotropy on seismic moment tensors and radiation patterns for pure-shear and tensile-type sources. Anisotropy can significantly influence the interpretation of the source mechanisms. For example, the orientation of the slip within the fault plane may affect the total seismic moment. Also, moment tensors due to pure- shear and tensile faulting can have similar characteristics depending on the orientation of the elastic tensor. Furthermore, the tensile nature of an earthquake can be obscured by near-source anisotropic properties. As an application, we consider effects of inhomogeneous anisotropic properties on the seismic moment tensor and the radiation patterns of a selected type of micro-earthquakes observed in W-Bohemia. The combined effects of near-source and along- path anisotropy cause characteristic amplitude distortions of the P, S1 and S2 waves. However, the modeling suggests that neither homogeneous nor inhomogeneous anisotropic properties alone can explain the observed large non-double-couple components. The results also indicate that a correct analysis of the source mechanism, in principle, is achievable by application of anisotropic moment tensor inversion Y1 - 2004 SN - 0039-3169 ER - TY - JOUR A1 - Weber, Michael H. A1 - Wicks, Chuck A1 - Krüger, Frank A1 - Jahnke, Gunnar A1 - Baumann, M. T1 - Reply to comment on "Asymmetric radiation of seismic waves from an atoll : Nuclear tests in French Polynesia" by A. Douglas Y1 - 2000 ER - TY - JOUR A1 - Brechner, Stefan A1 - Klinge, Klaus A1 - Krüger, Frank A1 - Plenefisch, Thomas T1 - Backazimuthal variations of splitting parameters of teleseismic SKS phases observed at the broadband stations in Germany Y1 - 1998 ER - TY - JOUR A1 - Weber, Michael H. A1 - Wicks, Chuck A1 - Krüger, Frank A1 - Jahnke, Gunnar A1 - Schlittenhardt, Jörg T1 - Asymmetric radiation of seismic waves from an atoll : nuclear tests in French Polynesia Y1 - 1998 ER - TY - JOUR A1 - Krüger, Frank A1 - Grosser, H. A1 - Baumbach, M. A1 - Berckhemer, Hans T1 - The Erzincan (Turkey) earthquake (Ms 6.8) of March 13, 1992 and its aftershock sequence Y1 - 1998 ER - TY - JOUR A1 - Scherbaum, Frank A1 - Krüger, Frank A1 - Weber, Michael H. T1 - Double beam imaging : mapping lower mantle heterogeneities using combinations of source and receiver arrays Y1 - 1997 ER - TY - JOUR A1 - Freybourger, Marion A1 - Krüger, Frank A1 - Achauer, Ulrich T1 - A 22 degree long seismic profile for the study of the top D" Y1 - 1999 ER - TY - JOUR A1 - Friedrich, Andree A1 - Krüger, Frank A1 - Klinge, Klaus T1 - Ocean generated microseismic noise located with the Graefenberg array Y1 - 1998 ER - TY - JOUR A1 - Knapmeyer-Endrun, Brigitte A1 - Krüger, Frank A1 - Legendre, C. P. A1 - Geissler, Wolfram H. T1 - Tracing the influence of the trans-european suture zone into the mantle transition zone JF - Earth & planetary science letters N2 - Cratons with their thick lithospheric roots can influence the thermal structure, and thus the convective flow, in the surrounding mantle. As mantle temperatures are hard to measure directly, depth variations in the mantle transition zone (MTZ) discontinuities are often employed as a proxy. Here, we use a large new data set of P-receiver functions to map the 410 km and 660 km discontinuities beneath the western edge of the East European Craton and adjacent Phanerozoic Europe across the most fundamental lithospheric boundary in Europe, the Trans-European Suture Zone (TESZ). We observe significantly shorter travel times for conversions from both MTZ discontinuities within the craton, caused by the high velocities of the cratonic root. By contrast, the differential travel time across the MTZ is normal to only slightly raised. This implies that any insulating effect of the cratonic keel does not reach the MTZ. In contrast to earlier observations in Siberia, we do not find any trace of a discontinuity at 520 km depth, which indicates a rather dry MTZ beneath the western edge of the craton. Within most of covered Phanerozoic Europe, the MTZ differential travel time is remarkably uniform and in agreement with standard Earth models. No widespread thermal effects of the various episodes of Caledonian and Variscan subduction that took place during the amalgamation of the continent remain. Only more recent tectonic