Field Signatures of the SE-Asian Mega-Tsunami along the West Coast of Thailand Compared to Holocene Paleo-Tsunami from the Atlantic Region

The Andaman-Sumatra Tsunami of Dec. 26, 2004, was by far the largest tsunami catastrophe in human history. An earthquake of 9 to 9.3 on the Richter scale, the extension of waves over more than 5000 km of ocean and run-ups up to 35 m are its key features. These characteristics suggest significant changes in coastal morphology and high sediment transport rates. A field survey along the west coast of Thailand (Phuket Island, Khao Lak region including some Similan Islands, Nang Pha mangrove areas and Phi Phi Don Islands) seven to nine weeks after the tsunami, however, discovered only small changes in coastal morphology and a limited amount of dislocated sediments, restricted to the lower meters of the tsunami waves. This is in striking contrast to many paleo-tsunami's events of the Atlantic region. Explanations for this discrepancy are sought in: a. Mechanics of the earthquake. A rather slow shock impulse on the water masses over the very long earthquake zone, b. Shallow water in the earthquake zone, and c. Bathymetry of the foreshore zone at the impacted sites. Shallow water west of Thailand has diminished wave energy significantly. The differences in geomorphological and sedimentological signatures of this tsunami compared with many paleo-tsunami worldwide makes it unsuitable to be used as a model for old and future tsunami imprints by an event of this extreme energy and extension.     

达县—宣汉地区长兴组礁滩白云岩成岩过程中的孔隙演化

川东北达县—宣汉长兴组礁滩白云岩具有良好的油气储集潜力。作者通过大量岩石常规薄片、铸体薄片观察研究,发现该礁滩白云岩储层储集空间主要为次生成因的晶间孔、晶间溶孔、粒间粒内溶孔、生物体腔内溶孔和生物格架间溶孔。这些孔隙的形成和演化除了受沉积作用、构造作用和有机质热演化史的影响外,还受成岩作用的控制。首先在海底-暴露-浅埋藏环境下,压实及胶结使原生孔隙基本消失;而准同生混合水白云石化及早期暴露溶蚀作用改变了沉积物内部结构,形成众多微小孔隙的网络及溶孔,为后期形成大量孔隙创造了条件。其次在中—深埋藏环境下,强烈的重结晶作用和溶蚀作用使得岩石形成大量的次生孔隙,大大提高了礁滩白云岩的储集性能。     

陕南川北志留系兰多维列统特列奇阶宁强组的生物礁

志留纪兰多维列世（Llandovery）扬子地台持续上升。特列奇期（Telychian）griestoniensis笔石带上部至spiralis-grandis带代表的时限内,地处扬子地台西北缘的宁强湾,在温暖浅海的环境中沉积了宁强组巨厚的泥页岩,其中夹含8套碳酸盐岩。在与之对应的8期小型局限碳酸盐岩台地的不同部位建造了生物礁和生物滩。生物礁的类型包括骨架礁、生物层和灰泥丘。生物礁群落由底栖固着的造礁珊瑚、苔藓虫、海百合、藻类、层孔虫,以及非固着的附礁生物腕足类、鹦鹉螺、三叶虫等组成。通过宁强广元地区不同地点和层位的生物礁组合分析,论述它们在生态组合、生长形状和发育过程中的多样性。     

中国石炭纪生物礁造礁群落演化

中国石炭纪造礁群落是弗拉斯期—法门期生物绝灭事件后新兴起的。该群落在早期演化过程中经历了形成、发展、完善和衰落的过程,构成一个群落演化旋回。晚期又开始新一轮的旋回,群落的二分性十分显著。显然,石炭纪造礁群落代表一个不连续的演化过程。     

洪水演算理论与计算方法的若干进展与评论

从洪水波运动的小扰动分析、水力学洪水演算方法及新技术在洪水演算中的应用等方面,总结了近20年来国内外洪水演算理论与计算方法研究的若干进展,并作了简要的评论.     

