The reconstruct of the stick-slip and creep histories is essential for understanding fault activities and seismic hazard assessment. Distinguishing stick-slip and creep using geodetic technology has become a hot research area in recent years, but distinguishing and estimating seismic slip and creep on geological timescales(e.g., over hundreds of years)is challenging due to the lack of historical, geodetic and remote sensing data extending back more than a few hundred years. This study uses a newly developed dating technique(rock surface optically-stimulated-luminescence(OSL)dating)combined with the OSL decay parameters of granite samples from the Langshan fault in Inner Mongolia to simulate optically stimulated OSL-depth curves and depths of half saturation of luminescence signal under various scenarios such as fault seismic slipping, creeping, and erosion of colluvial wedge. The study compares these OSL-depth profiles, especially the depths of the half saturation, under different slipping modes, and summarizes their features.

During fault seismic slip, samples at different heights along the fault scarp display a “step-like” distribution pattern at their depths of half saturation. While during creep, however, they exhibit a “slope-like” pattern. Such differences may lie in that the slope during accelerating creeping is steeper than the slope during constant-speed creeping. Correspondingly, the resolution of residual luminescence-depth profile and depth of half saturation is also higher during accelerating creeping. During intra-earthquake creep events between seismic slip occurrences on the bedrock fault scarp, the distribution of half-saturation depth in the samples includes segments resembling both “steps” and “slopes”, which indicate the seismic slip and creep activities of the fault respectively. If the samples at the base of the colluvial wedge have had a sufficiently long last exposure time, the luminescence-depth profile and half-saturation depth distribution due to the erosion of the colluvial wedge would be approximately the same as in the three-phase seismic slip scenario. This indicates that samples previously buried by the colluvial wedge may be considered within the seismic displacement. Conversely, if the last exposure time of the base samples at the base of the colluvial wedge is short, the bleaching depth of the luminescence signal of these base samples will be noticeably shallower than that of the other samples within the seismic displacement, indicating the observed erosion of the colluvial wedge in this case. Furthermore, the seismic displacement ideally should include the buried location of the colluvial wedge. Therefore, when the luminescence curves and half-saturation depth distributions fail to identify the presence of the colluvial wedge, it is acceptable to include the buried location of the colluvial wedge in the seismic displacement calculation. Conversely, the luminescence-depth curves and half-saturation depth distributions document the erosion caused by the colluvial wedge. The simulation results demonstrate that this method can effectively distinguish between fault slipping and creeping, obtain corresponding displacements, and potentially record the erosion of colluvial wedge.

This study also analyzes the temporal resolution of the method for distinguishing fault activity times and the spatial resolution for quantifying displacements. The specific situation is as follows. When exposure age of the bedrock fault scarp is within a thousand years, the rock surface OSL dating method can easily distinguish types of active slips and seismic displacements for the earthquakes with a recurrence interval of hundreds of years. When exposure age of the bedrock fault scarp is in the range of 10⁰-10¹ka, the method can easily distinguish types of active slips and seismic displacements for the earthquakes with a recurrence interval exceeding a thousand years. When exposure age of the bedrock fault scarp is over ten-thousand years, the resolution of this method may be significantly reduced. The spatial resolution of seismic displacements using this method depends on interval between sampling and testing samples, typically in 10~30cm.

