共查询到20条相似文献，搜索用时 62 毫秒
1.
In this study we investigate co-seismic geo-center change based on a dislocation theory for a spherically symmetric, non-rotating, perfectly elastic and isotropic model. We first introduce the basic theory with emphasis on the dislocation Love numbers of degree 1, and then we present methods for computing co-seismic geo-center movement. It is found that the geo-center change reaches maximum value when δ = 45° and λ = 90°, i.e., a 45° declined dip fault causes the maximum geo-center movement. As an application, we apply the methods to compute the geo-center movement caused by the 2004 Sumatra earthquake (Mw9.3) and the 2011 Tohoku-Oki earthquake (Mw9.0). Results show that the maximum co-seismic geo-center movements for the two events are 0.87 mm and 0.43 mm, respectively. 相似文献
2.
GPS data from Crustal Movement Observation Network of China (CMONOC) are used to derive far-field co-seismic displacements induced by the Mw 9.0 Tohoku Earthquake. Significant horizontal displacements about 30 mm, 10 mm, and 20 mm were caused by this large event in northeast China, north China, and on the Korean peninsula respectively. Vectors of relatively large horizontal displacements with dominant east components pointed to the epicenter of this earthquake. The east components show an exponential decay with the longitude, which is characteristic of the decay of the co-seismic horizontal displacements associated with earthquakes of thrust rupture. The exponential fit of the east components shows that the influence of the co-seismic displacements can be detected by GPS at a distance of about 3200 km from the epicenter of the earthquake. By considering the capability of the far field displacements for constraining the inversion of the fault slip model of the earthquake, we use spherically stratified Earth models to simulate the co-seismic displacements induced by this event. Using computations and comparisons, we discuss the effects of parameters of layered Earth models on the results of dislocation modeling. Comparisons of the modeled and observed displacements show that far field GPS observations are effective for constraining the fault slip model. The far field horizontal displacements observed by GPS are used to modify the slips and seismic moments of fault slip models. The result of this work is applicable as a reference for other researchers to study seismic source rupture and crustal deformation. 相似文献
3.
In this study, remediation results of trace metals in natural water and treated water using three functionalized nanofiber mats of cellulose and chitosan are reported. The nanofiber materials, packed in mini-columns, were employed for the remediation of five toxic trace metals (Cd, Pb, Cu, Cr and Ni) from natural water samples. Trace metals in real water samples were undetectable as the concentrations were lower than the instrument’s detection limits of 0.27 × 10−3 (Cd) and 4.2 × 10−2 (Pb) μg mL−1, respectively. However, after percolation through the functionalised biosorbents in cartridges, detectability of the metal ions was enhanced. The starting volume of the natural water sample was 100 mL, which was passed through a column containing the nanofibers sorbent and the retained metals eluted with 5 mL of 2.0 M nitric acid. The eluate was analyzed for metals concentrations. An enrichment factor of 20 for the metals was realized as a result of the pre-concentration procedure applied to handle the determination of the metals at trace levels. The order of remediation of the studied metals using the nanofibers was as follows: chitosan/PAM-g-furan-2,5-dione < cellulose-g-furan-2,5-dione < cellulose-g-oxolane-2,5-dione. The modified biopolymer nanofibers were able to adsorb trace metals from the river water and treated water, thereby confirming their capability of water purification. These materials are proposed as useful tools and innovative approach for improving the quality of drinking for those consumers in small scale households. 相似文献
4.
The influence of the elastic Earth properties on seasonal or shorter periodic surface deformations due to atmospheric surface pressure and terrestrial water storage variations is usually modeled by applying a local half-space model or an one dimensional spherical Earth model like PREM from which a unique set of elastic load Love numbers, or alternatively, elastic Green's functions are derived. The first model is valid only if load and observer almost coincide, the second model considers only the response of an average Earth structure. However, for surface loads with horizontal scales less than 2500 km2, as for instance, for strong localized hydrological signals associated with heavy precipitation events and river floods, the Earth elastic response becomes very sensitive to inhomogeneities in the Earth crustal structure.We derive a set of local Green's functions defined globally on a 1° × 1° grid for the 3-layer crustal structure TEA12. Local Green's functions show standard deviations of ±12% in the vertical and ±21% in the horizontal directions for distances in the range from 0.1° to 0.5°. By means of Green's function scatter plots, we analyze the dependence of the load response to various crustal rocks and layer thicknesses. The application of local Green's functions instead of a mean global Green's function introduces a variability of 0.5–1.0 mm into the hydrological loading displacements, both in vertical and in horizontal directions. Maximum changes due to the local crustal structures are from −25% to +26% in the vertical and −91% to +55% in the horizontal displacements. In addition, the horizontal displacement can change its direction significantly. The lateral deviations in surface deformation due to local crustal elastic properties are found to be much larger than the differences between various commonly used one-dimensional Earth models. 相似文献
5.
