Evaluation of micro-behavior of strain field in Chinese mainland with the GPS time series

Introduction In the last 20 years, with observation technique development in space monitoring to Earth, a large progress has been made in monitoring crustal movement. This makes it possible for us to study crustal movement and the present geodynamic. Continuous GPS observation conducted in Chinese mainland and its neighboring region provides us for studying the present strain field of crustal micro-behavior tectonic. Crustal micro-behavior tectonic means that we can study the dif-ference bet…     

Ground deformation effects from the ~M6 earthquakes (2014–2015) on Cephalonia–Ithaca Islands (Western Greece) deduced by GPS observations

The implications of the earthquakes that took place in the central Ionian Islands in 2014 (Cephalonia, M _w6.1, M _w5.9) and 2015 (Lefkas, M _w6.4) are described based on repeat measurements of the local GPS networks in Cephalonia and Ithaca, and the available continuous GPS stations in the broader area. The Lefkas earthquake occurred on a branch of the Cephalonia Transform Fault, affecting Cephalonia with SE displacements gradually decreasing from north (~100 mm) to south (~10 mm). This earthquake revealed a near N–S dislocation boundary separating Paliki Peninsula in western Cephalonia from the rest of the island, as well as another NW–SE trending fault that separates kinematically the northern and southern parts of Paliki. Strain field calculations during the interseismic period (2014–2015) indicate compression between Ithaca and Cephalonia, while extension appears during the following co-seismic period (2015–2016) including the 2015 Lefkas earthquake. Additional tectonically active zones with differential kinematic characteristics were also identified locally.     

GPS Observation and Study on Recent Crustal Movement in the Northeastern Area of Pamir,Xinjiang

Calculation of repeated observation data at the densified GPS monitoring network in northeastern area of Pamir together with data from IGS stations in the peribphyery of the area yielded the movement rate of more than 40GPS station sites in the area,and,hence,the recent crustal deformation rate pattern and time series of fiductial GPS stations in the area were obtained.The result indicates that the principal movement direction of the GPS station sites is NNW,basically diagonal to the strike of Tianshan fold belt,i.e.a normal compression occurs in the Tianshan region.The movement pattern near Jiashi and its southwestern zone is some different from that of station sites in their surrounding areas,indicating a certain relation of tectonic deformation in Jiashi area to seismic activity during last years.The movement rate of station sites in the periphery of Taim basin less varies and its direction is basically consistent It indicates less or basically no deformation within Tarim basin.     

New constraints on the HIMU mantle from neon and helium isotopic compositions of basalts from the Cook–Austral Islands

High ⁴He/³He ratios of 100 000 to 160 000 found at HIMU ocean islands (“high μ,” where μ is the U/Pb ratio) are usually attributed to the presence of recycled oceanic crust in the HIMU mantle source. However, significantly higher ⁴He/³He ratios are expected in recycled crust after residence in the mantle for periods greater than 1 Ga. In order to better understand the helium isotopic signatures in HIMU basalts, we have measured helium and neon isotopic compositions in a suite of geochemically well-characterized basalts from the Cook–Austral Islands. We observe ⁴He/³He ratios ranging from 56 000 to 141 000, suggesting the involvement of mantle reservoirs both more and less radiogenic than the mantle source for mid-ocean ridge basalts (MORBs). In addition, we find that the neon isotopic compositions of HIMU lavas extend from the MORB range to compositions less nucleogenic than MORBs. The Cook-Austral HIMU He–Ne isotopic compositions, along with Sr, Nd, Pb, and Os isotopic compositions, indicate that in addition to recycled crust, a relatively undegassed mantle end-member (e.g., FOZO) is involved in the genesis of these basalts. The association of relatively undegassed mantle material with recycled crust provides an explanation for the close geographical association between HIMU lavas and EM (enriched mantle)-type lavas from this island chain: EM-type signatures represent a higher mixing proportion of relatively undegassed mantle material. Mixing between recycled material and relatively undegassed mantle material may be a natural result of entrainment processes and convective stirring in deep mantle.     