Phytoliths have shown a lot of advantages in dating due to their widespread distribution, structural stability, and preservation integrity, especially since phytolith carbon was used in radiocarbon dating. However, there is a problem of overestimation of phytolith carbon ¹⁴C ages, which may be due to its structure destruction during pre-treatment processes of the rapid oxidation and high temperature. It is necessary to identify the subtle changes in its structure under high-temperature conditions based on its chemical composition and certain physical properties. As a special amorphous hydrated SiO₂, using their luminescence signals for thermoluminescence(TL)or optically stimulated luminescence(OSL)dating can be directly compared with their ¹⁴C ages even as an alternative dating method, and the luminescence property changes of phytoliths may have a reference value for identifying the physical structure changes. In this paper, modern phytolith samples extracted from dry rice straw were taken as an example to study the stability of OSL and isothermal TL(ITL)signals. We conducted a series of conditional experiments to determine the specific experimental process of OSL and ITL₁₆₅ signals, and discussed the feasibility and reliability of the dose-signal response relationship and test process under different given doses of dose recovery experiments. Moreover, the OSL signal were tested by a conventional single-aliquot regenerative-dose(SAR)protocol which firstly preheated at 200℃/180℃ to remove the instability signal and then blue excited at 125℃. The OSL signal of phytolith sample rapidly decays under blue light and is basically reset within 5s of excitation. The sensitivity corrected OSL signal intensity and regeneration dose can respond one by one and a growth curve can be established, indicating that there is also a trap structure within the phytolith particles that can generate relatively stable OSL signals. However, there are still some problems which need further to be solved such as relatively weak signal intensity and poor sensitivity. The results of bleaching experiment show that the OSL signal intensity of phytolith particles decays exponentially under sunlight, and the OSL signal irradiated by given dose of 85Gy can be bleached about 90%within 100s and bleached completely around 800s, which suggests that the phytolith samples have good sunlight bleaching susceptibility. There is a stable and easily bleached OSL signal in natural phytolith particles, however, the experimental procedure is only suitable for samples with lower given doses(below about 200Gy)and the dose recovery rate of older samples is lower. On the other hand, 425℃ TL peaks were found in the ITL₅₀₀ curves of phytolith at both a higher given dose(850Gy)and a lower given dose(85Gy), but they could not be used for dating because of instability. There was a remarkble and stable TL peak at 165℃ under a higher given dose(850Gy). The relatively stable ITL₁₆₅ signal has the potential to be used in dating research and its experimental procedure is also by SAR method. The dose recovery rate of ITL₁₆₅ signal under different given doses(above about 50Gy)was in the range of 0.8-1.2. Both OSL and ITL₁₆₅ signals have the potential to be used in dating studies but need to be tested with samples of known-age. The characteristic dose D₀ of OSL and ITL₁₆₅ signals of phytoliths are(326.8±19.5)Gy and(504.9±49.9)Gy, which implys that phytoliths have a greater saturation level than quartzes. Meanwhile, the ITL₅₀₀ curve heated at different annealing temperatures has the potential to identify changes in phytolith luminescence properties and physical structure. The structure of phytoliths begins to change at around 300-350℃, and irreversible structural changes have occurred at around 600℃ and gradually become sensitized. This also means that the extraction process of phytoliths using wet ashing rather than dry ashing may destroy the structural integrity of phytoliths and resulting in an overestimation of phytolith carbon AMS ¹⁴C ages. Whether it is by using AMS ¹⁴C dating method or OSL/TL dating method which phytoliths as the main dating material, phytolith particles should not be placed in a high temperature environment above 300℃ at any stage during the experiment in order to avoid irreversible damage to its structure. The luminescence age obtained by the OSL signal and ITL₁₆₅ signal of phytoliths can be compared with the ¹⁴C age to determine whether there exists an overestimation, and if the two ages can be verified, there is no need to use other dating minerals which is of great significance for the dating of precious archaeological materials.