We used GPS velocities from approximately 700 stations in western China to study the crustal deformation before the Wenchuan MS8.0 earthquake. The processing methods included analyses of the strain rate field, inversion of fault locking and the GPS velocity profiles. The GPS strain rate in the E-W direction in the Qinghai-Tibet block shows that extensional deformation was dominant in the western region of the block (west of 92.5° E), while compressive deformation predominated in the eastern region of the block (from 92.5° E to 100° E). On a regional scale, the hypocentral region of the Wenchuan earthquake was located at the edge of an intense compression deformation zone of about 1.9 × 10−8/a in an east-west direction. The characteristic deformation in the seismogenic fault was compressive with a dextral component. The compression deformation rate was greater in the fault's western region than in its eastern region, and the strain accumulation was very slow on the fault scale. The results of a fault locking inversion show that the locking fraction and slip deficit was greater in the middle-northern section of the seismogenic fault than in the southern section. The GPS velocity profile before the Wenchuan earthquake shows that the compression deformation was smaller than the dextral deformation, which is asymmetrical with respect to the distribution of co-seismic displacement. These deformation characteristics should provide some clues to the Wenchuan earthquake which occurred in the later period of the earthquake cycle. 相似文献
6.
Consecutive earthquakes occurred on October 23rd, 2011 in Ercis and on November 9th, 2011 in Edremit that are townships located 90 km and 18 km far from Van city in Turkey, respectively. A total of 28,000 buildings were damaged or collapsed in the city center and the surrounding villages after the Ercis earthquake. This number reached 35,000 after the Edremit earthquake. In the area where the earthquakes occurred, almost all the reinforced concrete buildings were affected.This study presents field observations of damages on reinforced concrete buildings due to the consecutive earthquakes that occurred in Van, Turkey. Damages appearing in the buildings may occur due to several reasons such as site effect, poor construction quality, poor concrete strength, poor detailing in beam-column joints, detailing of stronger beam than column, soft stories, weak stories, inadequate reinforcement, short lap splices, incorrect end hook angle, and short columns. Aftershocks also caused progressive damages on the buildings within 17 days after the earthquakes. According to the results of this study, most of the damaged buildings were not designed and constructed according to the Turkish earthquake code, the so-called Specification for Buildings to be built in Seismic Zones. 相似文献
7.
Detailed mapping of geomorphological and biological sea-level markers around the Capo Vaticano promontory (western Calabria, Italy), has documented the occurrence of four Holocene paleo-shorelines raised at different altitudes. The uppermost shoreline (PS1) is represented by a deeply eroded fossiliferous beach deposit, reaching an elevation of ∼2.2 m above the present sea-level, and by a notch whose roof is at ∼2.3 m. The subjacent shoreline PS2 is found at an elevation of ∼1.8 m and is represented by a Dendropoma rim, a barnacle band and by a wave-cut platform. Shoreline PS3 includes remnants of vermetid concretions, a barnacle band, a notch and a marine deposit, and reaches an elevation of ∼1.4 m. The lowermost paleo-shoreline (PS4) includes a wave-cut platform and a notch and reaches an elevation of ∼0.8 m. Radiocarbon dating of material from individual paleo-shorelines points to an average uplift rate of 1.2–1.4 mm/yr in the last ∼6 ka at Capo Vaticano. Our data suggest that Holocene uplift was asymmetric, with a greater magnitude in the south-west sector of the promontory, in a manner similar to the long-term deformation attested by Pleistocene terraces. The larger uplift in the south-western sector is possibly related to the additional contribution, onto a large-wavelength regional signal, of co-seismic deformation events, which are not registered to the north-east. We have recognized four co-seismic uplift events at 5.7–5.4 ka, 3.9–3.5 ka, ∼1.9 ka and <1.8 ka ago, superposed on a regional uplift that in the area, is occurring at a rate of ∼1 mm/yr. Our findings places new constrains on the recent activity of border faults south of the peninsula and on the location of the seismogenic source the 1905 destructive earthquake. 相似文献
8.