Projected streamflow in the Huaihe River Basin (2010–2100) using artificial neural network

Climate projections for the Huaihe River Basin, China, for the years 2001–2100 are derived from the ECHAM5/MPI-OM model based on observed precipitation and temperature data covering 1964–2007. Streamflow for the Huaihe River under three emission scenarios (SRES-A2, A1B, B1) from 2010 to 2100 is then projected by applying artificial neural networks (ANN). The results show that annual streamflow will change significantly under the three scenarios from 2010 to 2100. The interannual fluctuations cover a significant increasing streamflow trend under the SRES-A2 scenario (2051–2085). The streamflow trend declines gradually under the SRES-A1B scenario (2024–2037), and shows no obvious trend under the SRES-B1 scenario. From 2010 to 2100, the correlation coefficient between the observed and modeled streamflow in SRES-A2 scenario is the best of the three scenarios. Combining SRES-A2 scenario of the ECHAM5 model and ANN might therefore be the best approach for assessing and projecting future water resources in the Huaihe basin and other catchments. Compared to the observed period of streamflows, the projected periodicity of streamflows shows significant changes under different emission scenarios. Under A2 scenario and A1B scenario, the period would delay to about 32–33a and 27–28a, respectively, but under B1 scenario, the period would not change, as it is about 5–6a and the observed period is about 7–8a. All this might affect drought/flood management, water supply and irrigation projects in the Huaihe River basin.     

GPS monitoring of recent crustal movements in Kamchatka and the Commander Islands during 1997–2007

This is a review of the geodetic monitoring of the horizontal component of recent crustal movements (RCMs) in Kamchatka and the Commander Islands for the period 1979–2007. Examples are provided of the RCMs recorded in Kamchatka and the Commander Islands for the period 1997–2007 by the Kamchatka regional GPS network (KAMNET) set up by workers at the Kamchatka Branch of the RAS Geophysical Service (KB GS RAS) in collaboration with the Institute of Volcanology and Seismology of the Far East Division of the Russian Academy of Sciences to study the geodynamic processes that are occurring in the Kamchatka subduction zone. An interpretation of examples of recorded RCMs is given.     

Crustal Movements and Deformations in Eastern Turkey in Connection with the Van Earthquake (October 23, 2011, Мw = 7.2): Study from GPS Data

Izvestiya, Physics of the Solid Earth - Abstract—A devastating earthquake with magnitude Mw = 7.2 occurred in the Van region, Eastern Turkey, on October 23, 2011. This study analyzes the...     

Determination of active units with different kinematic property and their activity pattern in North China based on the data from GPS remeasurements

IntroductionWith the most feasible and powerful technical support provided by the high-precision GPS measurement for the study on horizontal crustal deformation, the obtainment of various-scale horizontal movement data and its study over the whole world is now in the ascendant, and its applicable fields is now expanding successively. In China, besides the GPS monitoring networks for different applications arranged by many agencies and departments, the key scientific project Crustal Movement…     

Study on the Relationship Between Recent Crustal Deformation and the Temporal-Spatial Distribution of Strong Earthquakes ( Ms ≥6.0) in the Sichuan-Yunnan Region

Analysis of deformation data measured across the faults, regional vertical deformation data and GPS measurements in the Sichuan-Yunnan region made since the 1980s permitted us to conclude that the crustal deformation in the region during this period of time was relatively weak and caused the occurrence of earthquakes (Ms≥6.0), which were not distributed along the major boundary active faults in the region after the 1981 I)awu Ms 6.9 earthquake and that the seismic activity is characterized by quasi-clockwise migration. Thus, it follows that earthquake prediction research should be focused on the central part of the Sichuan-Yunnan region in the coming years. Finally, a concept of temporal division of the region into active blocks is suggested and the preliminary result of the division is given in the paper.     

