bluuebunny/crossref_metadata_2025 huggingface dataset:
The absorption-peak map of Mare Serenitatis obtained by a hyper-spectral telescope
Authors: Okuno Hideaki , Yamanoi Yuta , Saiki Kazuto
Published: August 2014

The Mg-number [Mg#=atomic Mg/(Mg+Fe)] serves as an important petrologic discriminator when analyzing and understanding lunar rocks. Variations in the Mg# shift the wavelength of the absorption spectra of ferrous iron, which peak at around 1000 nm. Based on the image cubes of the Moon obtained by the Advanced Lunar Imaging Spectrometer (ALIS), we detected the shift in the absorption spectra of ferrous iron and built up an absorption-peak map of Mare Serenitatis. The wavelength of the absorption peak shows an 11-nm shift in Mare Serenitatis. Since the degree of space weathering can be considered to be almost the same as that within the same lava unit and Ca content cannot change without changing Mg# during magma differentiation, these shifts of the peak absorption spectra suggest that there is Mg# variation in at least the same lava unit.
InSAR-based mapping of surface subsidence in Mokpo City, Korea, using JERS-1 and ENVISAT SAR data
Authors: Kim Sang-Wan , Wdowinski Shimon , Dixon Timothy H. , Amelung Falk , Won Joong-Sun , Kim Jeong Woo
Published: August 2014

Mokpo City, located on the southwestern coast of the Korean Peninsula, has been built on one of the largest areas of reclaimed coastal land in Korea. This reclaimed land is currently experiencing significant ground subsidence due to soil consolidation. We have estimated the subsidence rate of Mokpo City (8 × 8 km) using the synthetic aperture radar interferometry (InSAR) and InSAR permanent scatterer (PSInSAR) techniques to analyze 26 JERS-1 SAR images acquired between 1992 and 1998 and six ENVISAT ASAR images acquired in 2004–2005. Mean subsidence velocity, which was clearly related to reclaimed land, was computed from the JERS-1 PSInSAR analysis. The results indicate a continuous and significant subsidence at three sites (Dongmyung, Hadang and Wonsan), where the subsidence velocity has reached more than 5–7 cm/yr in the area of maximum subsidence. The subsidence rate was found to have decreased in Wonsan and Hadang between 1992 and 1998, while it remained steady or increased in Dongmyung during the same period. The subsidence extended to the period of 2004–2005, and the subsidence rate predicted by the JERS-1 PSInSAR analysis using a linear model was confirmed by the ENVISAT ASAR InSAR results. Our results show that InSAR/PSInSAR-based subsidence maps are useful for the long-term monitoring of soil consolidation and for defining risk zones in coastal reclaimed regions.
Assessing intraplate earthquake hazards from satellite geopotential field observations
Authors: von Frese Ralph R. B. , Kim Jeong Woo , Hernandez Orlando , Kim Hyung Rae , Asgharzadeh Mohammad F.
Published: August 2014

Satellite magnetic and gravity field observations provide important constraints on the poorly understood lithospheric properties of intraplate earthquakes because they map lateral long-wavelength contrasts in magnetization and density, respectively, related to petrological, structural, and thermal variations that help control the distribution of lithospheric stress. These anomalies are each a product of the vertically integrated physical property times the layer thickness. Thus, they constrain and enhance the geological utility of near-surface geopotential surveys, as well as seismic, GPS, and other geophysical observations that map the geological and dynamic properties of the lithosphere. To illustrate this synergy, we consider the influence of the US Transcontinental Magnetic Anomaly (TMA) on crustal stress and earthquake activity along the 38thparallel. In another example, we compare crustal earthquake stress constraints from gravity and seismic observations of the US mid-continent and North Andes microplate where starkly contrasting plate tectonic forces operate.
Effects of latitudinal distributions of particle density and wave power on cyclotron resonant diffusion rates of radiation belt electrons
Authors: Summers Danny , Ni Binbin
Published: August 2014

We evaluate cyclotron resonant interactions of radiation belt electrons with VLF chorus, plasmaspheric ELF hiss and electromagnetic ion cyclotron (EMIC) waves. We assume that the Earth’s magnetic field is dipolar and that each wave mode has a Gaussian spectral density. The dependence of the resonant electron diffusion rates on the latitudinal distributions of particle density and wave power is examined. We find that while the diffusion rates can be sensitive to the latitudinal distributions of density and wave power, in general the sensitivity depends on wave mode, equatorial pitch-angle, electron energy and L-shell. We determine the effects of the latitudinal distributions of density and wave power on the electron precipitation loss timescale due to combined scattering by VLF chorus, ELF hiss and EMIC waves. Accurate modeling of radiation belt electron dynamics requires observational data on the global distributions of particle number density and wave power.
Temporal characteristics of high band-pass filtered teleseismic P-waveforms from large shallow earthquakes
Authors: Hara Tatsuhiko
Published: August 2014

We measured time differences between P-wave arrivals and the times at which squared amplitudes of high bandpass (2–4 Hz) filtered P-waves became the largest for large shallow earthquakes that occurred during the period 1995–2007. The time differences were then normalized by twice the centroid time shift for the corresponding earthquakes. We found that most of the seismograms had normalized time differences that congregated at about 50% (corresponding to centroid time shifts). Few normalized time differences were found in the 0–20% range. These results support the use of this time difference to infer the order of the source duration and, thereby, the effectiveness of the duration measurement procedure of the high-frequency energy radiation that we recently developed.
Source parameters of the 2007 Noto Hanto earthquake sequence derived from strong motion records at temporary and permanent stations
Authors: Maeda Takahiro , Ichiyanagi Masayoshi , Takahashi Hiroaki , Honda Ryo , Yamaguchi Teruhiro , Kasahara Minoru , Sasatani Tsutomu
Published: August 2014

