Paleomagnetic dating of the Cenjiawan Paleolithic site in the Nihewan Basin, northern China

It draws much attention of scientists how early hu- mans occupy and adapt to the rigorous climate and environment at high northern latitudes in East Asia after they stepped out of Africa, passed West Asia and finally arrived in East Asia[1-4]. Reliable age determi- nations of Paleolithic sites from northeastern Asia not only help to find out the earliest occupation of early humans in this region, but also relate to the founda- tion of the overall framework of human origin and migration[1-8]…     

Method of expected earthquake losses estimation based on the frequency of seismic site intensity

Ｍｅｔｈｏｄｏｆｅｘｐｅｃｔｅｄｅａｒｔｈｑｕａｋｅｌｏｓｓｅｓｅｓｔｉｍａｔｉｏｎｂａｓｅｄｏｎｔｈｅｆｒｅｑｕｅｎｃｙｏｆｓｅｉｓｍｉｃｓｉｔｅｉｎｔｅｎｓｉｔｙ高孟潭Ｍｅｎｇ－ＴａｎＧＡＯ（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ,Ｓｔａｔｅ...     

Performance of “G-Pisa” ring laser gyro at the Virgo site

The ring laser gyroscope ??G-Pisa?? has been taking data inside the Virgo interferometer central area with the aim of performing high sensitivity measurements of rotations in the vertical as well as in the horizontal orientation. We discuss the main characteristics of the instrument, describing its mechanical design and presenting the measured sensitivity limit. By applying a simple effective model for the laser gyroscope, we show that the stability of the sensor above 10?s of integration time is mainly limited by backscattering effects. The horizontal rotation rate signal is also compared with the signals recorded by the Virgo environmental monitoring system and by a biaxial mechanical tiltmeter rigidly fixed on top of the gyrolaser mounting frame.     

Seismic vulnerability estimation of the building considering seismic environment and local site condition

Introduction The estimation of damage probability distribution among different damage states of rein-forced concrete buildings is a key component of earthquake loss estimation for modern city or a group of cities. With the development of city, the reinforced concrete buildings are major compo-nent parts of modern cities. Vulnerability estimates for these kinds of buildings are of importance to those responsible for civil protection, relief, and emergency services to enable adequate contin-genc…     

Study on the method of optimal location on explosion events at near-source site

IntroductionEarthquake location is one of the inverse problems in seismology. The accurate earthquake source location is the basis of studies of earthquake images, the relation analysis between seismicity and tectonics, and the important parameters of earthquakes. It is also the basic data used to study the space distribution of aftershocks after a strong earthquake. The earthquake location accuracy mainly depends on reliability of the velocity models for the earth(s crust, the reasonable desi…     

A zooarchaeological study of bone assemblages from the Ma’anshan Paleolithic site

Ten thousands of bone fragments were recovered from the Ma’anshan Paleolithic site, of which 4358 pieces can be identified to skeletal elements or species. In this research, the bone assemblages are quantified based on elements of MNI, MNE, and MAU. Then bone surface modifications and skeletal element profiles of the bone assemblages are studied to understand shlepping behaviors and reveal the technique of disarticulating and defleshing the animals’ bodies, etc. Based on the analyses of bone assemblages and the comparative study with the ethnoarchaeological as well as experimental data, it is assumed that later hominids at the site made fuller use of the game animals than the earlier hominids. Incorporating the lines of evidence from chronological dating, paleoenvironment, and polished bone tools between the two cultural layers, here we propose three hypotheses suggesting that the changes of environment, the migrations of the hominids from the North, or the demographic pulses may cause such a behavioral difference. However, it is yet to be determined which hypothesis can better explain the changes.     

