本文是针对迄今为止中国在地震大小的度量方面存在的主要问题撰写的.在阐明地震大小物理含义的基础上,首先指出由震源辐射能量ER出发所定义的传统震级标度ML,mb(mB),MS都存在着“以偏概全”,“震级饱和”和ML震级标度的“局限性”,以及不同标度的震级之间不可相互换算等问题.而由在地震破裂的整个过程中震源区“等效力”所做的功出发导出的地震矩M0是对地震大小最科学的度量.为继续应用“震级”这一术语来描述地震的大小,由M0所定义的矩震级标度MW不仅克服了传统震级标度存在的各种问题,而且适用对不同大小、不同震中距、不同震源深度地震大小的度量.因此近20年已被国际地震学界普遍采用.最后强调推进地震大小的度量与国际接轨是推进中国地震科技现代化必须解决的重要基础性工作,不仅有利于国际地震科技交流合作,而且有助于增强防震减灾工作的科学性.

Using the regional stress tensor damping inversion method and focal mechanism data （466 ML≥3.5 earthquakes focal mechanism solutions from January 2009 to August 2017 and 259 M≥4.5 earthquakes focal mechanism solutions from January 1976 to August 2017 from the GCMT）, we have obtained the distribution of the stress field by 1.0°×1.0° grid region in the North-South Seismic Belt and its adjacent regions. The spatial distributions of stress field show that, because of the complex dynamic environment, there are differences between the maximum principal stress direction inside the North-South Seismic Belt which is the east boundary of the Tibetan Plateau. The maximum principal stress direction in the northern segment of the North-South Seismic Belt is NE. In and surround the middle segment of the North-South Seismic Belt, the maximum principal stress direction is nearly EW except the NE segment of the Longmenshan fault zone whose direction is NW-NNW. The direction of the maximum principal stress in the middle and southern segments of the North-South Seismic Belt changes gradually, from nearly EW to NW/NE then to nearly NS. Overall, the maximum principal stress in the North-South Seismic Belt and its adjacent regions has a clockwise rotational pattern from north to south. Inside the Sichuan-Yunnan rhombic block the maximum principal stress is in NNW direction, while to the west of the west boundary the direction is NNE, to the east of the east boundary the direction is NW. The stress direction transition bands have well corresponded with the Sichuan-Yunnan rhombic block boundary. According to the analysis of regional tectonic stress field, it is difficult to apply the North-South Seismic Belt as a unified seismic belt to the medium and long-term earthquake prediction.

地震带的划分是中长期地震预测研究的重要基础工作之一.近几十年来围绕地震带的划分取得了不少进展,各种方法在解释一些强震发生的问题时获得了某些成功,但划分结果具有很大的差异性,并遇到了这样或那样问题的挑战.基于前人的研究工作,本研究以区域构造应力场特征为出发点,提出地震带应具备的3个基本条件.

基于CAP方法,使用地震波形资料,计算得到了2009年1月～2017年8月期间南北地震带及周边区域466个3.5级以上地震震源机制解.在补充收集1976年1月～2017年8月GCMT公布的259个4.5级以上地震震源机制解的基础上,分析了南北地震带地震震源机制解和应力特征.震源机制空间分布显示,不同断裂带、块体间表现出不同的震源机制空间分布特征,该特征与南北地震带不同段落活动构造性质基本吻合.作为青藏高原东边界的南北地震带,由于动力环境复杂,其内部P轴方向具有明显的差异性.这种差异主要表现为:南北地震带北段P轴呈NE向分布;龙门山断裂带及周边除NE段P轴取向为NW—NNW向外,其他地段P轴近EW向;川滇菱形块体内部P轴呈NNW向,而其西边界以西呈NNE向,东边界以东呈NW向,应力方向转换带的与川滇菱形块体边界基本一致.整体而言,南北地震带及近邻P轴方向由北到南发生了顺时针转动.

Combination of velocity, Poisson's ratio, and attenuation structure is a powerful tool to investigate the characteristics of media, and it is especially useful to infer the lithology, porosity, water content of rocks, fluid infiltration depth, and distribution in the reservoir area. Using data from 4967 earthquakes recorded by a high-density seismic network, we carried out high-resolution 3D V-P, V-P/P-S Q(P), and Q(S) tomography research in the Three Gorges Reservoir area of China, where the world's largest high-capacity hydroelectric power station is located. We found two regions with significantly low V-P, high V-P/V-S, and low Q(P) and Q(S); one is the region between the Shuitianba fault and the western edge of the Huangling dome, and the other is the Badong region on the upstream Yangtze River, where more than 2000 earthquakes occurred in four months after the reservoir was first impounded. We infer that there is significant fluid infiltration in the two regions. The interior area of the Zigui basin is shown as a low-V-P region at depths of 0-6 km, which is consistent with the depth to crystalline basement. The Three Gorges dam area is a region with moderately high V-P, low V-P/V-S, and prominently high Q(P) and Q(S), demonstrating no obvious water infiltration around the dam area. Combining present results with previous studies, we draw a conclusion that the distance away from main rivers, lithologies, and the presence of faults are the main factors contributing to the fluid infiltration distribution beneath the reservoir region.

