Mining-related and tectonic seismicity in the East Mountain area Wasatch Plateau,Utah, U.S.A.

As part of a larger multi-institutional seismic monitoring experiment during June–August 1984 in the eastern Wasatch Plateau, Utah, data from a subarray of 20 portable seismographs were used to investigate seismicity in the East Mountain area, an area of active underground coal mining and intense microseismicity. Eight stations of the subarray were concentrated on top of East Mountain, about 600 m above mine level, at an average spacing of 2 to 3 km. The primary objective was the accurate resolution of hypocenters and focal mechanisms for seismic events originating at submine levels. Data from high-resolution seismic reflection profiles and drill-hole sonic logs yielded a detailed velocity model. This model features a strong velocity gradient in the uppermost 1 km, which has a significant effect on takeoff angles for first-arrivingP-waves from shallow seismic events. Two hundred epicenters located with a precision of ±500 m cluster within an area about 5 km in diameter and show an evident spatial association with four sites of longwall mining during the study period. A special set of foci rigorously tested for focal-depth reliability indicates submine seismicity predominating within 500 m of mine level and extending at least to 1 km, and perhaps to 2 km, below mine level. Continuous monitoring for a 61-day period (June 15–August 15) bracketed a 16-day mining shutdown (July 7–22) during which significant seismicity, comparable to that observed before the shutdown, was observed. Ten focal mechanisms for seismic events originating at or down to 2 km below mine level nearly all imply reverse faulting, consistent with previous results and the inferred tectonic stress field. Enigmatic events recorded with all dilatational first motions can be fit with double-couple normal-faulting solutions if they in fact occurabove mine level, perhaps reflecting overburden subsidence. If these events are constrained to occur at mine level, their first-motion distributions are incompatible with a double-couple source mechanism.     

Microearthquake activity associated with underground coal-mining in Buchanan County,Virginia, U.S.A.

Microearthquake activity (impulsive, transient seismic events, with durations up to several seconds at a distance of 500 m, that exhibit a coda with a shift toward lower frequencies with increasing time) was monitored for a three-month period by a single seismograph sited directly above an undergound longwall mine in the coal-mining region of Buchanan County, Virginia, U.S.A. The purpose of this investigation was to determine if precursory increases in microseismicity prior to cavings (subsidence) of overburden in the mine were present and, if so, could they be detected by surface seismographic observations. The first two recording weeks were prior to the beginning of coal removal operations at the monitored mine. A comparision of the before and after levels of microearthquake occurrence indicated a sevenfold increase to about seven seismic events/hour that was attendant with the development of the time over the level of the background, non-coal-mining period seismicity.A total of over 15,000 microearthquakes were recorded during the monitoring period, most of which occurred during the actual coal-mining operations. The workday rate exceeded 30 seismic events/hour in contrast with the non-workday rate of about seven such events/hour. Rock and coal fracturing ahead of the mine plow are believed to be the primary cause of the majority of these very small seismic events. Cavings and rockbursts (violent eruptions that propel rock debris into the mine) also contributed to the total seismic activity. It appears that cavings, some of which were large enough to be felt on ground surface, are the primary source of the non-plowing related seismicity as larger free surface areas are opened underground. Any seismic activity premonitory to cavings, however, was effectively masked by the high workday rate. Thus, the use of surface seismic monitoring, in an attempt to document any increases of localized seismicity precursory to cavings, failed in this instance.The exact location of the mine and the survey dates are not given in this paper at the request of the mine operator.     

The Alabama,U.S.A., seismic event and strata collapse of May 7, 1986

On May 7, 1986, the residents of Tuscaloosa, Alabama, felt a seismic event of local magnitude 3.6 that occurred at the same time as a rock burst and roof collapse in an active longwall coal mine. Visual inspection of the seismograms reveals a deficiency in energy at frequencies above 20 Hz compared to tectonic earthquakes or surface blasts. The predominance of energy below 5 Hz may explain reports of body wave magnitudes (m _b ) greater than 4.2. Also, 1.0 Hz surface waves were more strongly excited than body waves and may explain local felt effects more typically associated with greater epicentral distances. All recorded first motions were dilatational. The concentration of stations in the northern hemisphere allows reverse motion on an east-trending near-vertical plane or strike-slip motion on northwest or southeast trending planes. The reverse focal mechanism is preferred, because the area of roof collapse and the area of active longwall mining are located between two east-striking loose vertical fracture zones. The characteristics of the seismic event suggest that it might have been sudden shear failure resulting from accumulated strain energy in overlying strata behind an active longwall. Although an alternate interpretation of the focal mechanism as an implosion or shear failure in the strata above previously mined out areas is also allowed by the first motion data, this alternate intepretation is not supported by geological data.     