Separation of source and site effects by generalized inversion technique using the aftershock recordings of the 2009 L��Aquila earthquake

We exploit S-wave spectral amplitudes from 112 aftershocks (3.0 ≤ M_L ≤ 5.3) of the L’Aquila 2009 seismic sequence recorded at 23 temporary stations in the epicentral area to estimate the source parameters of these events, the seismic attenuation characteristics and the site amplification effects at the recording sites. The spectral attenuation curves exhibit a very fast decay in the first few kilometers that could be attributed to the large attenuation of waves traveling trough the highly heterogeneous and fractured crust in the fault zone of the L’Aquila mainshock. The S-waves total attenuation in the first 30 km can be parameterized by a quality factor Q_S(f) = 23f ^0.58 obtained by fixing the geometrical spreading to 1/R. The source spectra can be satisfactorily modeled using the omega-square model that provides stress drops between 0.3 and 60 MPa with a mean value of 3.3±2.8 MPa. The site responses show a large variability over the study area and significant amplification peaks are visible in the frequency range from 1 to more than 10 Hz. Finally, the vertical component of the motion is amplified at a number of sites where, as a consequence, the horizontal-to-vertical spectral ratios (HVSR) method fails in detecting the amplitude levels and in few cases the resonance frequencies.     

Evaluation of site effects in the Aterno river valley (Central Italy) from aftershocks of the 2009 L��Aquila earthquake

A temporary network of 33 seismic stations was deployed in the area struck by the 6th April 2009, Mw 6.1 (Scognamiglio et?al. in Seism Res Lett 6/81, 2010), L??Aquila earthquake (central Italy), with the aim to investigate the site amplification within the Aterno river Valley. The seismograms of 18 earthquakes recorded by 14 of the 33 stations were used to evaluate the average horizontal to vertical spectral ratio (HVSR) for each site and the standard horizontal spectral ratio (SSR) between a site and a reference station. The obtained results have been compared to the geological and geophysical information in order to explain the resonance frequencies and the amplification levels with respect to surface geology of the valley. The results indicate that there is no uniform pattern of amplification, because of the complex geologic setting, as the thickness and degree of cementation of the deposits is highly variable.     

The effect of the Jessica grounding on Galápagos reef fish communities adjacent to the wreck site

The grounding of the oil tanker Jessica off San Cristóbal Island, Galápagos, resulted in generally elevated rather than depressed densities of fishes adjacent to the wreck site 15 weeks post spill. Species richness of fishes declined along transects out from the wreck; however, patterns were inconsistent for different depth strata, with the most clearly defined decline evident for the intermediate 5-7 m depth stratum. Fish species attracted to the immediate wreck site, most notably the surgeonfish Prionurus laticlavius, the damselfish Microspathodon dorsalis and the angelfish Holacanthus passer, were considered to be responding either to the heterogeneity provided by the wreck structure or elevated densities of macroalgae. The fish community at the wreck site lay outside the range of variation for other sites investigated in the region; however, contrary to predictions of grounding impacts, the fish assemblage immediately adjacent to the wreckage showed greater faunal similarity to reference sites than did fish assemblage at 60-90 m distance from the grounding.     

The effect of the Jessica grounding on subtidal invertebrate and plant communities at the Galápagos wreck site

Impacts of the grounding of the oil tanker Jessica off San Cristóbal island, Galápagos, included both effects of oil on biota and also mechanical effects associated with a shallow furrow 50 m x 30 m gouged across the rocky seafloor and wreckage strewn over 7500 m(2). The wreckage represented a minor but potentially chronic source of pollution to the surrounding environment through delayed releases of oil, antifouling compounds and other toxic chemicals, and a possible source of exotic marine taxa. Investigation at the wreck site indicated that impacts on subtidal plant and macro-invertebrate communities were largely confined within 100 m of the wreck site itself. Observed population effects included significant increases in cover of opportunistic algae (filamentous green algae, filamentous red algae and Ulva sp.) and the hydroid Ectopleura media adjacent to the wreck, while densities of the green sea urchin Lytechinus semituberculatus significantly decreased from 0.3 m(-2) adjacent to the wreck to 11 m(-2) at 100 m distance.     

