黔西南高砷煤中砷存在形式的初步研究

利用电子探针、扫描电镜_能谱分析、X衍射分析、低温灰化、透射电镜、X射线吸收精细结构分析、化学成分分析结果对黔西南高砷煤中砷的存在形式进行了初步研究 ,高砷煤中的砷主要以 5价 (含砷磷酸盐和砷酸盐 )的形式存在 ,少量砷以含砷硫化物如含砷黄铁矿、毒砂、雌黄 ( ?)形式存在 .在砷含量最高的H2样品中可能主要以有机砷的形式存在 .     

蠕滑中的断层:是福，还是祸？

地球构造板块运动驱动断层滑动。一些断层会以地震的形式快速破裂,释放大量能量;另一些断层则以更加平稳的方式滑动,从而缓慢的释放能量。后者就是所谓的蠕滑断层,通常被认为地震危险性较小,但是越来越多的证据表明它们比先前认识的更为复杂,依然具有显著的致灾性。Harris[1]最新的一篇综述报道了全球范围内浅层大陆断层带蠕滑断层的地震潜力。本文通过对已有的研究进行全面的回顾,重点关注了何时、何地,为什么发生断层蠕滑,以及哪些情况下断层蠕滑可能代表着高地震危险性,并对未来工作方向提出一些建议。      

地震预警:ShakeAlert在太平洋西北部的应用

对地震预警算法ElarmS-2(地震报警系统第二版)在太平洋西北部的应用效果进行了评估。本文数据来源于美国俄勒冈州、加利福尼亚州、华盛顿州和加拿大的不列颠哥伦比亚省(这里的3州1省即本文所指太平洋西北部——译注,下同)的实时监测数据和历史地震数据。在测试的地震中,矩震级最大的为7.2级,这也是ElarmS-2算法可以精确测量的最大震级。在台网范围内,ElarmS-2可以准确检测到台网内编目震级大于等于3级的地震,但是对于发生在海上或台网边缘的地震,ElarmS-2能准确识别的事件的截止震级会偏高。对ElarmS-2算法进行若干调整后,降低了发出错误的多重警报的概率。通过模拟历史地震事件,发现新的配置改善了发生在台网边缘的地震事件的算法的性能,而且不会影响台网密集区域的地震事件良好约束的解。我们希望误报数量减少,而且不会误报大地震事件。虽然ElarmS-2假设固定的震源深度,但是震中距和震级估计值仍然是足够准确的,可以提供对震动强度的准确预测。     

用经验格林函数方法模拟汶川M_W7.9地震的强地震动

汶川M_W7.9地震的发生震惊了中国乃至全世界,不仅仅因为该地震震级巨大,还因为其可怕的伤亡。评估汶川M_W7.9地震的复杂性及破坏力需对其地震特征进行研究。本文运用经验格林函数方法(EGF)模拟了地震的强地震动。首先,选取了4个震级为M_W4.9和M_W5.0的余震,对这些余震的运动利用格林函数进行了模拟。通过模拟,可以估算出包括断层规模和应力降在内的余震震源参数。然后,通过试错法正演模拟得出M_W7.9地震凹凸体(强震动生成区)的震源模型。为验证该震源模型的准确性,运用经验格林函数方法模拟合成了9个台站的强地震动。将模拟得出的强地震动与观测记录到的加速度波形、速度波形和拟加速度反应谱相比较。尽管有一些差异,但在大部分台站,合成的强地震动与观测记录结果相吻合。在模拟得出的震源模型中,断层面上3个凹凸体的应力降约为10MPa,而凹凸体面积与破裂面积比为0.24,接近经验关系式得出的结果0.22。     

Geophonino-3D的设计与测试:应用H/V谱比法的低成本三分量地震噪声记录仪

地震效应与地震发生地的地质特性密切相关,会加强该地区的地表运动,尤其是软土地区。加强的程度与共振频率相关,可通过水平与垂直谱比法(H/V谱比法)测量地震噪声从而估算共振频率。本文设计了一种低成本用户友好型数据采集系统(Geophonino-3D),用于记录三分量地震噪声。可开发的系统由信号调节电路和安装有SD Shield(用于存储数据)的Arduino Due组成。本设备首先在实验室中对其实验灵敏度、内部噪声稳定性、通道一致性进行了测试,评估了其是否适用于H/V谱比法。随后,通过在阿利坎特省(西班牙东南部)8个土壤特性不同的场地记录地震噪声,进行了实验验证。根据比较商用地震记录仪测出的功率谱密度和H/V峰值,评估了所开发数据采集系统的性能。所得结果表明本数据采集系统适用于应用H/V谱比法记录地震噪声。Geophonino-3D采用开源和开放硬件系统,部件价格远低于其他商用设备,对于资金短缺的研究团队来说,这是明显的进步。     

Deadly oasis:Recurrent annihilation of Cretaceous desert bryophyte colonies;the role of solar,climate and lithospheric forcing

Many oases(wet interdunes)are sedimentary systems characterized by high-frequency water-level oscillations,marked changes in salinity and intense biological activity at their margins.They are considered to be one of the most challenging environments on Earth for ecosystem development.These dynamic,depositional settings are usually unfavourable for fossilization and subsequent preservation of vegetal remains.This paper describes bryophyte(liverwort)assemblages occurring in three successive horizons interpreted to represent(i)recurrent early successional phases of biological soil crust colonization of wet interdune margins or(ii)exceptional preservation of floating or riparian liverworts in oasis pond waters associated with a progressive fall of the interdune water level.The record of in situ colonization surfaces characterized by delicate(e.g.lignin-free)three-dimensional structures represents an exceptional type of preservation herein associated with a rapid variation in phreatic interdune water level and the subsequent establishment of anoxic and reducing conditions.The occurrence of exceptionally preserved liverwort colonies coincides with the sedimentary record of,at least,three seismite levels in the oasis.Data gathered from the site suggests that the water table of the oasis was controlled by a combination of(i)a positive creation of accommodation space due to subsidence associated with movement on syn-sedimentary extensional faults,and(ii)the rise and fall of the oasis water table controlled by the oscillations of the groundwater system due to orbital changes which appear to drive the variability of the climate system.Rising groundwater levels flooded the oasis soil crusts and lead to the exceptional recurrent preservation of liverwort colonies at the oasis margins.Alternatively,considering the hypothesis of floating or riparian liverworts in the oasis pond waters,the fall in the level of the oasis water table placed the floating liverworts in contact with the oasis bottom sediments.This fall in the level of the oasis water table could indicate a cessation of accommodation space by syn-sedimentary extensional faults and/or a regional lowering of the groundwater system level associated with drought periods.Preliminary results indicate that oasis lamination between liverwort colonies records decadal and sub-decadal cyclicity,related with 11-year Schwabe sunspot and sub-decadal NAO cyclicities,conferring for every sedimentary cycle between liverwort colonies a duration of approximately 200 years,that otherwise matches the expected recurrence period for the De Vries cycle of solar activity.