events, related to Alpine subduction and Quarternary volcanism in the Eifel area, can be traced. While the East European craton shows no distinct imprint into the MTZ, we discover the signature of the TESZ in the MTZ in the form of a linear region of about 350 km width with a 1.5 s increase in differential travel time, which could either be caused by high water content or decreased temperature. Taking into account results of recent S-wave tomographies, raised water content in the MTZ cannot be the main cause for this observation. Accordingly, we explain the increase, equivalent to a 15 km thicker MTZ, by a temperature decrease of about 80 K. We discuss two alternative models for this temperature reduction, either a remnant of subduction or an indication of downwelling due to small-scale, edge-driven convection caused by the contrast in lithospheric thickness across the TESZ. Any subducted lithosphere found in the MTZ at this location is unlikely to be related to Variscan subduction along the TESZ, though, as Eurasia has moved significantly northward since the Variscan orogeny. KW - mantle transition zone KW - Trans-European Suture Zone KW - East European Craton KW - edge-driven convection KW - receiver functions Y1 - 2013 U6 - https://doi.org/10.1016/j.epsl.2012.12.028 SN - 0012-821X SN - 1385-013X VL - 363 SP - 73 EP - 87 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kinscher, Jannes A1 - Krüger, Frank A1 - Woith, H. A1 - Lühr, B. G. A1 - Hintersberger, E. A1 - Irmak, T. Serkan A1 - Baris, S. T1 - Seismotectonics of the Armutlu peninsula (Marmara Sea, NW Turkey) from geological field observation and regional moment tensor inversion JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - The Armutlu peninsula, located in the eastern Marmara Sea, coincides with the western end of the rupture of the 17 August 1999, Izmit M-W 7.6 earthquake which is the penultimate event of an apparently westward migrating series of strong and disastrous earthquakes along the NAFZ during the past century. We present new seismotectonic data of this key region in order to evaluate previous seismotectonic models and their implications for seismic hazard assessment in the eastern Marmara Sea. Long term kinematics were investigated by performing paleo strain reconstruction from geological field investigations by morphotectonic and kinematic analysis of exposed brittle faults. Short term kinematics were investigated by inverting for the moment tensor of 13 small to moderate recent earthquakes using surface wave amplitude spectra. Our results confirm previous models interpreting the eastern Marmara Sea Region as an active transtensional pull-apart environment associated with significant NNE-SSW extension and vertical displacement. At the northern peninsula, long term deformation pattern did not change significantly since Pliocene times contradicting regional tectonic models which postulate a newly formed single dextral strike slip fault in the Marmara Sea Region. This area is interpreted as a horsetail splay fault structure associated with a major normal fault segment that we call the Waterfall Fault. Apart from the Waterfall Fault, the stress strain relation appears complex associated with a complicated internal fault geometry, strain partitioning, and reactivation of pre-existing plane structures. At the southern peninsula, recent deformation indicates active pull-apart tectonics constituted by NE-SW trending dextral strike slip faults. Earthquakes generated by stress release along large rupture zones seem to be less probable at the northern, but more probable at the southern peninsula. Additionally, regional seismicity appears predominantly driven by plate boundary stresses as transtensional faulting is consistent with the southwest directed far field deformation of the Anatolian plate. (C) 2013 Elsevier B.V. All rights reserved. KW - Seismotectonics KW - Moment tensor inversion KW - Brittle fault analysis KW - Morphotectonics KW - North Anatolian Fault Zone (NAFZ) KW - Marmara Sea Y1 - 2013 U6 - https://doi.org/10.1016/j.tecto.2013.07.016 SN - 0040-1951 SN - 1879-3266 VL - 608 IS - 46 SP - 980 EP - 995 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kieling, Katrin A1 - Rößler, Dirk A1 - Krüger, Frank T1 - Receiver function study in