A large crustal earthquake, the 2007 Noto Hanto earthquake, occurred west off the Noto peninsula in Ishikawa prefecture, Japan, on March 25, 2007. We started temporary strong motion observation at five sites within the aftershock area from about 13 h after the main shock occurrence. We first applied the spectral inversion method toS-wave strong ground motion records at the temporary and permanent stations. We obtained source specta of the main shock and aftershocks,Qs(quality factor forS-wave) values (Qs= 34.5f0.95) and site responses at 22 sites. We then estimated a source model of the main shock using the empirical Green’s function method. The source model consists of three strong motion generation areas and well explains the observed records. Finally, we examined the consistency of the main-shock source models estimated from the above two analyses. The high-frequency level of the acceleration source spectrum based on the main-shock source model is consistent with the source spectrum estimated from the spectral inversion. The combined area of strong motion generation areas is approximately half of the value expected by the empirical relationship, and the high-frequency level of acceleration source spectrum is approximately 2.5 times larger than the empirical relationship for shallow inland and inter-plate earthquakes.
Characterization of the 2007 Noto Hanto, Japan, earthquake
Authors: Horikawa Haruo
Published: August 2014

Characterization of the 2007 Noto Hanto, Japan, earthquake (MS6.9), a moderate-size crustal event, was performed. The rupture process was firstly inferred from strong motion data. Inversion analysis revealed that the overall rupture finished within 6 s, and the seismic moment of this earthquake was estimated to be 1.1×1019N m (Mw6.6). Two areas of large slip and stress drop (asperities) were inferred on the fault plane. The maximum static stress drop calculated from the derived slip distribution exceeded 16 MPa for the major asperity, and the minor asperity has a similar maximum value. An area of negative stress drop corresponding to the distribution of small slip exists between the two asperities. This strongly suggests that the fault is segmented. A boundary between surface faults was located above the major asperity, but an area of negative stress drop appeared between the asperity and fault boundary. This suggests that the configuration of the surface faults reflects only a shallow part of the causative fault. The ratio of radiated energy to seismic moment was also estimated for the purpose of estimation of fault activity. Comparison of the derived value with those of other Japanese earthquakes suggests that the causative fault of the Noto Hanto earthquake is not very active.
Paleointensity data from Early Cretaceous Ponta Grossa dikes (Brazil) using a multisample method
Authors: Brandt Daniele , Hartmann Gelvam A. , Yokoyama Elder , Catelani Edgard L. , Trindade Ricardo I. F.
Published: August 2014

Definition of the long-term variation of the geomagnetic virtual dipole moment requires more reliable paleointensity results. Here, we applied a multisample protocol to the study of the 130.5 Ma Ponta Grossa basaltic dikes (southern Brazil) that carry a very stable dual-polarity magnetic component. The magnetic stability of the samples was checked using thermomagnetic curves and by monitoring the magnetic susceptibility evolution through the paleointensity experiments. Twelve sites containing the least alterable samples were chosen for the paleointensity measurements. Although these rocks failed stepwise double-heating experiments, they yielded coherent results in the multisample method for all sites but one. The coherent sites show low to moderate field intensities between 5.7±0.2 and 26.4±0.7 μT (average 13.4±1.9 μT). Virtual dipole moments for these sites range from 1.3±0.04 to 6.0±0.2 × 1022 A m2 (average 2.9±0.5 × 1022 A m2). Our results agree with the tendency for low dipole moments during the Early Cretaceous, immediately prior to the Cretaceous Normal Superchron (CNS). The available paleointensity database shows a strong variability of the field between 80 and 160 Ma. There seems to be no firm evidence for a Mesozoic Dipole Low, but a long-term tendency does emerge from the data with the highest dipole moments occurring at the middle of the CNS.
Gilbert-Gauss geomagnetic reversal recorded in Pliocene volcanic sequences from Georgia (Lesser Caucasus): revisited
Authors: Goguitchaichvili Avto , Cervantes Miguel Angel , Rathert Manuel Calvo , Camps Pierre , Sologashvili Jemal , Maissuradze Givi
Published: August 2014

We carried out a detailed paleomagnetic, rock-magnetic, and Thellier paleointensity study of an ~3.6 My Pliocene lava flow succession in southern Georgia. An earlier study (Camps et al., 1996) revealed that several consecutive lava flows record an intermediate polarity direction at the base of the section followed by a thick reverse polarity zone. The transitional field was interpreted as an excursion within chron 2Ar or an upper Cochiti-Gilbert reversal. New paleomagnetic data reported here have been obtained from nearby lava successions. In total, about 170 standard paleomagnetic cores belonging to 22 lava flows were collected during the 2005 sample collection campaign. Rock-magnetic experiments showed that the remanence is carried by Ti-poor titanomagnetite in most of the samples. The fraction of grains with multidomain magnetic structure does not seem to be important. Characteristic remanent magnetization was successfully determined on all samples. The direct correlation with the original (Thoki) sequence, previous preliminary measurements of natural remanent magnetization (Sologashvili, 1986), and field observations allowed us to establish a new magnetic stratigraphy. The lower part of section is characterized by intermediate magnetic polarity followed by thick reversely magnetized lavas. The upper sequence, represented by 18 consecutive flows yielded normal magnetic polarity. The mean paleointensity of the intermediate field is drastically reduced with respect to the post-transitional field strength. Based on all available radiometric ages and new paleomagnetic data, it may be speculated that Gilbert-Gauss (R-N) reversal was recorded at the upper part of sequence. Lower intermediate polarity flows possibly represent a form of precursor of this reversal that is similar to the Matuyama-Brunhes geomagnetic transition.
Anisotropy of magnetic susceptibility analysis of the Cantera Ignimbrite, San Luis Potosi, México: flow source recognition
Authors: Caballero-Miranda C. I. , Torres-Hernández J. R. , Alva-Valdivia L. M.
Published: August 2014