The Sichuan-Yunnan region is located in the southeastern part of the Qinghai-Tibet Plateau. Because of the compression and collision dynamics of the Indian Plate and the Eurasian Plate, the tectonic deformation is strong and seismic activities occur frequently. There have been many earthquakes above magnitude 7.0 in history. A series of active fault zones have developed in the region, among which the Sichuan-Yunnan rhombus block bounded by multiple active faults has attracted great research interests in recent years. The Longpan-Qiaohou fault zone is a boundary fault of the Sichuan-Yunnan rhombus block. The fault zone starts from Longpan in the north, passes through Jiuhe, Jianchuan, and Shaxi in the south, and ends at Qiaohou. It is about 120km long and the fault trend is 15°~20°. This fault zone is large in scale and highly active, with frequent seismic activity, complex mechanical properties, and variable movement patterns. The Mesozoic movement was intense. In the early Cenozoic, compression-thrust movement was dominant, and in the late Cenozoic, tension-strike movement was dominant. Since the Holocene, the fault zone has been characterized by left-lateral strike-slip movement with normal faulting properties, and earthquakes of magnitude 5 or above have occurred many times. Therefore, studying the activity of this fault zone is of great significance for the prediction and evaluation of regional strong earthquake risk. Thick calcite veins are well developed on the Henancun Fault of the Jianchuan section of the Longpan-Qiaohou fault zone, providing very valuable materials for fault dating. Calcite veins are coseismic rapid precipitation formed during seismic activity or syntectonic precipitation that filled along fractures after seismic activity. Therefore, their ages represent the latest time at which seismic activity occurred. Previous studies have shown that tensional fissures formed during coseismic events can close in a short period of time(days to months), suggesting that the filling of calcite veins within fault fissures is a relatively rapid process. This paper uses the ESR method to conduct dating study on the calcite veins in the study area. The results show that the ages of the four calcite veins(HNC-ESR01, HNC-ESR02, HNC-ESR03 and HNC-ESR04) are: (7.1±0.8)ka, (7.1±0.9)ka, (7.3±1.7)ka and (6.9±1.5)ka, respectively. The age results are concentrated, and the average age is(7.1±1.3)ka, indicating that the fault was active no later than(7.1±1.3)ka. The age results are consistent within the error range with the second paleoseismic event time revealed by trenching work in the area(between(6 130±30)a BP and(6 320±40)a BP), indicating that the dating of ESR in the fault zone is an effective dating method for the study of active tectonics and paleo-earthquakes. It is an effective chronological method for research, but it can be seen that compared with ¹⁴C and luminescence dating, the error of ESR results is relatively large. For faults with short earthquake recurrence intervals, it is still very challenging to accurately judge their activity. In the follow-up work, it is necessary to further improve the experimental process and reduce experimental errors, including refinement of sample pretreatment, accurate monitoring of irradiation dose, and accurate calculation of dose rate. In addition, by using five fitting functions(LIN, SSE, DSE, EXP+LIN and D_gamma)to calculate the equivalent dose values of calcite vein samples in this study, we found that the SSE function is capable of providing the best fitting effect.

According to the Unified Earthquake Catalogue of China Earthquake Networks, using the seismic phase data compiled by the Seismic Data Center, the observations of 101 fixed and mobile seismic stations in the Yunnan region and its surrounding seismic network from May 18 to 28, 2021, we conducted precise positioning research on the foreshock-mainshock-aftershock sequence of the Yangbi earthquake using the double-difference positioning method, and obtained the precise locations of 2 144 earthquakes. It is found that the distribution of the main aftershocks and the long axis orientation of the intensity isoseismal are not consistent with the image position of the Weixi-Qiaohou Fault, and the strike intersects with a small angle. The seismogenic fault of this earthquake may be a secondary fault of the Weixi-Qiaohou Fault. On the basis of the precision positioning results, the Bayesian Bootstrap Optimization(BABO)algorithm is used to perform a moment tensor inversion on the M6.4 earthquake and the M3.6 and above earthquake sequences in Yangbi, Yunnan from May 18 to 28, 2021. The results show that the sequence of Yangbi earthquake in Yunnan has obvious segmentation. The M6.4 Yangbi main shock is of right-handed strike-slip type with a small amount of normal dip-slip component, and the centroid depth is 5.9km. Most aftershocks have the same focal mechanism as the main shock, mainly right-handed strike-slip, except for the earthquakes in the west branch of the southeast section of the aftershock area, where the source property is obviously different, showing a normal strike-slip motion. The centroid depth of the entire earthquake sequence is 3.5~8.2km. The inversion results show that the principal compressive stress field of the earthquake area is in the near NS direction and the strike-slip dislocation is associated with a slight normal dip-slip component.

The spatial distribution of earthquakes shows that this earthquake sequence gradually developed from NW to SE, and the seismic density gradually dispersed from NW to SE. Therefore, it can be considered that the stress was mainly concentrated in the NW direction before the earthquake, and then gradually spread to the SE. Therefore, the main power source of this earthquake may be the southeastward extrusion of the Sichuan-Yunnan block. The rupture process and rupture pattern of this earthquake represents the “relaxation” process of the Sichuan-Yunnan rhombic block after being extruded.

The southern part of the Sichuan-Yunnan block is the material diffusion zone resulting from the eastward extrusion of Qinghai-Tibet Plateau. In this area, the subduction and westward retreat of the Indian plate led to the absence of lateral restraint on the Sichuan-Yunnan block, which may be the main reason causing the earthquake sequences in this area changing from convergence to dispersion, from strike-slip to normal fault type.