Evidence of multiple strain fields beneath the eastern flank of Mt. Etna volcano (Sicily,Italy) deduced from seismic and geodetic data during 2003–2004

We carried out a study of the seismicity and ground deformation occurring on Mt. Etna volcano after the end of the 2002–2003 eruption and before the onset of the 2004–2005 eruption. Data were recorded by the permanent local seismic network run by Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Catania and by geodetic surveys carried out in July 2003 and July 2004 on the GPS network. Most earthquakes were grouped in two main clusters located in the northeastern and southeastern sectors of the volcano. The areal distribution of seismic energy associated with the recorded earthquakes allowed us to highlight the main seismogenic areas of Mt. Etna. In order to better understand the kinematic processes of the volcano, 3D seismic locations were used to compute fault plane solutions, and a selected dataset was inverted to determine stress and strain tensors. The focal mechanisms in the northeastern sector show clear left-lateral kinematics along an E-W fault plane, consistent with events occurring along the Pernicana Fault system. The fault plane solutions in the southeastern sector show mainly right-lateral kinematics along a NNE and ENE fault plane and left lateral-kinematics along NW fault planes that together suggest roughly E-W oriented compression. Surface ground deformation affecting Mt. Etna measured by GPS surveys highlighted a marked inflation during the same period and exceptionally strong seawards motion of its eastern flank. The 2D geodetic strain tensor distribution was calculated and the results show mainly ENE-WSW extension coupled with WNW-ESE contraction, indicating right-lateral shear along a NW-SE oriented fault plane. The different deformation of the eastern sector of the volcano, as measured by seismicity and ground deformation, must be interpreted by considering the different depths of the two signals. Seismic activity in the southeastern sector of volcano is located between 3 and 8 km b.s.l. and can be associated with a very strong additional E-W compression induced by a pressurizing source just westwards and at the same depth, located by inverting GPS data. Ground deformation, in contrast, is mainly affected by the shallower dynamics of the fast moving eastern flank which produces a shallower opposing E-W extension. The entire dataset shows that two different processes affect the eastern flank at the same time but at different depths; the boundary is clearly located at a depth of 3 km b.s.l. and could represent the décollement surface for the mobile flank.     

Gravity wave activity and dynamical effects in the middle atmosphere (60–90km): observations from an MF/MLT radar network,and results from the Canadian Middle Atmosphere Model (CMAM)

It has become increasingly clear that Gravity Waves (GW) have an essential and often dominant role in the dynamics of the Middle Atmosphere. This leads to them having strong impacts upon the thermal structure and the distribution of atmospheric constituents. However, the radar observations of GW have been limited in their latitudinal extent during the past decade, and although satellite observations are now significantly contributing, global-seasonal climatologies of important characteristics are still inadequate. With regard to models, the inclusion of GW-drag effects has been problematic. Usually no seasonal or latitudinal variation in the subgrid-scale GW-drag parameterization scheme is included, and varieties of parameterization schemes have been used. Although these often make conflicting assumptions, they generally produce similarly acceptable end-products, e.g. zonal-mean zonal wind fields. In this paper, we report upon the beginnings of a substantial program, using observations from a network of MF radars (North America, Pacific and Europe), and data from the Canadian Middle Atmosphere Model (CMAM). This model allows the tidal and planetary wave fields to be assessed, characteristics and climatologies of which are well known from the MF Radars. Here we focus upon the tides. There are useful similarities in the observed and modeled background wind and wave fields, and strong indications that the two non-orographic GW-drag parameterization schemes (Hines; Medvedev–Klaassen) have significant and differing effects upon the dynamics of the modeled atmosphere. It is shown that this comparison process is valuable in the evaluation, and potentially the optimization, of parameterization schemes.     

Anomalous directions and paleointensity of the geomagnetic field based on paleomagnetic investigations of rocks from the Karadzha Range (Azerbaijan) of the age 45–20 ka

Paleomagnetic investigations of marine and subaqueous deposits in the 12-meter marine terrace of a section of the Karadzha Range (Azerbaijan) are performed. These deposits correspond to OI stage 3 and encompass the time interval ～45–20 ka. Four anomalous deviations of the magnetization from the dipole field at the sampling site are recorded in the upper and lower transgressive members of deposits. Investigations of the influence of the anisotropy of the magnetic susceptibility (AMS) on directions of the natural remanent magnetization (NRM) showed that only three of the four identified intervals can actually reflect geomagnetic field changes. The fourth interval of the anomalous NRM behavior is recorded in samples demonstrating the presence of the identified AMS direction pointing to a possible deformation of layers, which could turn the NRM vector toward the direction of the acting factor. Based on the age of the terrace under investigation, three other anomalous horizons could correspond to heavily reduced records of the Mono and Lashamp excursions of the geomagnetic field.     

