Evidence for P P asymmetrical scattering at near podal distances
|
|
- Bryce Miles
- 5 years ago
- Views:
Transcription
1 GEOPHYSICAL RESEARCH LETTERS, VOL. 39,, doi: /2012gl052179, 2012 Evidence for P P asymmetrical scattering at near podal distances Wenbo Wu, 1,2 Sidao Ni, 2 and Xiangfang Zeng 1 Received 3 May 2012; accepted 8 May 2012; published 7 June [1] We report strong short period ( Hz) precursors to P P df at podal to short distances (0 50 ) with advance time around 60s. From FK analysis, we find that the precursors at epicentral distance of 35 arrive along backazimuth about +/ 120 off the great circle paths (asymmetrical path) with slowness between 2 4 sec/deg, arguing against propagation path in the inner core. Polarization analysis also supports wave propagation in the outer core. Timing and shape of the precursors waveform envelopes are well matched with synthetic envelopes taking into account the scattering from the rough free surface and volumetric heterogeneities inside the Earth along asymmetrical propagation path. Therefore the precursors are very probably generated with asymmetrical scattering mechanism. This interpretation does not require extra discontinuities or a layer of strong small scale heterogeneities in the upper mantle, which are inferred from P P precursors when only symmetrical scattering is assumed. Citation: Wu, W., S. Ni, and X. Zeng (2012), Evidence for P P asymmetrical scattering at near podal distances, Geophys. Res. Lett., 39,, doi: / 2012GL Introduction [2] Short scale heterogeneities in the mantle have significant implications for geodynamical studies. For example, short scale heterogeneities (10 km) almost only result from chemical mixing in the Earth, because temperature anomalies are expected to be smooth with rapid thermal diffusions [Ni et al., 2002; Shearer and Earle, 2008]. Short period (1 Hz) scattered waves are effective probes to the Earth s structure with scales around 10 km. Among them, precursors to P P have the advantage of less contamination from P coda, and have been applied to studies of scatterers [Earle et al., 2011]. Precursors to P P with advance time less than 70 s have been interpreted as evidence for discontinuities at depths from km, assuming that the precursors are associated with symmetric reflection paths (hereafter referred to as the symmetric scattering mechanism) [Adams, 1968]. Alternatively, the propagation path could also be asymmetrical (Figure 1a, dashed lines) [King and Cleary, 1974; Haddon et al., 1977; Vinnik, 1981] (hereafter referred to as the asymmetrical scattering mechanism). At short distances of 30 50, Earle et al. [2011] demonstrated that the P P 1 Mengcheng National Geophysical Observatory, University of Science and Technology of China, Hefei, China. 2 State Key Laboratory of Geodesy and Earth s Dynamics, Institute of Geodesy and Geophysics, Wuhan, China. Corresponding author: S. Ni, State Key Laboratory of Geodesy and Earth s Dynamics, Institute of Geodesy and Geophysics, Wuhan , China. (sdni@whigg.ac.cn) American Geophysical Union. All Rights Reserved. precursors are from off-azimuth path with fk analysis of waveform data at LASA array. Based on further studies with Monte-Carlo simulations, they proposed that the precursors most likely originate from scattering of PKPbc-to-PKPbc in the Earth s crust and upper mantle. [3] But the symmetrical reflection is claimed to be responsible for the strong precursors to P P at near-podal distances (7 degrees), and a layer of scatterers at depth of km is proposed (Figure 1a) [Tkalcic et al., 2006]. Such a layer of small scale heterogeneity on global scale would have significant geodynamical implications. For example, it may help resolve controversies regarding the 210 discontinuity which is present in the global model of PREM, but has not been observed globally yet [Deuss and Woodhouse, 2004]. However, if the precursors are associated with asymmetrical paths, crustal or shallow mantle heterogeneity may generate the precursors, and this layer is not necessarily required. Therefore, more seismological investigations are needed to resolve which scattering mechanism is involved in generating the precursors at near-podal distances. [4] In the following sections, we present observation of strong precursors to P P for almost podal distances (1 )up to 50, then perform array analysis to determine their slowness vector and match observation with synthetic waveform envelopes to demonstrate that the rough free surface or shallow heterogeneities with asymmetrical scattering mechanism is capable of generating the precursors. 2. Data and Analysis 2.1. Observation of P P Precursors [5] Following notation by Earle et al. [2011], we label precursors due to propagation along the symmetrical path of reflection at depth d as P dp. For example, P 210P represents the precursors generated from reflection/scattering at depth of 210 km (Figures 1a and 1b). As for signals due to scattering along the asymmetrical paths (dashed line in Figure 1a), we use d to represent the scattering at the depth of d. The asymmetrical scattering includes the rough free surface scattering (P 0 P ), and scattering due to volumetric heterogeneity which includes two mechanisms: the back scattering (P d P ) and the forward scattering(p d pp and P p d P ) (Figure 1c). The forward scattering P d pp represents the PKP scattered by the heterogeneity at depth of d, then up to free surface as p and reflected as PKP according to Snell law. There is also the phase of P p d P due to reciprocity between source and receiver. The back scattering P d P (red dashed line) is the PKP wave scattered by heterogeneity at depth d and directly back to the receiver. P d P arrives earlier than P 0 P, while P d pp slight later than P 0 P (Figure 1d). For small d, the phases P d pp and P p d P arrive almost at the same time as P 0 P, so we use P surfp to denote the precursors associated with the three 1of6
2 Figure 1. Probable mechanisms for P P precursors. (a) The ray paths of the symmetrical scattering-p 210P (the solid line) and the asymmetrical scattering (the dashed line). This figure just shows the great circle plane, actually the asymmetrical scattering wave can be from the off great circle direction (shown in Figure S2). (b) The symmetrical scattering path P 210P in the upper mantle. (c) The asymmetrical scattering includes three possible mechanisms: rough free surface scattering P 0 P (green dashed line), forward scattering P d pp (blue dashed line) and P p d P (purple dashed line) and back scattering P d P. (d) The possible main phases theoretical travel time for ak135 model. P 0 P has constant arrival time (the dashed line P 0 P ). phases because they are all caused by interaction on the free surface. [6] Global stations record strong short period P P precursors at epicentral distances from almost-podal distance of 1 to short distance of 50, for almost any deep earthquake stronger than Mw 6 (Figure 2a). The waveform data in Figure 2 are obtained from broadband seismic stations of IRIS DMC and CENC (China Earthquake Networks Center) for earthquakes deeper than 70 km (Table S1 in the auxiliary material). 