China Seismic Experimental Site(CSES):A systems engineering perspective

China Seismic Experimental Site(CSES)deals with a long-term process of development of a multidisciplinary technical system.In the construction,maintenance,and upgrading of CSES,ideas of systems engineering play an important role.This article discusses several concepts which might be useful for CSES,including system metaphor,system performance evaluation,and system design.

China Seismic Experimental Site(CSES): Challenges of Deep Earth Exploration and Practice(DEEP)

Since May 2018,the planning,construction and functioning of China Seismic Experimental Site(CSES)has attracted much attention in earthquake science(CSES,2020 a,b,c;Wu,2020;Li et al.,2021).Different from traditional earthquake prediction experiment projects,such as the Parkfield earthquake prediction experiment(Roeloffs,2000).

An Analysis on the Experience and Routines of Experimental Site of New-countryside Construction of Xianhong in Hubei

The paper tends to make an empirical analysis on the experimental site of new countryside construction of Xianhong in Hubei, pointing out that the inner and outer dependence on routines of experimental construction. The paper also puts forward the beneficial policies, focusing on the agricultural production and fostering professional farmers, to reduce much dependence on routines.

Three dimensional velocity model and its tectonic implications at China Seismic Experimental Site,eastern margin of the Tibetan Plateau

The China Seismic Experimental Site(CSES)is located at the intersection of the Tibetan Plateau,South China Block,and Indian Plate and has complex geological settings and intense crustal deformation,making it one of the most seismically active areas in Chinese mainland.A high-resolution,three-dimensional(3D)crust-mantle velocity structure is crucial for understanding seismotectonic environments,lithospheric deformation mechanisms,and deep dynamic processes.We first constructed a high-vertical-resolution 3D initial velocity model using the joint inversion of receiver functions and surface waves and then obtained a 3D P-and S-wave velocity model(CSES-VM1.0)with the highest lateral resolution of 0.25°for the CSES using double-difference tomography.Owing to the limitations of the Sn observation data,the resolution of the S-wave velocity model in the lower crust and upper mantle was reduced,making it closer to the initial model provided by joint inversion.A comparison with explosive-source seismic data showed that the synthetic P-wave first-arrival travel times of the new model were closer to the observations than those of the previous velocity models.The velocity cross-sections across the source areas of the 2022 Lushan MS6.1 and Ludian MS6.8 earthquakes reveal that the former earthquake occurred near a weak contact zone between the Tibetan Plateau and Sichuan Basin,and the rupture of the latter earthquake occurred in a granitic area,with the northern end blocked by rigid high-velocity bodies.A clear high-velocity anomaly zone is distributed along the western margin of the Yangtze Block,revealing the spatial distribution of Neoproterozoic intermediate-basic intrusions.This high-velocity zone significantly controls the morphology of fault zones and influences the rupture processes of major earthquakes.Two northeast-southwest and north-south trending high-velocity anomalies were found near Panzhihua,potentially related to Neoproterozoic and Middle-Late Permian intermediate-basic intrusions.The imaging results revealed the spatial distribution of the Lincang granitoid batholith,the uplifted zone of the central axis fault in the Simao Basin,and the Ailaoshan complex belt in the southwestern CSES,demonstrating a higher spatial resolution compared to previous results.Our velocity model provides an essential foundation for deep structural studies,high-precision earthquake locations,and strong ground motion simulations in the CSES.

Spatial-temporal characterization of the San Andreas Fault by fault-zone trapped waves at seismic experiment site,Parkfield,California