Evidence for induced seismicity in the vicinity of Fierza reservoir,Northern Albania

The reservoir of Fierza on the Drini River, Northern Albania, is Albania's largest reservoir and it is one of the world's largest reservoirs of high dams (reservoir volume at maximum water level, 2.8 * 10⁹ m³; dam height, 167 m and dam capacity 8 * 10⁶ m³). We compare pre-and postimpounding seismicity of the area surrounding the Fierza reservoir. An increase of seismic microactivity was observed after the impounding of the reservoir. More than 300 microearthquakes, occurred in the immediate vicinity of the main body of the reservoir, with local magnitude ranging between 1.3 and 3.6. A significant change of theb value in the magnitude-frequency relationship was observed. One swarm of microtremors occurred in the northern part of the reservoir on April 4–5, 1981, where an alteration of the tensor of natural tectonic stresses is revealed. The theoretical additional stress and displacement induced by water-load in the bank of the reservoir were estimated for four cross-profiles of the reservoir area and the maximum values resulted near the location of the above swarm.     

2010年青海玉树地震及震后青藏高原强震趋势分析

2010年4月14日青海玉树发生7.1级地震,这是该区历史上发生的最为强烈的地震。该地震属走滑型,地处青藏高原巴颜喀拉地块南边界,发震断裂为甘孜—玉树—风火山左旋走滑断裂,地震破裂主要向震中东南方向。该地震是巴颜喀拉地块与羌塘地块以不同速率向东运动,地块间的差异运动使其边界应力积累到一定程度引发破裂的结果。根据地震定标律估算的主震断层破裂参数和应力参数为:地震矩M0=1.78×1019N.m,矩震级MW=6.8,断层破裂面积S=468km2,断层错距D=1.4m,断层破裂长度L=37km,断层破裂宽度W=12.6km,剪应力τ0=16.8MPa,应力降Δσ=7.03MPa。历史地震分析表明,玉树7.1级地震是在世界8级以上地震、中国西部大三角7.8级以上地震、南北地震带7级以上地震和巴颜喀拉块体7级以上地震处于强烈活动背景下发生的。玉树地震后,青藏高原巴颜喀拉地块、羌塘地块及川滇菱形块体未来发生7级以上地震的危险性较大。     

The significance of scarp retreat for cenozoic landform evolution on the Colorado Plateau,U.S.A.

Since the beginning of the Cenozoic period several hundreds of metres of the sedimentary cover have been removed from the Colorado Plateau. Palaeoclimatic considerations show that the Colorado Plateau has been dominated by dry climates throughout the Cenozoic with the possible exception of the early Palaeocene. Today in the still prevailing arid climate, which strongly accentuates differences in rock resistance, the relief shows a structurally controlled cuesta scarp topography in the slightly deformed strata of alternating resistance. In examining whether the denudational efficiency of scarp retreat was sufficient to account for the wide erosional gaps in the sedimentary cover, rates of scarp retreat were determined by using the information of dated volcanic material and by applying a new method, which calculates the amount of retreat from the width of beheaded valleys of known age. Rates of retreat range from 0·5 to 6·7 km my^?1. The results show that the rates of retreat are controlled by the thickness and resistance of the caprocks. A model of Cenozoic scarp retreat demonstrates that the rates of recession calculated for the scarps in Upper Cretaceous rocks were sufficient to bring them into their present positions from the centre of the Monument Uplift on the central Colorado Plateau. The late Eocene positions of the cliffs in the Early Tertiary formations give an indication of their maximal extent. After the Upper Cretaceous sediments had been removed from the uplifts, erosion cut through successively older rocks, and activated scarps in stratigraphically lower positions. Scarp retreat can operate simultaneously and independently at different levels, which enabled this erosional mechanism to remove great proportions of the sedimentary cover of the Colorado Plateau during the Cenozoic.     