R/S analysis is used in this work to investigate the fractal correlations in terms of the Hurst exponent for the 1998–2011 seismicity data in Southern Mexico. This region is the most seismically active area in Mexico, where epicenters for severe earthquakes (e.g., September 19, 1985, Mw = 8.1) causing extensive damage in highly populated areas have been located. By only considering the seismic events that meet the Gutenberg–Ritcher law completeness requirement (b = 0.97, MGR = 3.6), we found time clustering for scales of about 100 and 135 events. In both cases, a cyclic behavior with dominant spectral components at about one cycle per year is revealed. It is argued that such a one-year cycle could be related to tidal effects in the Pacific coast. Interestingly, it is also found that high-magnitude events (Mw ≥ 6.0) are more likely to occur under increased interevent correlations with Hurst exponent values H > 0.65. This suggests that major earthquakes can occur when the tectonic stress accumulates in preferential directions. In contrast, the high-magnitude seismic risk is reduced when stresses are uniformly distributed in the tectonic shell. Such cointegration between correlations (i.e., Hurst exponent) and macroseismicity is confirmed for spatial variations of the Hurst exponent. In this way, we found that, using the Hurst exponent standpoint, the former presumed Michoacan and the Guerrero seismic gaps are the riskiest seismic zones. To test this empirical finding, two Southern Mexico local regions with large earthquakes were considered. These are the Atoyac de Alvarez, Guerrero (Mw = 6.3), and Union Hidalgo, Oaxaca (Mw = 6.6), events. In addition, we used the Loma Prieta, California, earthquake (October 17, 1989, Mw = 6.9) to show that the high-magnitude earthquakes in the San Andreas Fault region can also be linked to the increments of determinism (quantified in terms of the Hurst exponent) displayed by the stochastic dynamics of the interevent period time series. The results revealed that the analysis of seismic activity by means of R/S analysis could provide further insights in the advent of major earthquakes. 相似文献
9.
The ground motion owing to the collapse of a large-scale cooling tower under strong earthquakes was appropriately predicted using a comprehensive approach. The predicted results can be used for the safety evaluation of nuclear-related facilities adjacent to the cooling tower as well as in the planning of nuclear power plant construction in China. In this study, a cooling tower–soil model was first developed based on a falling weight–soil model, which the authors verified by falling weight tests. Then the collapse process of a cooling tower was simulated, and the collapse-induced ground vibrations were assessed by using the proposed model. Finally, the ground motion, which was a combination of the earthquake-induced ground motion and the collapse-induced ground vibrations, was estimated based on the superposition principle of waves. It was found that the cooling tower may collapse under strong earthquakes with the peak ground accelerations (PGAs) in the range of 0.35–0.45 g in x (EW) and y (NS) directions, respectively. These PGAs are far beyond the PGA range of major earthquakes in the common seismic design in China. The types of the site geologies of towers can significantly affect the collapse-induced ground vibrations. For a typical hard soil consisting of strongly weathered sandy slate, moderate ground vibrations may occur in the considered region. The collapse-induced PGAs were in the range of 0.017–0.046 g for the observed points at distances of 350 m in radial direction. For a rock-like foundation, the collapse-induced radial PGAs may be as high as 0.08 g at distances of 350 m, indicating that the effect of the collapse-induced ground vibrations on the nuclear-related facilities should be seriously assessed in certain scenarios. 相似文献
10.
《Physics of the Earth and Planetary Interiors》2002,129(3-4):283-300
The Pannonian depression is an extensional back-arc basin in central Europe and is an integral part of the Alpine–Carpathian orogenic mountain belts. It can be characterized by thinned lower crust, shallow Moho discontinuity, high surface heat flow and Moho temperature, implying recent active tectonic processes. Imaging the velocity structure of the upper mantle may help us to better understand the structure and formation of the Pannonian region.In this paper, Pn traveltimes from regional earthquakes are used to tomographically image the lateral velocity variations in the uppermost mantle beneath the Pannonian basin. The set of linear tomographic equations, built up of the time term equation for each source–receiver pair, is solved by a truncated singular value decomposition algorithm. The explicit computation of the generalized inverse of the tomographic equations makes it possible to deduce both the resolution matrix and the model covariance matrix, allowing us to estimate the resolution and reliability of the solution.The mean compressional wave velocity in the uppermost mantle beneath the Pannonian basin is 7.9 km/s, substantially lower than the average continental Pn velocity of 8.1 km/s. It is mostly due to the high Moho temperature having values on average 400–500 °C more than those in the surrounding areas. The velocity anomalies range from −0.3 to 0.3 km/s relative to the mean velocity of 7.9 km/s. Due to high Moho temperature, below the North Hungarian range low (7.6–7.7 km/s) velocities can be found. High-velocity anomalies of around 8.1 km/s can be detected along the W-SW boundaries of Hungary and at the junction of the Pannonian basin and the Southern Carpathians. The Great Hungarian Plain shows average (7.9 km/s) Pn velocities. 相似文献
11.
