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91.
以陕西前兆台网24年的资料为基础,分析了少震区前兆异常的一些特性。在这个建网以来未发生过5级以上地震,每年平均发生2~3次3级多地震,年最大震级的平均值仅3.6级的陕西前兆台网中,每年年度会商所提出的各类测项异常比在11%~20%之间,综合异常比为15%。这些异常比的变化曲线与陕西省内地震频次的强度变化曲线不同步,它们是与地震无关的测值变化,可能是未被人们认识的外界干扰,也可能是地壳内部应力积聚又释放但又无地震发生的一种地壳蠕动结果。 相似文献
92.
Precise tidal gravity recorded with superconducting gravimeters at stations Wuhan (China) and Kyoto (Japan) 总被引:9,自引:0,他引:9
Three long series of tidal gravity observations, totalizing approximately 24 years and recorded with three superconducting
gravimeters, T004, T008, and T009, at stations Wuhan (China) and Kyoto (Japan), are studied. The tidal amplitude factors and
phase differences are determined precisely using Eterna and Nsv techniques. The precision of the main tidal amplitudes is
at the same level of 0.01 μGal. The atmospheric gravity signals are corrected using the coefficients determined with a regression
method between tidal gravity residual and station air pressure. The oceanic gravity signals are modeled based on five global
oceanic models. It is found that the oceanic models developed by the analysis of measurements from Topex/Poseidon altimeters
have the best fit to the superconducting gravimeter measurements, since the observed residuals and the discrepancies between
the amplitude factors and the theoretical tidal models are reduced more significantly. The long-period gravity variations
are dominated by the non-linear drift phenomena of the instruments, and the short-term variations in gravity are due to the
background noise at the stations.
Received: 20 January 2000 / Accepted: 15 September 2000 相似文献
93.
短期前兆动态变化与地震关系的研究 总被引:1,自引:2,他引:1
应用地震前周、月会商中各前兆手段提出了短期兆异常动态变化,研究了地震短临异常的某些特征和综合预报指标,其最大的特点是应用在不知未来是否有地震的情况下提供的短期异常,总结了地震预报的经验,所以,是从一个新的角度研究的,而不同于以往的震例总结,因此,该经验更接近于日常实际的预报,可能更具有实用性。 相似文献
94.
With the rapid development of BeiDou satellite navigation system (BDS), high-quality service has been provided in the Asia-Pacific region currently, which will be extended to the whole world very soon. BDS is the first Global Navigation Satellite System that all satellites broadcast the triple-frequency signals. The triple-frequency signals in theory can improve the cycle slip detection that is one of the preconditions in precise positioning by making use of carrier phase. This paper discusses the development of a cycle slip detection method for undifferenced BDS triple-frequency observations in kinematic scenario. In this method, two geometry-free extra-wide-lane combinations and one geometry-free narrow-lane (NL) combinations are employed. The key is to mitigate the between-epoch ionospheric biases in the geometry-free NL combinations. We propose to predict the ionospheric biases of current epoch by using those from its consecutive foregoing epochs. The method is tested with extensive experiments in varying observation scenarios. The results show that in case of sampling interval as small as 5 s, the between-epoch ionospheric biases can be ignored and the correct cycle slips can be determined. Meanwhile in case of lower sampling frequency, one needs to compensate the ionospheric biases of current epoch by using the predicted ionospheric biases. The presented method can correctly detect all cycle slips even if they are as small as 1 cycle. 相似文献
95.
An even–odd signal decomposition is performed on a complex shoreline having a longshore sediment transport gradient. The expected impact of erosion due to a navigation channel and structures is discussed and implications of the transport gradient on the decomposed shoreline signal are noted. 相似文献
96.
97.
主要介绍了一种在GNSS信号中抑制多径信号的鉴相方法,接收机接收到的GNSS信号中往往包含多径信号,GNSS信号进行下变频生成中频信号后,进行模数转换;将经过模数转换后的GNSS信号进行载波剥离,得到I路和Q路的信号,在码跟踪环路中,对I路和Q路信号进行码剥离,得到多径信号的互相关功率后,采用基于精密TK采样间隔的TK—EML5鉴相方法,能够起到有效地抑制多径信号的效果。 相似文献
98.
99.
在综合分析兴海6.6级地震前震(前)兆异常及其时空演化特征的基础上,探讨预报过程中存在的科学问题。 相似文献
100.
以嘉峪关台的原始资料为依据,着重探讨了肃南5.3级地震前祁连山西段的地震活动性异常。将本台的地磁Z分量与兰州、天水地磁台进行比较,结果认为:肃南5.3级地震的发生基本符合祁连山西段地震活动的周期性特征,前兆资料无明显的临震异常显示,但本台的自然电场,地磁日幅差和Z分量的日均值资料有明显的短期趋势性异常显示。 相似文献