Sporadic and recurrent geomagnetic disturbances in 1859–1860 according to the archived data from the Russian network of stations

Based on an analysis of the available archived data from the Russian network of geomagnetic stations, it has been indicated that the known event of August–September 1859 was the first and the greatest event in the series of the recurrent geomagnetic storms. Similar series were repeatedly observed in the next years. These series are caused by the processes on the Sun and in the heliosphere related to the superposition of the solar wind flows. The sporadic and regular components in joint activity of the complex, including active regions and coronal holes on the rotating Sun, play the role of the Bartels M regions responsible for initiation and development of geomagnetic storms. Neither coronal holes nor active regions can separately explain observations. During interpretation, active regions and coronal holes should be considered as a unified complex.     

Identifying the precursors of large (M ≥ 6.0) earthquakes in Kamchatka based on data from the Kamchatka Branch of the Russian expert council on earthquake prediction: 1998–2011

This paper describes the activities of the Kamchatka Branch of the Russian Expert Council on Earthquake Prediction, Assessment of Seismic Hazard and Risk (KB REC) over a 14 year period. We provide brief information on how the KB REC functions, the methods that are used for earthquake prediction in expert assessments, forecasts, and precursors of M ≥ 6.0 Kamchatka earthquakes for the 1998–2011 period. The efficiency of prediction using several methods is estimated.     

Assessing the potential for future explosive activity from Teide–Pico Viejo stratovolcanoes (Tenerife,Canary Islands)

Since the onset of their eruptive activity within the Cañadas caldera, about 180 ka ago, Teide–Pico Viejo stratovolcanoes have mainly produced lava flow eruptions of basaltic to phonoltic magmas. The products from these eruptions partially fill the caldera, and the adjacent Icod and La Orotava valleys, to the north. Although less frequent, explosive eruptions have also occurred at these composite volcanoes. In order to assess the possible evolution Teide–Pico Viejo stratovolcanoes and their potential for future explosive activity, we have analysed their recent volcanic history, assuming that similar episodes have the highest probability of occurrence in the near future. Explosive activity during the last 35000 years has been associated with the eruption of both, mafic (basalts, tephro–phonolites) and felsic (phono–tephrites and phonolites) magmas and has included strombolian, violent strombolian and sub-plinian magmatic eruptions, as well as phreatomagmatic eruptions of mafic magmas. Explosive eruptions have occurred both from central and flank vents, ranging in size from 0.001 to 0.1 km³ for the mafic eruptions and from 0.01 to < 1 km³ for the phonolitic ones. Comparison of the Teide–Pico Viejo stratovolcanoes with the previous cycles of activity from the central complex reveals that all them follow a similar pattern in the petrological evolution but that there is a significant difference in the eruptive behaviour of these different periods of central volcanism on Tenerife. Pre-Teide central activity is mostly characterised by large-volume (1–> 20 km³, DRE) eruptions of phonolitic magmas while Teide–Pico Viejo is dominated by effusive eruptions. These differences can be explained in terms of the different degree of evolution of Teide–Pico Viejo compared to the preceding cycles and, consequently, in the different pre-eruptive conditions of the corresponding phonolitic magmas. A clear interaction between the basaltic and phonolitic systems is observed from the products of phonolitic eruptions, indicating that basaltic magmatism is the driving force of the phonolitic eruptive activity. The magmatic evolution of Teide–Pico Viejo stratovolcanoes will continue in the future with a probably tendency to produce a major volume of phonolitic magmas, with an increasing explosive potential. Therefore, the explosive potential of Teide–Pico Viejo cannot be neglected and should be considered in hazard assessment on Tenerife.     