Objective: Single-channel noise reduction (SCNR) and dynamic range compression (DRC) are important elements in hearing aids. Only relatively few studies have addressed interaction effects and typically used real hearing aids with limited knowledge about the integrated algorithms. Here the potential benefit of different combinations and integration of SCNR and DRC was systematically assessed. Design: Ten different systems combining SCNR and DRC were implemented, including five serial arrangements, a parallel and two multiplicative approaches. In an instrumental evaluation, signal-to-noise ratio (SNR) improvement and spectral contrast enhancement (SCE) were assessed. Quality ratings at 0 and +6dB SNR, and speech reception thresholds (SRTs) in noise were measured using stationary and babble noise. Study sample: Thirteen young normal-hearing (NH) listeners and 12 hearing-impaired (HI) listeners participated. Results: In line with an increased segmental SNR and spectral contrast compared to a serial concatenation, the parallel approach significantly reduced the perceived noise annoyance for both subject groups. The proposed multiplicative approaches could partly counteract increased speech distortions introduced by DRC and achieved the best overall quality for the HI listeners. Conclusions: For high SNRs well above the individual SRT, the specific combination of SCNR and DRC is perceptually relevant and the integrative approaches were preferred.

利用谱振幅相关系数法对发生在我国东北地区的2次中强地震进行研究.结果显示,1999年辽宁岫岩5.4级地震前震序列谱振幅相关系数平均值为0.90,2013年吉林前郭5.8级震群谱振幅相关系数平均值为0.88,表明二者均表现出较强的震源机制相似性,具有发生强震的背景条件,与已有研究结果一致.此外,岫岩5.4级地震余震序列的谱振幅相关系数有所下降.值得注意的是,前郭震群序列前期相关系数维持在高值,5次强震发生后其值有下降的趋势,表现出震源机制相似性的减弱,这对中强震群后续趋势的判定具有一定的启发意义.

This paper discusses the spatiotemporal pattern of seismicity during the impoundment of the Xiaowan reservoir area, Yunnan Province, China, in the period from May 21, 2005 to December 31, 2012. The filling operations took place in five phases, starting on December 16, 2008. A notable increase in seismicity was only observed during the third filling phase, starting on July 15, 2010. Seismicity increase was mostly localized within two clusters, located to the northwest and west of the dam. Seismicity rates in these clusters showed a significant correlation with the water level increase, with the seismicity starting to increase when the water level reached the area covered by the two clusters, which additionally support they were induced by the reservoir impoundment. We further investigate source parameters for 44 pre-impoundment earthquakes and 164 post-impoundment earthquakes with M L ≥ 2.0. Corner frequencies, seismic moments, and stress drops are obtained based on the spectral analysis of regional data, upon corrections for geometrical spreading, frequency-dependent Q, and site effects. Our results show that during the post-impoundment phase reservoir-induced seismicity (RIS) inside the two clusters have systematically lower stress drops with respect to those occurring at further distance, and surrounding natural tectonic earthquakes, by a factor of about two to three times, suggesting a possible source characteristic that differentiate reservoir-induced seismicity from natural tectonic earthquakes. However, temporal stress drops changes within the clusters cannot be resolved. To compare the difference in stress drop between RIS and natural tectonic earthquakes, not only the difference in stress drop due to different region, but also the temporal change of background stress level even in the same region should be taken into account.