1 P P and its precursors are usually not identifiable on raw broadband seismograms, but after short period filtering ( Hz, 4th order Butterworth bandpass) strong signals show up clearly about seconds before the theoretical arrival of P P df (Figure 2b). As short period seismograms are difficult to model wiggle by wiggle, smoothed envelopes are adopted and displayed in Figure 2c [Shearer and Earle, 2008]. The waveform envelopes of P P precursors are also observed for distances up to 50 degrees, but P P df is not readily recognizable, probably due to its low amplitude because it is strongly attenuated at short period after twice traverse in the inner core. Unlike the emergent onset and long duration of the precursors, strong PKKKP 1 Auxiliary materials are available in the HTML. doi: / 2012GL (P3KP) is easily identified with sharp onset and short duration (Figure 2c). The strong P3KP wave may present contamination to studies of P P precursors, especially for distances around 18 degrees, where they cross over. Two distance windows can be chosen to avoid the contamination, that is, either for distances larger than 30 degrees where P3KP coda is well ahead of P P precursors, or for distances less than 10 degrees where P3KP arrives much later than P P precursors. At lower frequency ( Hz), P P precursors are identifiable but with much lower signal noise ratio (SNR). In this band, P P df seems to be coherent (Figure S1a) as expected from lower absorption in the inner core at lower frequencies. At higher frequency (1 3 Hz), P P precursors are still observable (Figure S1b). The different frequency dependences between P P precursors and P P df suggests that they propagate with different paths. One possible scenario is that the waves associated with the precursors do not propagate in the highly attenuating inner core (Q = ). Another scenario is that the scattered waves do not propagate in asthenosphere [Tkalcic et al., 2006]. However, P P df travels almost 4800 km in the inner core and only about 200 km in the asthenosphere, so the inner core is more effective in attenuating high frequency waves. Therefore, the precursors are more likely caused by waves not travelling in the inner core. 2of6
3 Figure 2. Observation of the P P precursors. (a) Earthquakes (red star) and stations(blue triangle) (b) The raw seismogram (bottom) and the Hz bandpass filtered record (top) at MDJ station for the event at distance around 1 degree (Figure S5a). (c) Record sections of globally observed short period ( Hz) P P df precursor at distances from 0 50 degree. The red circles indicate the identified onset of P surfp + P d P. [7] The seismogram envelopes in Figure 2c have been aligned after correction of travel time due to different focal depths. The precursors have almost constant travel time of 2350 s after the earthquake origin time for all distances, and are about 60 seconds earlier than P P df [Earle, 2002; Rost and Earle, 2010]. In contrast, P P df is expected to show substantial move-outs for distances from 0 to 50 degrees (Figure 2c). Different from seismic phase associated with geometrical rays which usually feature impulsive onsets, the envelope of P P precursors behaves like a spindle with emergent onset and slow decaying tail. They rise gradually starting at 2350 sec, reach the peak about 20 sec later, then return to noise level about 60 sec later. The emergent onset is suggestive of wave origin due to scattering [Vidale and Earle, 2000]. These observations are similar with that of Earle et al. [2011]. [8] According to the symmetrical scattering hypothesis, P 210P also arrives at 60s before P P df [Tkalcic et al., 2006]. But their study only samples two isolated areas of the Earth, and our dataset consists of global observation of P P precursors at near-podal distances. As the km discontinuity or strong heterogeneity layer is not a global structure [Lehmann, 1961; Benz and Vidale, 1993; Rost and Weber, 2001; Deuss and Woodhouse, 2004], our dataset of globally observed precursors are probably not caused by the heterogeneities at depth of km Synthetic Envelopes With the Asymmetrical Scattering Mechanism [9] Though travel time of P 210P is similar to that of P surfp or P d P for small d, their slowness and direction of arrival are different. As the rays propagate in the inner core, the slowness of P 210P is similar to that of P P df and should be less than 1.9 s/deg. In contrast, the slowness of P surfp or P d P should be larger because the ray paths only sample the outer core. Moreover, P 210P is expected to arrive from the great circle path. So the frequency-wave number analysis (fk-analysis) can be used to resolve where the scattered wave is generated [Rost and Thomas, 2002]. [10] Figure S2 displays fk analysis of P P precursors observed on Yellow Knnife (YK) and Warramunga (WR) arrays (with the Generic Array Processing Code by K. Koper, Source code available on ftp://ftp.eas.slu.edu/pub/koper/gap. 1.0.tar.gz). From the fk analysis, it is observed that the precursors arrive with azimuth of about +/ 120 off the great circle paths and with slowness larger than 1.9 sec/deg. Ray-tracing with PREM predicts that P surfp or P d P arrive with 120 degrees deviation from great circle path at epicentral distances around 30 degrees (Figure S3). These results are direct evidences to support the hypothesis of asymmetrical scattering, and are consistent with Earle et al. s [2011] study. The polarization from three-components waveform records provides extra constraints on the propagation paths of scattered waves. Because of the much smaller 3of6
4 Figure 3. Synthetic and observed envelopes of P P precursors. (a) The Green s function of asymmetrical scattering at different distances. The solid black and green line are back and forward scattering with autocorrelation length a = 2 km. The dashed line corresponds the case of a = 13 km. The free surface s roughness is described with a model of rms 100 m height variation and L = 7 km for Gaussian ACF. The scattered signal from free surface (red line) is stronger than that from back scattering mechanism but weaker than that from the forward scattering mechanism. The blue lines give the total scattered energy including the rough surface, forward scattering and back scattering. (b) The amplitude-normalized observed (black) and synthetic (red) P P precursors at three stations for event (c) The Green s function for asymmetrical scattering from all the three mechanisms (blue line, they are the same with Figure 3a) and symmetrical scattering (black line). The solid line corresponds to a = 2 km while dashed line with a = 13 km. For the symmetrical scattering, we set the km layer with 5% perturbation for Vp, Vs and density. The black lines are plotted with amplification by a factor of 100. ray parameter of the P 210P wave at podal distances, the radial component of PKPbc or PKPab is much larger than that of PKPdf at antipodal