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Experimental studies were carried out in laboratory in order to investigate the effects of fracture on compressional (P) wave and shear (S) wave velocity propagation and therefore the relations between seismic properties and rock mass parameters. The discontinuity index, Id, fracture density parameter C, linear fracture parameter Γ and the rock quality designation (RQD) were used to describe the rock mass parameters. These parameters are analyzed and then related to the seismic properties. Four vertical aligned fractures were created on an intact calcarenite block, 0.6 m long, 0.4 m thick and 0.4 m width, by sawing. The measures were carried out in four different blocks of cacarenite, having the same physical properties, and in four different phases: in first block the fractures were filled with air; in the second block the fractures were filled with “terra rossa”; in third block the fractures were filled with wet “terra rossa” and in the fourth block the fractures were filled with clay. The test results were statistically analysed using the method of least squares regression and polynomial relationships with high correlation coefficient were found between the fractured rock parameters and P-wave, S-wave velocities and Vp/Vs ratio. The investigations suggest that the P-wave and S-wave velocities decrease with increasing the fracture parameters, while the Vp/Vs ratio increases with decreasing the fracture parameters.
Furthermore the results of the experimental studies were applied on the seismic refraction tomography data acquired in a great measurements campaign undertaken in the Adriatic salentina coast (south Italy) in order to monitor the coastal erosion.
The geophysical results, using the polynomial relationships between the fractured rock parameters and P-wave velocity, are in good agreement with the geomorphological and geological results. 相似文献
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Crustal Poisson’s ratio anomalies in the eastern part of North China and their origins 总被引：1，自引：0，他引：1
Seismic tomography can provide both fine P-wave and S-wave velocity structures of the crust and upper mantle.In addition,with proper computation,Poisson’s ratio images from the seismic velocities can be determined.However,it is unknown whether Poisson’s ratio images have any advantages when compared with the P-wave and S-wave velocity images.For the purposes of this study,high-resolution seismic tomography under the eastern part of North China region was used to determine detailed 3-D crustal P- and S-wave seismic velocities structure,as well as Poisson’s ratio images.Results of Poisson’s ratio imaging show high Poisson’s ratio(high-PR) anomalies located in the Hengshan-North Taihang-Zhangjiakou(H-NT-Z) region,demonstrating that Poisson’s ratio imaging can provide new geophysical constraints for regional tectonic evolution.The H-NT-Z region shows a prominent and continuous high-PR anomaly in the upper crust.Based on Poisson’s ratio images at different depths, we find that this high-PR anomaly is extending down to the middle crust with thickness up to about 26 km.According to rock physical property measurements and other geological data,this crustal Poisson’s ratio anomaly can be explained by Mesozoic partial melting of the upper mantle and basaltic magma underplating related to the lithospheric thinning of the North China craton. 相似文献
4.
针对新疆某工区强非均质性岩溶缝洞型碳酸盐岩储层,提出了一种基于地震多属性优化与电成像测井信息融合的碳酸盐岩储层缝洞带识别评价与钻井轨迹优化设计方法。首先,利用相干体、蚂蚁体等多种地震属性与张量约束的稀疏脉冲反演结果综合实现缝洞发育带空间分布预测与雕刻,确定可能油气圈闭的分布范围;然后,基于数学形态学滤波方法,由电成像测井资料自动拾取井壁的裂缝和溶蚀孔洞分布,统计井壁裂缝倾向和倾角;再次,用工区内钻孔多臂井径资料计算的井筒崩落信息与电成像资料拾取的诱导缝信息预测工区的最大和最小主应力方向;最后,融合地震属性与电成像测井信息评价的缝洞分布结果,预测工区内走滑断裂带的最大主应力方向以NE—SW为主,局部为NW—SE,且以中高角度为主的裂缝走向与主应力近乎平行。采用预测主应力分布方法实现了沿NW—SE方向的大斜度井与水平井优化设计,钻遇了大规模优质储集体,获得了稳定油流,并以此为基础在周围打井若干口,极大地降低了深层勘探的钻井风险。 相似文献
5.