The object of this paper is to investigate the seismogenic fault structures and stress field where M(S)7. 3 Yushu earthquake sequence occurred in April 2010, and then tentatively discuss the triggering mechanism for the Yushu M(S)7. 3 mainshock and M(S)5. 9 strong aftershock sequences.We adopted double difference algorithm for earthquake hypocenter relocation by using different seismic velocity models, and chose the outcome with the maximal proportion of relocated earthquakes in total events as our final result. With the combination of focal mechanism solutions and earthquake relocation, the fault structures and stress field for Yushu earthquake sequences were comprehensively analyzed.After the relocation of M-L >= 1. 0 earthquakes among Yushu earthquake sequence from April 14 to October 31, 2010, we obtained precise locations of 1545 earthquakes. Relocation results show that Yushu earthquake sequence was mainly composed of two intersecting seismic strips west trending seismic zone along Ganzi-Yushu fault. This seismic strip extended for about 80 kilometers with 300 degree trending and indicated a high-angle fault plane that is close to upright. The M(S)5. 9 aftershock on May 29 occurred in a wide NEE rectangular strip, which extended approximately 40 kilometers with a width of 18 kilometers, indicating a possible buried fault. The relocated Yushu earthquake sequences occurred from ground surface to around 15 kilometer in depth, but were mainly concentrated in the depth range of 8 to 12 kilometers. Combined analysis of double difference and focal mechanism leads to the conclusion that the NW fault plane in the focal mechanism solution for mainshock is most likely the seismogenic fault of mainshock sequence. The mainshock fault is a NW trending, nearly vertical, and sinistral strike-slip fault. The seismogenic fault plane for M(S)5. 9 aftershock is an NEE, almost upright sinistral strike-slip fault. The maximum principal stress direction in mainshock seismic zone is consistent with the regional principal stress direction, while the maximum principal stress direction in the M(S)5. 9 aftershock zone equals to the direction after 34 degrees counterclockwise rotation of the maximum principal stress in the main quake zone, which might be attributable to local stress accumulation and adjustment after the mainshock.The seismogenic structure for M(S)7. 3 Yushu earthquake consists of two NW trending and NEE trending faults. The mainshock occurred in NW Ganzi-Yushu fault, while M(S)5. 9 aftershock possibly took place in an NEE trending buried fault. Both of these faults appear to be upright. Ganzi-Yushu fault is the tectonic boundary between Qiangtang Block and Bayan Har Block. Due to differential block movements of Qiangtang Block and Bayan Har block, the segment within Ganzi-Yushu Fault with strong coupling tends to accumulate stress dramatically, and when accumulated strain energy exceeded the rupture strength of rock, the M(S)7. 3 earthquake took place. The left-lateral slip of Ganzi-Yushu fault induced by the mainshock resulted in a significant reduction of normal stress, leading to the increase of Coulomb stress. After 45 days, the M(S)5. 9 aftershock sequence was triggered by the mainshock.

作为谱振幅相关分析法的拓展应用,计算了2014年10月7日云南景谷MS6.6地震、2015年3月1日云南沧源MS5.5地震余震序列的谱振幅相关系数.结果显示,景谷地震后谱振幅相关系数维持在高值,主震后2个月,发生了MS5.8、5.9强余震.该高值体现出震源机制具有较高的一致性和较强的区域应力水平,有利于强余震的发生和区域中强地震丛集.沧源余震序列谱振幅相关系数的结果与景谷地震相似,一直处于高值.景谷地震与沧源地震所在地区历史地震序列以主一余型为主,不能简单地利用谱振幅相关系数的绝对值预测后续地震的大小,但两个序列的高值也许显示滇南较大区域目前正处于强应力状态下,存在发生中强地震的背景.

本文对我国地震应急工作由单类事件到多类事件的应急，由被动的应急到有准备的应急的发展历程作了简要的回顾。阐明地震应急具有鲜明的社会性、科学性、时代性特征，是一项复杂的系统工程。依此对地震应急的要素作了简要的讨论，指出地震应急工作的成效首先取决于主体的协调联动，同时有赖于全民防震减灾意识的增强及有关知识水平的提高和现代科学技术，尤其地震科学技术的进步与应用。

This paper describes an online algorithm for enhancing monaural noisy speech. First, a novel phase-corrected low-delay gammatone filterbank is derived for signal subband decomposition and resynthesis; the subband signals are then analyzed frame by frame. Second, a novel feature named periodicity degree (PD) is proposed to be used for detecting and estimating the fundamental period ( P0) in each frame and for estimating the signal-to-noise ratio (SNR) in each frame-subband signal unit. The PD is calculated in each unit as the multiplication of the normalized autocorrelation and the comb filter ratio, and shown to be robust in various low-SNR conditions. Third, the noise energy level in each signal unit is estimated recursively based on the estimated SNR for units with high PD and based on the noisy signal energy level for units with low PD. Then the a priori SNR is estimated using a decision-directed approach with the estimated noise level. Finally, a revised Wiener gain is calculated, smoothed, and applied to each unit; the processed units are summed across subbands and frames to form the enhanced signal. The P 0 detection accuracy of the algorithm was evaluated on two corpora and showed comparable performance on one corpus and better performance on the other corpus when compared to a recently published pitch detection algorithm. The speech enhancement effect of the algorithm was evaluated on one corpus with two objective criteria and showed better performance in one highly non-stationary noise and comparable performance in two other noises when compared to a state-of-the-art statistical-model based algorithm.

