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1.
In the present paper, the parameters affecting the uncertainties on the estimation of M max have been investigated by exploring different methodologies being used in the analysis of seismicity catalogue and estimation of seismicity parameters. A critical issue to be addressed before any scientific analysis is to assess the quality, consistency, and homogeneity of the data. The empirical relationships between different magnitude scales have been used for conversions for homogenization of seismicity catalogues to be used for further seismic hazard assessment studies. An endeavour has been made to quantify the uncertainties due to magnitude conversions and the seismic hazard parameters are then estimated using different methods to consider the epistemic uncertainty in the process. The study area chosen is around Delhi. The b value and the magnitude of completeness for the four seismogenic sources considered around Delhi varied more than 40% using the three catalogues compiled based on different magnitude conversion relationships. The effect of the uncertainties has been then shown on the estimation of M max and the probabilities of occurrence of different magnitudes. It has been emphasized to consider the uncertainties and their quantification to carry out seismic hazard assessment and in turn the seismic microzonation.  相似文献   

2.
This paper presents a seismic hazard evaluation and develops an earthquake catalogue for the Constantine region over the period from 1357 to 2014. The study contributes to the improvement of seismic risk management by evaluating the seismic hazards in Northeast Algeria. A regional seismicity analysis was conducted based on reliable earthquake data obtained from various agencies (CRAAG, IGN, USGS and ISC). All magnitudes (M l, m b) and intensities (I 0, I MM, I MSK and I EMS) were converted to M s magnitudes using the appropriate relationships. Earthquake hazard maps were created for the Constantine region. These maps were estimated in terms of spectral acceleration (SA) at periods of 0.1, 0.2, 0.5, 0.7, 0.9, 1.0, 1.5 and 2.0 s. Five seismogenic zones are proposed. This new method differs from the conventional method because it incorporates earthquake magnitude uncertainty and mixed datasets containing large historical events and recent data. The method can be used to estimate the b value of the Gutenberg-Richter relationship, annual activity rate λ(M) of an event and maximum possible magnitude M max using incomplete and heterogeneous data files. In addition, an earthquake is considered a Poisson with an annual activity rate λ and with a doubly truncated exponential earthquake magnitude distribution. Map of seismic hazard and an earthquake catalogue, graphs and maps were created using geographic information systems (GIS), the Z-map code version 6 and Crisis software 2012.  相似文献   

3.
We conducted a study of the spatial distributions of seismicity and earthquake hazard parameters for Turkey and the adjacent areas, applying the maximum likelihood method. The procedure allows for the use of either historical or instrumental data, or even a combination of the two. By using this method, we can estimate the earthquake hazard parameters, which include the maximum regional magnitude Mˆmax, the activity rate of seismic events and the well-known bˆ value, which is the slope of the frequency-magnitude Gutenberg-Richter relationship. These three parameters are determined simultaneously using an iterative scheme. The uncertainty in the determination of the magnitudes was also taken into consideration. The return periods (RP) of earthquakes with a magnitude M ≥ m are also evaluated. The whole examined area is divided into 24 seismic regions based on their seismotectonic regime. The homogeneity of the magnitudes is an essential factor in such studies. In order to achieve homogeneity of the magnitudes, formulas that convert any magnitude to an MS-surface scale are developed. New completeness cutoffs and their corresponding time intervals are also assessed for each of the 24 seismic regions. Each of the obtained parameters is distributed into its respective seismic region, allowing for an analysis of the localized seismicity parameters and a representation of their regional variation on a map. The earthquake hazard level is also calculated as a function of the form Θ = (Mˆmax,RP6.0), and a relative hazard scale (defined as the index K) is defined for each seismic region. The investigated regions are then classified into five groups using these parameters. This classification is useful for theoretical and practical reasons and provides a picture of quantitative seismicity. An attempt is then made to relate these values to the local tectonics.  相似文献   

