TY - JOUR A1 - Panet, I. A1 - Chambodut, Aude A1 - Diament, M. A1 - Holschneider, Matthias A1 - Jamet, O. T1 - New insights on intraplate volcanism in French Polynesia from wavelet analysis of GRACE, CHAMP, and sea surface data JF - Journal of geophysical research : Solid earth N2 - [ 1] In this paper, we discuss the origin of superswell volcanism on the basis of representation and analysis of recent gravity and magnetic satellite data with wavelets in spherical geometry. We computed a refined gravity field in the south central Pacific based on the GRACE satellite GGM02S global gravity field and the KMS02 altimetric grid, and a magnetic anomaly field based on CHAMP data. The magnetic anomalies are marked by the magnetic lineation of the seafloor spreading and by a strong anomaly in the Tuamotu region, which we interpret as evidence for crustal thickening. We interpret our gravity field through a continuous wavelet analysis that allows to get a first idea of the internal density distribution. We also compute the continuous wavelet analysis of the bathymetric contribution to discriminate between deep and superficial sources. According to the gravity signature of the different chains as revealed by our analysis, various processes are at the origin of the volcanism in French Polynesia. As evidence, we show a large-scale anomaly over the Society Islands that we interpret as the gravity signature of a deeply anchored mantle plume. The gravity signature of the Cook-Austral chain indicates a complex origin which may involve deep processes. Finally, we discuss the particular location of the Marquesas chain as suggesting that the origin of the volcanism may interfere with secondary convection rolls or may be controlled by lithospheric weakness due to the regional stress field, or else related to the presence of the nearby Tuamotu plateau. Y1 - 2006 U6 - https://doi.org/10.1029/2005JB004141 SN - 0148-0227 VL - 111 PB - Union CY - Washington ER - TY - JOUR A1 - Diallo, Mamadou Sanou A1 - Kulesh, Michail A1 - Holschneider, Matthias A1 - Kurennaya, Kristina A1 - Scherbaum, Frank T1 - Instantaneous polarization attributes based on an adaptive approximate covariance method JF - Geophysics N2 - We introduce a method for computing instantaneous-polarization attributes from multicomponent signals. This is an improvement on the standard covariance method (SCM) because it does not depend on the window size used to compute the standard covariance matrix. We overcome the window-size problem by deriving an approximate analytical formula for the cross-energy matrix in which we automatically and adaptively determine the time window. The proposed method uses polarization analysis as applied to multicomponent seismic by waveform separation and filtering. Y1 - 2006 U6 - https://doi.org/10.1190/1.2227522 SN - 0016-8033 SN - 1942-2156 (0nline) VL - 71 IS - 5 SP - V99 EP - V104 PB - SEG CY - Tulsa ER - TY - JOUR A1 - Holschneider, Matthias A1 - Teschke, Gerd T1 - Existence and computation of optimally localized coherent states JF - Journal of mathematical physics N2 - This paper is concerned with localization properties of coherent states. Instead of classical uncertainty relations we consider "generalized" localization quantities. This is done by introducing measures on the reproducing kernel. In this context we may prove the existence of optimally localized states. Moreover, we provide a numerical scheme for deriving them. Y1 - 2006 U6 - https://doi.org/10.1063/1.2375031 SN - 0022-2488 SN - 1089-7658 VL - 47 IS - 3 SP - 211 EP - 214 PB - Elsevier CY - Melville ER - TY - JOUR A1 - Le Mouel, Jean-Louis A1 - Narteau, Clement A1 - Greff-Lefftz, Marianne A1 - Holschneider, Matthias T1 - Dissipation at the core-mantle boundary on a small-scale topography N2 - The parameters of the nutations are now known with a good accuracy, and the theory accounts for most of their values. Dissipative friction at the core-mantle boundary (CMB) and at the inner core boundary is an important ingredient of the theory. Up to now, viscous coupling at a smooth interface and electromagnetic coupling have been considered. In some cases they appear hardly strong enough to account for the observations. We advocate here that the CMB has a small- scale roughness and estimate the dissipation resulting from the interaction of the fluid core motion with this topography. We conclude that it might be significant Y1 - 2006 UR - http://www.agu.org/journals/jb/ U6 - https://doi.org/10.1029/2005jb003846 SN - 0148-0227 ER - TY - JOUR A1 - Diallo, Mamadou Sanou A1 - Kulesh, Michail A1 - Holschneider, Matthias A1 - Scherbaum, Frank A1 - Adler, Frank T1 - Characterization of polarization attributes of seismic waves using continuous wavelet transforms N2 - Complex-trace analysis is the method of choice for analyzing polarized data. Because particle motion can be represented by instantaneous attributes that show distinct features for waves of different polarization characteristics, it can be used to separate and characterize these waves. Traditional methods of complex-trace analysis only give the instantaneous attributes as a function of time or frequency. However. for transient wave types or seismic events that overlap in time, an estimate of the polarization parameters requires analysis of the time-frequency dependence of these attributes. We propose a method to map instantaneous polarization attributes of seismic signals in the wavelet domain and explicitly relate these attributes with the wavelet-transform coefficients of the analyzed signal. We compare our method with traditional complex-trace analysis using numerical examples. An advantage of our method is its possibility of performing the complete wave-mode separation/ filtering process in the wavelet domain and its ability to provide the frequency dependence of ellipticity, which contains important information on the subsurface structure. Furthermore, using 2-C synthetic and real seismic shot gathers, we show how to use the method to separate different wave types and identify zones of interfering wave modes Y1 - 2006 UR - http://geophysics.geoscienceworld.org/ U6 - https://doi.org/10.1190/1.2194511 SN - 0016-8033 ER -