Anisotropy of magnetic susceptibility (AMS) was selected as the key technique to find the source of the widespread Cantera Ignimbrite and to seek its possible relationship with the San Luis Potosí Caldera. Eighteen sites (372 specimens from 155 cores) from the Oligocene Cantera Ignimbrite were sampled. AMS was measured on a KLY2 Kappabridge. AMS data were processed with Anisoft 3 software using Jelinek statistics as well as ‘SpheriStat’ principal components and density distribution. Mean susceptibilities range from 290 to 5026 × 10-6 SI (average = 2526 × 10-6 SI). The anisotropy degree (P
j) ranges from 1.005 to 1.055, with only one site displaying a value of 1.134 (P
j average = 1.031). AMS ellipsoid shapes are mostly oblate, with the T-factor ranging from 0.843 to 0.144 (T average = 0.529), although one site is mainly prolate (T = -0.005), and three additional sites have an important proportion of prolate specimens. Magnetic fabrics of most sites shows k3 axes around nearly circular distributions and k
1-k
2 axes around elongated-girdle distributions defining sub-horizontal foliation planes; exceptions to this are related to sites with a significant percentage of prolate specimens. Flow directions inferred from AMS analysis indicate several ignimbrite sources located along selected NW-SE linear features (faults and fractures such as El Potosino Fault) as well as along the rim of the caldera structure. The geometry of volcanic outcrops, the NW-SE faulting-fracture system, as well as the AMS results suggest that this is a caldera structure resembling the trapdoor-type (Lipman, 1997).
Shear-wave splitting analysis of the upper mantle at the Niigata-Kobe Tectonic Zone with the data of the Joint Seismic Observations at NKTZ
Authors: Iidaka Takashi , Hiramatsu Yoshihiro ,   The Japanese University Group of the Joint Seismic Observations at NKTZ
Published: August 2014

We conducted seismic observations with a spatially high density seismic network at the Niigata-Kobe Tectonic Zone, central Japan. The seismic network was used for the analysis of shear-wave splitting. Large lateral variations were found in the polarization direction data: the northern part of the research area yields polarization directions ofNW-SE (Region A), the central part of the research area with the polarization direction of NNE-SSW (Region B), the eastern part of the research area with the polarization direction of NE-SW (Region C), and the southern part of the research area with the polarization direction of E-W (Region D). The polarization directions in Regions B and C could be explained by the preferred orientation of olivine caused by the flow of the subducting Philippine Sea plate. However, the cause of anisotropic region which was related to the heterogeneous structure was also plausible. The polarization direction in Region A might be related to the flow caused by both of the subducting Philippine Sea and Pacific slabs. The polarization direction at the Region D could not be produced by the flow in the wedge and might be related to an anisotropic region beneath the slab. The lateral variation of the polarization direction does not support a model that the NKTZ is a collision region.
Rupture process at the beginning of the 2007 Chuetsu-oki, Niigata, Japan, earthquake
Authors: Takenaka Hiroshi , Yamamoto Yosuke , Yamasaki Hirokazu
Published: August 2014

The rupture process at the beginning stage of the 2007 Chuetsu-oki, Niigata, Japan, earthquake (MW6.6) is investigated by analyzingP-wave records from local strong-motion stations. TheP-wave portion of the nearsource strong-motion records shows about 2 s of small but increasing amplitude arrival (so-called “initial rupture phase”) followed by the onset of the main energy release (“main rupture phase”). Two issues are addressed in this paper: (1) where the initial rupture process occurred and (2) where the seismic energy corresponding to the main rupture phase was released at the primary stage of the main rupture. The first issue is addressed by locating the main rupture onset position, and the second issue is then approached by introducing a method for mapping the wave energy onto plausible fault planes. Eventually, the following were revealed. The rupture initiated and propagated on the NW-dipping plane, which is a nodal plane of the focal mechanism solution. At 2.1 s after rupture initiation the subsequent main rupture started at a position of approximately 4 km away, southwestward and updipward from the hypocenter. The main rupture at this stage has two possible rupture planes: the same plane as the initial rupture plane, and the conjugated plane, which shares the main rupture onset point with the initial rupture plane. Although it is difficult to determine which plane was actually ruptured at the primary stage of the main rupture, we found that the possible areas radiating strong wave energy on the two possible planes, which could correspond to the first asperity of this earthquake, are located between the hypocenter and the Kashiwazaki-Kariwa nuclear power plant.
Modeling of substorms and flares by the fast reconnection mechanism
Authors: Ugai M. , Kondoh K. , Shimizu T.
Published: August 2014