4.
The aim of the present work is to compile and update a catalogue of the instrumentally recorded earthquakes in Egypt, with uniform and homogeneous source parameters as required for the analysis of seismicity and seismic hazard assessment. This in turn requires a detailed analysis and comparison of the properties of different available sources, including the distribution of events with time, the magnitude completeness, and the scaling relations between different kinds of magnitude reported by different agencies. The observational data cover the time interval 1900–2004 and an area between 22°–33.5° N and 25°–36° E. The linear regressions between various magnitude types have been evaluated for different magnitude ranges. Using the best linear relationship determined for each available pair of magnitudes, as well as those identified between the magnitudes and the seismic moment, we convert the different magnitude types into moment magnitudes M W, through a multi-step conversion process. Analysis of the catalogue completeness, based on the M W thus estimated, allows us to identify two different time intervals with homogeneous properties. The first one (1900–1984) appears to be complete for M W ≥ 4.5, while the second one (1985–2004) can be considered complete for magnitudes M W ≥ 3.  相似文献   

5.
A probabilistic seismic hazard assessment is developed here using maximum credible earthquake magnitude statistics and earthquake perceptibility hazard. Earthquake perceptibility hazard is defined as the probability a site perceives ground shaking equal to or greater than a selected ground motion level X, resulting from an earthquake of magnitude M, and develops estimates for the most perceptible earthquake magnitude, M P(max). Realistic and usable maximum magnitude statistics are obtained from both whole process and part process statistical recurrence models. These approaches are extended to develop relationships between perceptible earthquake magnitude hazard and maximum magnitude recurrence models that are governed by asymptotic and finite return period properties, respectively. Integrated perceptibility curves illustrating the probability of a specific level of perceptible ground motion due to all earthquakes over the magnitude range extending from ?∞ to a magnitude M i are then developed from reviewing site-specific magnitude perceptibility. These lead on to achieving site-specific annual probability of exceedance hazard curves for the example cities of Sofia and Thessaloniki for both horizontal ground acceleration and ground velocity. Both the maximum credible earthquake magnitude M 3 and the most perceptible earthquake magnitude M P(max) are of importance to the earthquake engineer when approaching anti-seismic building design. Both forms of hazard are illustrated using contoured hazard maps for the region bounded by 39°–45°N, 19°–29°E. Patterns are observed for these magnitude hazard estimates—especially M P(max) specific to horizontal ground acceleration and horizontal ground velocity—and compared to inferred patterns of crustal deformation across the region. The full geographic region considered is estimated to be subject to a maximum credible earthquake magnitude M 3—estimated using cumulative seismic moment release statistics—of 7.53 M w, calculated from the full content of the adopted earthquake catalogue, while Bulgaria’s capital, Sofia, is estimated a comparable value of 7.36 M w. Sofia is also forecast most perceptible earthquake magnitudes for the lowest levels considered for horizontal ground acceleration of M PA(50) = 7.20 M w and horizontal ground velocity of M PV(5) = 7.23 M w for a specimen focal depth of 15 km.  相似文献   

6.
Turkey has been divided into eight different seismic regions taking into consideration the tectonic environments and epicenters of the earthquakes to examine relationships of the modal values (a/b), the expected maximum magnitudes (Mmax) and the maximum intensities (Imax). For this purpose, the earthquakes for the time period 1900–1992 from the Global Hypocenter Data Base CD-ROM prepared by USGS, and for the time period 1993–2001 from the PDE data and IRIS data are used. Concerning the relationships developed between different magnitude scales and between surface wave magnitudes (MS) and intensity for different source regions in Turkey, we have constructed a uniform catalog of MS. We have estimated the values of Mmax and Imax using the Gumbel III asymptotic distribution. Highest a-values are observed in the Aegean region and the lowest b-values are estimated for the North Anatolian Fault. Maximum values of a/b, Mmax and Imax are related to the eastern and western part of the North Anatolian Fault and the Aegean Arc. The lowest values of all parameters are observed near the Mid Anatolian Fault system. Linear relationships have been calculated between a/b, Mmax and Imax using orthogonal regression. If one of the three parameters is computed, two other parameters can be calculated empirically using these linear relationships. Hazard maps of Mmax and Imax values are produced using these relationships for a grid of equally spaced points at 1°. It is observed that the maps produced empirically may be used as a measure of seismic hazard in Turkey.  相似文献   