《Geofísica Internacional》2014,53(1):17-26
We analyzed records of eight seismic stations of the autonomous broadband seismograph network of a joint project between Utrecht University (the Netherlands), California Institute of Technology, and Centro de Investigación Científica y de Estudios Superiores de Ensenada (CICESE). These stations recorded the Mw 5.6 earthquake that occurred on 12 November 2003 at Salsipuedes basin in the middle of the Gulf of California 2 km west of the island Angel de la Guarda. This event was located at 29.16º N and 113.37º W, 30 km northeast of Bahia de los Angeles. A foreshock and hundreds of aftershocks were recorded in the 48 hours after its origin time. With the location of 29 earthquakes we identified the active segment, perpendicular to the main transform fault NW–SE of Canal de Ballenas, representing the transtensional boundary between the Pacific and North American plates. The direction of the active fault described is consistent with the normal fault mechanism reported by the National Earthquake Information Center (strike=39º, dip=34º, slip=–44º).From the duration magnitude of 456 aftershocks, we calculated a b-value of 1.14±0.28; furthermore, we calculated a seismic moment of (3.5 ±3.3) X1017Nm, a source radius of 3.7 ± 2.63 km, and a static stress drop of 3.94 ± 1.15 MPa (39.4 ± 11.5 bar.). 相似文献
12.
Zafeiria Roumelioti Anastasia Kiratzi Christoforos Benetatos 《Journal of Geodynamics》2011,51(2-3):179-189
We present a catalog of moment tensor (MT) solutions and moment magnitudes, Mw, for 119 shallow (h ≤ 40 km) earthquakes in Greece and its surrounding lands (34°N–42°N, 19°E–30°E) for the years 2006 and 2007, computed with the 1D Time-Domain Moment Tensor inversion method (TDMT_INV code of Dreger, 2003). Magnitudes range from 3.2 ≤ Mw ≤ 5.7. Green's functions (GF) have been pre-computed to build a library, for a number of velocity profiles applicable to the broader Aegean Sea region, to be used in the inversion of observed broad band waveforms (10–50 s). All MT solutions are the outcome of a long series of tests of different reported source locations and hypocenter depths. Quality factors have been assigned to each MT solution based on the number of stations used in the inversion and the goodness of fit between observed and synthetic waveforms. In general, the focal mechanisms are compatible with previous knowledge on the seismotectonics of the Aegean area. The new data provide evidence for strike-slip faulting along NW–SE trending structures at the lower part of Axios basin, close to the heavily industrialized, and presently subsiding, region of the city of Thessaloniki. Normal faulting along E–W trending planes is observed at the Strimon basin, and in Orfanou Gulf in northern Greece. A sequence of events in the east Aegean Sea close to the coastline with western Anatolia sheds light on an active structure bounding the north coastline of Psara–Chios Islands about 20–25 km in length exhibiting right lateral strike-slip faulting. 相似文献
13.
14.
The strong earthquake (M = 7) that occurred in the Fucino basin (central Italy) on January 13, 1915 was followed by six earthquakes of M > 5.5 and several other shocks of M > 5 in the major seismic zones of the northern Apennines from 1916 to 1920. This seismicity pattern is consistent with the implications of the present tectonic setting in the study area, which suggests that strong decoupling earthquakes in the central Apennines cause a significant increase of tectonic load, and possibly of seismicity, in the northern Apennines. A numerical simulation, carried out by an elastic-viscous model, of the stress diffusion induced by the Fucino and successive largest earthquakes, shows that each of the above shocks occurred when the respective zone was reached by the highest values of the strain and strain rate perturbation triggered by the previous events. Furthermore, the computed strain regime at each earthquake site is consistent with the known faulting pattern. The results provide important insights into the physical mechanism that controls the interaction of seismic sources in the central and northern Apennines. 相似文献
15.