The 3D spontaneous fast reconnection model is applied to well-known signatures of geomagnetic substorms and solar flares. First, it is applied to the traveling compression regions (TCRs) associated with plasmoids propagating down the tail plasma sheet, known as a definite signature of geomagnetic substorms, and the in-situ satellite observations can be precisely explained, both qualitatively and quantitatively. Then, it is demonstrated that the magnetospheric current wedge drastically evolves through field-aligned currents to link the tail current to the auroral electrojet. It is also found that the well-known morphological features of two-ribbon flares can be explained by the fast reconnection model. In particular, the joule heating, associated with the flare current wedge, is shown to be important for the two-ribbon heating. Therefore, it is suggested that both solar flares and geomagnetic substorms result from the same physical mechanism, i.e., the fast reconnection mechanism.
Patchy reconnection in a Y-type current sheet
Authors: Linton M. G. , DeVore C. R. , Longcope D. W.
Published: August 2014

We study the evolution of the magnetic field in a Y-type current sheet subject to a brief, localized magnetic reconnection event. The reconnection produces up- and down-flowing reconnected flux tubes which rapidly decelerate when they hit the Y-lines and underlying magnetic arcade loops at the ends of the current sheet. This localized reconnection outflow followed by a rapid deceleration reproduces the observed behavior of post-CME downflowing coronal voids. These simulations support the hypothesis that these observed coronal downflows are the retraction of magnetic fields reconnected in localized patches in the high corona.
Non-thermal electrons at the Earth’s bow shock: A ‘gradual’ event
Authors: Oka M. , Terasawa T. , Fujimoto M. , Matsui H. , Kasaba Y. , Saito Y. , Kojima H. , Matsumoto H. , Mukai T.
Published: August 2014

The Earth’s bow shock is known to produce non-thermal electrons which are generally observed as a ‘spike’ in their flux profile. Here, in this paper, we present an analysis of electron and whistler wave properties for a quasi-perpendicular shock crossing that is supercritical, but subcritical to the so-called whistler critical Mach number, M
crit
w
, above which whistler waves cannot propagate upstream. We have found that the amplitudes of whistler waves increased exponentially as a function of time prior to the shock encounter, while the suprathermal (>2 keV) electron flux similarly increased with time, although with differing e-folding time scales. Comparison of the electron energy spectrum measured within the ramp with predictions from diffusive shock acceleration theory was poor, but the variation of pitch angle distribution showed scattering of non-thermal electrons in the upstream region. While not finding a specific mechanism to account for the electron diffusion, we suggest that the whistlers seen probably account for the differences observed between this ‘gradual’ event and the ‘spike’ events seen at shocks with no upstream whistlers.
Statistically predicting Dst without satellite data
Authors: Parnowski A. S.
Published: August 2014

In this paper we construct a regression relationship for predicting Dst 1 hour ahead. Our model uses only previous Dst values. This regression is totally unbiased and does not rely on any physical model, except for the fact that Dst somehow contains the information on the recurrent geomagnetic storms. This regression has the prediction efficiency of 0.964, linear correlation with official Dst index of 0.982, and RMS of 4.52 nT. These characteristics are inferior only to our other model, which uses satellite data and provides the prediction efficiency of 0.975, linear correlation with official Dst index of 0.986, and RMS of 3.76 nT. This makes it quite suitable for prediction purposes when satellite data are not available.
Properties of dayside nonlinear rising tone chorus emissions at large L observed by GEOTAIL
Authors: Verkhoglyadova Olga P. , Tsurutani Bruce T. , Omura Y. , Yagitani S.
Published: August 2014

This paper studies some wave properties of nonlinear rising tone chorus emissions in the outer regions of the dayside equatorial magnetosphere at ∼(6.3,–4.7, 0.7R
E) in GSE coordinates. We analyze data obtained with the PWI and WFC receivers on GEOTAIL associated with a substorm on April 29, 1993. Fine structure of the chorus elements and inter-element spacings are shown. Directions of propagation of the chorus elements relative to the local magnetic field lines are analyzed. Wave polarizations, intensities and spectral properties of chorus in the equatorial Earth’s magnetosphere are discussed.
The total failures of GPS functioning caused by the powerful solar radio burst on December 13, 2006
Authors: Afraimovich E. L. , Demyanov V. V. , Smolkov G. Ya.
Published: August 2014

We investigated failures in the GPS performance produced by extremely dense solar radio burst fluxes associated with the intense (X3.4 in GOES classification) solar flare and Halo CME recorded by SOHO/LASCO on December 13, 2006. According to substantial experimental evidence, high-precision GPS positioning on the entire sunlit side of the Earth was partially disrupted for more than 12–15 min; the high level of GPS slips resulted from the wideband solar radio noise emission. Our results are in agreement with the data obtained recently for the extreme solar radio burst on December 6, 2006, and provide a sound basis for revising the role of space weather factors in the functioning of state-of-the-art satellite systems and for taking a more thorough account of these factors in their development and operation.
Aeronomic effects of the solar flares in the topside ionosphere
Authors: Leonovich L. A. , Taschilin A. V.
Published: August 2014