Mohamed K. Salah 《地学前缘(英文版)》2014,5(6):845-854
The 3-D P- and S-wave velocity models of the upper crust beneath Southwest Iberia are determined by inverting arrival time data from local earthquakes using a seismic tomo~raphy method. We used a total of 3085 P- and 2780 S-wave high quality arrival times from 886 local earthquakes recorded by a per- manent seismic network, which is operated by the Institute of Meteorology （IM）, Lisbon, Portugal. The computed P- and S-wave velocities are used to determine the 3-D distributions of Vp/Vs ratio. The 3-D velocity and Vp/Vs ratio images display clear lateral heterogeneities in the study area. Significant veloc- ity variations up to ~6% are revealed in the upper crust beneath Southwest lberia, At 4 km depth, both P- and S-wave velocity take average to high values relative to the initial velocity model, while at 12 km, low P-wave velocities are clearly visible along the coast and in the southern parts. High S-wave velocities at 12 km depth are imaged in the central parts, and average values along the coast; although some scattered patches of low and high S-wave velocities are also revealed. The Vp/Vs rztio is generally high at depths of 4 and 12 km along the coastal parts with some regions of high Vp/Vs ratio in the north at 4 km depth, and low Vp/Vs ratio in the central southern parts at a depth of 12 km, The imaged low velocity and high Vp/Vs ratios are related to the thick saturated and unconsolidated sediments covering the region; whereas the high velocity regions are generally associated with the Mesozoic basement rocks. 相似文献
6.
First arrival times from P-wave refraction and reflection seismic surveys along Bear Creek Valley on the Oak Ridge Reservation,
Tennessee, were inverted to produce refraction tomographic velocity images showing seismic velocity variations within thinly
mantled karstic bedrock to a depth of approximately 20 m. Inverted velocities are consistent with two distinct bedrock groups:
the Nolichucky Shale (2,730–5,150 m/s) and Maynardville Limestone (3,940–7,575 m/s). Low-velocity zones (2,700–4,000 m/s)
in the tomographic images correspond to previously inferred cross-valley strike-slip faults; in places, these faults create
permeability barriers that offset or block groundwater flowing along Bear Creek Valley. These faults may also force groundwater
contaminants, such as dense non-aqueous phase liquids, to migrate laterally or downward, spreading contamination throughout
the groundwater system. Other, previously unmapped cross-valley faults may also be visible in the tomographic images. Borehole
logs suggest the low-velocity values are caused by low rigidity fractured and vuggy rock, water zones, cavities and collapse
features. Surface streams, including Bear Creek, tend to lie directly above these low-velocity zones, suggesting fault and
fracture control of surface drainage, in addition to the subsurface flow system. In some cases, fault zones are also associated
with bedrock depressions and thicker accumulations of unconsolidated sediment. 相似文献
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Crustal structure of the northeastern margin of the Tibetan plateau from the Songpan-Ganzi terrane to the Ordos basin 总被引：20，自引：0，他引：20
Mingjun Liu Walter D. Mooney Songlin Li Nihal Okaya Shane Detweiler 《Tectonophysics》2006,420(1-2):253
The 1000-km-long Darlag–Lanzhou–Jingbian seismic refraction profile is located in the NE margin of the Tibetan plateau. This profile crosses the northern Songpan-Ganzi terrane, the Qinling-Qilian fold system, the Haiyuan arcuate tectonic region, and the stable Ordos basin. The P-wave and S-wave velocity structure and Poisson's ratios reveal many significant characteristics in the profile. The crustal thickness increases from northeast to southwest. The average crustal thickness observed increases from 42 km in the Ordos basin to 63 km in the Songpan-Ganzi terrane. The crust becomes obviously thicker south of the Haiyuan fault and beneath the West-Qinlin Shan. The crustal velocities have significant variations along the profile. The average P-wave velocities for the crystalline crust vary between 6.3 and 6.4 km/s. Beneath the Songpan-Ganzi terrane, West-Qinling Shan, and Haiyuan arcuate tectonic region P-wave velocities of 6.3 km/s are 0.15 km/s lower than the worldwide average of 6.45 km/s. North of the Kunlun fault, with exclusion of the Haiyuan arcuate tectonic region, the average P-wave velocity is 6.4 km/s and only 0.5 km/s lower than the worldwide average. A combination of the P-wave velocity and Poisson's ratio suggests that the crust is dominantly felsic in composition with an intermediate composition at the base. A mafic lower crust is absent in the NE margin of the Tibetan plateau from the Songpan-Ganzi terrane to the Ordos basin. There are low velocity zones in the West-Qinling Shan and the Haiyuan arcuate tectonic region. The low velocity zones have low S-wave velocities and high Poisson's ratios, so it is possible these zones are due to partial melting. The crust is divided into two layers, the upper and the lower crust, with crustal thickening mainly in the lower crust as the NE Tibetan plateau is approached. The results in the study show that the thickness of the lower crust increases from 22 to 38 km as the crustal thickness increases from 42 km in the Ordos basin to 63 km in the Songpan-Ganzi terrane south of the Kunlun fault. Both the Conrad discontinuity and Moho in the West-Qinling Shan and in the Haiyuan arcuate tectonic region are laminated interfaces, implying intense tectonic activity. The arcuate faults and large earthquakes in the Haiyuan arcuate tectonic region are the result of interaction between the Tibetan plateau and the Sino–Korean and Gobi Ala Shan platforms. 相似文献
9.