Distribution and geochronology of Oregon Plateau (U.S.A.) flood basalt volcanism: The Steens Basalt revisited

The timing and petrogenesis of mid-Miocene flood basalt volcanism in the northwest United States has been extensively addressed, yet the chemical characteristics and temporal details of the Steens Basalt, exposed on the Oregon Plateau, are poorly defined. Steens Basalt volcanism has generally been accepted to have occurred at ∼ 16.6 Ma, coeval and/or just prior to the onset of Columbia River Basalt Group volcanism to the north. New major and trace element analyses and nine ⁴⁰Ar/³⁹Ar ages ranging from 15.51 ± 0.28 to 16.58 ± 0.18 Ma were obtained on Oregon Plateau flood basalt lava flows from stratigraphic sections in close proximity to Steens Mountain. Additionally, new ⁴⁰Ar/³⁹Ar ages were obtained on the uppermost and thirty-first lava flow down from the top of the ∼ 1 km section of Steens Basalt exposed at Steens Mountain and yield eruption ages of 16.59 ± 0.10 and 16.55 ±0.10 Ma, respectively. Field relations between these basalt sections suggest that multiple eruptive centers were present in the vicinity of Steens Mountain.     

Petrogenesis and tectonic setting of the Queershan composite granitic pluton,eastern Tibetan Plateau: Constraints from geochronology,geochemistry and Hf isotope data

The Queershan composite granitic pluton is located in the north of the late Paleozoic Yidun arc collision-orogenic belt, eastern Tibetan Plateau. The main rock types are coarse-grained porphyritic alkalic-monzonite granite with minor fine-grained porphyritic monzogranite and granodiorite distributed in the eastern and southwestern regions. Here we report their zircon U-Pb ages and geo- chemical data. The intrusive contact relations indicate that granodiorite was formed earlier than the alkalic-monzonite granite(105.9±1.3 Ma) and monzogranite(102.6±1.1 Ma). These suggest that the Queershan composite granitic pluton was formed through three-stage magmatic events. The alkalic-monzonite granite(105.9±1.3 Ma) and monzogranite(102.6±1.1 Ma) are characterized by high SiO2(73.5%–77.7%), K2O+Na2O(6.9%–8.5%), Ga/Al ratios(2.6–3.4) and low Al2O3(11.8%–14.5%), CaO(0.25%–1.5%), MgO(0.18%–0.69%), negative Ba, Sr and Eu anomalies, showing A-type granite affinities. The granodiorite exhibits lower SiO2, P2O5 and K2O+Na2O contents, but higher Al2O3, CaO and MgO contents than alkalic-monzonite granite and monzogranite, showing I-type granite affinity. 176Hf/177 Hf ratios of the alkalic-monzonite granite and the monzogranite are 0.282692–0.282749 and 0.282685–0.282765, respectively, and with similar ?Hf(t) values(?0.56 to 1.43 and ?0.87 to 1.90 respectively). They also present similar TDM2 model ages(1.04–1.22 and 1.07–1.2 Ga respectively), indicating they may be sourced from a similar rock source, mostly like Kangding Complex. The homogeneity of the Hf isotopic compositions and the absence of the MMEs demonstrate that little depleted mantle materials have contributed to the source. We propose that the Mesoproterozoic crust materials of the Yangtze Craton exist beneath the Yidun arc terrane and support it was a dismembered part of the Yangtze Craton. The A-type granites of Queershan composite granitic pluton are most probably related to the closure of the Bangong-Nujiang Tethys ocean.     

The influence of debris flows on channels and valley floors in the Oregon Coast Range,U.S.A.

Debris flows are one of the most important processes which influence the morphology of channels and valley floors in the Oregon Coast Range. Debris flows that initiate in bedrock hollows at heads of first-order basins erode the long-accumulated sediment and organic debris from the floors of headwater, first- and second-order channels. This material is deposited on valley floors in the form of fans, levees, and terraces. In channels, deposits of debris flows control the distribution of boulders. The stochastic nature of sediment supply to alluvial channels by debris flows promotes cycling between channel aggradation which results in a gravel-bed morphology, and channel degradation which results in a mixed bedrock- and boulder-bed morphology. Temporal and spatial variability of channel-bed morphology is expected in other landscapes where debris flows are an important process.     