We obtained that according to the GPS data at altitudes of the topside ionosphere (h >300 km) a flare is able to cause a decrease of the electron content. Using the theoretical model it is shown that the intense transport of O+ ions into the above-situated plasma caused by a sharp increase in the ion production rate and thermal expansion of the ionospheric plasma is a cause of the formation of the negative disturbance in the electron concentration in the topside ionosphere.
Effect of stochastic ionospheric delay modeling for GPS ambiguity resolution
Authors: Hong Chang-Ki , Grejner-Brzezinska Dorota A. , Kwon Jay Hyoun , Arslan Niyazi
Published: August 2014

The network-derived ionospheric delay can improve the fast and accurate determination of the long baseline in both the rapid-static and kinematic Global Positioning System (GPS) positioning mode. In this study, an interpolation of the undifferenced (UD) ionospheric delays is performed on a satellite-by-satellite and epoch-by-epoch basis, respectively, using the least-squares collocation (LSC) to provide not only ionospheric delays but also their variances. The developed method retains the simplicity of the two-dimensional (2-D) model, but it does not introduce errors due to the thin-shell assumption made in the single-layered model. Our method also provides flexibility in forming the predicted double-differenced (DD) ionospheric delays. Faster and more reliable positioning solutions can be obtained when the developed method is used to predict DD ionospheric delays. The numerical test applying the method to the Ohio Continuously Operating Reference Station network shows a 23% improvement in mean time-to-fix with the network-derived ionospheric delays.
Nonstationary ray decomposition in a homogeneous half space
Authors: Kinoshita Shigeo
Published: August 2014

Amethod for decomposing anSH-wave at the surface into the instantaneous power of shearing strain associated with rays in a homogeneous half space as a function of lapse timetand depth time τ, which is the travel time for the depth direction, is demonstrated. The instantaneous power in the (t, τ) space shows local maxima at the intersections of up-coming and down-going rays, which correspond to the velocity boundaries of the real layered structure beneath the site. Thus, the proposed method provides a tool for estimating the velocity boundaries of real layered structure from only surface recordings. The estimated results obtained by applying the proposed method to strong-motion data recorded at two Kanto sediment sites are in good agreement with the velocity boundaries previously determined by means of down-hole methods.
Geographical variations of the 0S0 normal mode amplitude: predictions and observations after the Sumatra-Andaman earthquake
Authors: Rosat Severine , Watada Shingo , Sato Tadahiro
Published: August 2014

The radial seismic normal mode 0S0 was strongly excited by the 2004 Mw = 9.3 Sumatra-Andaman earthquake at a period of 20.5 min. In a spherically symmetric Earth model, 0S0 amplitude is the same everywhere on the Earth’s surface. However, when the ellipticity and rotation of the Earth are taken into consideration, theoretical computations predict an amplitude of 0S0 1% higher at the pole than at the equator. Based on a realistic three-dimensional heterogeneous rotating elliptic Earth model, our predictions indicate that the amplitude of 0S0 is 2% higher at the pole than at the equator. A longitude dependency of 0S0 amplitude is also shown. The analysis of 13 superconducting gravimeter (SG) records of the 2004 Sumatra-Andaman earthquake supports the predicted geographical variations of 0S0 amplitude. We have also obtained new estimates for the frequency and Q of 0S0: 0.8146566±1.6 10−6 mHz and 5506±19.
Ionospheric temporal and spatial variations during the 18 August 2003 storm over China
Authors: Wen Debao , Yuan Yunbin , Ou Jikun , Huo Xingliang , Zhang Kefei
Published: August 2014

The effects of the 18 August 2003 geomagnetic storm on the ionosphere over China have been first studied by combining dual-frequency Global Positioning System (GPS) observation data from the Crustal Movement Observation Network of China (CMONOC) using the computerized ionospheric tomography (CIT) technique. The temporal and spatial variations of the ionosphere are analyzed using a time series of ionospheric electron density (IED) maps, and the ionospheric storm evolution process is revealed. The tomographic results show that the main ionospheric effects of this storm over China are: (1) that positive storm phase effects usually happen in the low-latitude ionosphere, (2) that negative storm phase effects occur in the mid-latitude ionosphere, and (3) that the equatorial anomaly structure can also be found. In contrast to the quiet period of the ionosphere on 17 August 2003, the equatorial anomaly crest moved to the north in the main phase of the storm and then moved back to the original location in the recovery phase on 19 August 2003. We compared the peak density NmF2 and the peak height hmF2 obtained from the ionosonde observations at Wuhan station and those inverted by the CIT technique to confirm the reliability of the GPS-based tomographic technique. The tomographic results revealed that the GPS-based CIT technique can be used to monitor large-scale ionospheric disturbances during geomagnetic storms.
Weak interplate coupling beneath the subduction zone off Fukushima, NE Japan, inferred from GPS/acoustic seafloor geodetic observation
Authors: Matsumoto Yoshihiro , Ishikawa Tadashi , Fujita Masayuki , Sato Mariko , Saito Hiroaki , Mochizuki Masashi , Yabuki Tetsuichiro , Asada Akira
Published: August 2014

We have been carrying out GPS/acoustic seafloor geodetic observations at several reference points situated along the Japan Trench, a major plate boundary of subduction. A time series of horizontal coordinates of one of the seafloor reference points, located off Fukushima, obtained from seven campaign observations for the period 2002-2008, exhibits a linear trend with a scattering root mean square of about 3 cm. A linear fit to the time series gives an intraplate crustal movement velocity of 3.1 cm per year in a westerly direction, which is significantly smaller than that at the other seafloor reference point 120 km away along the trench axis. This result implies weak interplate coupling in this region.
Subsurface structures derived from receiver function analysis and relation to hypocenter distributions in the region from the eastern Shikoku to the northern Chugoku districts, Southwest Japan
Authors: Ueno Tomotake , Shibutani Takuo , Ito Kiyoshi
Published: August 2014