7.
Using 4.0 and greater magnitude earthquakes which occurred between 1 January 1900 and 31 Dec 2008 in the Sinop province of Turkey this study presents a seismic hazard analysis based on the probabilistic and statistical methods. According to the earthquake zonation map, Sinop is divided into first, second, third and fourth-degree earthquake regions. Our study area covered the coordinates between 40.66°– 42.82°N and 32.20°– 36.55°E. The different magnitudes of the earthquakes during the last 108 years recorded on varied scales were converted to a common scale (Mw). The earthquake catalog was then recompiled to evaluate the potential seismic sources in the aforesaid province. Using the attenuation relationships given by Boore et al. (1997) and Kalkan and Gülkan (2004), the largest ground accelerations corresponding to a recurrence period of 475 years are found to be 0.14 g for bedrock at the central district. Comparing the seismic hazard curves, we show the spatial variations of seismic hazard potential in this province, enumerating the recurrence period in the order of 475 years.  相似文献   

8.
Richter magnitudes ML have been determined for 718 well recorded South Australian earthquakes by converting amplitudes derived from existing seismograph stations to equivalent Wood‐Anderson amplitudes, and substituting in Richter's formula (Richter 1935), derived for such instruments and for Southern California. The magnitudes so determined were generally found to increase with distance A for each earthquake, at least for events at distances below a few hundred kilometres, reflecting lower attenuation of crustal S waves in South Australia.

A distance‐dependent correction, which must be subtracted from Richter magnitudes, was obtained by integrating the weighted least squares fit to the (A, dML/dA) data. The correction increases to one‐half of a magnitude unit at a distance of 400 km, and thereafter decreases smoothly to 0.3 units at 600 km. Station corrections, due to local geological variations, have also been determined. Values range from ‐0.6 to + 0.2 units.

Empirical relationships between the revised ML scale and the previously used local magnitude scales mL and MN (White 1968; Stewart 1975) and the body wave magnitude scale mb have been established. The latter yields results consistent with the well known Gutenberg‐Richter formula (Richter 1958)  相似文献   

9.
A regional time and magnitude predictable model has been applied to estimate the recurrence intervals for large earthquakes in the vicinity of 8 October 2005 Kashmir Himalaya earthquake (25°–40°N and 65°–85°E), which includes India, Pakistan, Afghanistan, Hindukush, Pamirs, Mangolia and Tien-Shan. This region has been divided into 17 seismogenic sources on the basis of certain seismotectonics and geomorphological criteria. A complete earthquake catalogue (historical and instrumental) of magnitude Ms ≥ 5.5 during the period 1853–2005 has been used in the analysis. According to this model, the magnitude of preceding earthquake governs the time of occurrence and magnitude of future mainshock in the sequence. The interevent time between successive mainshocks with magnitude equal to or greater than a minimum magnitude threshold were considered and used for long-term earthquake prediction in each of seismogenic sources. The interevent times and magnitudes of mainshocks have been used to determine the following predictive relations: logT t = 0.05 M min + 0.09 M p − 0.01 log M 0 + 01.14; and M f = 0.21 M min − 0.01 M p + 0.03 log M 0 + 7.21 where, T t is the interevent time of successive mainshocks, M min is minimum magnitude threshold considered, M p is magnitude of preceding mainshock, M f is magnitude of following mainshock and M 0 is the seismic moment released per year in each seismogenic source. It was found that the magnitude of following mainshock (M f) does not depend on the interevent time (T t), which indicates the ability to predict the time of occurrence of future mainshock. A negative correlation between magnitude of following mainshock (M f) and preceding mainshock (M p) indicates that the larger earthquake is followed by smaller one and vice versa. The above equations have been used for the seismic hazard assessment in the considered region. Based on the model applicability in the studied region and taking into account the occurrence time and magnitude of last mainshock in each seismogenic source, the time-dependent conditional probabilities (PC) for the occurrence of next shallow large mainshocks (Ms ≥ 6.5), during next 20 years as well as the expected magnitudes have been estimated.  相似文献   