distances. Figure S4 shows that the radial component of P P precursor at near-podal distance is similar to that of PKPbc or PKPab near the caustic distance 145, consistent with the asymmetrical path of P surfp or P d P. In contrast, it is much larger than that of PKPdf at antipodal distances, as expected for the symmetric path of P 210P. This is a direct evidence supporting that the asymmetric scattering mechanism is responsible for the P P precursors. [11] The envelope shapes of the precursors provide further evidences for asymmetric scattering mechanism. For example, when seismic waves are generated only with asymmetric scattering and not associated with any geometric arrivals, waveforms show emergent onset and spindle-like envelope shapes [Shearer and Earle, 2008]. Moreover, duration of the waveform envelopes is long for scattering from large area, for example, Vidale and Earle [2000] reported a seismic phase with long duration due to the inner core scattering. The specific behaviors (shown in Figure 1c) of each scattering mechanism will be demonstrated with synthetic enveloped seismograms. Since the crust is the most heterogeneous portion of the earth, for simplicity we just assume heterogeneities in the upper most 10 km crust, though the deeper crust and upper mantle s heterogeneities can also contribute to the scattering. [12] We use ray theory to compute synthetic seismograms for scattering from the topography of free surface and the forward and back scattering caused by the volumetric heterogeneities [Scott and Helmberger, 1983; Wu and Aki, 1985; Sato and Fehler, 1998]. We only consider single scattering events, and this might underestimate effects due to multiple scattering which would better be modeled with Monte Carlo methods [Shearer and Earle, 2008]. We use ray tracing for PREM model to calculate the geometric spreading factor and transmission coefficient at core mantle boundary. Combination of PKPab and PKPbc leads to four pairs of scattering paths whose energy contributions are calculated respectively. Our methods are only valid for smooth topography and weak volumetric heterogeneities. The free surface s topography of the Earth is described with Gaussian autocorrelation function (ACF), Rr ðþ¼h 2 e r2 L 2, where h is the root of mean square (rms) height variation and L is the autocorrelation length. The rms h is larger than 50 m for most free surface s topography and the autocorrelation length ranges from 1kmto10 km [Goff et al., 1997]. The upper mantle and crust s heterogeneities is described with exponential ACF, Rr ðþ¼ɛ 2 e r a [Sato and Fehler, 1998], where ɛ is the rms variation of either seismic velocities or densities, and a is the autocorrelation length. The rms ɛ of S wave perturbation can be up to 10% for shallow crust [Sato, 1984] and a ranges from 100 meters to 10 kilometers 4of6
5 [Capon, 1974; Wu and Aki, 1985; Yoshimoto et al., 1997]. According to the scattering theory, more scattering is excited in the forward scattering when a increases, so the forward scattering is strong for ak > 1while k is the wave number of incident waves [Wu and Aki, 1985; Sato and Fehler, 1998]. [13] The calculation of the amplitude of short period seismic waves is difficult since the quality factor Q at short period is one of the challenging parameters to be well resolved. But it is fortunate that the ray path of rough surface s scattering is almost the same as the ray path of scattering from shallow heterogeneity. So we assume their attenuation effects are same. We adopt isotropic radiation pattern of large earthquakes at high frequency [Boore, 2003]. We assume h = 100 m and L = 7 km for free surface topography. For the crust, we choose seismic velocities (P and S) and density perturbation of rms ɛ = 5%, and two correlation length a = 2 km and 13 km are tested respectively. From previous studies, a is taken to be larger than 10 km [Capon, 1974; Wu and Aki, 1985]. Figure 3a illustrates the back and forward scattered energy (black and green line) caused by heterogeneities within the upper most 10 km in the crust and the rough surface (red line). From Figure 3a we observe that the forward scattering is strongest, then the rough surface scattering, while the back scattering is the weakest. The forward scattering is two order of magnitudes stronger than back scattering for a = 13 km. For the case of a = 2 km, the forward scattering is a little bit weaker, but still dozens of time stronger than the back scattering mechanism. So it demonstrates that the main contribution of P P precursor should be from the heterogeneity s forward scattering and the rough free surface scattering but not from the heterogeneity s back scattering. [14] The synthetics in Figure 3a do not take earthquake source function into account, therefore they are better named as Green s function. In order to compare the synthetics with observed data, we take the direct P wave s envelope as source time function and convolve it with the Green s function. Figure 3b shows the synthetics (red line) and the observed data (black line) for a deep event (020628). The synthetics onset times and shapes match the observed data well, both showing rapid increase of amplitude at 2290 s and gradual decay about 30s later. More data and synthetics are displayed in Figure S5, where we just model the P P precursors at distance <10 to avoid the P3KP interference. Therefore, asymmetric scattering from free surface roughness and shallow heterogeneities is capable of explaining both the timing, duration and waveform feature of observed P P precursor. Furthermore, we estimate strength of the asymmetrical (P surfp +P d P ) and symmetrical scattering (P 210P ) based on the mantle Q model by Shearer and Earle [2004] and the core Q model by Li and Cormier [2002]. We find that the symmetrical scattering should be two orders of magnitude weaker than the asymmetrical scattering (Figure 3c). 3. Discussion and Conclusion [15] Precursors to P P and other multiples phases (SS, PP, etc) are important in studying mantle discontinuities for the case of symmetric paths, and indeed have led to significant discoveries of depth and sharpness of 410 and 660 discontinuities [Shearer and Flanagan, 1999; Xu et al., 2003]. Maybe there are substantial heterogeneities at depths of km, and we can not rule out that some components of P P precursors are from the symmetric back scattering of P 210P. However, the crust as one of the most inhomogeneous portion in the Earth and the free surface as the strongest discontinuity imply that the globally observed short period P P precursors are probably dominated by P surfp and P d P. The nearly constant onset travel time and deviation of direction of arrival from great circle path with array analysis argue that the asymmetrical scattering P surfp or P d P as the source of P P precursor. The polarization analysis provides extra direct evidences of asymmetrical scattering for the near-podal distances. Recent studies also demonstrated that the asymmetrical scattering is responsible for precursors to P