Studying the depth-dependent variation of site magnification factor in Dongchuan by earthquakes observed in borehole

IntroductionMany seismologists both at home and abroad have recognized the importance of site effect on structures of damaging earthquakes. Lots of great earthquakes occurred in China and foreign countries clearly indicate that the site response of buildings located in the seismic area has huge impact on the damage of building(s structure (JIANG, et al, 1997). The digitization of seismometer and development of computer have laid foundation of substance for quantitatively studying spatial var…     

OSL dating of individual quartz ‘supergrains’ from the Ancient Middle Palaeolithic site of Cuesta de la Bajada,Spain

Dose saturation represents a fundamental limitation for obtaining finite optically stimulated luminescence (OSL) quartz ages over Middle Pleistocene timescales. Single-grain OSL studies typically reveal significant intra- and inter-sample variability in quartz dose saturation properties at the individual grain level. This enhanced variability may offer the potential to obtain extended-range chronologies exceeding the traditional upper age limits of multiple-grain OSL dating. However, there have been relatively few detailed assessments of single-grain OSL properties over high dose ranges. In this study we investigate extended-range single-grain OSL dating potential at Cuesta de la Bajada, one of the most important Ancient Middle Palaeolithic sites in the Iberian Peninsula. The quartz samples from this site exhibit exceptional dose saturation properties and contain significant populations of individual ‘supergrains’ with bright OSL signals, very high characteristic saturation dose (D₀) limits of 200 to >600 Gy, and dose-response curves that closely conform to single saturating exponential functions. Assessments of OSL signal composition and the ability to successfully recover a known laboratory dose of 470 Gy support the potential for obtaining high equivalent dose (D_e) values with reasonable fitting uncertainties. A series of novel sensitivity tests are used to assess potential biases in supergrain D_e estimation over high dose ranges related to (i) thermally transferred signal contributions, (ii) choice of dose-response curve fitting function, and (iii) insufficient dose saturation properties of individual grains. The single-grain D_e values obtained using the standard quality assurance criteria and novel sensitivity tests are consistent at 2σ, and are in agreement with quartz Ti-centre ages obtained on two of three paired electron spin resonance (ESR) samples collected from Cuesta de la Bajada. These comparisons support the suitability of our single-grain OSL results and suggest there may be good potential for using quartz supergrains to establish extended-range chronologies at some Middle Pleistocene sites. Comparisons with other single-grain OSL studies across the Iberian central plains suggest that favourable dose saturation properties may be influenced by regional-scale geological controls. The importance of undertaking single-grain OSL dating at Cuesta de la Bajada is also demonstrated by the results of synthetic aliquot experiments, which reveal multiple-grain age offsets of 60–170 ka when unsuitable grain types are inadvertently included in the final age calculations. The single-grain OSL results indicate that the main archaeological horizon at Cuesta de la Bajada (unit CB3) accumulated between 264 ± 22 and 293 ± 24 ka. These ages are consistent with the chronologies of other key early Middle Palaeolithic sites in the region (Ambrona AS6 and Gran Dolina TD10) and indicate that the Ancient Middle Palaeolithic techno-complex likely spread across Iberia from at least Marine Isotope Stage 9 onwards.     

The earliest archaeobiological evidence of the broad-ening agriculture in China recorded at Xishanping site in Gansu Province

The crop types and agricultural characteristic are reconstructed using the archaeobiological proxies of pollen, seed and phytolith at Xishanping site in Gansu Province between 5250 and 4300 cal a BP. The agricultural activity strengthened in Xishanping from 5100 cal a BP. It appeared the earliest cultivation of prehistoric rice in the most northwest China at 5070 cal a BP. The sudden disappearance of conifers and expansion of chestnut trees is likely to be the result of selective hewing of conifers and cultivation of chestnuts at about 4600 cal a BP. There existed 8 crop types of foxtail millet, broomcorn millet, rice, wheat, barley, oats, soybean and buckwheat at Xishanping between 4650 and 4300 cal a BP, which cover the main crop types of the two origin centers of East and West Asia. Not only has the wheat and barley been approved to spread to northwestern China, but the earliest complexity agriculture in Neo-lithic China appeared in Tianshui, Gansu Province.     