High-resolution seismic-reflection/refraction data were acquired on the ground surface at six locations to compare with near-surface seismic-velocity downhole measurements. Measurement sites were in Seattle, WA, the San Francisco Bay Area, CA, and the San Fernando Valley, CA. We quantitatively compared the data in terms of the average shear-wave velocity to 30-m depth (Vs30), and by the ratio of the relative site amplification produced by the velocity profiles of each data type over a specified set of quarter-wavelength frequencies. In terms of Vs30, similar values were determined from the two methods. There is <15% difference at four of the six sites. The Vs30 values at the other two sites differ by 21% and 48%. The relative site amplification factors differ generally by less than 10% for both P- and S-wave velocities. We also found that S-wave reflections and first-arrival phase delays are essential for identifying velocity inversions. The results suggest that seismic reflection/refraction data are a fast, non-invasive, and less expensive alternative to downhole data for determining Vs30. In addition, we emphasize that some P- and S-wave reflection travel times can directly indicate the frequencies of potentially damaging earthquake site resonances. A strong correlation between the simple S-wave first-arrival travel time/apparent velocity on the ground surface at 100 m offset from the seismic source and the Vs30 value for that site is an additional unique feature of the reflection/refraction data that could greatly simplify Vs30 determinations. 相似文献
10.
裂缝性碳酸盐岩储层声波时差曲线的波动和增幅分析 总被引：2，自引：2，他引：0
研究了裂缝性碳酸盐岩储层声波时差曲线的波动和增幅现象,认为是裂缝对声波的衰减导致到达远接收器的初至波幅度降低,因而形成3～4μs/ft的时差增幅,从而有效解释了声波时差曲线的波动和增幅现象。利用成像资料和常规测井资料相结合,研究增幅发生条件和规律,发现低角度、较大开度的裂缝导致时差增幅。 相似文献
11.
A detailed field investigation of P- and S-wave velocities was carried out for the Wyoming trona deposit. The velocity measurement was performed at two field sites and included 11 transmission surveys. A total of 97 independent ray paths were generated from these surveys and utilized for the velocity calculation. The test sites consisted of two large pillars. The average travel distance of the signals utilized for the survey was 100 m. A high resolution data acquisition system was used with the sampling rate set at 50 kHz. The sensors were high sensitive accelerometers, with a flat response range of 50–5,000 Hz. These sensors were installed in the boreholes to avoid the attenuation problem caused by the fractured pillar surface. A special sensor installation technique was employed for reliable sensor installation in boreholes which could be oriented in any directions. The signals acquired from the transmission surveys were of very high quality. The frequencies of these signals were very high, ranged from 2,500 to 5,000 Hz, with 5,000 Hz being most typical. The P- and S-waves were well defined and separated. The timing error was estimated within 0.05 ms. The velocities calculated for all 97 survey lines were very consistent. The average P- and S-wave velocities were 5,108 and 2,640 m/s, respectively. The mean standard deviations were small, only 2.4 and 1.9 % for the P- and S-wave velocities. The 95 % two-sided confidence interval for the true P-wave velocity was 5,108 ± 24 m/s and for the S-wave velocity was 2,640 ± 10 m/s. With the consideration of the test conditions associated with this investigation, including multiple test sites, large pillars, excellent signal quality, a very large database, and extremely consistent results, we believe that the P- and S-wave velocities determined from this investigation are accurate, reliable and representative for the Wyoming trona deposit. 相似文献
12.