P at distances from degrees [Earle et al., 2011], consistent with our near-podal analysis. Moreover, our study consists of seismic records from global stations and earthquakes, thus suggesting that the asymmetrical scattering mechanism is applicable for the whole Earth. However, we can not specify whether the rough free surface or the volume heterogeneity inside the Earth is the main contributor because of the limited knowledge of the global crust and upper mantle s heterogeneity, though the topography of free surface is accurately known. [16] From quantitative calculation we suggest that P surfp or P d P could be from the scattering of rough free surface or the forward scattering of heterogeneity in crust and upper mantle, and the back scattering from these structures could be fairly weak. But maybe at some quiet stations the back scattering of the crust or upper mantle s heterogeneity could be well observed, as the signals are earlier than the observed P surfp [Earle et al., 2011]. If so, the earlier precursors may reveal more information of the crust and upper mantle s heterogeneity, for example the autocorrelation length can be constrained from the ratio of the forward and back scattering energy. [17] Acknowledgments. We are grateful that two reviewers provide constructive comments. Data are provided by IRIS/DMC and Chinese Seismic Network/CSNDMC. Supported by NSFC , References Adams, R. D. (1968), Early reflections of P P as an indication of upper mantle structure, Bull. Seismol. Soc. Am., 58, Benz, H. M., and J. E. Vidale (1993), Sharpness of upper mantle discontinuities determined from high-frequency reflections, Nature, 365, , doi: /365147a0. Boore, D. M. (2003), Simulation of ground motion using the stochastic method, Pure Appl. Geophys., 160, , doi: /pl Capon, J. (1974), Characterization of crust and upper mantle structure under LASA as random medium, Bull. Seismol. Soc. Am., 64, Deuss, A., and J. H. Woodhouse (2004), The nature of the Lehmann discontinuity from its seismological Clapeyron slope, Earth Planet. Sci. Lett., 225(3 4), , doi: /j.epsl Earle, P. S. (2002), Origins of high-frequency scattered waves near PKKP from large aperture seismic array data, Bull. Seismol. Soc. Am., 92, , doi: / Earle, P. S., S. Rost, P. M. Shearer, and C. Thomas (2011), Scattered P P waves observed at short distances, Bull. Seismol. Soc. Am., 101, , doi: / Goff, J. A., Y. Ma, A. Shah, J. R. Cochran, and J. C. Sempere (1997), Stochastic analysis of seafloor morphology on the flank of the Southeast Indian Ridge: The influence of ridge morphology on the formation of abyssal hills, J. Geophys. Res., 102, 15,521 15,534, doi: / 97JB Haddon, R. A. W., E. S. Husebye, and D. W. King (1977), Origins of precursors to P P, Phys. Earth Planet. Inter., 14, 41 70, doi: / (77) King, D. W., and J. R. Cleary (1974), A note on the interpretation of precursors to PKPPKP, Bull. Seismol. Soc. Am., 64, of6
6 Lehmann, I. (1961), S and the structure of the upper mantle, Geophys. J. R. Astron. Soc., 4, , doi: /j x.1961.tb06808.x. Li, X., and V. F. Cormier (2002), Frequency-dependent seismic attenuation in the inner core: 1. A viscoelastic interpretation, J. Geophys. Res., 107(B12), 2361, doi: /2002jb Ni, S. D., E. Tan, M. Gurnis, and D. V. Helmberger (2002), Sharp sides to the African superplume, Science, 296, , doi: / science Rost, S., and P. S. Earle (2010), Identifying regions of strong scattering at the core-mantle boundary from analysis of PKKP precursor energy, Earth Planet. Sci. Lett., 297, , doi: /j.epsl Rost, S., and C. Thomas (2002), Array seismology: Methods and applications, Rev. Geophys., 40(3), 1008, doi: /2000rg Rost, S., and M. Weber (2001), A reflector at 210 km depth beneath the NW Pacific, Geophys. J. Int., 147, 12 28, doi: /j x x. Sato, H. (1984), Attenuation and envelope formation of three-component seismograms of small local earthquakes in randomly inhomogeneous lithosphere, J. Geophys. Res., 89, , doi: / JB089iB02p Sato, H., and M. Fehler (1998), Seismic Wave Propagation and Scattering in the Heterogeneous Earth, Springer, New York, doi: / Scott, P., and D. V. Helmberger (1983), Application of the Kirchhoff- Helmholtz integral to problems in seismology, Geophys. J. R. Astron. Soc., 72, , doi: /j x.1983.tb02815.x. Shearer, P. M., and P. S. Earle (2004), The global short-period wavefield modelled with a Monte Carlo seismic phonon method, Geophys. J. Int., 158, , doi: /j x x. Shearer, P. M., and P. S. Earle (2008), Observing and modeling elastic scattering in the deep Earth, in Earth Heterogeneity and Scattering Effects on Seismic Waves, Adv. Geophys., vol. 50, edited by H. Sato and M. Fehler, pp , Elsevier, New York, doi: /s (08)00006-x. Shearer, P., and M. Flanagan (1999), Seismic velocity and density jumps across the 410- and 660-kilometer discontinuities, Science, 285, , doi: /science Tkalcic, H., M. P. Flanagan, and V. F. Cormier (2006), Observation of nearpodal P P precursors: Evidence for back scattering from the km zone in the Earth s upper mantle, Geophys. Res. Lett., 33, L03305, doi: /2005gl Vidale, J. E., and P. S. Earle (2000), Fine scale heterogeneity in the Earth s inner core, Nature, 404, , doi: / Vinnik, L. P. (1981), Evaluation of the effective cross-section of scattering in the lithosphere, Phys. Earth Planet. Inter., 26, , doi: / (81) Wu, R. S., and K. Aki (1985), Elastic wave scattering by a random medium and the small-scale in homogeneities in the lithosphere, J. Geophys. Res., 90, 10,261 10,273, doi: /jb090ib12p Xu, F., J. E. Vidale, and P. S. Earle (2003), Survey of precursors to P P : Fine structure of mantle discontinuities, J. Geophys. Res., 108(B1), 2024, doi: /2001jb Yoshimoto, K., H. Sato, and M. Ohtake (1997), Short-wavelength crustal heterogeneities in the Nikko area, central Japan, revealed from the three-components envelope analysis, Phys. Earth Planet. Inter., 104, 63 73, doi: /s (97) of6
Estimation of S-wave scattering coefficient in the mantle from envelope characteristics before and after the ScS arrival
GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 24, 2248, doi:10.1029/2003gl018413, 2003 Estimation of S-wave scattering coefficient in the mantle from envelope characteristics before and after the ScS arrival
More informationProbing Mid-Mantle Heterogeneity Using PKP Coda Waves
Probing Mid-Mantle Heterogeneity Using PKP Coda Waves Michael A.H. Hedlin and Peter M. Shearer Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics Scripps Institution of Oceanography,
More informationSeismic Scattering in the Deep Earth
Seismic Scattering in the Deep Earth Peter Shearer IGPP/SIO/U.C. San Diego September 2, 2009 Earthquake Research Institute Mantle mixing calculations Heterogeneity is likely at all scales Davies (2002)
More informationMYRES Seismic Constraints on Boundary Layers. Christine Thomas
MYRES 2004 Seismic Constraints on Boundary Layers Christine Thomas Outline Seismic constraints: what can we resolve? how can we detect seismic structures? how well can we resolve these structures? (resolution