northern Sumatra and the Malaysian peninsula JF - Journal of seismology N2 - In this receiver function study, we investigate the structure of the crust beneath six seismic broadband stations close to the Sunda Arc formed by subduction of the Indo-Australian under the Sunda plate. We apply three different methods to analyse receiver functions at single stations. A recently developed algorithm determines absolute shear-wave velocities from observed frequency-dependent apparent incidence angles of P waves. Using waveform inversion of receiver functions and a modified Zhu and Kanamori algorithm, properties of discontinuities such as depth, velocity contrast, and sharpness are determined. The combination of the methods leads to robust results. The approach is validated by synthetic tests. Stations located on Malaysia show high-shear-wave velocities (V (S)) near the surface in the range of 3.4-3.6 km s (-aEuro parts per thousand 1) attributed to crystalline rocks and 3.6-4.0 km s (-aEuro parts per thousand 1) in the lower crust. Upper and lower crust are clearly separated, the Moho is found at normal depths of 30-34 km where it forms a sharp discontinuity at station KUM or a gradient at stations IPM and KOM. For stations close to the subduction zone (BSI, GSI and PSI) complexity within the crust is high. Near the surface low V (S) of 2.6-2.9 km s (-aEuro parts per thousand 1) indicate sediment layers. High V (S) of 4.2 km s (-aEuro parts per thousand 1) are found at depth greater than 6 and 2 km at BSI and PSI, respectively. There, the Moho is located at 37 and 40 km depth. At station GSI, situated closest to the trench, the subducting slab is imaged as a north-east dipping structure separated from the sediment layer by a 10 km wide gradient in V (S) between 10 and 20 km depth. Within the subducting slab V (S) a parts per thousand aEuro parts per thousand 4.7 km s (-aEuro parts per thousand 1). At station BSI, the subducting slab is found at depth between 90 and 110 km dipping 20A degrees +/- 8A degrees in approximately N 60A degrees E. A velocity increase in similar depth is indicated at station PSI, however no evidence for a dipping layer is found. KW - Receiver functions KW - Absolute shear-wave velocity KW - Sumatra KW - Subduction zone structure Y1 - 2011 U6 - https://doi.org/10.1007/s10950-010-9222-7 SN - 1383-4649 VL - 15 IS - 2 SP - 235 EP - 259 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Blaser, Lilian A1 - Krüger, Frank A1 - Ohrnberger, Matthias A1 - Scherbaum, Frank T1 - Scaling relations of earthquake source parameter estimates with special focus on subduction environment N2 - Earthquake rupture length and width estimates are in demand in many seismological applications. Earthquake magnitude estimates are often available, whereas the geometrical extensions of the rupture fault mostly are lacking. Therefore, scaling relations are needed to derive length and width from magnitude. Most frequently used are the relationships of Wells and Coppersmith (1994) derived on the basis of a large dataset including all slip types with the exception of thrust faulting events in subduction environments. However, there are many applications dealing with earthquakes in subduction zones because of their high seismic and tsunamigenic potential. There are no well-established scaling relations for moment magnitude and length/width for subduction events. Within this study, we compiled a large database of source parameter estimates of 283 earthquakes. All focal mechanisms are represented, but special focus is set on (large) subduction zone events, in particular. Scaling relations were fitted with linear least-square as well as orthogonal regression and analyzed regarding the difference between continental and subduction zone/oceanic relationships. Additionally, the effect of technical progress in earthquake parameter estimation on scaling relations was tested as well as the influence of different fault mechanisms. For a given moment magnitude we found shorter but wider rupture areas of thrust events compared to Wells and Coppersmith (1994). The thrust event relationships for pure continental and pure subduction zone rupture areas were found to be almost identical. The scaling relations differ significantly for slip types. The exclusion