The March 2004 Kalamata seismic sequence: a case of efficient seismicity monitoring in the area of Peloponnese,southern Greece,by the Tripoli Seismic Array

On March 1, 2004, a moderate earthquake occurred in the vicinity of the town of Kalamata, southern Peloponnese, Greece. The Tripoli Seismic Array (TRISAR), located in the centre of Peloponnese, recorded the mainshock as well as the large number of aftershocks that followed. Only a small number of these events were located by regional seismographic networks. Analysis of the Kalamata seismic sequence and evaluation of the results is presented in this article, as an example of the efficiency of TRISAR in seismicity monitoring and location in the area of Peloponnese.     

A case study of spatial heterogeneity of soil moisture in the Loess Plateau, western China： A geostatistical approach

Soil moisture distribution shows highly variation both spatially and temporally. This study assesses the spatial heterogeneity of soil moisture on a hill-slope scale in the Loess Plateau in West China by using a geostatistical approach. Soil moisture was measured by time-domain reflectometry （TDR） in 313 samples. Two kinds of sampling scales were used （2 × 2 m and 20 ×20 m） at two soil layers （0-30 cm and 30-60 cm）. The general characteristics of soil moisture were analyzed by a classical statistics method, and the spatial heterogeneity of soil moisture was analyzed using a geostatistical approach. The results showed that the spherical model is the best-fit model to simulate soil moisture on the experimental hill-slope. The parameters of this model indicated that the spatial dependence of soil moisture in the selected hill-slope was moderate. Even the 2 × 2 m sampling scale was too coarse to show the detailed spatial variances of soil moisture in this area. The dependent distance increased from 27.4 m to 494.16 m as the sampling scale became coarse （from 2× 2 m to 20 ×20 m）. A map of soil moisture was generated by using original soil moisture data and interpolated values determined by the Kriging method. The average soil moisture （area weighted） in the different layers of soil was calculated on the basis of this map （10.94% for the 0-30 cm soil layer, 11.88% for the 30-60 cm soil layer）. This average soil moisture is lower than the corresponding average effective soil moisture, which suggests that the soil moisture is not sufficient to support vegetation in this area.     

MT约束的青藏高原东南缘上地幔热结构研究——以兰坪—贵阳剖面为例

青藏高原东南缘是青藏高原软弱物质运移的关键位置,研究其深部结构有助于理解青藏高原的扩张机制.本文利用穿过青藏高原东南缘的一条起始于兰坪—思茅块体,穿过川滇菱形块体,终止于华南块体的长约750 km的大地电磁测深（MT）剖面的电阻率结构,基于上地幔矿物和熔融体温度与电导率的关系,获得了研究区上地幔温度结构与熔融百分比分布.结果表明,采用随深度变化的含水熔融上地幔矿物组分模型才能合理地获得整个上地幔温度;上地幔全岩含水量约4.69（40 km深度）~0.13 wt%（150 km深度）,矿物熔融百分比约0~1.4%之间,并在70 km深度附近出现了较明显的局部熔融带;上地幔温度位于400~1300℃之间,随深度加深而逐渐增加;70 km以浅的温度表现出相对强烈的横向变化,且川滇和兰坪—思茅块体的上地幔温度和矿物熔融百分比的深度平均值明显高于华南块体.

     

青藏高原东缘虎牙断裂带南北段运动方式差异性机理：来自数值模拟的约束

虎牙断裂带作为青藏高原物质东向扩展的前缘断裂之一,其运动方式和强震活动类型表现出显著的南北差异.研究虎牙断裂带运动方式的差异性机理,对于认识地震发生机制与高原东向扩展模式有着重要意义.本文构建包含虎牙断裂带的三维黏弹性有限元模型,研究介质流变性差异与断层几何形态对区域地壳变形及断层三维滑动速率的影响.数值实验结果表明,在青藏高原物质东向挤出的动力学背景下,在虎牙断裂带南段,中下地壳介质流变性横向差异控制着断层以逆冲性质为主的运动,且随着中下地壳断层两侧流变性差异的增大,断层西侧物质的水平运动更易发生向垂向运动的转换.在断层两侧流变强度差1~2个数量级时,断层倾向滑动速率与走向滑动速率的比值达3.3~4.0,表现出显著的逆冲运动,与松潘—平武强震所反映的断层运动特征基本一致.相反,在断裂带北段,考虑断层两侧中下地壳较小的流变性差异时,断层即表现出明显的逆冲运动,这与九寨沟M_S7.0等强震反映的断层以走滑性质为主的运动明显不符,表明虎牙断裂带北段可能不存在中下地壳介质流变性的横向差异,断层以走滑为主的运动方式主要受断裂带几何展布控制.研究结果为认识青藏高原东缘同一构造区内断层运动方式差异与发震机制以及高原东向扩展模式提供了理论依据.