The Sichuan-Yunnan block is one of the most insensive areas where the Qinghai-Tibet Plateau squeezes out and escapes southeastward. Regarding the regional dynamic mode, we believe that under the background of continuous eastward extrusion of the material in the eastern part of the Qinghai-Tibet Plateau, and due to the lack of rigid blocks in the horizontal direction, it is more prone to velocity migration in the horizontal direction when the Sichuan-Yunnan block extrudes in the direction of SE and crosses the eastern structural junction and Longmen Mountains. The velocity migration in the study area may be caused by plate subduction or mantle underplating. The study of the lithospheric structure in the Sichuan-Yunnan area found that the crustal thickness of the sub-blocks in central Yunnan gradually thinned from north to south, and the lithospheric thickness in the area west of the Honghe fault zone shows a gradual thinning trend from east to west. It may be related to the intrusion of hot mantle material caused by the subduction and westward retreat of the Indian plate. Tomography results show that in the Ailaoshan-Honghe fault zone, the Yangtze block subducted downwards accompanied by mantle disturbance and asthenosphere upwelling, which led to magmatic activity and intrusion in the Cenozoic. Both of the above two effects can make the western boundary of the Sichuan-Yunnan block have a tensile stress background, and make the focal mechanism of major earthquakes on the nearby tectonic belt possible to appear normal. In summary, the dynamic source of earthquakes in the study area mainly comes from the escape of the Sichuan-Yunnan block to the southeast, and plate subduction or mantle underplating is possibly the deep-seated dynamic background for the lateral velocity migration of the study area.

The Langshan range-front fault (LRF)is a Holocene active normal fault that bounds the Langshan Mountain and Hetao Basin at the northwest corner of the Ordos Plateau. Paleoseismic trenching research at three sites, Dongshen Village trench (TC1), Qingshan trench (TC2)and Wulanhashao trench (TC3)from north to south was performed in this study to reveal the seismic hazard risk in Hetao Basin. The paleoevents ED1, ED2, ED3 from TC1 can be constrained to have occurred (6±1.3)ka, (9.6±2)ka and (19.7±4.2)ka respectively, while the paleoevent EQ1 from TC2 occurred about (6.7±0.1)ka and the paleoevents EW1, EW2, EW3 at TC3 took place about (2.3±0.4)ka, (6±1)ka and before 7ka respectively. In combination with paleoseismic results of previous researchers, the Holocene earthquake sequence of the LRF could be established as 2.3~2.43ka BP (E1), 4.41~3.06ka BP (E2), 6.71~6.8ka BP (E3), 7.6~9.81ka BP (E4), and (19.7±4.2)ka BP (E5). Although the possibility of missing events cannot totally be ruled out, based on the analysis on faulted geomorphology at Wulanhashao site, we argue the paleoearthquake history of the LRF during Holocene may be complete with an average recurrent interval about 2500 yrs. The apparent displacements associated with events E1, E3 and E4 are significantly larger than that of event, E2, that suggests that they might be great events with magnitudes 7.5 to even over 8 that ruptured the entire LRF, while the event E2 may be a smaller event that only ruptured a segment of the fault. The magnitude of event E2 might be about M7. This poses a significant seismic hazard to the area of the Linhe depression in the western Hetao graben region. With the further limitation of previous radiocarbon dating result near our trench site at Wulanhashao, the slip rate at Wulanhashao should be not smaller than, but close to 0.66mm/a since 15ka BP. And the slip rate at Qingshan site is supposed to be about 1.4~1.6mm/a since 6.8ka BP. Both our combined most recent paleoseismic cognition and current tectonic geomorphologic research results supports to reveal that the Langshan range-front fault now is an unsegmented fault, preferring to rupture the whole fault in a surface-rupture event. Considering the most recent event E1 and fault slip rate obtained above, the accumulated strain on the LRF could be estimated as about 1.52~3.94m. Given the ~2500a recurrent interval, we argue that the elapsed time since last major quake, E1, is approaching or even over the recurrence, and the seismic risk for another major quake is imminent, at least cannot be ignored.

