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121.
122.
<正>可操作地震预测(OEF)是不断更新和发布基于物理机制的短期(数日)破坏性地震发生概率的一种实践。尽管我们赞赏OEF的高尚意图,而且使用地震活动性进行短期预测分析具有一定的科学价值,可是我们仍然担心广泛推广短期地震预测,可能让公众相信对地震的防范程度可以像对待天气预报一样在数天或数周的时间尺度内波动。支持OEF的科学家的确认识到长期预测(数十年或数百年)的重要性。Jordan[1]指 相似文献
123.
受仪器限制,地面旋转运动直到过去10年才被观测到。日本对地震近场旋转的观测(Takeo,1998)表明,地面旋转运动是经典弹性理论估计值的很多倍。由于利用类似Takeo所用的旋转传感器没有得到有价值的地面旋转运动,于是我们在台湾东部HGSD台站布设了灵敏得多的旋转速度传感器(R-1型)。在2004年12月7日至2006年11月12日的一期观测实施期间共记录到数百个地震。这主要是解决野外观测问题的一次实习;一期观测最终因其中两台R-1传感器停止工作而结束。2007年春我们重新安装了K2+R1型仪器,从而开展了二期观测。从2007年5月8日到2008年2月17日,我们观测了52个地方震,记录到信噪比~5的好的旋转速度信号和信噪比~10的极好的平移加速度信号。可惜的是,2008年2月中旬HGSD台站被洪水淹没,野外观测由此中断,一直到2008年6月才恢复正常观测。本文叙述了迄今为止HGSD台站对地面旋转和平移运动的观测,集中描述了我们的仪器和二期观测期间所得到的52个地方震的数据,并给出一些很初步的结果。 相似文献
124.
Dry playa lakes and sabkhat often represent the terminus of large ground water flow systems and act as integrators of both upgradient (recharge) and downgradient discharge (evaporation). Ground water levels beneath playa/sabkha systems show a variety of surprising responses driven by large evaporation demands and chemical processes not typically encountered in more humid regions. When the water table is very close to the land surface, almost instantaneous rises can be observed with little observed change in either upgradient ground water recharge or potential evaporation. Conversely, when water tables are several meters below the playa surface, water table responses to interannual variability of recharge can be damped and lag significantly behind such changes. This review of the dynamics of shallow water tables in playa lakes and sabkhat discusses the pertinent hydraulic and solute processes and extracts a simple but comprehensive model based on soil physics for predicting the water table response to either upstream recharge changes or changes in potential evaporation at the playa/sabkha. Solutes and associated authigenic minerals are also shown to be important in discriminating both the causes and effects of water level fluctuations. 相似文献
125.
Thompson J Roach A Eaglesham G Bartkow ME Edge K Mueller JF 《Marine pollution bulletin》2011,62(12):2869-2875
Perfluorinated alkyl compounds (PFCs) including perfluorooctane sulphonate (PFOS) and perfluorooctanoate (PFOA) were measured in environmental samples collected from around Homebush Bay, an urban/industrial area in the upper reaches of Sydney Harbour and Parramatta River estuary. Water, surface sediment, Sea Mullet (Mugil cephalus), Sydney Rock Oyster (Saccostrea commercialis) and eggs of two bird species; White Ibis (Threskiornis molucca), and Silver Gull (Larus novaehollandiae) were analysed. In most samples PFOS was the dominant PFC. Geometric mean PFOS concentrations were 33 ng/g ww (wet weight) in gull eggs, 34 ng/g ww in ibis eggs, and 1.8 ng/g ww and 66 ng/g ww in Sea Mullet muscle and liver, respectively. In sediment the PFOS geometric mean was 1.5 ng/g, in water average PFOS and PFOA concentrations ranged from 7.5 to 21 ng/L and 4.2 to 6.4 ng/L, respectively. In oysters perfluorododecanoic acid was most abundant, with a geometric mean of 2.5 ng/g ww. 相似文献
126.
We present moderate-resolution (lambda/delta lambda = 300 to 370) reflectance spectra of Mars from 2.04 to 2.44 micrometers that were obtained at UKIRT during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO(2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 micrometers). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 micrometers) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 micrometers may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates or (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals. 相似文献
127.
128.
从数据共享的角度描述了华北地区遥测地震台网联网的基本要求、预期目标、技术途径、总体结构及联网后取得的效益,说明遥测地震台网联网是实现地震观测数据共享的一种有效手段。 相似文献
129.
设计了一套单机地震数据采集软件系统NCDAS。文中描述了该软件的总体结构,各任务块的功能,事件检测算法以及硬件环境。 相似文献
130.
介绍了《地震观测技术与仪器》一书的主要内容和特点,说明了在翻译该书过程中遇到的一些问题,概括了译者的几点认识. 相似文献