We carried out receiver function imaging to estimate detailed configurations of the Philippine Sea (PHS) slab beneath the Shikoku and Chugoku districts and crustal structures in the region. We used two temporary seismic arrays with an average station spacing of about 10 km in the Chugoku district. Beneath Shikoku a clear northward dipping discontinuity at about 20–40 km depth was found, with other discontinuities below. We present a new interpretation that the clear boundary corresponds to the under surface of a low velocity layer in the upper part of the PHS slab. We also found a discontinuity at about 60 km depth beneath the Chugoku district, which is thought to be the aseismic PHS slab. Small scale discontinuities were found in the crust beneath the source area of the 2000 western Tottori Earthquake and around the Median Tectonic Line. The discontinuities might relate to the occurrence of large inland earthquakes.
Planetary wave oscillations in sporadic E layer occurrence at Wuhan
Authors: Zuo Xiaomin , Wan Weixing
Published: August 2014

Quasi 6-day oscillations in E
s occurrence were observed to occur in relation with planetary wave activity at Wuhan, China (30.6°N, 114.5°E). Wavelet analysis of E
s occurrence time series revealed that a strong 5- to 7-day oscillation was present during the period from about day 120 to 137 of 2003. The same quasi 6-day planetary wave oscillation was also found to dominate the spectrum of concurrent wind data measured in the 80- to 100-km region by a meteor radar, in agreement with the E
s occurrence. There is also a great deal of similarity between the 5- to 7-day band-pass filtered waveforms of E
s occurrence and the wind data. By estimating the wave phase changes with altitude, the quasi 6-day PW in the zonal wind was found to be in phase with the sporadic E layer critical frequency, f
o
E
s, at about 115 km, close to the observed E
s height. The quasi 6-day PW modulation was also present in the amplitude of the 12-h and 24-h periodicities which existed in the f
o
E
s time series. The present results provide new evidence in favor of a planetary wave indirect role on E
s formation through the modulation of tides, which in line with previous studies by Haldoupis and Pancheva (2002), and Pancheva et al. (2003).
Coseismic deformation of the 2007 Chuetsu-oki earthquake derived from PALSAR/InSAR and its fault model
Authors: Ozawa Taku
Published: August 2014

The 2007 Chuetsu-oki earthquake (Mj6.8) occurred offshore of Niigata Prefecture, northeast Japan, on 16 July 2007. I applied PALSAR/InSAR to detect coseismic deformation associated with the earthquake. The interferogram generated from descending data revealed a slant-range shortening exceeding 20 cm in the coastal area of Kashiwazaki adjacent to the epicenter and a maximum slant range extension of approximately 15 cm southeast of the slant-range shortening pattern. The interferogram generated from descending data is consistent with GPS displacements, but the non-crustal deformation component was large in the interferogram generated from ascending data. Based on a fault plane dipping to the southeast, a fault-slip distribution was estimated from the descending interferogram and GPS displacements. The largest fault-slip was located in the southwestern deeper part of the mainshock hypocenter. In the northern part of the focal region, the fault-slip was dominant at depths of 5–15 km, but it was limited to shallower depths in the southern part of the focal region. Such fault-slip distribution is consistent with the aftershock distribution. This consistency supports the assumption that the fault rupture in the mainshock has primarily occurred in the nodal plane dipping to the southeast.
Local time variation of the amplitude of geomagnetic sudden commencements (SC) and SC-associated polar cap potential
Authors: Araki T. , Tsunomura S. , Kikuchi T.
Published: August 2014

Local time (LT) variations of the averaged H-component amplitude of geomagnetic sudden commencements (SCs) observed at Memambetsu (geomagnetic latitude 35.4°) are derived separately for the summer and winter season. The amplitude was found to be higher at nighttime than daytime in both seasons, and the LT variations showed a good agreement with calculated LT variations of the resultant magnetic field due to a pair of fieldaligned currents (FACs) and ionospheric currents produced by the FACs. The DL- and DP-component of the disturbance field of SC can be separated based on a comparison of the observed and calculated LT variations. A method is introduced by which we can estimate the potential voltage difference associated with the FACs in the polar cap.
Possible influence of ultra-fast Kelvin wave on the equatorial ionosphere evening uplifting
Authors: Takahashi H. , Abdu M. A. , Wrasse C. M. , Fechine J. , Batista I. S. , Pancheva D. , Lima L. M. , Batista P. P. , Clemesha B. R. , Shiokawa K. , Gobbi D. , Mlynczak M. G. , Russell J. M.
Published: August 2014

Equatorial 3.5-day ultra-fast Kelvin wave was observed in the MLT zonal wind measured by meteor radar at Cariri (7.4°S, 36.5°W, geomag. 8°S) and in the stratosphere-mesosphere temperature structures from the TIMED/SABER data. The ionospheric F-layer bottom-side virtual height hT’F and the critical frequency f
o
F
2 observed at Fortaleza (3.9°S, 38.4°W, geomag. 5°S) also showed similar oscillation structures, indicating an influence of the Kelvin wave in the F region height and modulation of E × B uplifting during the evening period. Consequently the ionospheric spread F onset time was also modulated in the same period, around 4 days.
Propagation characteristics of nighttime mesospheric and thermospheric waves observed by optical mesosphere thermosphere imagers at middle and low latitudes
Authors: Shiokawa K. , Otsuka Y. , Ogawa T.
Published: August 2014