This paper proposes an algorithm that aims at analyzing and enhancing the periodicity of voiced speech in aperiodic noise. Three types of periodicity features, including normalized autocorrelation (NAC), comb filter ratio (CFR), and combination of NAC and CFR, are tried in the algorithm. The signal is decomposed into framesubband units, and the signal-to-noise ratio (SNR) of each unit is estimated based on the periodicity feature and the uncorrelated assumption of speech and noise. Based on the estimated SNR, continuous Wiener gain or binary masking gain are calculated and applied to the units. The evaluation using two instrumental measures, the overall SNR and the PESQ quality measure, shows that the combination of NAC and CFR feature with continuous Wiener gain generally performs best on a voiced utterance corpus in white, burst, and "cocktail party" noise. In comparison to two state-of-art single-microphone noise reduction algorithms with different complexity, the proposed algorithm achieves better PESQ scores.

In this paper, the research history of earthquake size measurement was reviewed in the first place. And on this basis the following points were pointed out: (1) In recent decades, the ML, mb(mB), MS magnitude scales were widely used as the measures of an earthquake size. However, they not only had "overgeneralization" or "magnitude saturation" problem, but also were just inaccurate measurement because of not fully taking into account the regional differences of seismic attenuation, especially the differences of the site response on the ground motion amplification. (2) The seismic moment M0 not only has clear physical meaning, but can also overcome many scaling problems of the ML, mb(mB), MS magnitudes. It is the most suitable physical parameter for measuring earthquakes scientifically. In order to continue the term of "magnitude", Kanamori defined the moment magnitude scale MW, although the prerequisite assumptions remain to be studied, it is still a reasonable measure of the relative size of the earthquake. (3) For measuring earthquakes more scientifically, we must make full use of a large number of waveform data by the modern regional digital seismograph network, and strengthen the research on seismic wave attenuation characteristics, site effects, the measurement of source parameters and related scaling relations. On the basis of improving measurement methods of the ML, mb(mB), MS, we should focus on improving MW scale in order to gradually advance MW as a unified physical quantity to measure the earthquake relative size, it would lay a more substantial foundation for research on earthquake science and earthquake prediction.

The temporal and spatial characteristics of 1924 post-impoundment earthquakes (M-L -0.3 to 3.1) recorded by 26 temporary stations from 16 March 2009 to 14 July 2010 in the Three Gorges reservoir area, Hubei Province, China, are investigated in this paper. The epicenters are mainly concentrated in three clusters and located along the Yangtze river within the range of 10 km from the reservoir waterfront. The hypocentral depths range from 0 to 15 km and appear to increase with the epicenters approaching the dam. Source parameters for 97 selected reservoir-induced earthquakes of M-L >= 1.5 were estimated after applying corrections for geometrical spreading, frequency-dependent Q, and site effects. The results show that the seismic moments (M-0) are between 3.96 x 10(11) and 4.07 x 10(13) N.m, whereas static stress drops (Delta sigma) are 0.01-0.26 MPa. We find the static stress drops in this area vary with seismic moment for our data range, approximately as Delta sigma proportional to M-0(0.46). Apparent stresses we obtained lie between 0.0019 and 0.049 MPa and also increase with increasing seismic moment, indicating that large earthquakes radiate more energy per seismic moment than smaller ones in the Three Gorges reservoir area and do so more efficiently. Our results show that reservoir-induced earthquakes appear to have systematically lower stress drop with respect to natural tectonic earthquakes, by about one order of magnitude. This may be attributed to the high pore pressures of the underground medium, and the presence of water decreasing the coefficient of friction.

The source rupture process of the M S 7.0 Lushan earthquake was here evaluated using 40 long-period P waveforms with even azimuth coverage of stations. Results reveal that the rupture process of the Lushan M S 7.0 event to be simpler than that of the Wenchuan earthquake and also showed significant differences between the two rupture processes. The whole rupture process lasted 36 s and most of the moment was released within the first 13 s. The total released moment is 1.9×10 19 N m with M W =6.8. Rupture propagated upwards and bilaterally to both sides from the initial point, resulting in a large slip region of 40 km×30 km, with the maximum slip of 1.8 m, located above the initial point. No surface displacement was estimated around the epicenter, but displacement was observed about 20 km NE and SW directions of the epicenter. Both showed slips of less than 40 cm. The rupture suddenly stopped at 20 km NE of the initial point. This was consistent with the aftershock activity. This phenomenon indicates the existence of significant variation of the medium or tectonic structure, which may prevent the propagation of the rupture and aftershock activity. The earthquake risk of the left segment of Qianshan fault is worthy of attention.