of events prior to 1964 when the worldwide standard seismic network was established resulted in a remarkable effect on strike-slip scaling relations: the data do not show any saturation of rupture width of strike- slip earthquakes. Generally, rupture area seems to scale with mean slip independent of magnitude. The aspect ratio L/W, however, depends on moment and differs for each slip type. Y1 - 2010 UR - http://bssa.geoscienceworld.org/ U6 - https://doi.org/10.1785/0120100111 SN - 0037-1106 ER - TY - JOUR A1 - Blaser, Lilian A1 - Ohrnberger, Matthias A1 - Krüger, Frank A1 - Scherbaum, Frank T1 - Probabilistic tsunami threat assessment of 10 recent earthquakes offshore Sumatra JF - Geophysical journal international N2 - Tsunami early warning (TEW) is a challenging task as a decision has to be made within few minutes on the basis of incomplete and error-prone data. Deterministic warning systems have difficulties in integrating and quantifying the intrinsic uncertainties. In contrast, probabilistic approaches provide a framework that handles uncertainties in a natural way. Recently, we have proposed a method using Bayesian networks (BNs) that takes into account the uncertainties of seismic source parameter estimates in TEW. In this follow-up study, the method is applied to 10 recent large earthquakes offshore Sumatra and tested for its performance. We have evaluated both the general model performance given the best knowledge we have today about the source parameters of the 10 events and the corresponding response on seismic source information evaluated in real-time. We find that the resulting site-specific warning level probabilities represent well the available tsunami wave measurements and observations. Difficulties occur in the real-time tsunami assessment if the moment magnitude estimate is severely over- or underestimated. In general, the probabilistic analysis reveals a considerably large range of uncertainties in the near-field TEW. By quantifying the uncertainties the BN analysis provides important additional information to a decision maker in a warning centre to deal with the complexity in TEW and to reason under uncertainty. KW - Probabilistic forecasting KW - Tsunamis KW - Early warning KW - Indian Ocean Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-246X.2011.05324.x SN - 0956-540X VL - 188 IS - 3 SP - 1273 EP - 1284 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Gassner, Alexandra A1 - Thomas, Christine A1 - Krüger, Frank A1 - Weber, Michael H. T1 - Probing the core-mantle boundary beneath Europe and Western Eurasia: A detailed study using PcP JF - Physics of the earth and planetary interiors N2 - We use PcP (the core reflected P phase) recordings of deep earthquakes and nuclear explosions from the Grafenberg (Germany) and NORSAR (Norway) arrays to investigate the core-mantle boundary region beneath Europe and western Eurasia. We find evidence for a previously unknown ultra-low velocity zone 600 km south-east of Moscow, located at the edge of a middle-size low shear- velocity region imaged in seismic tomography that is located beneath the Volga river region. The observed amplitude variations of PcP can be modelled by velocity reductions of P and S-waves of -5% and -15%, respectively, with a density increase of +15%. Travel time delays of pre-and postcursors are indicating a thickness of about 13 km for this ultra-low velocity region (ULVZ). However, our modelling also reveals highly ambiguous amplitude variations of PcP and a reflection off the top of the anomaly for various ULVZs and topography models. Accordingly, large velocity contrasts of up to -10% in V-P and -20% in Vs cannot be excluded. In general, the whole Volga river region shows a complex pattern of PcP amplitudes caused most likely by CMB undulations. Further PcP probes beneath Paris, Kiev and northern Italy indicate likely normal CMB conditions, whereas the samples below Finland and the Hungary-Slovakia border yield strongly amplified PcP signals suggesting strong CMB topography effects. We evaluate the amplitude behaviour of PcP as a function of distance and several ULVZ models using the 1D reflectivity and the 2D Gauss beam method. The influence of the velocity and density perturbations is analysed as well as the anomaly thickness, the