We review measurements of nighttime atmospheric/ionospheric waves in the upper atmosphere in Japan, Indonesia, and Australia, using all-sky airglow imagers of optical mesosphere thermosphere imagers (OMTIs). The imagers observe two-dimensional patterns of airglow emissions from oxygen (wavelength: 557.7 nm) and hydroxyl (OH) (near-infrared band) in the mesopause region (80–100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200–300 km). Several statistical studies were done to investigate propagation characteristics of small-scale (less than 100 km) gravity waves in the mesopause region and medium-scale traveling ionospheric disturbances (MSTIDs, ∼100–1,000 km) in the thermosphere/ionosphere. Clear seasonal variations of occurrence and propagation directions were reported for these waves. The propagation directions in the mesopause region are controlled by wind filtering, ducting processes and relative location to the wave sources in the troposphere. Poleward-propagating waves tend to be observed in the summer in the mesopause region at several stations, suggesting that mesospheric gravity waves are generated by intense convective activity in the equatorial troposphere. On the other hand, systematic equatorward and westward motions were observed for all seasons for nighttime MSTIDs in the midlatitude ionosphere with geomagnetic conjugacy between the northern and southern hemispheres. Ionospheric instabilities may play important role for the generation and propagation of these MSTIDs. We also give an example of simultaneous observation of quasi-periodic southward-moving waves in the mesopause region and in the thermosphere at the geographic equator. From these results, we discuss mean wind acceleration by mesospheric gravity waves and penetration of gravity waves from the mesosphere to the thermosphere.
Surface fair-weather potential gradient measurements from a small tropical island station Suva, Fiji
Authors: Kumar Vickal V. , Ramachandran V. , Buadromo V. , Prakash J.
Published: August 2014

Systematic analysis of the surface fair-weather potential gradient (PG) measured for 13 months (July 2005–July 2006) at 10 s resolution over a small tropical island station Suva (18.08°S, 178.45°E), Fiji is presented. Based on the solar radiation (>800 W m−2) and surface wind speed (<4.5 m s−1) conditions, 63 fair-weather days were selected. After sorting the data into a range of 0–1000 V m−1, the average PG was ∼139 V m−1. The measured fair-weather PG had a semi-diurnal structure, with a more pronounced peak at 0730 LT (1930 UT) and a reduced peak at 2200 LT (1000 UT). The time of occurrence of the morning peak and the noontime minima agreed well with the Carnegie curve. However, the variation about the global mean in the measured PG was 150% whereas for the Carnegie curve it was only 35%. The effects of the local meteorological parameters on the PG measurements were found to be small. On average, the PG during the dry season (May–October) was always greater than in the wet season (November–April). In contrast, analysis of regional (0–60°S and 100°E–160°W) lightning activity on fair-weather days showed a peak at ∼2000 LT and higher lightning activity during the wet season. These results indicate that the regional thunderstorm activity has no direct connection with the local fair-weather PG at the site.
Collisions between protoplanets: data analysis and classification
Authors: Nouda Akiyoshi , Emori Hiroyuki , Nakazawa Kiyoshi
Published: August 2014

Collisions between protoplanets are common events in the later stage of the planetary formation process. Protoplanets grew into present-day planets through these collisional events. It is therefore necessary to obtain information about redistribution of mass and angular momentum between colliding two bodies in order to study the growth rates of planets and the origin of their spin. We have started a series of systematic studies on this theme, and this is our first report. Here, we concentrate on the impact between one protoplanet, which has one Earth mass, and another protoplanet with 0.06 Earth mass. The motion of two bodies are pursued numerically by the SPH simulation method. We change the minimum distance between the two bodies as the variable parameter to specify their orbital angular momentum. For each value of the parameter, we repeat the numerical simulations and obtain final states of bodies. Such various final states are examined by criteria developed to distinguish some clusters formed by many SPH particles. We determine instantaneous orbital elements for relative motion between central protoplanet and each cluster. From this information, we forecast the destiny of each cluster, for example, to be merged into the target body or trapped. Then we determine the initial conditions that result in final characteristic states. The 5 states are the merging state in which the impactor is absorbed to the target, the multiple impact state in which the impactor collides with the target again and again, the disruption escaping state in which the impactor is tidally disrupted and a large part of the impactor escapes from the target, the trapping state in which the impactor is trapped by the target, and the passing state in which the impactor passes through as it is.
A study on the evaluation of the geoid-quasigeoid separation term over Pakistan with a solution of first and second order height terms
Authors: Sadiq Muhammad , Ahmad Zulfiqar , Akhter Gulraiz
Published: August 2014