More information29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies
TRANSITION ZONE WAVE PROPAGATION: CHARACTERIZING TRAVEL-TIME AND AMPLITUDE INFORMATION Peter M. Shearer and Jesse F. Lawrence University of California San Diego, Institute of Geophysics and Planetary Physics
More informationWaveform search for the innermost inner core
Waveform search for the innermost inner core Vernon F. Cormier 1 and Anastasia Stroujkova 1,2 University of Connecticut Storrs, CT 06269-3046 Abstract Waveforms of the PKIKP seismic phase in the distance
More informationSupporting Online Material for
www.sciencemag.org/cgi/content/full/1131692/dc1 Supporting Online Material for Localized Temporal Change of the Earth s Inner Core Boundary This PDF file includes: Materials and Methods Figs. S1 to S3
More information29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies
ANALYSIS AND SIMULATION OF THREE-DIMENSIONAL SCATTERING DUE TO HETEROGENEOUS CRUSTAL STRUCTURE AND SURFACE TOPOGRAPHY ON REGIONAL PHASES; MAGNITUDE AND DISCRIMINATION Arben Pitarka 1, Don V. Helmberger
More informationSelected Seismic Observations of Upper-Mantle Discontinuities
Selected Seismic Observations of Upper-Mantle Discontinuities Peter Shearer IGPP/SIO/U.C. San Diego August 31, 2009 Earthquake Research Institute Interface Depth vs. Publication Date Most depths are sampled
More informationImaging sharp lateral velocity gradients using scattered waves on dense arrays: faults and basin edges
2017 SCEC Proposal Report #17133 Imaging sharp lateral velocity gradients using scattered waves on dense arrays: faults and basin edges Principal Investigator Zhongwen Zhan Seismological Laboratory, California
More informationScattering and intrinsic attenuation structure in Central Anatolia, Turkey using BRTR (PS-43) array
Scattering and intrinsic attenuation structure in Central Anatolia, Turkey using BRTR (PS-43) array CTBT: Science & Technology 2011 Korhan Umut SEMIN Nurcan Meral OZEL B.U. Kandilli Observatory & Earthquake
More informationSurvey of precursors to P 0 P 0 : Fine structure of mantle discontinuities
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B1, 2024, doi:10.1029/2001jb000817, 2003 Survey of precursors to P 0 P 0 : Fine structure of mantle discontinuities Fei Xu and John E. Vidale Department of
More informationOne-Dimensional Modeling of Multiple Scattering in the Upper Inner Core: Depth Extent of a Scattering Region in the Eastern Hemisphere
Journal of Earth Science, Vol. 24, No. 5, p. 706 715, October 2013 ISSN 1674-487X Printed in China DOI: 10.1007/s12583-013-0366-6 One-Dimensional Modeling of Multiple Scattering in the Upper Inner Core:
More informationChapter 12 Seismic Detections of Small-Scale Heterogeneities in the Deep Earth
Chapter 12 Seismic Detections of Small-Scale Heterogeneities in the Deep Earth Sebastian Rost, Paul S. Earle, Peter M. Shearer, Daniel A. Frost and Neil D. Selby Abstract We report the detection of coherent
More informationLateral variation of the D 00 discontinuity beneath the Cocos Plate
GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L15612, doi:10.1029/2004gl020300, 2004 Lateral variation of the D 00 discontinuity beneath the Cocos Plate T. Lay Earth Sciences Department, University of California,
More informationInner core attenuation anisotropy
Earth and Planetary Science Letters 245 (2006) 581 594 www.elsevier.com/locate/epsl Inner core attenuation anisotropy Wen-che Yu, Lianxing Wen Department of Geosciences, State University of New York at
More informationboundaries with additional record sections, as emphasized in Fig. S2. The observations at the
Data used to Sample African Anomaly. The great circle paths of the source-receiver combinations used in this study are shown in Fig. S1. The event information is given in Table S1. Abrupt Changes across
More informationThe global short-period wavefield modelled with a Monte Carlo seismic phonon method
Geophys. J. Int. (24) 158, 113 1117 doi: 1.1111/j.1365-246X.24.2378.x The global short-period wavefield modelled with a Monte Carlo seismic phonon method Peter M. Shearer 1 and Paul S. Earle 2 1 Institute
More informationSeismogram Interpretation. Seismogram Interpretation
Travel times in the Earth Ray paths, phases and their name Wavefields in the Earth: SH waves, P-SV waves Seismic Tomography Receiver Functions Seismogram Example Long-period transverse displacement for
More informationSeismic interferometry with antipodal station pairs
GEOPHYSICAL RESEARCH LETTERS, VOL. 4, 1 5, doi:1.12/grl.597, 213 Seismic interferometry with antipodal station pairs Fan-Chi Lin 1 and Victor C. Tsai 1 Received 25 June 213; revised 19 August 213; accepted
More information29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies MODELING P WAVE MULTIPATHING IN SOUTHEAST ASIA
MODELING P WAVE MULTIPATHING IN SOUTHEAST ASIA Ali Fatehi and Keith D. Koper Saint Louis University Sponsored by the Air Force Research Laboratory ABSTRACT Contract No. FA8718-06-C-0003 We have used data
More informationSUMMARY. fractured reservoirs in the context of exploration seismology.
Modeling scattering of cross-well seismic waves using Radiative Transfer Theory Josimar A. Da Silva Jr, Oleg V. Poliannikov and Michael Fehler, Earth Resources Laboratory / M.I.T SUMMARY We model P and
More informationMain Menu. Summary. Introduction
Kyosuke Okamoto *, JSPS Research Fellow, Kyoto University; Ru-shan Wu, University of California, Santa Cruz; Hitoshi Mikada, Tada-nori Goto, Junichi Takekawa, Kyoto University Summary Coda-Q is a stochastic
More informationEstimation of Coda Wave Attenuation Quality Factor from Digital Seismogram Using Statistical Approach
Science and Technology 2012, 2(1): 1-7 DOI: 10.5923/j.scit.20120201.01 Estimation of Coda Wave Attenuation Quality Factor from Digital Seismogram Using Statistical Approach Jwngsar Brahma School of Petroleum
More informationGlobal P, PP, and PKP wave microseisms observed from distant storms
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L23306, doi:10.1029/2008gl036111, 2008 Global P, PP, and PKP wave microseisms observed from distant storms Peter Gerstoft, 1 Peter M. Shearer, 1 Nick Harmon, 1 and
More informationTime dependence of PKP(BC) PKP(DF) times: could this be an artifact of systematic earthquake mislocations?
Physics of the Earth and Planetary Interiors 122 (2000) 221 228 Time dependence of PKP(BC) PKP(DF) times: could this be an artifact of systematic earthquake mislocations? Xiaodong Song Department of Geology,
More informationSupporting Information for An automatically updated S-wave model of the upper mantle and the depth extent of azimuthal anisotropy
GEOPHYSICAL RESEARCH LETTERS Supporting Information for An automatically updated S-wave model of the upper mantle and the depth extent of azimuthal anisotropy Eric Debayle 1, Fabien Dubuffet 1 and Stéphanie
More informationTeleseismic receiver function using stacking and smoothing of multi seismic-records at a single station
Earthq Sci (2012)25: 75 81 75 doi:10.1007/s11589-012-0833-7 Teleseismic receiver function using stacking and smoothing of multi seismic-records at a single station Yi Yang and Fuhu Xie Earthquake Administration