10.
Tokutaro Hatori 《GeoJournal》1996,38(3):313-319
The regional characteristics of tsunami magnitudes in the SE Asia region are discussed in relation to earthquake magnitudes during the period from 1960 to 1994. Tsunami magnitudes on the Imamura-Iida scale are investigated by the author's method (Hatori 1979, 1986) using the data of inundation heights near the source area and tide-gauge records observed in Japan. The magnitude values of the Taiwan tsunamis showed relatively to be small. On the contrary, the magnitudes of tsunamis in the vicinities of the Philippines and Indonesia exceed more than 1–2 grade (tsunami heights: 2–5 times) compared to earthquakes with similar size on the circum-Pacific zone. The relation between tsunami magnitude, m, and earthquake magnitude, M s, is expressed as m = 2.66 M s– 17.5 for these regions. For example, the magnitudes for the 1976 Mindanao tsunami (M s= 7.8, 3702 deaths) and the 1992 Flores tsunami (M s= 7.5, 1713 deaths) were determined to be m = 3 and m = 2.5, respectively. The focal depth of tsunamigenic earthquakes is shallower thand< 36 km, and the detectively of tsunamis is small for deep earthquakes being d > 40 km. For future tsunamis, it is indispensable to take precautions against shallow earthquakes having the magnitudes M s> 6.5.  相似文献   

11.
A homogenous earthquake catalog is a basic input for seismic hazard estimation, and other seismicity studies. The preparation of a homogenous earthquake catalog for a seismic region needs regressed relations for conversion of different magnitudes types, e.g. m b , M s , to the unified moment magnitude M w. In case of small data sets for any seismic region, it is not possible to have reliable region specific conversion relations and alternatively appropriate global regression relations for the required magnitude ranges and focal depths can be utilized. In this study, we collected global events magnitude data from ISC, NEIC and GCMT databases for the period 1976 to May, 2007. Data for mb magnitudes for 3,48,423 events for ISC and 2,38,525 events for NEIC, M s magnitudes for 81,974 events from ISC and 16,019 events for NEIC along with 27,229 M w events data from GCMT has been considered. An epicentral plot for M w events considered in this study is also shown. M s determinations by ISC and NEIC, have been verified to be equivalent. Orthogonal Standard Regression (OSR) relations have been obtained between M s and M w for focal depths (h < 70 km) in the magnitude ranges 3.0 ≤ M s  ≤ 6.1 and 6.2 ≤ M s  ≤ 8.4, and for focal depths 70 km ≤ h ≤ 643 km in the magnitude range 3.3 ≤ M s  ≤ 7.2. Standard and Inverted Standard Regression plots are also shown along with OSR to ascertain the validation of orthogonal regression for M s magnitudes. The OSR relations have smaller uncertainty compared to SR and ISR relations for M s conversions. ISR relations between m b and M w have been obtained for magnitude ranges 2.9 ≤ m b  ≤ 6.5, for ISC events and 3.8 ≤ m b  ≤ 6.5 for NEIC events. The regression relations derived in this study based on global data are useful empirical relations to develop homogenous earthquake catalogs in the absence of regional regression relations, as the events catalog for most seismic regions are heterogeneous in magnitude types.  相似文献   

12.
以穿越汶川震区的成兰铁路龙门山关键段为例, 探索提出了强震扰动背景下重大工程场区多尺度滑坡危险性评估方法。利用信息量模型反演评估了汶川地震诱发的同震滑坡空间分布特征, 以此为前提开展了区域和局地两种空间尺度的滑坡危险性预测评估。在区域廊带尺度上, 分别利用可能最大降雨量预测方法和信息量模型, 进行了日超越概率10%的最大降雨量时空分布预测及其诱发滑坡的危险性评估; 同时, 结合地震危险性区划成果, 开展了50年超越概率10%的基本地震动诱发滑坡的危险性评估。在局地场站尺度上, 利用基于崩塌运动过程模拟的Rockfall Analyst软件, 开展了柿子园大桥周边崩塌运动学特征(Runout)模拟和危险性评估。滑坡和崩塌危险性评估的结果分别为铁路规划选线和场站防护设计提供了不同尺度的地质安全依据。   相似文献   