Alina Marie Hasbi Mohammed Awad Momani Mohd Alauddin Mohd Ali Norbahiah Misran Kazuo Shiokawa Yuichi Otsuka Kiyohumi Yumoto 《Journal of Atmospheric and Solar》2009,71(17-18):1992-2005
This paper investigates the ionospheric and geomagnetic responses during the 28 March 2005 and 14 May 2005 Sumatran earthquakes using GPS and magnetometer stations located in the near zone of the epicenters. These events occurred during low solar and geomagnetic activity. TEC oscillations with periods of 5–10 min were observed about 10–24 min after the earthquakes and have horizontal propagation velocities of 922–1259 m/s. Ionospheric disturbances were observed at GPS stations located to the northeast of the epicenters, while no significant disturbances were seen relatively east and south of the epicenters. The magnetic field measurements show rapid fluctuations of 4–5 s shortly after the earthquake, followed by a Pc5 pulsation of 4.8 min about 11 min after the event. The correlation between the ionospheric and geomagnetic responses shows a good agreement in the period and time lag of the peak disturbance arrival, i.e. about 11–13 min after the earthquake. 相似文献
16.
J. Laštovička J. Baše F. Hruška J. Chum T. Šindelářová J. Horálek J. Zedník V. Krasnov 《Journal of Atmospheric and Solar》2010,72(16):1231-1240
Various pre-seismic and co-seismic effects have been reported in the literature in the solid Earth, hydrosphere, atmosphere, electric/magnetic field and in the ionosphere. Some of the effects observed above the surface, particularly some of the pre-seismic effects, are still a matter of debate. Here we analyze the co-seismic effects of a relatively weak earthquake of 28 October 2008, which was a part of an earthquake swarm in the westernmost region of the Czech Republic. Special attention is paid to unique measurements of infrasonic phenomena. As far as we know, these have been the first infrasonic measurements during earthquake in the epicentre zone. Infrasonic oscillations (～1–12 Hz) in the epicentre region appear to be excited essentially by the vertical seismic oscillations. The observed oscillations are real epicentral infrasound not caused by seismic shaking of the instruments or by meteorological phenomena. Seismo-infrasonic oscillations observed 155 km apart from the epicentre were excited in situ by seismic waves. No earthquake-related infrasonic effects have been observed in the ionosphere. Necessity to make vibration tests of instruments is pointed out in order to be sure that observed effects are not effects of mechanical shaking of the instrument. 相似文献
17.
Many authors have proposed that the study of seismicity rates is an appropriate technique for evaluating how close a seismic gap may be to rupture. We designed an algorithm for identification of patterns of significant seismic quiescence by using the definition of seismic quiescence proposed by Schreider (1990). This algorithm shows the area of quiescence where an earthquake of great magnitude may probably occur. We have applied our algorithm to the earthquake catalog on the Mexican Pacific coast located between 14 and 21 degrees of North latitude and 94 and 106 degrees West longitude; with depths less than or equal to 60 km and magnitude greater than or equal to 4.3, which occurred from January, 1965 until December, 2014. We have found significant patterns of seismic quietude before the earthquakes of Oaxaca (November 1978, Mw = 7.8), Petatlán (March 1979, Mw = 7.6), Michoacán (September 1985, Mw = 8.0, and Mw = 7.6) and Colima (October 1995, Mw = 8.0). Fortunately, in this century earthquakes of great magnitude have not occurred in Mexico. However, we have identified well-defined seismic quiescences in the Guerrero seismic-gap, which are apparently correlated with the occurrence of silent earthquakes in 2002, 2006 and 2010 recently discovered by GPS technology. 相似文献
18.