In this article,we review our previous research for spatial and temporal characterizations of the San Andreas Fault(SAF)at Parkfield,using the fault-zone trapped wave(FZTW)since the middle 1980s.Parkfield,California has been taken as a scientific seismic experimental site in the USA since the 1970s,and the SAF is the target fault to investigate earthquake physics and forecasting.More than ten types of field experiments(including seismic,geophysical,geochemical,geodetic and so on)have been carried out at this experimental site since then.In the fall of 2003,a pair of scientific wells were drilled at the San Andreas Fault Observatory at Depth(SAFOD)site;the main-hole(MH)passed a~200-m-wide low-velocity zone(LVZ)with highly fractured rocks of the SAF at a depth of~3.2 km below the wellhead on the ground level(Hickman et al.,2005;Zoback,2007;Lockner et al.,2011).Borehole seismographs were installed in the SAFOD MH in 2004,which were located within the LVZ of the fault at~3-km depth to probe the internal structure and physical properties of the SAF.On September 282004,a M6 earthquake occurred~15 km southeast of the town of Parkfield.The data recorded in the field experiments before and after the 2004 M6 earthquake provided a unique opportunity to monitor the co-mainshock damage and post-seismic heal of the SAF associated with this strong earthquake.This retrospective review of the results from a sequence of our previous experiments at the Parkfield SAF,California,will be valuable for other researchers who are carrying out seismic experiments at the active faults to develop the community seismic wave velocity models,the fault models and the earthquake forecasting models in global seismogenic regions.

Design and Site Experiment of Groyne in Bore Surging Area of Qiantang River

The groyne has been used widely in bank protection and river regulation. The plane layout and structural style of groyne are closely related to the stability of the groyne itself and the effect of bank protection. In this paper, based on the preliminary summary of the design of bank protection in the bore surging area of Qiantang River, some problems regarding the structure of groyne are pointed out and an improved plan is put forward. Site experiment was carried out combined with an emergency repair. The results of the experiment indicate that the improved project is reliable and successful.

Improvement of surface flux calculation:A study based on measurements over alpine meadow in the eastern Tibet Plateau in summer

An improved flux-gradient relationship between momentum φm（ζ） and sensible heat φh（ζ） is obtained by the use of the observational data over an alpine meadow in the eastern Tibet Plateau, in Maqu of China during the period June to August, 2010. The empirical coefficients of Businger-Dyer type function for the cases of unstable and stable stratification are modified. Non-dimensional vertical gradients of wind and potential temperature are calculated by three fitting func- tions; that is, the log-linear, log-square, and log--cubic functions, respectively. It is found that the von Karman constant approaches 0.4025 and the Prandtl number is about 1.10 based on the measurements in near-neutral conditions, which are within reasonable range proposed in previous studies. The revised flux-gradient profile functions of -1/5 power law for momentum and - 1/3 power law for sensible heat are best fitted in unstable stratification conditions. Meanwhile, 2/5 power law, instead of linear functions, is more appropriate in stable stratification cases for momentum and sensible heat. Com- pared with results from previous studies in which traditional functions are used, the momentum and sensible heat fluxes estimated by the revised profile functions in the current study are much closer to the observations for the unstable and stable stratification conditions.

Full scale amendment of a contaminated wood impregnation site with iron water treatment residues

Iron water treatment residues （Fe-WTR） are a free by-product of the treatment of drinking water with high concentration of iron oxides and potential for arsenic sorption. This paper aims at applying Fe- WTR to a contaminated site, measuring the reduction in contaminant leaching, and discussing the design of delivery and mixing strategy for soil stabilization at field scale and present a cost-effective method of soil mixing by connnon contractor machinery. Soil contaminated by As, Cr, and Cu at an abandoned wood impregnation site was amended with 0.22% （dw） Fe-WTR. To evaluate the full scale amendment a 100 mtest site and a control site （without amendment） were monitored for 14 months. Also soil analysis of Fe to evaluate the degree of soil and Fe-WTR mixing was done. Stabilization with Fe-WTR had a significant effect on leachable contaminants, reducing pore water As by 93%, Cu by 91% and Cr by 95% in the upper samplers. Dosage and mixing of Fe-WTR in the soil proved to be difficult in the deeper part of the field, and Pire water concentrations of arsenic was generally higher.Despite water logged conditions no increase in dissolved iron or arsenic was observed in the amended soil. Our field scale amendment of contaminated soil was overall successful in decreasing leaching of As, Cr and Cu. With minor improvements in the mixing and delivery strategy, this stabilization method is suggested for use in cases, where leaching ofCu, Cr and As constitutes a risk for groundwater and freshwater.