The mesoscale eddies and Kuroshio transport in the western North Pacific east of Taiwan from 8-year (2003–2010) model reanalysis

The relationship between the Kuroshio volume transport east of Taiwan (~24°N) and the impinging mesoscale eddies is investigated using 8-year reanalysis of a primitive equation ocean model that assimilates satellite altimetry and SST data. The mean and fluctuations of the model Kuroshio transport agree well with the available observations. Analysis of model dynamic heights and velocity fields reveals three dominant eddy modes. The first mode describes a large eddy of ~500 km in diameter, centered at ~22° N. The second mode describes a pair of the north–south counter-rotating eddies of?~?400 km in diameter each, centered at 23° and 20° N, respectively. The third mode describes a pair of the east–west counter-rotating eddies of?~?300 km in diameter each, centered at 21° N. The associated velocity fields indicate eddies extending to 600–700 m in depth with vertical shears concentrated in the upper 400 m. All three modes and the model Kuroshio transport have similar dominant timescales of 70–150 days and generally are coherent. The decreased Kuroshio volume transports typically are associated with the impinging cyclonic eddies and the increased transports with the anticyclonic eddies. Selected drifter trajectories are presented to illustrate the three eddy modes and their correspondence with the varying Kuroshio transports.     

Mean vertical wind in the mesosphere-lower thermosphere region (80–120 km) deduced from the WINDII observations on board UARS

The WINDII interferometer placed on board the Upper Atmosphere Research Satellite measures temperature and wind from the O(¹S) green-line emission in the Earths mesosphere and lower thermosphere. It is a remote-sensing instrument providing the horizontal wind components. In this study, the vertical winds are derived using the continuity equation. Mean wind annually averaged at equinoxes and solstices is shown. Ascendance and subsidence to the order of 1–2 cm s^–1 present a seasonal occurrence at the equator and tropics. Zonal Coriolis acceleration and adiabatic heating and cooling rate associated to the mean meridional and vertical circulations are evaluated. The line emission rate measured together with the horizontal wind shows structures in altitude and latitude correlated with the meridional and vertical wind patterns. The effect of wind advection is discussed.     

Bounds on the Time–history and Holocene Mass Budget of Antarctica from Sea–level Records in SE Tunisia

Solving the sea–level equation for a Maxwell Earth, we analyze the sensitivity of Holocene sea–level records in SE Tunisia to the time–history of remote ice sheets. Assuming that mantle viscosity increases moderately with depth, we find that in this region the sea–level variations driven by the Northern Hemisphere ice sheets cancel, so that the late–Holocene sea–level high–stand suggested by the geological record merely reflects the melting history of Antarctica. New insight into the history of this ice sheet is obtained analyzing the information contained in a revised set of relative sea–level observations for sites across the Mediterranean covering the last 8 kyrs. From a trial–and–error misfit analysis, it holds true that in this region the match between model predictions and observations improves when the volume of water released from Antarctica is well below the value imposed by the ICE3G chronology and when a sudden meltwater pulse is allowed between 8 and 7 kyrs before present, corresponding to the epoch of the catastrophic rise event known as CRE3.     

Identifying complexity of annual precipitation variation in Iran during 1960–2010 based on information theory and discrete wavelet transform

The hydrologic process and dynamic system of precipitation is influenced by many physical factors which are excessively complex and variable. Present study used a wavelet transform based multiscale entropy (WME) and wavelet-based multiscale relative entropy (WMRE) approach in order to analyze and gage the complexity of the precipitation series and spatially classify the raingauges in Iran. For this end, historical annual precipitation data of 51 years (1960–2010) from 31 raingauges was decomposed using WT in which smooth Daubechies (db) mother wavelet (db5–db10), optimal level of decomposition and boundary extensions were considered. Next, entropy concept was applied for components obtained from WT to measure of dispersion, uncertainty, disorderliness and diversification in a multi-scale form. Spatial classification of raingauges was performed using WME and WMRE values as input data to SOM and k-means approaches. Three validity indices namely Davis Bouldin (DB), Silhouette coefficient (SC) and Dunn index were used to validate the proposed model’s efficiency. Based on results, it was observed that k-means approach had better performance in determining homogenous areas with SC = 0.337, DB = 0.769 and Dunn = 1.42. Finally, spatial structure of precipitation variation in latitude and longitude directions demonstrated that WME and WMRE values had a decreasing trend with latitude, however, it was seen that WME and WMRE had an increasing relationship with longitude in Iran.