13.
This study presents the future seismic hazard map of Coimbatore city, India, by considering rupture phenomenon. Seismotectonic map for Coimbatore has been generated using past earthquakes and seismic sources within 300 km radius around the city. The region experienced a largest earthquake of moment magnitude 6.3 in 1900. Available earthquakes are divided into two categories: one includes events having moment magnitude of 5.0 and above, i.e., damaging earthquakes in the region and the other includes the remaining, i.e., minor earthquakes. Subsurface rupture character of the region has been established by considering the damaging earthquakes and total length of seismic source. Magnitudes of each source are estimated by assuming the subsurface rupture length in terms of percentage of total length of sources and matched with reported earthquake. Estimated magnitudes match well with the reported earthquakes for a RLD of 5.2% of the total length of source. Zone of influence circles is also marked in the seismotectonic map by considering subsurface rupture length of fault associated with these earthquakes. As earthquakes relive strain energy that builds up on faults, it is assumed that all the earthquakes close to damaging earthquake have released the entire strain energy and it would take some time for the rebuilding of strain energy to cause a similar earthquake in the same location/fault. Area free from influence circles has potential for future earthquake, if there is seismogenic source and minor earthquake in the last 20 years. Based on this rupture phenomenon, eight probable locations have been identified and these locations might have the potential for the future earthquakes. Characteristic earthquake moment magnitude (M w ) of 6.4 is estimated for the seismic study area considering seismic sources close to probable zones and 15% increased regional rupture character. The city is divided into several grid points at spacing of 0.01° and the peak ground acceleration (PGA) due to each probable earthquake is calculated at every grid point in city by using the regional attenuation model. The maximum of all these eight PGAs is taken for each grid point and the final PGA map is arrived. This map is compared to the PGA map developed based on the conventional deterministic seismic hazard analysis (DSHA) approach. The probable future rupture earthquakes gave less PGA than that of DSHA approach. The occurrence of any earthquake may be expected in near future in these eight zones, as these eight places have been experiencing minor earthquakes and are located in well-defined seismogenic sources.  相似文献   

14.
The maximum likelihood estimation of earthquake hazard parameters (maximum regional magnitudem max, activity rate λ, and theb parameter in the Gutenberg-Richter distribution) is extended to the cases of incomplete and uncertain data. The method accepts mixed data containing only large (extreme) events and a variable quality of complete data with different threshold magnitude values. Uncertainty of earthquake magnitude is specified by two values, the lower and upper magnitude limits. It is assumed that such an interval contains the real unknown magnitude. The proposed approach allows the combination of different quality catalog parts, e.g. those where the assignment of magnitude is questionable and those with magnitudes precisely determined. As an illustration of the method, the seismic hazard analysis for western Norway and adjacent sea area (4–8°E, 58–64°N) is presented on the basis of the strongest earthquakes felt during the period 1831–1889 and three complete catalog parts, covering the period 1890–1987.  相似文献   

15.
North-east India is seismically very active and has experienced many widelydistributed shallow, large earthquakes. Earthquake generation model for the region was studied using seismicity data [(1906–1984) prepared by National Geophysical Data Centre (NGDC), Boulder Colorado, USA]. For establishing statistical relations surface wave magnitudes (M s≥5·5) have been considered. In the region four seismogenic sources have been identified which show the occurrences of atleast three earthquakes of magnitude 5·5≤M s≤7·5 giving two repeat times. It is observed that the time interval between the two consecutive main shock depends on the preceding main shock magnitude (M p) and not on the following main shock magnitude (M f) revealing the validity of time predictable model for the region. Linear relation between logarithm of repeat time (T) and preceding main shock magnitude (M p) is established in the form of logT=cM p+a. The values ofc anda are estimated to be 0–36 and 1–23, respectively. The relation may be used for seismic hazard evaluation in the region.  相似文献   

16.
The earthquake hazard parameters and earthquake occurrence probabilities are computed for the different regions of the North Anatolia Fault Zone (NAFZ) using Bayesian method. A homogenous earthquake catalog for M S magnitude which is equal or larger than 4.0 is used for a time period between 1900 and 2015. Only two historical earthquakes (1766, M S = 7. 3 and 1897, M S = 7. 0) are included in Region 2 (Marmara Region) where a large earthquake is expected in the near future since no large earthquake has been observed for the instrumental period. In order to evaluate earthquake hazard parameters for next 5, 10, 20, 50, 100 years, M max (maximum regional magnitude), β value, λ (seismic activity or density) are computed for the different regions of NAFZ. The computed M max values are changed between 7.11 and 7.89. While the highest magnitude value is calculated in the Region 9 related to Tokat-Erzincan, the lowest value in the Region 10 including the eastern of Erzincan. The “quantiles” of “apparent” and “true” magnitudes of future time intervals of 5, 10, 20, 50, and 100 years are calculated for confidence limits of probability levels of 50, 70 and 90 % of the 10 different seismic source regions. The region between Tokat and Erzincan has earthquake hazard level according to the determined parameters. In this region the expected maximum earthquake size is 7.8 with 90 % occurrence probability in next 100 years. While the regional M max value of Marmara Region is computed as 7.61, expected maximum earthquake size is 7.37 with 90 % occurrence probability in next 100 years.  相似文献   