More informationFenglin Niu and Hitoshi Kawakatsu. Earthquake Research Institute, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo , Japan
Earth Planets Space, 50, 965 975, 1998 Determination of the absolute depths of the mantle transition zone discontinuities beneath China: Effect of stagnant slabs on transition zone discontinuities Fenglin
More informationOn the observation of high frequency PKiKP and its coda in Australia
Physics of the Earth and Planetary Interiors 146 (2004) 497 511 On the observation of high frequency PKiKP and its coda in Australia G. Poupinet a,b,, B.L.N. Kennett a a RSES, Australian National University,
More informationSEISMIC WAVE PROPAGATION AND SCATTERING IN THE HETEROGENEOUS EARTH
Haruo Sato Tohoku University, Japan Michael C. Fehler Massachusetts Institute of Technology, U.S.A. Takuto Maeda The University of Tokyo, Japan SEISMIC WAVE PROPAGATION AND SCATTERING IN THE HETEROGENEOUS
More informationIntrinsic and Scattering Seismic Attenuation in W. Greece
Pure appl. geophys. 153 (1998) 703 712 0033 4553/98/040703 10 $ 1.50+0.20/0 Intrinsic and Scattering Seismic Attenuation in W. Greece G-AKIS TSELENTIS 1 Abstract Intrinsic (Q 1 i ) and scattering (Q 1
More informationBroadband converted phases from midmantle discontinuities
Earth Planets Space, 50, 987 997, 1998 Broadband converted phases from midmantle discontinuities Lev Vinnik 1,2, Fenglin Niu 1, and Hitoshi Kawakatsu 1 1 Earthquake Research Institute, University of Tokyo,
More informationEarthquake location at teleseismic distances from 3-component records (Tutorial with exercise by hand)
Topic Author Version Earthquake location at teleseismic distances from 3-component records (Tutorial with exercise by hand) Peter Bormann (formerly GFZ German Research Centre for Geosciences, D-14473 Potsdam,
More informationFigures S1 S4 show the measurements taken from the synthetic vespagrams where a)
Figures S1 S4 show the measurements taken from the synthetic vespagrams where a) is the differential travel time versus the Dʺ discontinuity height, b) is the differential travel time versus δv S, c) is
More informationGlobal propagation of body waves revealed by cross-correlation analysis of seismic hum
GEOPHYSICAL RESEARCH LETTERS, VOL. 4, 1691 1696, doi:1.12/grl.5269, 213 Global propagation of body waves revealed by cross-correlation analysis of seismic hum K. Nishida 1 Received 1 January 213; revised
More informationSupplementary Online Material for. Seismic evidence for a chemically distinct thermochemical reservoir in Earth s deep mantle beneath Hawaii
Supplementary Online Material for Seismic evidence for a chemically distinct thermochemical reservoir in Earth s deep mantle beneath Hawaii Authors: Chunpeng Zhao 1, Edward J. Garnero 1,*, Allen K. McNamara
More informationComparison of crustal and upper mantle heterogeneity in different time periods: Indonesian subduction zone to northern Australia
Earthq Sci (2014) 27(1):47 55 DOI 10.1007/s11589-013-0059-3 RESEARCH PAPER Comparison of crustal and upper mantle heterogeneity in different time periods: Indonesian subduction zone to northern Australia
More informationGeophysical Journal International
Geophysical Journal International Geophys. J. Int. (2012) 188, 293 300 doi: 10.1111/j.1365-246X.2011.05256.x An analysis of SS precursors using spectral-element method seismograms L. Bai, Y. Zhang and
More informationLocalized temporal variation of Earth s inner-core boundary from high-quality waveform doublets
Earthq Sci (2015) 28(3):175 185 DOI 10.1007/s11589-015-0125-0 RESEARCH PAPER Localized temporal variation of Earth s inner-core boundary from high-quality waveform doublets Danhua Xin. Xiaodong Song. Tao
More informationStationary phase approximation in the ambient noise method revisited
Earthq Sci (010)3: 45 431 45 Doi: 10.1007/s11589-010-0741-7 Stationary phase approximation in the ambient noise method revisited Zhongwen Zhan 1 and Sidao Ni, 1 Mengcheng National Geophysical Observatory,
More informationHigh-precision location of North Korea s 2009 nuclear test
Copyright, Seismological Research Letters, Seismological Society of America 1 High-precision location of North Korea s 2009 nuclear test Lianxing Wen & Hui Long Department of Geosciences State University
More informationUnified Explanation of Envelope Broadening and Maximum-Amplitude. Decay of High-Frequency Seismograms based on the Envelope
submitted to J. Geophys. Res. Unified Explanation of Envelope Broadening and Maximum-Amplitude Decay of High-Frequency Seismograms based on the Envelope Simulation using the Markov Approximation: Forearc
More informationScattering objects in the lower mantle beneath northeastern China observed with a short-period seismic array
Physics of the Earth and Planetary Interiors 138 (2003) 55 69 Scattering objects in the lower mantle beneath northeastern China observed with a short-period seismic array Tadashi Kito a,, Takuo Shibutani
More informationContents of this file
Geophysical Research Letters Supporting Information for Coseismic radiation and stress drop during the 2015 Mw 8.3 Illapel, Chile megathrust earthquake Jiuxun Yin 1,2, Hongfeng Yang 2*, Huajian Yao 1,3*
More informationDistinct layering in the hemispherical seismic velocity structure of Earth s upper inner core
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116,, doi:10.1029/2011jb008650, 2011 Distinct layering in the hemispherical seismic velocity structure of Earth s upper inner core Lauren Waszek 1 and Arwen Deuss
More informationConstraints on density and shear velocity contrasts at the inner core boundary
Geophys. J. Int. (00) 57, 6 5 doi: 0./j.65-6X.00.00.x FAST TRACK PAPER Constraints on density and shear velocity contrasts at the inner core boundary Aimin Cao and Barbara Romanowicz Seismological Laboratory,
More informationGeophysical Journal International
Geophysical Journal International Geophys. J. Int. (2013) 195, 2005 2015 Advance Access publication 2013 October 1 doi: 10.1093/gji/ggt368 A low attenuation layer in the Earth s uppermost inner core Lauren
More informationGlobal variation of body wave attenuation in the upper mantle from teleseismic P wave and S wave spectra
GEOPHYSICAL RESEARCH LETTERS, VOL. 38,, doi:10.1029/2011gl046812, 2011 Global variation of body wave attenuation in the upper mantle from teleseismic P wave and S wave spectra Y. K. Hwang, 1 J. Ritsema,
More informationDetection of motion and heterogeneity in Earth s liquid outer core
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L16311, doi:10.1029/2008gl034895, 2008 Detection of motion and heterogeneity in Earth s liquid outer core Wei Dai 1 and Xiaodong Song 1 Received 5 June 2008; revised
More informationImaging Global Seismic Phase Arrivals by Stacking Array Processed Short-Period Data
Imaging Global Seismic Phase Arrivals by Stacking Array Processed Short-Period Data Sebastian Rost, Michael S. Thorne, and Edward J. Garnero Sebastian Rost, 1, Michael S. Thorne,,3 and Edward J. Garnero