     

岩芯XRF扫描在湖泊年纹层研究中的应用——以青藏高原东南缘新路海为例

湖泊年纹层以其精确到年乃至季节尺度的高分辨率优势,成为研究古气候环境变化的重要载体.X射线荧光(XRF)岩芯扫描由于其有分辨率高、分析快速等特点,在湖泊年纹层研究中发挥了重要的作用.本文以青藏高原东南缘新路海年纹层为研究对象,采用X射线荧光(XRF)岩芯扫描,对新路海湖泊纹层计年、纹层形成机理及古气候重建进行了研究.结果表明:利用X射线图像明暗层、Rad峰值、Zr和Fe元素峰值标记法获得的年代序列基本一致,并且与独立的放射性测年(²¹⁰Pb/¹³⁷Cs)结果吻合,证实了上述各种纹层计年方法的可行性和可靠性.新路海年纹层层偶是由粗颗粒碎屑层和细颗粒碎屑层交互组成的,较厚且Zr和Si元素高的粗颗粒层形成于春、夏季,而较薄且Fe元素含量高的细颗粒层形成于秋、冬季.纹层的厚度能够指示西南季风降水量的大小,近100年以来新路海纹层厚度反映的西南季风演化,与利用昆明地区历史文献重建的湿度记录(干旱/洪水指数)、树轮δ¹⁸O重建的尼泊尔喜马拉雅地区的季风降水基本一致.近100年来新路海的纹层厚度具有7～8、4～5和2年的周期,表明新路...     

Beach erosion as a function of variations in the sediment budget,Sandy Hook,New Jersey,U.S.A.

Many of the world's beaches have recently been eroding, even on progradational landforms. This study uses the sediment budget approach to identify and rank the causes of the hazard along Sandy Hook spit where the primary recreational beach has been eroding at about 10 m/yr since 1953 and 23 m/yr in the 1970s. Large spatial variations in longshore sediment transport are found to result from differences in refracted wave energies and intersegmental sediment transport. Erosion results from a 60 per cent deficit (-270,000 m³/yr) in the sediment budget that is primarily caused by (1) refraction induced locally high waves that increase the transport rate by 100,000 m³, and (2) shore protection structures that have lessened the longshore sediment inputs by an additional 100,000 m³/yr. A storm index is presented to analyse secular climatic variation. It suggests that the annual sediment transport rate may vary by as much as ±50 per cent about the mean and that recently, above normal storm wave energies are responsible for about 60,000 m³/yr of the budget deficit. Rising sea levels and storm overwash each account for only about one per cent of the sediment loss. Pulses of sediment, induced by accelerated erosion at the feeder beach locale of spit segments, are found to move downdrift. They alter the geomorphology of the spit through episodic extensions of the spit segments with lag times exceeding one year per segment.     

中、美、欧抗震规范底部剪力法的对比研究

目前,底部剪力法是各国计算水平地震作用的基本方法,应用该方法时需要使用各自国家的抗震设计反应谱。本文汇总了中、美、欧抗震设计规范的反应谱和底部剪力法,在相同重现期和场地条件的基础上,对比了不同烈度下3本规范反应谱的异同,并通过算例对比了分别采用3本规范的底部剪力法算出的不同设防烈度下同一结构的底部地震剪力和层间地震剪力。对比结果表明,3本规范的反应谱和底部剪力法在本质上是相同的,只在表达形式和参数设置上存在差异。     

Comparison analysis of the summer monsoon precipitation between northern and southern slopes of Tanggula Mountains,Qinghai–Xizang (Tibetan) Plateau: a case study in summer 1998

Based on the precipitation data obtained through GEWEX Asian Monsoon Experiment–Tibet fieldwork from May to September 1998, this study investigated the features of the summer monsoon precipitation on the northern and southern slopes of the huge Tanggula Mountains in the Qinghai–Xizang (Tibetan) Plateau. The results show that the precipitation on the southern slope is about 50% higher than on the northern slope, whereas the frequency and diurnal pattern of the precipitation are very similar. The mean precipitation intensity on the southern slope is larger than on the northern slope. In most cases, the daily precipitation showed similar variation on both slopes, demonstrating that the precipitation processes might be similar. In the summer monsoon period, the local convective precipitation contributed to the total precipitation on both slopes and such a contribution on the southern slope is larger. Copyright © 2006 John Wiley & Sons, Ltd.     