In the study of active faults, obtaining the exact age of the strata is an extremely important step. The optically stimulated luminescence (OSL) dating method, a technique closely related to thermoluminescence (TL), is developing extensively on dating for Quaternary sediments in recent years. Fukang Faults, located in the eastern Tianshan arc nappe tectonic zone, are typical arc thrusting faults. The dating samples collected from Dahuangshan trench of Fukang Fault zone are used to determine the activity of the fault. 23 OSL samples were obtained from the trench. We selected 4～11μm fine-grained quartz through pre-treatment process and analysed them by using sensitivity-corrected multiple aliquot regenerative-dose (SMAR) protocol. Equivalent dose (De) preheat plateau test is an often used approach to determine the appropriate preheat temperature in OSL dating. The preheat plateau test of sample LED12-297 shows that 220～260℃ are the appropriate preheat plateau temperature regions to get fundamental De. The dating results show that the OSL stratigraphic ages of the samples are consistent with stratigraphic sequence and that Fukang Fault is a Holocene active fault. It is found that the last event of Fukang Fault occurred (1.90±0.14) ka to (3.47±0.17) ka ago. The OSL ages and their related stratigraphic vertical displacement are used to calculate the vertical slip rate of the fault, which is 0.17mm/a.

Lowering uncertainties of paleoseismic data is very important, which facilitates medium and long-term earthquake prediction and seismic risk assessment in paleoseismic studies. Among these uncertainties, paleoseismic timing is highly focused and its constraint is one of the most key factors in lowering uncertainties. To get the age as true as possible, choosing right dating, sampling methods and techniques on event ages are essential. Among the several primary dating techniques, radiocarbon dating is prior to the other methods. We should choose material that is breached completely during transportation for OSL dating, and samples that are hardly affected by kinds of factors for ¹⁰Be dating. Sampling at appropriate sites based on analysis of tectonic background and using sequential ages to constrain paleoseismic events are the primary keys of techniques on accurate event dating. Interval value is suggested for age constraint when using stratigraphic chronology. When there are multiple ages for different samples within a layer, we should choose the youngest and reliable age. These rules are recommended when constraining paleoseismic ages at a single site. Temporal and spatial correlation such as successive limit method, Z statistics, overlapping distributions likelihood approach, event window and ad hoc weighted overlap methods are the primary analysis approaches for event dating at multiple sites along faults or fault segments.

In recent times, some moderate-large earthquakes occurred in active folds and thrusts, which seem not directly related with known active faults on the surface and did not form surface ruptures. Although such individual earthquakes might correspond to a known surface active fault, most of them occurred under active folds, formed by displacement of burial thrusts which are located at depth of tens kilometers beneath the folds. Stein named such earthquake as "folding earthquake". It is quite a challenging issue to study and assess the seismic hazards of folding earthquakes occurring in compressive tectonic regions with active folds and burial thrusts. Derived from active folding secondary faults such as flexural-slip faults, bend-moment faults, it is easier to identify that the fold itself. These secondary faults have coseismic slip at the surface and record the active history of seismogenic thrusts which provide an effective way to study the seismic activity of blind thrusts. Many flexural-slip fault scarps are developed on several terrace surfaces at the two limbs of Mingyaole anticline, located along the western margin of the Tarim Basin. These scarps mainly form on the limb of steep beds closest to active axial surfaces(dips of 74°～89°, 18°～20° and 45°～60°, separately), within a range of 50～1 200m from active axial surface, and most are 90～1 000m wide. Overall, the height of the flexural-slip fault scarps gradually deceases away from the active axial surface. These scarps occur at nearly equidistant or multiple distance spacing on the same terrace surface. The strike of the flexural-slip fault scarp is consistent with the strike of underlying bedrock, which is dominated by interbedded medium-thick layered sandstone or fine-grain sandstone with similar rock mechanical properties. Since the abandonment of terrace T3 at the south limb of the Mingyaole anticline, the shortening rate and uplift rate absorbed by flexural-slip faults are at least (1.0±0.2)mm/a, (1.2±0.1)mm/a, respectively. Movement of the flexural-slip faults is characterized by repeatability and neo-activity.

The research of optical dating about modern strong earthquake sediments will be useful for understanding geological significance of paleoearthquake related sediments,improving dating precision and accuracy,and better understanding the law of earthquake occurrence.This article chooses some typical sediments related with 2008 Wenchuan earthquake, such as dammed lake deposits,floodwater deposits and ejected sands, to do optical dating of fine-grained quartz.Preliminary results from optical dating of fine-grained quartz extracted from 11 samples suggest that fine-grained quartz is sensitive and D_e values obtained from the three sections indicate residual D_e up to 10Gy. Caution should be taken for optical dating of sediments related to paleoearthquake with a recurrence interval of hundreds or thousands of years,but the effect can be neglected for the paleoearthquake with a recurrence interval of ten thousands or hundred thousands of years.Residual D_e values less than 0.2Gy are observed in two samples collected from pre-earthquake surface.Therefore,we should collect samples on pre-earthquake surface to limit the event time.