17.
The Gulf of Aqaba is considered seismically as one of the most active zones of the Dead Sea Transform region. The main shock of the 1995 Gulf of Aqaba earthquake sequence is considered as the largest shock in the (surface wave magnitude Ms?=?7.2) since the sixteenth century. The present study is a trial to detect the probabilistic seismic hazard analysis (PSHA) for Nuweiba site. Data used for this study was a combination of both historical and recent instrumental data. Results of the hazard assessment, expressed as in the worst case scenario, reveal that Nuweiba is exposed to the occurrence of a maximum credible earthquake of magnitude $ m_{{\max }} ~ = ~7.4 \pm 0.31 $ , at hypocentral distance of 15.6?±?10 km. For structure with the return period of 100 years, with a 90% probability of exceedance, the maximum expected earthquake magnitude (ML) is 5.9 in this lifetime. The possibility of the maximum peak ground acceleration at the Nuweiba site is 0.41 g. Results of the hazard assessment can be used as an input data to assess the seismic risk for site of interest.  相似文献   

18.
Seismicity of Gujarat   总被引：2，自引：2，他引：0  
Paper describes tectonics, earthquake monitoring, past and present seismicity, catalogue of earthquakes and estimated return periods of large earthquakes in Gujarat state, western India. The Gujarat region has three failed Mesozoic rifts of Kachchh, Cambay, and Narmada, with several active faults. Kachchh district of Gujarat is the only region outside Himalaya-Andaman belt that has high seismic hazard of magnitude 8 corresponding to zone V in the seismic zoning map of India. The other parts of Gujarat have seismic hazard of magnitude 6 or less. Kachchh region is considered seismically one of the most active intraplate regions of the World. It is known to have low seismicity but high hazard in view of occurrence of fewer smaller earthquakes of M????6 in a region having three devastating earthquakes that occurred during 1819 (M w7.8), 1956 (M w6.0) and 2001 (M w7.7). The second in order of seismic status is Narmada rift zone that experienced a severely damaging 1970 Bharuch earthquake of M5.4 at its western end and M????6 earthquakes further east in 1927 (Son earthquake), 1938 (Satpura earthquake) and 1997 (Jabalpur earthquake). The Saurashtra Peninsula south of Kachchh has experienced seismicity of magnitude less than 6.  相似文献   

19.
The maximum likelihood estimation of earthquake hazard parameters (maximum regional magnitudem max, activity rate , and theb parameter in the Gutenberg-Richter distribution) is extended to the cases of incomplete and uncertain data. The method accepts mixed data containing only large (extreme) events and a variable quality of complete data with different threshold magnitude values. Uncertainty of earthquake magnitude is specified by two values, the lower and upper magnitude limits. It is assumed that such an interval contains the real unknown magnitude. The proposed approach allows the combination of different quality catalog parts, e.g. those where the assignment of magnitude is questionable and those with magnitudes precisely determined.As an illustration of the method, the seismic hazard analysis for western Norway and adjacent sea area (4–8°E, 58–64°N) is presented on the basis of the strongest earthquakes felt during the period 1831–1889 and three complete catalog parts, covering the period 1890–1987.Paper presented at the 21st General Assembly of the European Seismological Commission held in Sofia, 1988.On leave from Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland.  相似文献   

20.
Creepex, defined as the systematic deviation of the magnitude of a single earthquake from the linear orthogonal regression between local magnitude ML and coda duration magnitude Md, calculated for the whole region, is used as a measure of the frequency content of the seismic sources in the Italian region. Predominantly high-frequency events are found in the two areas of Quaternary tectonic shortening in North-Central Italy and in the Calabrian Arc. This result, confirmed by two independent statistical tests, is in agreement with the global pattern obtained from the study of the regression between body-wave magnitude, mb, and surface-wave magnitude Ms: systematic shift to high frequencies in the energy release of seismic sources located in subduction zones and to low frequencies in zones of spreading. The analysis of the correlation between the patterns of heat flow and of seismic source spectral properties indicates that these source properties, in general, do not reflect thermal conditions in the lithosphere, but rather represent the result of tectonic processes.  相似文献   

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