Tomographic evidence for the subducting oceanic crust and forearc mantle serpentinization under Kyushu, Japan 总被引：1，自引：0，他引：1
We determined high-resolution three-dimensional P- and S-wave velocity (Vp, Vs) structures beneath Kyushu in Southwest Japan using 177,500 P and 174,025 S wave arrival times from 8515 local earthquakes. A Poisson's ratio structure was derived from the obtained Vp and Vs values. Our results show that significant low-Vp, low-Vs and high Poisson's ratio zones are extensively distributed along the volcanic front in the uppermost mantle, which extend and dip toward the back-arc side in the mantle wedge. In the crust, low-Vp, low-Vs and high Poisson's ratio anomalies exist beneath the active volcanoes. The subducting Philippine Sea slab is clearly imaged as a high-Vp, high-Vs and low Poisson's ratio zone from the Nankai Trough to the back-arc. A thin low-velocity zone is detected above the subducting Philippine Sea slab in the mantle wedge, and earthquakes in the upper mantle are distributed along the transition zone between this thin low-velocity zone and the high-velocity Philippine Sea slab, which may imply that oceanic crust exists on the top of the slab and the forearc mantle wedge is serpentinized due to the slab dehydration. The seismic velocity of the subducting oceanic crust with basaltic or gabbroic composition is lower than that of the mantle according to the previous studies. The serpentinization process could also dramatically reduce the seismic velocity in the forearc mantle wedge. 相似文献
13.
Modes and compositions of minerals in Slave mantle xenoliths, together with their pressures and temperatures of equilibrium were used to derive model depth profiles of P- and S-wave velocities (Vp, Vs) for composites equivalent to peridotite, pyroxenite and eclogite. The rocks were modeled as isotropic aggregates with uniform distribution of crystal orientations, based on single-crystal elastic moduli and volume fractions of constituent minerals. Calculated seismic wave velocities are adjusted for in situ pressure and temperature conditions using (1) experimental P- and T- derivatives for bulk rocks' Vp and Vs, and (2) calculated P- and T- derivatives for bulk rocks' elastic moduli and densities. The peridotite seismic profiles match well with the globally averaged IASP91 model and with seismic tomography results for the Slave mantle. In peridotite, an observed increase of seismic wave velocities with depth is controlled by lower degrees of chemical depletion in the deeper upper mantle. In eclogite, seismic velocities increase more rapidly with depth than in peridotite. This follows from contrasting first-order pressure derivatives of bulk isotropic moduli for eclogite and peridotite, and from the lower compressibility of eclogite at high pressures. Our calculations suggest that depletion in cratonic mantle has a distinct seismic signature compared to non-cratonic mantle. Depleted mantle on cratons should have slower Vp, faster Vs and should show lower Poisson's ratios due to an orthopyroxene enrichment. For the modelled Slave craton xenoliths, the predicted effect on seismic wave velocities would be up to 0.05 km/s. 相似文献
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15.
Crosshole seismic tomography and borehole logging for engineering site characterization in Sikeston, MO, USA 总被引：1，自引：0，他引：1
Tiziana Angioni Richard D. Rechtien Steven J. Cardimona Ronaldo Luna 《Tectonophysics》2003,368(1-4):119
This paper presents a geophysical investigation performed in the median separating the east and west bound lanes of U.S. Highway 60, approximately 15 km west from the town of Sikeston, MO, USA. Two boreholes, drilled at depth of 45 m, approximately located 6 m from the Wahite Ditch Bridge in U.S. Highway 60, were used to carry out the geophysical tests. The objective of the survey was to obtain the density distribution of soil materials and high-resolution compressional and shear wave velocities of the shallow subsurface for computation of elastic engineering properties of the unconsolidated material interposed between the two investigated boreholes.The studied site is located in the New Madrid Seismic Zone (NMSZ), one of the major seismic source zones in the eastern United States. Although no major seismic events have occurred in the New Madrid area since the catastrophic earthquakes of 1811–1812, more intensive studies in this area are required to better understand the local soil effects and the liquefaction potential of unconsolidated earth materials on strong ground motion.Joint interpretation of borehole logs and velocity images obtained by P- and S-wave traveltime inversions outlined shallow anomalies, which were interpreted as caused by variation in relative porosity and compactness of saturated unconsolidated soil materials. In the interval between 17 and 19 m of depth, a velocity anomaly with distinct characteristics is recognized. Analysis of traveltimes of P-wave energy propagated from common source-receiver depth positions at that depth interval delineated a low velocity zone (lower than estimated P-wave velocity in water) in which propagated S-wave energy was negligible. Analysis of porosity logs did not outline any porosity anomaly for that region. The anomaly is interpreted as caused by the presence of a gas-bearing zone extending for 1.5 m (+0.76 m from the top and the bottom of the depth interval), through which propagation of shear energy was almost prevented and compressional energy traveled a very low speed. Relative lower values of shear modulus were computed for the gas-bearing zone; the same depth interval also exhibited relative lower values of bulk modulus, relative higher values of compressibility and relative high porosity. However, the low velocity anomaly is not caused by relative increased porosity but rather to replacement of water by gas in the pore volumes of this zone.The presence of a shallow thin gas-bearing zone is interpreted as hazardous in the occurrence of strong motion in the New Madrid Seismic Zone. Shallow water table, as detected by seismic and log measurements in the area, increases the risk of liquefaction of the sampled soil under strong ground motions. 相似文献
16.