dominant period of the source wavelet and interface topographies. Strong variation of the PcP amplitude are obtained as a function of distance and of the impedance contrast. We also consider two types of topographies: undulations atop the CMB in the presence of flat ULVZs and vice versa. Where a broad range of CMB topography dimensions lead to large PcP amplitude variations, only large ULVZ undulations generate significant amplitude scattering. Consequently, this indicates that topography effects of anomalies may mask the true medium parameters as well as the ULVZ thickness. Moreover, there might be a possibility of misinterpreting the precursor as PcP, in particular for thin ULVZs. (C) 2015 Elsevier B.V. All rights reserved. KW - Core-mantle boundary KW - Ultra-low velocity zones KW - Seismology KW - Amplitude and waveform analysis of PcP KW - Earthquakes KW - Nuclear explosions Y1 - 2015 U6 - https://doi.org/10.1016/j.pepi.2015.06.007 SN - 0031-9201 SN - 1872-7395 VL - 246 SP - 9 EP - 24 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lontsi, Agostiny Marrios A1 - Jose Sanchez-Sesma, Francisco A1 - Camillo Molina-Villegas, Juan A1 - Ohrnberger, Matthias A1 - Krüger, Frank T1 - Full microtremor H/V(z,f) inversion for shallow subsurface characterization JF - Geophysical journal international N2 - The H/V spectral ratio has emerged as a single station method within the seismic ambient noise analysis field by its capability to quickly estimate the frequency of resonance at a site and through inversion the average profile information. Although it is easy to compute from experimental data, its counter theoretical part is not obvious when building a forward model which can help in reconstructing the derived H/V spectrum. This has led to the simplified assumption that the noise wavefield is mainly composed of Rayleigh waves and the derived H/V often used without further correction. Furthermore, only the right (and left) flank around the H/V peak frequency is considered in the inversion for the subsurface 1-D shear wave velocity profile. A new theoretical approach for the interpretation of the H/V spectral ratio has been presented by Sanchez-Sesmaet al. In this paper, the fundamental idea behind their theory is presented as it applies to receivers at depth. A smooth H/V(z, f) spectral curve on a broad frequency range is obtained by considering a fine integration step which is in turn time consuming. We show that for practical purposes and in the context of inversion, this can be considerably optimized by using a coarse integration step combined with the smoothing of the corresponding directional energy density (DED) spectrum. Further analysis shows that the obtained H/V(z, f) spectrum computed by the mean of the imaginary part of Green's function method could also be recovered using the reflectivity method for a medium well illuminated by seismic sources. Inversion of synthetic H/V(z, f) spectral curve is performed for a single layer over a half space. The striking results allow to potentially use the new theory as a forward computation of the H/V(z, f) to fully invert the experimental H/V spectral ratio at the corresponding depth for the shear velocity profile (Vs) and additionally the compressional velocity profile (Vp) using receivers both at the surface and in depth. We use seismic ambient noise data in the frequency range of 0.2-50 Hz recorded at two selected sites in Germany where borehole information is also available. The obtained 1-D Vs and Vp profiles are correlated with geological log information. Results from shallow geophysical experiment are also used for comparison. KW - Inverse theory KW - Interferometry KW - Site effects Y1 - 2015 U6 - https://doi.org/10.1093/gji/ggv132 SN - 0956-540X SN - 1365-246X VL - 202 IS - 1 SP - 298 EP - 312 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Kulikova, Galina A1 - Krüger, Frank T1 - Source process of the 1911 M8.0 Chon-Kemin earthquake: investigation results by analogue seismic records JF - Geophysical journal international N2 - Several destructive earthquakes have occurred in Tien-Shan region at the beginning of 20th century. However, the detailed seismological characteristics, especially source parameters of those earthquakes are still poorly investigated. The