Optical dating of St. Lawrence Iroquoian ceramics from the Mailhot-Curran site,southern Québec

Infrared-stimulated luminescence dating (IRSL) was applied on pottery sherds from the Mailhot-Curran archaeological site (BgFn-2), a Late Woodland period village located in the Saint-Anicet region, southern Québec (Canada). This site witnessed the presence of St. Lawrence Iroquoians and is thought to have been occupied roughly 500 years ago. The main goal of this study is to chronologically constrain the occupation of this site in order to establish a fine chronological sequence for the occupations of various sites found in this area. The IRSL is used to complement previous dating methods used for Mailhot-Curran (radiocarbon and seriation of the archaeological remains).Dating results are reported for ten samples of local ceramics made from Quaternary Champlain Sea clay. Luminescence dating on fine grains was preferentially used, since feldspar luminescence typically emit a decent luminescence signal. Although the latter was rather dim, anomalous fading was measured and luminescence ages were successfully corrected. It is therefore possible to validate the occupation age of this site.     

Evolution of vegetation and climate since the last glacial maximum recorded at Dahu peat site, South China

Sporopollen analysis on a 346 cm peat record at Dahu, Jiangxi, chronologically constrained by 16 AMS 14C datings, provides an opportunity to reconstruct the vegetation evolution stages responding to cli-mate change in South China since the last glacial maximum. The result shows that during 18330-15630 cal a B.P., broad-leaved forest dominated the area, corresponding to mild, cool and fairly humid climate. At the interval of 15630-11600 cal a B.P., several evergreen broad-leaved species appeared within the broad-leaved forest, indicating moderate and humid condition. During early Holocene, broad-leaved evergreen forest community was constructed as Castanopsis/Lithorcarpus principally developed, suggesting a warm and humid scenario until 6000 cal a B. P. Since 6000 cal a B. P., abrupt forest deterioration happened with an contemporary increase of fern and herb communities, repre-senting a turnover to relatively cool and dry condition and as well, possible impact from human activi-ties. Meanwhile, several relatively cool and dry events can be identified in the sporopollen record, they can be correlated to the North Atlantic Heinrich event, YD and Holocene millennial-scale oscillations, implying that the low latitude climate was coupled with high latitude influences. Moreover, the varia-tions of temperature and humidity since LGM at Dahu were much smaller when compared with the re-cords in north monsoonal China.     

High resolution OSL and post-IR IRSL dating of the last interglacial–glacial cycle at the Sanbahuo loess site (northeastern China)

Northeastern China is located in the East Asian monsoon region; it is sensitive to both high and low latitude global climate systems. Loess deposits in the region have considerable potential as sensitive archives of past climate changes. However, research into loess deposition and climate change in this region is restricted by the lack of independent age control. In this study, coarse-grained quartz SAR OSL and K-feldspar post-IR infrared (IR) stimulated luminescence (post-IR IRSL; pIRIR₂₉₀) methods have been used to date the Sanbahuo loess site in northeastern China. The quartz OSL characteristics are satisfactory. The measured pIRIR₂₉₀ D_e's do not vary significantly with IR stimulation temperatures between 50 °C and 260 °C; a first IR stimulation temperature of 200 °C was adopted. Dose recovery tests were performed by adding different laboratory doses to both laboratory bleached (300 h SOL2) samples and natural samples; the results are satisfactory up to ∼800 Gy. Resulting quartz OSL and feldspar pIRIR₂₉₀ ages are in good agreement at least back to ∼44 ka; beyond this feldspar pIRIR₂₉₀ ages are older. The feldspar ages are consistent with the expected age of the S1 palaeosol (MIS 5). There appears to have been a period of fast loess deposition at ∼62 ka, perhaps indicative of winter monsoon intensification with a very cold and dry climate that lead to a serious desertification of dunefields in northeastern China.     

