菲律宾棉兰老岛2019年4次MW>6.0地震断层运动模型及库仑应力传输研究

基于雷达干涉测量技术,利用ALOS-2、Sentinel-1卫星升降轨雷达影像,获得2019-10~12发生在菲律宾棉兰老岛的4次M_W>6.0地震的同震形变场,并以此形变结果为约束,反演得到4次地震的断层运动模型。综合分析发现,此次地震序列由3条断裂的破裂引起,其中2019-10-16和2019-10-31的2次地震为同一发震断裂,2019-10-31地震断层破裂区域位于2019-10-16地震断层破裂的东北延伸段,最大滑动量约为1.1 m,约为2019-10-16地震最大滑动量的2倍。2019-10-29地震由一条独立断层破裂引起,断层最大滑动量约为2.0 m。2019-12-15地震由一条东北向倾斜断层破裂引起,断层最大滑动量约为3.0 m。此外,2019-10-16地震引起2019-10-29地震显著滑动区明显的正向库仑应力传输;而2019-10-29地震显著增加了2019-10-31地震震源区域的库仑应力;前3次地震对2019-12-15地震孕震断层的库仑应力传输总和为负值,说明静态库仑应力传输可能不是此次地震触发的主要诱因。     

禁食暂养对卵形鲳鲹有水保活生理响应的影响

【目的】探究禁食暂养对卵形鲳鲹有水保活生理响应的影响,为卵形鲳鲹的保活运输奠定基础。【方法】通过测定暂养过程中水体的总氨氮和pH值、卵形鲳鲹血液生理生化指标、肌肉氧化应激指标等的变化,分析确定卵形鲳鲹有水保活的禁食暂养条件。【结果与结论】禁食暂养过程中,随着暂养时间的延长,水体总氨氮含量与pH值显著上升,但在禁食暂养时间为6 h时,其总氨氮质量浓度为3.22 mg/L和pH值为7.80;禁食暂养6 h可以降低或减少卵形鲳鲹的应激,使血液中乳酸脱氢酶(LDH)和谷草转氨酶(AST)活性以及皮质醇(Cortisol)、血糖(GLU)、尿素氮(BUN)和总胆固醇(T-CHO)含量处于较低水平,分别为2785.53 U/L、19.04 U/L、158.72 ng/mL、2.98 mmol/L、4.35 mmol/L和4.96 mmol/L;同时减轻了应激带来的肌肉组织氧化损失,使过氧化氢酶(CAT)活性和丙二醛(MDA)含量维持在较低水平,分别为6.34 U/L和5.86 mmol/L;卵形鲳鲹适宜的暂养条件为在鱼水比m鱼∶m水=1∶20和(25±1)℃的洁净海水中暂养6 h。     

水分胁迫对冷蒿和差不嘎蒿体内水分状况的影响

在土壤正常水分条件下,冷蒿的ψ_w,ψ_π和ψ_π100远远低于差不嘎蒿,RWD、Va及Va·Vs^-1远远大于差不嘎蒿,维系其生命活动的膨压只占差不嘎蒿的30%。土壤极端干旱时,差不嘎蒿的上述参数发生大幅度变化,抗旱能力随之提高。极旱的午后,二种灌木均遭旱害威胁,其水分状况参数值(ψ_w,ψ_O、Va和RWD)相差很小。旱后复灌的情况下,差不嘎蒿上述参数同样发生大幅度变化,各参数值可恢复到对照水平;冷蒿在干旱和复灌期间参数相对变化较小。多水环境使二种灌木束缚水含量明显提高,从外观生长状况看差不嘎蒿优于冷蒿。     

Spatial and interannual variations in sedimentation patterns recorded in nonglacial varved sediments from the Canadian High Arctic

Multiple cores taken throughout Nicolay Lake in the Canadian High Arctic contain laminated sediments that are interpreted as varved. Annual sediment accumulation during the last 197 years reveals three major patterns that have important implications for hydroclimatic reconstruction. Widespread sediment dispersal is evident during most years and contrasts with years when anomalous localized and bifurcating patterns of deposition occur. Localized deposition is limited to the centre of the lake and is attributed to turbidity currents that originate on the delta foreslope. In contrast, a bifurcating pattern is produced when the river supplying the delta switches from one to two delta distributaries, resulting in altered proximal accumulation. Principal component analysis reveals additional accumulation anomalies that are sedimentologically indistinct, but constitute important sources of localized variance. The recognition and removal of anomalous deposition patterns is critical for accurate reconstruction of sediment flux from the catchment, particularly in long records where geomorphic conditions may have changed. This study identifies potentially misleading depositional artifacts and a methodology to recognize similar depositional controls in other lakes.     