Chon-Kemin earthquake is the strongest instrumentally recorded earthquake in the Tien-Shan region. This earthquake has produced an approximately 200 km long system of surface ruptures along Kemin-Chilik fault zone and killed about similar to 400 people. Several studies presented the different information on the earthquake epicentre location and magnitude, and two different focal mechanisms were also published. The reason for the limited knowledge of the source parameters for the Chon-Kemin earthquake is the complexity of old analogue records processing, digitization and analysis. In this study the data from 23 seismic stations worldwide were collected and digitized. The earthquake epicentre was relocated to 42.996NA degrees and 77.367EA degrees, the hypocentre depth is estimated between 10 and 20 km. The magnitude was recalculated to m(B) 8.05, M-s 7.94 and M-w 8.02. The focal mechanism, determined from amplitude ratios comparison of the observed and synthetic seismograms, was: str = 264A degrees, dip = 52A degrees, rake = 98A degrees. The apparent source time duration was between similar to 45 and similar to 70 s, the maximum slip occurred 25 s after the beginning of the rupture. Two subevents were clearly detected from the waveforms with the scalar moment ratio between them of about 1/3, the third subevent was also detected with less certainty. Taking into account surface rupture information, the fault geometry model with three patches was proposed. Based on scaling relations we conclude that the total rupture length was between similar to 260 and 300 km and a maximum rupture width could reach similar to 70 km. KW - Earthquake source observations KW - Seismicity and tectonics KW - Body waves KW - Theoretical seismology Y1 - 2015 U6 - https://doi.org/10.1093/gji/ggv091 SN - 0956-540X SN - 1365-246X VL - 201 IS - 3 SP - 1891 EP - 1911 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Matos, Catarina A1 - Silveira, Graca A1 - Matias, Luis A1 - Caldeira, Rita A1 - Ribeiro, M. Luisa A1 - Dias, Nuno A. A1 - Krüger, Frank A1 - Bento dos Santos, Telmo T1 - Upper crustal structure of Madeira Island revealed from ambient noise tomography JF - Journal of volcanology and geothermal research N2 - We present the first image of the Madeira upper crustal structure, using ambient seismic noise tomography. 16 months of ambient noise, recorded in a dense network of 26 seismometers deployed across Madeira, allowed reconstructing Rayleigh wave Green's functions between receivers. Dispersion analysis was performed in the short period band from 1.0 to 4.0 s. Group velocity measurements were regionalized to obtain 20 tomographic images, with a lateral resolution of 2.0 km in central Madeira. Afterwards, the dispersion curves, extracted from each cell of the 2D group velocity maps, were inverted as a function of depth to obtain a 3D shear wave velocity model of the upper crust, from the surface to a depth of 2.0 km. The obtained 3D velocity model reveals features throughout the island that correlates well with surface geology and island evolution. (C) 2015 Elsevier B.V. All rights reserved. KW - Madeira island KW - Volcanic rift zone KW - Crustal structure KW - Ambient noise tomography Y1 - 2015 U6 - https://doi.org/10.1016/j.jvolgeores.2015.03.017 SN - 0377-0273 SN - 1872-6097 VL - 298 SP - 136 EP - 145 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Weber, Michael H. A1 - Wicks, Charles A1 - Le Stunff, Yves A1 - Romanowicz, Barbara A1 - Krüger, Frank T1 - Seismic evidence for a steeply dipping reflector-stagnant slab in the mantle transition zone JF - Geophysical journal international N2 - Studies of seismic tomography have been highly successful at imaging the deep structure of subduction zones. In a study complementary to these tomographic studies, we use array seismology and reflected waves to image a stagnant slab in the mantle transition zone. Using P and S (SH) waves we find a steeply dipping reflector centred at ca. 400 km depth and ca. 550 km west of the present Mariana subduction zone (at 20N, 140E). The discovery of this anomaly in tomography and independently in array seismology (this paper) helps in understanding the evolution of the Mariana margin. The reflector/stagnant slab may be the remains of the hypothetical North New Guinea