In historical records,no earthquake of magnitude comparable with that of the Wenchuan M_S 8.0 earthquake has ever been reported in Chengdu and Longmenshan regions.The penultimate event similar to the 12 May 2008 M_S 8.0 was revealed by the surface ruptures in the vicinity of Xiaoyudong.It is important,therefore,to date accurately when the prior large earthquake happened.This paper presents 7 optically stimulated luminescence(OSL)ages from Xiaoyudong trench.We investigate the use of simplified multiple aliquot regenerative-dose(SMAR)protocol and single aliquot regenerative-dose(SAR)protocol from fine-grain quartz to date deposits associated with earthquake.The results of SMAR and SAR protocols are consistent.The behavior of quartz to different internal consistency checks of SAR protocol(preheat plateau,thermal transfer,recycling ratio,recuperation and growth curves)and of SMAR protocol(dose recovery)used for the dose estimation method was satisfactory.Various internal consistency tests of the measurement protocols indicate that the dose estimates from the fine grain quartz are accurate and the optical ages are reliable.The preliminary OSL ages indicate that the last large earthquake happened between 1.7～2.2ka and the slip rate of Xiaoyudong Fault was 1.0±0.08mm/a at least in Holocene.

Paleoseismic studies conducted along the surface rupture of the Wenchuan earthquake(M_S 8.0)of 12th May 2008 provide important information regarding earthquake reoccurrence intervals and slip rates of the Longmen Shan Fault zone.The Leigu trench was excavated along the middle segment of the surface rupture of the Yingxiu-Beichuan Fault zone.Based on the syntectonic sedimentary structure,two earthquake events,including the Wenchuan event,were identified at this site.This study utilizes Optically Stimulated Luminescence(OSL)dating of samples collected from the Leigu trench section,using SMAR(Sensitivity-corrected Multiple Aliquot Regenerative-dose)protocols.AMS¹⁴C dating was also carried out on charcoal from the same sediments.OSL ages are generally consistent with the calibrated AMS¹⁴C ages(cal a BP)for the same units.The penultimate earthquake event similar to Wenchuan earthquake scale in this region occurred(2.1?0.2)ka to(1.1?0.2)ka.

We have developed an improved reconstruction algorithm for resistivity tomography. In this algorithm the perturbation approach is employed for calculating the Fr閏het derivatives. Comparing with other four methods the perturbation approach is more efficient as it needs only one time of forward calculation for each iteration. Theoretical analysis and numerical experiments show that this method has higher stability and computing efficiency. An example of field data processing demonstrates that this method is valid. This method can also be generalized to suit for seismic velocity tomography and electromagnetic wave tomography techniques since it is derived for nonhomogenious Helmholtz equations.

Field investigation on hydrogeological environment around Changping well reveals that the anomalous uprise of 'water table begining from Oct. 1988 was mainly caused by the leakage of water from the channel leading to Shisanling Reservoir, but not the precursor of Datong-Yanggao earthquake in Shanxi Province in 1989.

This paper briefly describes the geologic-tectonic setting of the tectonic melange in Northern Jiangshu-Southern Shandong region. This tectonic melange occures in the collision zone between North China and Yangzi Plates. The principal features of the sliding medium, shallow-middle- and deep-seated tectonic blocks. have been systematically studied in this paper as well. Based on the study of deep-seated tectonic blocks, a litho-logic column from upper mantle to crust-mantle transition zone bas been established, and the possible geologic process in upper mantle has been discussed.

The microbehaviour of groundwater level in a borehole is engendered by stress changes in the earth crust.These stresses are commonly produced by the earth tide,atmospheric pressure,loading of the precipitation,loading of the surface water,and activity of a fault etc..The formative process of the microbehaviour is as follows:(1)The earth stress is changed;(2)The stress change causes the deformation of an aquifer,and the deformation leads to generate the change in a pore pressure;(3)The change of pore pressure causes a water-flow between the aquifer and the borehole;(4)The flow results in the fluctuation of water level in the borehole.This paper discusses the key links in the above processes from the viewpoint of rock mechanics,soil mechanics and groundwater dynamics.Moreover,it suggests some principles to choose or evaluate a borehole for seismological observation.