城市化对上海的增温效应

上海城市热岛效应很强, 并对气温增暖产生影响。利用主成份分析法从上海及其从近到远的４ 个郊县的２９ 年月平均温度资料中,提炼出影响上海气温变暖的两个主要因子：城市化影响和区域气候变化, 并从而推算出２９ 年来城市化使上海年平均温度增加约０．２０℃, 若排除郊区城镇化因子的影响后, 该值将更高一些。     

燕山地区中生代构造应力场特征

燕山地区现今的构造、地貌景观,是在漫长的地质历史时期,经历了长期、复杂的建造、改造过程而形成的。从沉积建造及构造形变特点来看,自元古宙至古生界,本区构造运动平缓,建造和改造的特点主要反映基底断裂的控制作用。中、新生代构造运动是燕山地区主要造山作用期,基本特征是强烈挤压形成线状褶皱及推覆构造系统。
中生代时期,本区构造形变显示水平应力作用的主导性,新生代时期,则以均衡代偿导致的隆升作用为主。本文侧重中生代构造应力场及变形挠度场的重塑,借以恢复本区中、新生代构造形变形成的力学过程及运动程式。      

青藏高原西部日土-普兰一带古构造应力值的估算

本文用超显微构造的位错密度法,估算了该地区6次构造事件的古构造应力值。尽管从现在的构造形变特征来看,不同构造事件都是沿近南北方向的伸展或挤压,但其形变强度各不相同,印支运动（晚三叠世）最强,平均差应力值达201MPa,四川运动（白垩纪—早第三纪早期）次之,为183MPa,其它各次构造运动均较弱,阿森特运动（前寒武纪末期）为101MPa,海西运动（早二叠世晚期）为121MPa,燕山运动（晚侏罗世）为130Mpa,喜马拉雅运动（中新世末期以来）为110MPa,加里东运动在本区大部分地方较弱,我们未采集到能反映其构造应力状态的样品。     

海洋大数据序列时-空变化主成分分析方法

介绍海洋要素时－空变化大数据量主成分分析方法,讨论并澄清主成分分析在海洋大数据序列应用中的一些问题和易混淆的概念。根据美国国家海洋与大气局（NOAA）卫星观测的海表面温度红外资料,对加拿大温哥华岛西部大陆架区8个夏季海表面温度的空间变化进行主成分分析,以促进主成分方法在海洋大数据序列分析中的应用。     

两种显著性检验方法在海洋大数据序列主成分分析中的应用

介绍海洋大数据序列主成分分析的两种显著性检验方法,采用该两种方法可以辨别具有真实意义的主成分模与代表随机噪声信号的模态。此二法均能很好地应用于大数据序列主成分模的显著性检验。在进行海洋大数据序列时-空变化主成分分析中,为尽可能减少或避免数据中随机噪声的影响,建议对主成分模进行显著性检验。     

Influence of Bottom Stress on the Two-layer Flow Induced by Gravity Currents in Estuaries

Baroclinic circulation in highly stratified and partially stratified estuaries is characterised by a two-layer flow: a bottom salt- water inflow and a surface brackish-water outflow. Tidal period variation of the thicknesses of a two-layer flow is observed to be associated with mixing, bottom stress and hydraulic characteristics of superposed tidal and gravity currents. Here, both analytical two-layer hydraulic equations with weak friction and a numerical model including a turbulence closure were utilised to understand the mechanism of the layer tendency within a two-layer flow under different barotropic flow conditions. It has been found that in the weak bottom friction case, a gravity current has two critical solutions at the layer thickness equal to 0·5Hand 0·292H. The layer thickness towards a particular critical solution is dependent on the sign of the bottom stress, i.e. when the bottom stress is opposite (favor) to the bottom gravity current, its layer thickness converges to 0·5H(0·292H). In the case of strong bottom stress and mixing opposing the gravity current, the solutions of the gravity current layer thickness at 0·5Hand 0·292Hwill not be valid. Both mixing and vorticity produced by bottom stress erode the halocline, and produce a high velocity core in the mid-depth, which leads to the thickness of a bottom gravity current greater than 0·5H. These internal hydraulic tendency and mixing processes, varying with time-dependent barotropic tidal current forcing, determine the tidal period variation of the gravity current structure.