Plate, which was theorized to have subducted ca. 50 Ma. KW - Mantle processes KW - Composition of the mantle KW - Seismic tomography KW - Wave scattering and diffraction KW - Subduction zone processes KW - Volcanic arc processes KW - Continental margins: convergent KW - Pacific Ocean Y1 - 2015 U6 - https://doi.org/10.1093/gji/ggu438 SN - 0956-540X SN - 1365-246X VL - 200 IS - 2 SP - 1235 EP - 1251 PB - Oxford Univ. Press CY - Oxford ER - TY - GEN A1 - Zali, Zahra A1 - Rein, Teresa A1 - Krüger, Frank A1 - Ohrnberger, Matthias A1 - Scherbaum, Frank T1 - Ocean bottom seismometer (OBS) noise reduction from horizontal and vertical components using harmonic–percussive separation algorithms T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Records from ocean bottom seismometers (OBSs) are highly contaminated by noise, which is much stronger compared to data from most land stations, especially on the horizontal components. As a consequence, the high energy of the oceanic noise at frequencies below 1 Hz considerably complicates the analysis of the teleseismic earthquake signals recorded by OBSs. Previous studies suggested different approaches to remove low-frequency noises from OBS recordings but mainly focused on the vertical component. The records of horizontal components, which are crucial for the application of many methods in passive seismological analysis of body and surface waves, could not be much improved in the teleseismic frequency band. Here we introduce a noise reduction method, which is derived from the harmonic–percussive separation algorithms used in Zali et al. (2021), in order to separate long-lasting narrowband signals from broadband transients in the OBS signal. This leads to significant noise reduction of OBS records on both the vertical and horizontal components and increases the earthquake signal-to-noise ratio (SNR) without distortion of the broadband earthquake waveforms. This is demonstrated through tests with synthetic data. Both SNR and cross-correlation coefficients showed significant improvements for different realistic noise realizations. The application of denoised signals in surface wave analysis and receiver functions is discussed through tests with synthetic and real data. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1320 Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-588828 SN - 1866-8372 IS - 1320 ER - TY - JOUR A1 - Zali, Zahra A1 - Rein, Teresa A1 - Krüger, Frank A1 - Ohrnberger, Matthias A1 - Scherbaum, Frank T1 - Ocean bottom seismometer (OBS) noise reduction from horizontal and vertical components using harmonic–percussive separation algorithms JF - Solid earth N2 - Records from ocean bottom seismometers (OBSs) are highly contaminated by noise, which is much stronger compared to data from most land stations, especially on the horizontal components. As a consequence, the high energy of the oceanic noise at frequencies below 1 Hz considerably complicates the analysis of the teleseismic earthquake signals recorded by OBSs. Previous studies suggested different approaches to remove low-frequency noises from OBS recordings but mainly focused on the vertical component. The records of horizontal components, which are crucial for the application of many methods in passive seismological analysis of body and surface waves, could not be much improved in the teleseismic frequency band. Here we introduce a noise reduction method, which is derived from the harmonic–percussive separation algorithms used in Zali et al. (2021), in order to separate long-lasting narrowband signals from broadband transients in the OBS signal. This leads to significant noise reduction of OBS records on both the vertical and horizontal components and increases the earthquake signal-to-noise ratio (SNR) without distortion of the broadband earthquake waveforms. This is demonstrated through tests with synthetic data. Both SNR and cross-correlation coefficients showed significant improvements for different realistic noise realizations. The application of denoised signals in surface wave analysis and receiver functions is discussed through tests with synthetic and real data. Y1 - 2023 U6 - https://doi.org/10.5194/se-14-181-2023 SN - 1869-9529 VL - 14 IS - 2 SP - 181 EP - 195 PB - Coepernicus Publ. CY - Göttingen ER -