The ratio of P- to S-wave velocities (Vp/Vs) is regarded as one of the most diagnostic properties of natural rocks. It has been used as a discriminant of composition for the continental crust and provides valuable constraints on its formation and evolution processes. Furthermore, the spatial and temporal changes in Vp/Vs before and after earthquakes are probably the most promising avenue to understanding the source mechanics and possibly predicting earthquakes. Here we calibrate the variations in Vp/Vs in dry, anisotropic crustal rocks and provide a set of basic information for the interpretation of future seismic data from the Wenchuan earthquake Fault zone Scientific Drilling (WFSD) project and other surveys. Vp/Vs is a constant (φ0) for an isotropic rock. However, most of crustal rocks are anisotropic due to lattice-preferred orientations of anisotropic minerals (e.g., mica, amphibole, plagioclase and pyroxene) and cracks as well as thin compositional layering. The Vp/Vs ratio of an anisotropic rock measured along a selected pair of propagation-vibration directions is an apparent value (φij) that is significantly different from the value for its isotropic counterpart (φ0). The usefulness of apparent Vp/Vs ratios as a diagnostic of crustal composition depends largely on rock seismic anisotropy. A 5% of P- and S-wave velocity anisotropy is sufficient to make it impossible to determine the crustal composition using the conventional criteria (Vp/Vs<1.756 for felsic rocks, 1.756l.944 fluid-tidied porous/fractured or partially molten rocks) if the information about the wave propagation-polarization directions with respect to the tectonic framework is unknown. However, the variations in Vp/Vs measured from borehole seismic experiments can be readily interpreted according to the orientations of the ray path and the polarization of the shear waves with respect to the present-day principal stress directions (I.e., the orientation of cracks) and the frozen fabric (I.e., foliation and lineation). 相似文献
17.
Hsi-Ping Liu Yiguang Hu James Dorman Tzyy-Shiou Chang Jer-Ming Chiu 《Engineering Geology》1997,46(3-4):313-330
Vertical seismic compressional- and shear-wave (P-and S-wave) profiles were collected from three shallow boreholes in sediment of the upper Mississippi embayment. The site of the 60-m hole at Shelby Forest, Tennessee, is on bluffs forming the eastern edge of the Mississippi alluvial plain. The bluffs are composed of Pleistocene loess, Pliocene-Pleistocene alluvial clay and sand deposits, and Tertiary deltaic-marine sediment. The 36-m hole at Marked Tree, Arkansas, and the 27-m hole at Risco, Missouri, are in Holocene Mississippi river floodplain sand, silt, and gravel deposits. At each site, impulsive P- and S-waves were generated by man-made sources at the surface while a three-component geophone was locked downhole at 0.91-m intervals.
Consistent with their very similar geology, the two floodplain locations have nearly identical S-wave velocity (VS) profiles. The lowest VS values are about 130 m s−1, and the highest values are about 300 m s−1 at these sites. The shear-wave velocity profile at Shelby Forest is very similar within the Pleistocene loess (12 m thick); in deeper, older material, VS exceeds 400 m s−1.
At Marked Tree, and at Risco, the compressional-wave velocity (VP) values above the water table are as low as about 230 m s−1, and rise to about 1.9 km s−1 below the water table. At Shelby Forest, VP values in the unsaturated loess are as low as 302 m s−1. VP values below the water table are about 1.8 km s−1. For the two floodplain sites, the VP/VS ratio increases rapidly across the water table depth. For the Shelby Forest site, the largest increase in the VP/VS ratio occurs at 20-m depth, the boundary between the Pliocene-Pleistocene clay and sand deposits and the Eocene shallow-marine clay and silt deposits.