《Earth and Planetary Science Letters》2006,241(3-4):888-900
At longer periods, scattered ScS waves sometimes dominate over coda waves at large lapse times. Examining recordings of seismic envelopes at 9 IRIS seismic stations of regional earthquakes with focal depths deeper than 150 km in periods from 1 to 20 s for a wide lapse time range up to 2000 s, we found significant frequency dependence. The coda decay gradient at short periods is steeper than that at longer periods; however, the change of coda gradient associated with the ScS arrival becomes distinct as the period becomes longer. In particular, a clear offset of coda amplitude appears in central Asia for 10 and 15 s period bands. The multiple isotropic scattering process of S-waves in the heterogeneous mantle can be simply simulated by using the Monte Carlo simulation method based on the radiative transfer theory in scattering media. Assuming a two-plane-layer attenuation structure and smoothed velocity model of the PREM, we estimated the average total scattering coefficients of S-waves such as 7.52 × 10− 4∼1.32 × 10− 3 km− 1 and 2.08 × 10− 4∼6.23 × 10− 4 km− 1 at 4 s, and 4.51 × 10− 4∼7.37 × 10− 4 km− 1 and 2.80 × 10− 5∼2.71 × 10− 4 km− 1 at 10 s, for the lithosphere and the upper mantle and for the lower mantle, respectively. Our results indicate that scattering occurs mostly in the lithosphere and the upper mantle and support that medium heterogeneity spreads over the whole mantle though its scattering power is small. Strong scattering occurs beneath central Asia and Papua New Guinea, whereas the scattering beneath Italy and regions of east Russia is much weaker. The numerical calculation enables us to confirm that much stronger scattering than intrinsic attenuation causes the offset behavior with coda decay gradient change after the ScS arrival for 4 and 10 s period bands in some regions. 相似文献
19.
《Earth and Planetary Science Letters》2006,241(3-4):932-951
We report volatile (H2O, CO2, F, S, Cl) and trace element data for submarine alkalic basalt glasses from the three youngest Samoan volcanoes, Ta'u, Malumalu and Vailulu'u. Most samples are visibly sulfide saturated, so have likely lost some S during fractionation. Cl / K ratios (0.04–0.15) extend to higher values than pristine MORBs, but are suspected to be partly due to source differences since Cl / K roughly varies as a function of 87Sr / 86Sr. There are no resolvable differences in the relative enrichment of F among sources, and compatibility of F during mantle melting is established to be nearly identical to Nd. Shallow degassing has affected CO2 in all samples, and H2O only in the most shallowly erupted samples from Vailulu'u. Absolute water contents are high for Samoa (0.63–1.50 wt.%), but relative enrichment of water compared to equally incompatible trace elements (Ce, La) is low and falls entirely below normal MORB values. H2O / Ce (58–157) and H2O / La (120–350) correlate inversely with 87Sr / 86Sr compositions (0.7045–0.7089). This leads us to believe that, because of very fast diffusion of hydrogen in mantle minerals, recycled lithospheric material with high initial water and trace element content will lose water to the drier ambient mantle during storage within the inner Earth. The net result is the counter-intuitive appearance of greater dehydration with greater mantle enrichment. We expect that subducted slabs will experience a two-stage dehydration history, first within subduction zones and then in the ambient mantle during long-term convective mixing. 相似文献
20.
Active tectonics of the outer northern Apennines: Adriatic vs. Po Plain seismicity and stress fields
The recent earthquake sequences of 2012 (northern Italy) and 2013 (Marche offshore) provided new, fundamental constraints to the active tectonic setting of the outer northern Apennines. In contrast to the Po Plain area, where the 2012 northern Italy earthquakes confirmed active frontal thrusting, the new focal mechanisms obtained in this study for the 2013 Marche offshore earthquakes indicate that only minor thrust fault reactivation occurs in the Adriatic domain, even for a theoretically favourably oriented maximum horizontal compression. Recent seismicity in this domain appears to be mainly controlled by transcurrent crustal faults dissecting the Apennine thrust belt. The along-strike stress field variation from the Po Plain to the Adriatic area has been quantitatively investigated by applying the multiple inverse method (MIM) to the analysis of the entire seismicity recorded from January 1976 to August 2014, from the top 12 km of the crust (fault plane solutions from 127 earthquakes with MW ≥ 4), allowing us to obtain a comprehensive picture of the state of stress over the outer zone of the fold and thrust belt. The present-day stress field has been defined for 39 cells of 1.5° × 1.5° surface area and 12 km depth. The obtained stress field maps point out that, although the entire outer northern Apennines belt is characterized by a sub-horizontal maximum compressive axis (σ1), the minimum compression (σ3) is sub-vertical only in the Po Plain area, becoming sub-horizontal in the Adriatic sector, thus confirming that the latter region is dominated by an active tectonic regime of strike-slip type. 相似文献