A pronounced increase in seismicity started in and around Longtan reservoir, southwestern China after October 1, 2006 when it began the impoundment, and by the end of May 14, 2010, about 3,233 earthquakes with −0.6 ≤ M L ≤ 4.2 had been located. This seismicity which occurred in five clusters mainly concentrated in the areas where few earthquakes had occurred before the first filling. There were four water filling periods in the Longtan reservoir, and the observed reservoir-induced seismicity (RIS) shows a strong correlation with the filling cycles. After the first filling, there appears to be an instant undrained response due to an elastic response to the reservoir load in the third and fourth cluster. Then, this seismicity is followed by a delayed, drained response due to pore pressure diffusion, with the seismicity migrating outwards in one or more directions in the second and third filling period. The seismic diffusivity (α s) we estimated is about 4.54 × 105 cm2/s. The activity levels in the five clusters are different due to differences in the structures and permeabilities of the faults. The delayed seismic response to the filling in the third cluster was due to the combined effects of the lack of local fault intersecting the reservoir and lower permeability of the rock. The b value we obtained for reservoir-induced events was significantly different and higher than that of pre-impoundment natural tectonic earthquakes in the Longtan reservoir. The results of relocated earthquakes based on double difference earthquake location algorithm showed that their focal depths were mainly shallower than about 10 km and the distribution of relocated RIS in four clusters had no relation with these intersecting faults in the Longtan reservoir except the fifth cluster. All these characteristics of RIS in the Longtan reservoir indicate that they may relate to the coupled poroelastic response that includes both pore pressure diffusion and an undrained response, but the pore pressure diffusion and the water permeation appear to play a more important role on inducing the earthquakes in Longtan reservoir.

CHENFIT-AMP is a novel nonlinear strategy that combines the fitting (gain prescription) and amplification (gain implementation) procedures for cochlear hearing loss. The fitting part of CHENFIT-AMP prescribes gain for outer hair cell (OHC) and inner hair cell (IHC) loss, respectively. The gain for OHC loss varies with the cochlear gain decided by the value of OHC loss and the input level. The gain for IHC loss varies with the value of IHC loss only and will be limited to a constant if there is a "dead region." The amplification part of CHENFIT-AMP is responsible for estimating the input level and cochlear gain based on Chen's loudness model. CHENFIT-AMP is evaluated with four typical audiograms and nine individual audiograms. A widely used nonlinear fitting procedure, NAL-NL2, is evaluated to compare prescription results with CHENFIT-AMP; a standard nonlinear amplification algorithm, multichannel compression (MCC), with the parameters provided by NAL-NL2, is also evaluated to compare amplification results with CHENFIT-AMP. For long-term average speech spectrum (LTASS) inputs, CHENFIT-AMP generally prescribes similar gain as NAL-NL2 for the typical audiograms; however, gain prescribed by CHENFIT-AMP is more individualized than NAL-NL2 for the individual audiograms, especially when the audiograms have big deviations in the slope. For LTASS-shaped noise input, the gain implemented by MCC with parameters provided by NAL-NL2 cannot completely realize the gain prescribed by NAL-NL2. For speech sentence inputs, average ratings by subjects indicated that amplification by CHENFIT-AMP was preferred and led to a louder perception than that by MCC with parameters from NAL-NL2.

We investigate the relationship between the impoundment and seismicity in the Longtan reservoir, southwestern China and find evidence that the seismicity was reservoir induced. After the reservoir impoundment, a pronounced increase in seismicity was observed in five clusters mainly concentrated in the areas where few earthquakes had occurred before the first filling. The observed induced seismicity shows a strong correlation with the filling cycles. The activity levels in the five clusters are different due to differences in the structures and permeabilities of the faults. Source parameters for 1,616 earthquakes with M L 0.1–4.2 recorded by 24 fixed and temporary stations deployed around the reservoir were calculated after applying corrections for geometrical spreading, frequency-dependent Q, and site effects. The static stress drop and apparent stress in this area both appear to increase with increasing seismic moment over the entire magnitude range. Our results show that reservoir induced earthquakes have ten times lower average stress drop than natural tectonic earthquakes. These results may indicate that the reservoir induced seismicity can occur with a lower tectonic stress due to the high pore pressures of the underground medium, and that the effect of the water decreases the coefficient of friction.