An inversion of site response and Lg attenuation using Lg waveform

Based on spectral ratio method, a joint inversion method was used to obtain parameters of Lg wave attenuation and site response. The inversion method allows simple and direct (two-parameter) determination of Lg wave attenua- tion and site response from sparse spectral data, which are not affected by radiation pattern factor and different response of same instrument after geometrical spreading. The method was used successfully for estimating site re- sponse of stations of Zhejiang Seismic Network and measuring Lg wave attenuation. The study is based on 20 earth- quakes occurred in northeast of Taiwan with magnitude MS5.0~6.7 and 960 seismic wave records from 16 stations in Zhejiang area from 2002 to 2005. The parameters of site response and Lg attenuation were calculated with a fre- quency interval of 0.2 Hz in the range of 0.5 Hz to 10 Hz. Lg wave attenuation coefficient corresponding to U-D, E-W and N-S components are γ ( f )=0.00175 f 0.43485, γ ( f )=0.00145f 0.48467 and γ ( f )=0.0021f 0.41241, respectively. It is found that the site response is component-independent. It is also found that the site response of QIY station is significant above the frequency of 1.5 Hz, and that the site response of NIB station is low for most frequency     

Sediment cascades and the entangled relationship between human impact and natural dynamics at the pre-pottery Neolithic site of Göbekli Tepe,Anatolia

This study presents a meta-analysis of radiocarbon ages for the environs of Göbekli Tepe – one of the oldest monumental structures worldwide – using cumulative probability functions to diachronically assess phases of geomorphodynamic activity as controlled by natural or anthropogenic drivers. We employ sediment cascades as a heuristic framework to study the complex responses of the geomorphological system to various triggers at local to supra-regional scales. Possible triggers include climatic variability as documented by supra-regional hydroclimatic proxy data, regional demographic trends, and local to regional socioeconomic developments such as the emergence of sedentism or the introduction and dispersal of livestock herding. Our results show that phases of intensified geomorphodynamic activity occurred between ca. 7.4–7.0 and 5.8–3.3 ka BP. These phases roughly coincide with phases of population growth in southern Turkey and climatic variations in Turkey and the Levant. The phase between ca. 5.8–3.3 ka BP also corresponds to the time when organized agriculture and the seeder plough were introduced. Also, the identified phases are in agreement with the general trend of varying geomorphodynamic activity in the Eastern Mediterranean as driven by human impact and climatic change. However, neither the Younger Dryas–Holocene transition nor the development of herding during the Pre-Pottery Neolithic left a clear signature. We demonstrate how the different depositional environments in the studied landscape compartments vary with respect to their spatiotemporal coverage and discuss challenges when trying to understand processes that once shaped landscapes of past societies. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

S wave inelastic attenuation and site effect in the northern Tianshan area

In this paper,according to the relationship of observation spectrum with source spectrum,travel-path attenuationfactor and site effect,we use the digital seismic data of moderate-small earthquakes to invert the soft rock site ef-fect and S wave inelastic attenuation under the constraint of site effect,and determine the parameters of path andsite.The parameters obtained by this method exclude the topographic effect of seismic stations,and truly reflectthe seismic effect of free soft rock sites and the S wave inelastic attenuation in the studied region.The average softrock site effect is about 1.5 times in the frequency domain of 2～4 Hz and the S wave quality factor is obtained asQS=278 f0.346,which can be directly applied to the stochastic modeling of ground motions in the studied region.     

Numerical simulation of the influence of lower-crustal flow on the deformation of the Sichuan-Yunnan Region

On the basis of distribution of active fault and regional rheological structure, a three-dimensional finite element model of Sichuan-Yunnan region, China, is constructed to simulate contemporary crustal motion and stress distri- bution and discuss the dynamic mechanism of crustal motion and deformation in the Sichuan-Yunnan region. Lin- ear Maxwell visco-elastic model is applied, which includes the active fault zones, the elastic upper crust and vis- cous lower crust and upper mantle. Four different models with different boundary conditions and deep structure are calculated. Some conclusions are drawn through comparison. Firstly, the crustal rotation about the eastern syntaxis of the Himalaya in the Sicuan-Yunnan region may be controlled by the special dynamic boundary condition. The drag force of the lower-crust on the upper crust is not negligible. At the same time, the main active fault zones play an important role in the contemporary crustal motion and deformation in Sichuan-Yunnan region.