More informationImaging the Gutenberg Seismic Discontinuity beneath the Oceanic Crust of the North American Plate
Imaging the Gutenberg Seismic Discontinuity beneath the Oceanic Crust of the North American Plate Robbie Burgess 11-25-15 Dr. Nicholas Schmerr GEOL 394 1 1. Abstract: The lithosphere-asthenosphere boundary
More informationData Repository: Seismic and Geodetic Evidence For Extensive, Long-Lived Fault Damage Zones
DR2009082 Data Repository: Seismic and Geodetic Evidence For Extensive, Long-Lived Fault Damage Zones Fault Zone Trapped Wave Data and Methods Fault zone trapped waves observed for 2 shots and 5 local
More informationExistence of finite rigidity layer at the base of the Earth s liquid outer core inferred from anomalous splitting of normal modes
LETTER Earth Planets Space, 54, 67 7, 22 Existence of finite rigidity layer at the base of the Earth s liquid outer core inferred from anomalous splitting of normal modes Seiji Tsuboi,2 and Masanori Saito
More informationPEAT SEISMOLOGY Lecture 9: Anisotropy, attenuation and anelasticity
PEAT8002 - SEISMOLOGY Lecture 9: Anisotropy, attenuation and anelasticity Nick Rawlinson Research School of Earth Sciences Australian National University Anisotropy Introduction Most of the theoretical
More informationSome aspects of seismic tomography
Some aspects of seismic tomography Peter Shearer IGPP/SIO/U.C. San Diego September 7, 2009 Earthquake Research Institute Part 1: Global Tomography P velocity perturbations 200 km 1000 km 2700 km MIT 2006
More informationTomography of the 2011 Iwaki earthquake (M 7.0) and Fukushima
1 2 3 Auxiliary materials for Tomography of the 2011 Iwaki earthquake (M 7.0) and Fukushima nuclear power plant area 4 5 6 7 8 9 Ping Tong 1,2, Dapeng Zhao 1 and Dinghui Yang 2 [1] {Department of Geophysics,
More informationAPPLICATION OF RECEIVER FUNCTION TECHNIQUE TO WESTERN TURKEY
APPLICATION OF RECEIVER FUNCTION TECHNIQUE TO WESTERN TURKEY Timur TEZEL Supervisor: Takuo SHIBUTANI MEE07169 ABSTRACT In this study I tried to determine the shear wave velocity structure in the crust
More informationSURFACE WAVE GROUP VELOCITY MEASUREMENTS ACROSS EURASIA
SURFACE WAVE GROUP VELOCITY MEASUREMENTS ACROSS EURASIA A. L. Levshin, M. H. Ritzwoller, and L. I. Ratnikova Department of Physics, University of Colorado at Boulder -Contract Number F49620-95-1-0139 Sponsored
More informationMantle Transition Zone Topography and Structure Beneath the Yellowstone Hotspot
University of Wyoming Wyoming Scholars Repository Geology and Geophysics Faculty Publications Geology and Geophysics 9-17-2004 Mantle Transition Zone Topography and Structure Beneath the Yellowstone Hotspot
More informationPhysics of the Earth and Planetary Interiors
Physics of the Earth and Planetary Interiors 178 (2010) 80 91 Contents lists available at ScienceDirect Physics of the Earth and Planetary Interiors journal homepage: www.elsevier.com/locate/pepi Steep
More informationLower mantle tomography and phase change mapping
Click Here for Full Article JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113,, doi: 10.1029/2007JB005289, 2008 Lower mantle tomography and phase change mapping Daoyuan Sun 1 and Don Helmberger 1 Received 23 July
More informationEarth and Planetary Science Letters
Earth and Planetary Science Letters 319-32 (212) 55 64 Contents lists available at SciVerse ScienceDirect Earth and Planetary Science Letters journal homepage: www.elsevier.com/locate/epsl Detection of
More informationBasic Ray Tracing. Rick Aster and Sue Bilek. October 3, 2003
Basic Ray Tracing Rick Aster and Sue Bilek October 3, 3 A key observation that we can make about a seismic signal is its arrival time. From systematic observations of arrival times, we can deduce useful
More informationMODELING OF HIGH-FREQUENCY WAVE RADIATION PROCESS ON THE FAULT PLANE FROM THE ENVELOPE FITTING OF ACCELERATION RECORDS
MODELING OF HIGH-FREQUENCY WAVE RADIATION PROCESS ON THE FAULT PLANE FROM THE ENVELOPE FITTING OF ACCELERATION RECORDS Yasumaro KAKEHI 1 SUMMARY High-frequency (higher than 1 Hz) wave radiation processes
More informationBROADBAND STRONG MOTION SIMULATION OF THE 2004 NIIGATA- KEN CHUETSU EARTHQUAKE: SOURCE AND SITE EFFECTS
Third International Symposium on the Effects of Surface Geology on Seismic Motion Grenoble, France, 30 August - 1 September 2006 Paper Number: 105 BROADBAND STRONG MOTION SIMULATION OF THE 2004 NIIGATA-
More informationContinent-sized anomalous zones with low seismic velocity at the base of Earth s mantle
SUPPLEMENTARY INFORMATION DOI: 10.1038/NGEO2733 Continent-sized anomalous zones with low seismic velocity at the base of Earth s mantle Edward J. Garnero 1, Allen K. McNamara 1, and Sang-Heon D. Shim 1
More informationFOCAL MECHANISM DETERMINATION USING WAVEFORM DATA FROM A BROADBAND STATION IN THE PHILIPPINES
FOCAL MECHANISM DETERMINATION USING WAVEFORM DATA FROM A BROADBAND STATION IN THE PHILIPPINES Vilma Castillejos Hernandez Supervisor: Tatsuhiko Hara MEE10508 ABSTRACT We performed time domain moment tensor
More informationby Xiao-Bi Xie and Thorne Lay
Bulletin of the Seismological Society of America, Vol. 17, No. 1, pp. 22 33, February 217, doi: 1.1785/121623 E Effects of Laterally Varying Mantle Lid Velocity Gradient and Crustal Thickness on Pn Geometric
More informationNegative repeating doublets in an aftershock sequence
LETTER Earth Planets Space, 65, 923 927, 2013 Negative repeating doublets in an aftershock sequence X. J. Ma and Z. L. Wu Institute of Geophysics, China Earthquake Administration, 100081 Beijing, China
More informationSeismic Scattering in the Deep Earth
Seismic Scattering in the Deep Earth Peter M. Shearer Institute of Geophysics and Planetary Physics Scripps Institution of Oceanography University of California, San Diego La Jolla, CA 92093-0225 October
More informationEvidence of an axial magma chamber beneath the ultraslow spreading Southwest Indian Ridge
GSA Data Repository 176 1 5 6 7 9 1 11 1 SUPPLEMENTARY MATERIAL FOR: Evidence of an axial magma chamber beneath the ultraslow spreading Southwest Indian Ridge Hanchao Jian 1,, Satish C. Singh *, Yongshun
More informationEarth s inner core: revealing the structures behind the PKP core phase triplication
GEOPHYSICAL RESEARCH LETTERS, VOL.???, XXXX, DOI:10.1029/, Earth s inner core: revealing the structures behind the PKP core phase triplication N.A. Blom 1 supervisors: A.F. Deuss, 2 H. Paulssen, 1 The
More informationSynthetic sensitivity analysis of high frequency radiation of 2011 Tohoku-Oki (M W 9.0) earthquake
Earthq Sci (214) 27(4):355 364 DOI 1.17/s11589-14-88-6 RESEARCH PAPER Synthetic sensitivity analysis of high frequency radiation of 211 Tohoku-Oki (M W 9.) earthquake Haoran Meng Yongshun John Chen Received:
More informationContents of this file
Geophysical Research Letters Supporting Information for Intraplate volcanism controlled by back-arc and continental structures in NE Asia inferred from trans-dimensional ambient noise tomography Seongryong
More informationStructural features and shear-velocity structure of the Pacific Anomaly. Lianxing Wen a. Yumei He a,b