Until recently, seismic velocity data for the embayment basin came from eartquake studies, crustal-scale seismic refraction and reflection profiles, sonic logs, and from analysis of dispersed earthquake surface waves. Since 1991, seismic data for shallow sediment obtained from reflection, refraction, crosshole and downhole techniques have been obtained for sites at the northern end of the embayment basin. The present borehole data, however, are measured from sites representative of large areas in the Mississippi embayment. Therefore, they fill a gap in information needed for modeling the response of the embayment to destructive seismic shaking. 相似文献
18.
Fracture Length Estimation from Borehole Image Logs 总被引：1，自引：0，他引：1
Sait Ismail Özkaya 《Mathematical Geology》2003,35(6):737-753
We describe a method to estimate fracture length for circular fractures from borehole image logs. The relative frequency of fractures, which have complete circumference trace on image logs is related to fracture length. A simple functional relationship can be derived for the relative frequency of complete fracture traces in terms of average fracture inclination to borehole, borehole diameter and fracture length. This formulation however, tends to underestimate fracture length because a constant length is assumed. A more accurate length estimate can be obtained by assuming that fracture length is linearly correlated to fracture aperture or spacing. Cumulative frequency distribution of fracture aperture and spacing can be obtained from borehole image logs. The problem then transforms itself to finding the scaling factor between fracture length and aperture (or spacing) from the relative frequency of fractures with complete traces. The product of the scaling factor and average fracture spacing (or aperture) gives the average fracture length. 相似文献
19.
The core from two boreholes (13.1 and 19.2 m depth) drilled 500 m apart in the fractured, welded tuff near the summit of the Snowshoe Mountain, Colorado (47°30′N, 106°55′W) had unique petrographic and hydrodynamic properties. Borehole SM-4 had highly variable annual water levels, in contrast to SM-1a, whose water level remained near the land surface. Core samples from both boreholes (n=10 and 11) were examined petrographically in thin sections impregnated with epoxy containing rhodamine to mark the pore system features, and were analyzed for matrix porosity and permeability. Core from the borehole sampling the vadose zone was characterized by open fractures with enhanced porosity around phenocrysts due to chemical weathering. Fractures within the borehole sampling the phreatic zone were mineralized with calcite and had porosity characteristics similar to unweathered and unfractured rock. At the top of the phreatic zone petrography indicates that calcite is dissolving, thereby changing the hydrogeochemical character of the rock (i.e. permeability, porosity, reactive surface area, and mineralogy). Radiocarbon ages and C and O stable isotopes indicate that calcite mineralization occurred about 30 to 40 ka ago and that there was more than one mineralization event. Results of this study also provide some relationships between primary porosity development from 3 types of fracture in a welded tuff. 相似文献
20.
The article presents a statistical approach to characterize and predict engineering geological conditions in the up to 2000 m deep Faido tunnel and Gotthard base tunnel in Switzerland. Seismic investigations were conducted to improve the technology of interpreting seismic tomographic images. Overall, the goal of this study was to predict spacial maps of geological rock mass properties, such as, uniaxial compressive strength or total fracture spacing, by using up to six seismic features in combination, e.g., compression-wave and shear-wave velocities and dynamic Poisson's ratio. Self-Organizing Mapping (SOM), an artificial intelligent method, was used for the purposes of interpreting multi-dimensional geophysical attributes derived from seismic profiles of tomographic images along tunnel sidewalls. The SOM-method was applied in the Faido tunnel to delineate complex physical relations between the geological and seismic parameters. Then, the method was applied to predict geological properties around a segment of the Gotthard base tunnel with unknown geological–geotechnical conditions. The results illuminate that correlation analyses (pairwise parameter classification) are substantially less powerful than the SOM-method (multi-parameter classification) in order to interpret geological features from seismic in-situ data. Moreover, predicted spatial distributions of the total fracture spacing and the uniaxial compressive strength, for example, corresponded well with drill core and tunnel mapping results. The SOM-approach was a helpful tool for practitioners in predicting zones of instabilities and geological complexity during underground excavation processes of the Gotthard base tunnel. It is suggested to use such an interpretation method as decision support for purposes of sub/surface exploration and long-term geophysical monitoring of large-scale geoengineering projects, such as, disposals of nuclear waste and greenhouse gases or geopower plants for renewable energy (geothermal, biosoils). 相似文献