An attempt has been made to evaluate the geoid-quasigeoid separation term over Pakistan by using solutions of terms involving first and second order terrain heights. The first term, involving the Bouguer anomaly, has a significant value and requires being incorporated in any case for determination of the geoid from the quasigoidal solution. The results of the study show that the second term of separation, which involves the vertical gravity anomaly gradient, is significant only in areas with very high terrain elevations and reaches a maximum value of 2–3 cm. The integration radius of 18 km for the evaluation of the vertical gravity anomaly gradient was found to be adequate for the near zone contribution in the case of the vertical gravity anomaly gradient. The Earth Gravity Model EGM96 height anomaly gradient terms were evaluated to assess the magnitude of the model dependent part of the separation term. The density of the topographic masses was estimated with the linear operator of vertical gravity anomaly gradient using the complete Bouguer anomaly data with an initial arbitrary density of 2.67 g/cm3 to study the effect of variable Bouguer density on the geoid-quasigeoid separation. The density estimates seem to be reasonable except in the area of very high relief in the northern parts. The effect of variable density is significant in the value of the Bouguer anomaly-dependent geoid-quasigeoid separation and needs to be incorporated for its true applicability in the geoid-quasigeoid separation determination. The geoid height (N) was estimated from the geoid-quasigeoid separation term plus global part of height anomaly and terrain-dependant correction terms. The results were compared with the separation term computed from EGM96-derived gravity anomalies and terrain heights to estimate its magnitude and the possible amount of commission and omission effects.
The large tsunami of 26 December 2004: Field observations and eyewitnesses accounts from Sri Lanka, Maldives Is. and Thailand
Authors: Papadopoulos Gerassimos A. , Caputo Riccardo , McAdoo Brian , Pavlides Spyros , Karastathis Vassilios , Fokaefs Anna , Orfanogiannaki Katerina , Valkaniotis Sotiris
Published: August 2014

Post-event field surveys were conducted and measurements were taken in Sri Lanka and Maldives about two weeks after the catastrophic Indian Ocean tsunami of 26 December 2004. The measurements taken were cross-checked after interviewing with local people. In the southwest, south and east coastal zones of Sri Lanka maximum water levels ranging from h = 3 m to h = 11 m a.m.s.l. were estimated. The highest values observed were in the south of the island: Galle h ∼ 10 m, Hambantota h ∼ 11m. Maximum inundation of d ∼ 2 km was observed in Hambantota. The heavy destruction and thousands of victims caused in coastal communities, buildings and infrastructure, like railways and bridges, is attributed not only to physical parameters, like the strength of the tsunami hydrodynamic flow, coastal geomorphology and the wave erosional action in soil, but also to anthropogenic factors including the increased vulnerability of the non-RC buildings and the high population density. Local people usually described the tsunami as a series of three main waves. The leading wave phase was only a silent sea level rise of h ≤ 1.5 m and d ≤ 150 m, while the second wave was the strongest one. The first two waves occurred between 09:00 and 09:30 local time, depending on the locality. It is well documented that near Galle, southern part, the strong wave arrived at 09:25:30. In the west coast the third wave was a late arrival which possibly represents reflection phases. In Maldives, three waves were also reported to arrive between 09:00 and 09:30 local time. Maximum water level was only h ∼ 3 m in Laamu Atoll, which is interpreted by the wave amplitude damping by the coral reef to the east of the island complex as well as to that the tsunami did not arrived at high tide time. Damage was observed in several islands of Maldives but this was minimal as compared to the heavy destruction observed in Sri Lanka. About 25 Greek eyewitnesses, who happened to experience the tsunami attack in Padong and Blue Lagoon Port of Phuket island as well as in Maya Bay, Phi-Phi islands, Thailand, were interviewed on the basis of a standard questionnaire. The first sea motion was a retreat of at least 100 m. Then, two main waves arrived, the first being the strong one occurring at about 09:55–10:05 local time, with h ∼ 6m in Padong causing significant destruction and human victims. The collected information clearly indicates that the tsunami propagated as the leading crest wave to the west side, e.g. in Sri Lanka and Maldives, and as the leading trough wave to the east, e.g. in Thailand.
A clinical case of effective treatment of giant prolactinoma in patient with morbid obesity
Authors: Vorotnikova S , Dzeranova L , Pigarova E , Markina N
Published: August 2014

Numerous studies showed an association between prolactin levels and body weight, with increased prevalence of obesity in patients with prolactinomas. Recent data indicate potential positive influence of cabergoline treatment to metabolic disorders in these patients. This clinical case demonstrates of a man with morbid obesity and giant prolactinoma which was successfully treated by high-dose cabergoline.
Mitarbeiterführung in einer monopolistischen Kultur
Authors: Bartlakowski Katja
Published: August 2014

Für manche Vorgesetzte im Bibliothekswesen mag in der beziehungsorientierten Mitarbeiterführung keine besondere Herausforderung liegen. So verwundert es nicht, dass Führungsthemen in der bibliothekarischen Literatur häufig auf der aufgabenbezogenen Ebene behandelt werden. Doch gerade die nicht aufgabenbezogenen Führungsthemen haben es in sich. Wer glaubt, Mitarbeiter etwa fördern und weiterentwickeln zu können, ohne die kulturellen Bedingungen des öffentlichen Dienstes zu verstehen, wird nicht selten erstaunt darüber sein, wie vielfältig die Abwehrmechanismen sein können. Häufig ist dann die Rede von Demotivation und Minderleistung auf Seiten der Mitarbeiter. Und wer glaubt, kulturelle Veränderungen und Organisationsentwicklungen vornehmen zu können, ohne die Spielregeln des öffentlichen Dienstes zu berücksichtigen, wird mitunter über die Hartnäckigkeit der Beharrungskräfte verblüfft sein, die am Traditionellen festhalten. Wie funktioniert der öffentliche Dienst und wie kann Mitarbeiterführung in einer monopolistischen Verwaltungskultur gelingen?