Structural features and shear-velocity structure of the Pacific Anomaly Yumei He a,b Lianxing Wen a a Department of Geosciences, State University of New York at Stony Brook, Stony Brook, New York, USA
More informationSeismic scatterers within subducting slab revealed from ambient noise autocorrelation
GEOPHYSICAL RESEARCH LETTERS, VOL. 39,, doi:10.1029/2012gl053321, 2012 Seismic scatterers within subducting slab revealed from ambient noise autocorrelation Yoshihiro Ito 1 and Katsuhiko Shiomi 2 Received
More informationVelocity contrast along the Calaveras fault from analysis of fault zone head waves generated by repeating earthquakes
Click Here for Full Article GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L01303, doi:10.1029/2007gl031810, 2008 Velocity contrast along the Calaveras fault from analysis of fault zone head waves generated by
More information2008 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING
ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING Donald V. Helmberger 1, Arthur J. Rodgers 2, Sidao Ni 1,3, Shengji Wei 1, and Jeroen Tromp 1 California Institute of Technology 1, Lawrence Livermore
More informationOn the Nature of the P-Wave Velocity Gradient in the Inner Core beneath Central America
Journal of Earth Science, Vol. 24, No. 5, p. 699 705, October 2013 ISSN 1674-487X Printed in China DOI: 10.1007/s12583-013-0365-7 On the Nature of the P-Wave Velocity Gradient in the Inner Core beneath
More informationGlobal surface-wave tomography
Global surface-wave tomography Lapo Boschi (lapo@erdw.ethz.ch) October 7, 2009 Love and Rayleigh waves, radial anisotropy Whenever an elastic medium is bounded by a free surface, coherent waves arise that
More informationOrigin of Coda Waves: Earthquake Source Resonance
Origin of Coda Waves: Earthquake Source Resonance Yinbin Liu Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada Email: yliu@eoas.ubc.ca Abstract
More informationSupplementary Materials for
advances.sciencemag.org/cgi/content/full/4/3/eaao4915/dc1 Supplementary Materials for Global variations of large megathrust earthquake rupture characteristics This PDF file includes: Lingling Ye, Hiroo
More informationAspects of Observational Seismology
Aspects of Observational Seismology Peter M. Shearer Institute of Geophysics and Planetary Physics Scripps Institution of Oceanography University of California, San Diego Notes for Caltech class January
More informationSharp and seismically transparent inner core boundary region revealed by an entire network observation of near-vertical PKiKP
Earth Planets Space, 58, 855 863, 2006 Sharp and seismically transparent inner core boundary region revealed by an entire network observation of near-vertical PKiKP Hitoshi Kawakatsu Earthquake Research
More informationImagerie de la Terre profonde avec le bruit sismique. Michel Campillo (ISTERRE, Grenoble)
Imagerie de la Terre profonde avec le bruit sismique Michel Campillo (ISTERRE, Grenoble) Body waves in the ambient noise: microseisms (Gutenberg, Vinnik..) The origin of the noise in the period band 5-10s:
More informationMoment tensor inversion of near source seismograms
Moment tensor inversion of near source seismograms Yuji Yagi and Naoki Nishimura ABSTRACT We construct a program set for estimating moment tensor solution using near source seismograms. We take the effect
More informationEffects of Surface Geology on Seismic Motion
4 th IASPEI / IAEE International Symposium: Effects of Surface Geology on Seismic Motion August 23 26, 2011 University of California Santa Barbara TOMOGRAPHIC ESTIMATION OF SURFACE-WAVE GROUP VELOCITY
More informationNonparametric Methods for Detecting Structure and Dynamics of Earth s Deep Interior. The Wahba Conference June 6, 2014
Nonparametric Methods for Detecting Structure and Dynamics of Earth s Deep Interior The Wahba Conference June 6, 2014 Connection with Grace Ph.D with Chong Gu (First generation) Postdoc with Jun S Liu
More informationrevised October 30, 2001 Carlos Mendoza
Earthquake Sources in the circum-caribbean Region Puerto Rico Tsunami Mitigation and Warning Program Federal Emergency Management Agency Preliminary Report: Task 3 revised October 30, 2001 Carlos Mendoza
More informationTeleseismic waveform modelling of the 2008 Leonidio event
The 6 January 2008 (Mw6.2) Leonidio (southern Greece) intermediate depth earthquake: teleseismic body wave modelling Anastasia Kiratzi and Christoforos Benetatos Department of Geophysics, Aristotle University
More informationvolcanic tremor and Low frequency earthquakes at mt. vesuvius M. La Rocca 1, D. Galluzzo 2 1
volcanic tremor and Low frequency earthquakes at mt. vesuvius M. La Rocca 1, D. Galluzzo 2 1 Università della Calabria, Cosenza, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia Osservatorio Vesuviano,
More informationReceiver Function (RF) Estimation Using Short Period Seismological Data
Receiver Function (RF) Estimation Using Short Period Seismological Data Shantanu Pandey Department of Earth Sciences, Kurukshetra University, Kurukshetra-136119 Abstract The advent of the receiver function
More informationSUPPLEMENTARY INFORMATION
doi:10.1038/nature11492 Figure S1 Short-period Seismic Energy Release Pattern Imaged by F-net. (a) Locations of broadband seismograph stations in Japanese F-net used for the 0.5-2.0 Hz P wave back-projection
More informationThree-dimensional structure of the African superplume from waveform modelling
Geophys. J. Int. (5) 161, 283 294 doi: 1.1111/j.1365-X.5.258.x Three-dimensional structure of the African superplume from waveform modelling Sidao Ni, 1,2 Don V. Helmberger 2 and Jeroen Tromp 2 1 School
More informationInner core rotation from event-pair analysis
Earth and Planetary Science Letters 261 (2007) 259 266 www.elsevier.com/locate/epsl Inner core rotation from event-pair analysis Xiaodong Song a,, Georges Poupinet b a Department of Geology, University
More informationSouthern California ground motion envelopes over ranges of magnitudes, distances, and site conditions
55 Chapter 3 Average properties of Southern California ground motion envelopes over ranges of magnitudes, distances, and site conditions In this chapter, I use the envelope attenuation relationships derived
More informationOriginally published as:
Originally published as: Ryberg, T. (2011): Body wave observations from cross correlations of ambient seismic noise: A case study from the Karoo, RSA. Geophysical Research Letters, 38, DOI: 10.1029/2011GL047665
More informationBRIEF ARTICLE THE AUTHOR
BRIEF ARTICLE THE AUTHOR 1 2 THE AUTHOR S Pd K Pd S mantle OC IC CMB Figure 1 Figure 1. Illustration of the SPdKS / SKPdS ray-paths with sub-segments labeled. SPdKS is an SKS that intersects the source-side
More informationDepth dependence of anisotropy of Earth's inner core
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 100, NO. 87, PAGES 9805-9816, JUNE 10, 1995 Depth dependence of anisotropy of Earth's inner core Xiaodong Song 1 and Don V. Heimberger Seismological La.bora.tory,
More information