Using geostatistics and spectral analysis to study spatial patterns in the topography of southeastern Washington State,U.S.A.

Topography for four areas in the Palouse region of southeastern Washington State having different patterns and encompassing areas of about 900 ha each were quantitatively compared and described using two-dimensional semi-variograms and periodograms. The four areas studied were from the Garfield, La Crosse, Thornton, and Wilcox quadrangle topographic maps. Semivariance of elevation residuals were modelled using a combination of spherical, periodic, or linear semivariogram models. The range of the spherical component was interpreted as a relatively short-range scale of correlation which was not periodic. For each of the study areas a model was developed to describe the variation in range with orientation. Values for the range from this model reached maximum values of from about 700 m to 800 m at an orientation of from 35° to 55° (approximately northeast) in each study area. This orientation was interpreted as the dominant direction of non-periodic small-scale landscape features. The wavelength and amplitude of the periodic semivariogram component, which were highly correlated, were interpreted in terms of parallel northeast-trending ridges having relatively long scales of periodic correlation varying in size from about 1350 m to 2100 m. This attempt to identify the dominant orientation of periodic landscape features using models for the wavelength and amplitude was, however, not completely definitive. Two-dimensional spectral analysis provided significantly more detail concerning orientation and wavelengths of the periodic topographic patterns than the semivariogram analysis. In the Garfield study area, spectral analysis identified north-trending ridge systems separated by a wavelength of 1494 m and northeast-trending systems with a wavelength of 747 m. In the La Crosse study area, both north and northeast-trending patterns were identified having periodic spacings of 980 and 735 m. North-trending ridges separated by wavelengths of 996 m and northeast-trending ridges separated by wavelengths of 747 or 996 m were the predominant periodic features of topography in the Thornton study area. In the Wilcox study area, northeast-trending ridge systems separated by wavelengths of 373, 498, or 996 m were detected. A comparison of the results from geostatistical and spectral analysis of these complex topographic surfaces shows that each approach had significant strengths and weaknesses. Two-dimensional analysis with semivariograms was the only method which could be used for identifying the correlation scale and orientation of relatively small non-periodic landscape features. Two-dimensional spectral analysis accurately identified the predominant orientation of relatively large periodic features in topography, whereas semivariogram analysis was somewhat inconclusive. Also, semivariograms were generally unable to detect the presence of multiple or harmonic periodicities operating at different wavelengths along a given orientation.     

The Calculation Method for the Volume of Landslides and Dammed Lake Sediments Triggered by a Strong Historical Earthquake in the Loess Plateau: A Case Study of Qiuzigou, Gansu Province, Northwest China

The quantitative calculation of the volume of large earthquake-triggered landslides and related dammed lake sediments is of great significance in the study of secondary disasters and focal parameters of strong historical earthquakes. In this study, the dammed lake induced by Qishan M7 earthquake (Lingtai County, Gansu Province, Northwest China) is selected as the research object. Based on the information collected from the 4 boreholes in the dammed lake area, we further take advantage of the low-level Unmanned Aerial Vehicle (UAV) photogrammetry and the morphology recovery method,to calculate the volume of the dammed lake and landslides, respectively. Finally, major conclusions are obtained as follows:① the AMS-¹⁴C age at the bottom of the Qiuzigou Dammed Lake sediments is 2 890±30 BP, which coincides with the 780 BC Qishan earthquake; furthermore, the Qiuzigou Landslides seem to have been triggered by the earthquake, forming an enclosed dammed lake deposition environment after the upstream sediments accumulate;② the Qiuzigou landslides are opposite-sliding landslides that have blocked the river valley; in detail, landslide volumes at the right and left banks are 235×10⁴ m³ and 229×10⁴ m³, respectively. The length of the dammed lake is 2.6 km, with a thickness of approximately 43 m near the landslides, and the total sedimentary volume is 573×10⁴ m³; ③the erosion rate of Qiuzigou Landslide Dammed Lake is 0.44 mm/a, the accumulation rate is 15.05 mm/a, and the soil erosion modulus is 593 t/(km²/a), characterized as slight erosion. Quantitative research on the formation of landslides and dammed lakes from strong historical earthquakes is vital for increasing our understanding of the vibrational characteristics and surface action processes of these types of earthquakes.