Dynamics of a satellite orbiting a planet with an inhomogeneous gravitational field

We study the dynamics of a satellite (artificial or natural) orbiting an Earth-like planet at low altitude from an analytical point of view. The perturbation considered takes into account the gravity attraction of the planet and in particular it is caused by its inhomogeneous potential. We begin by truncating the equations of motion at second order, that is, incorporating the zonal and the tesseral harmonics up to order two. The system is formulated as an autonomous Hamiltonian and has three degrees of freedom. After three successive Lie transformations, the system is normalised with respect to two angular co-ordinates up to order five in a suitable small parameter given by the quotient between the angular velocity of the planet and the mean motion of the satellite. Our treatment is free of power expansions of the eccentricity and of truncated Fourier series in the anomalies. Once these transformations are performed, the truncated Hamiltonian defines a system of one degree of freedom which is rewritten as a function of two variables which generate a phase space which takes into account all of the symmetries of the problem. Next an analysis of the system is achieved obtaining up to six relative equilibria and three types of bifurcations. The connection with the original system is established concluding the existence of various families of invariant 3-tori of it, as well as quasiperiodic and periodic trajectories. This is achieved by using KAM theory techniques.     

Reef fishes recruited at midwater coral nurseries consume biofouling and reduce cleaning time in Seychelles,Indian Ocean

In coral reef restoration, coral gardening involves rearing coral fragments in underwater nurseries prior to transplantation. These nurseries become fish-aggregating devices and attract biofouling. We hypothesised that: (1) the presence of corals at a nursery is critical to recruit fish assemblages and (2) the recruited fish assemblages control biofouling, reducing person-hours invested in nursery cleaning. Three midwater coral nurseries were deployed at 8?m depth for 27 months within the marine protected area of Cousin Island Special Reserve, Seychelles, Indian Ocean. Each nursery consisted of a 6?m×6?m PVC pipe frame, layered with a recycled 5.5-cm-mesh tuna net. Human cleaning effort was calculated based on daily dive logs. Nursery-associated fish assemblages and behaviour were video-recorded prior to harvesting corals after a 20-month growth period and seven months post-coral harvesting. The density (ind. m–2) of blue-yellow damselfish Pomacentrus caeruleus was 12–16 times higher when corals were present than when corals were absent at the nurseries. Fish assemblages recruited into the nurseries included three trophic levels, from herbivores to omnivores, in six families: Ephippidae, Pomacentridae, Labridae (Scarinae), Gobiidae, Siganidae and Monacanthidae. Higher abundance of large fish (total number of individuals) resulted in 2.75 times less person-hours spent in nursery cleaning. These results have important implications for cost-effective coral reef restoration.     

Quadrupolar gravitational radiation as a test-bed for f(R)-gravity

The debate concerning the viability of f(R)-gravity as a natural extension of General Relativity could be realistically addressed by using results coming from binary pulsars like PSR 1913 + 16. To this end, we develop a quadrupolar approach to the gravitational radiation for a class of analytic f(R)-models. We show that experimental results are compatible with a consistent range of f(R)-models. This means that f(R)-gravity is not ruled out by the observations and gravitational radiation (in strong field regime) could be a test-bed for such theories.     

砾石堤坝和多孔方型鱼礁消浪护滩的试验研究——以北戴河西海滩为例

本文通过物理模型试验,研究了砾石堤坝、多孔方型鱼礁、堤坝+鱼礁等不同防护措施对岸滩的保护作用。通过测量不同防护措施的波浪透射系数、输沙率、水下坡度角及床面地形变化,并与无防护措施的工况进行对比,结果发现：不同试验条件下堤坝+鱼礁工况的透射系数仅为0.21～0.36,对波浪具有显著的消减作用;同一水位不同防护措施下的输沙率由大变小依次为：堤坝、堤坝+鱼礁、无工程、鱼礁;堤坝迎浪面的水下坡度角随极限波高呈现先增大、后减小的趋势,堤坝工况的水下坡度角约是堤坝+鱼礁工况的2～4倍;对于近岸的地形恢复,堤坝+鱼礁工况的效果比较明显,且对岸滩附近的侵蚀较少。堤坝+鱼礁的防护措施可明显减小波浪的透射系数,增加向岸输沙率,对恢复近岸地形、保护岸滩有显著作用。     

南沙珊瑚礁区波纹钩鳞鲀(Balistapus undulatus)食性和营养级分析

波纹钩鳞鲀(Balistapus undulatus)是一种在热带珊瑚礁海域中广泛分布的杂食性鱼类, 研究其自然环境中的食物组成有助于了解其食物来源及其在生态系统中的功能地位。但目前的认识仅限于他们是珊瑚礁区的海胆捕食者, 对其准确的食物组成和生态功能定位尚不清晰。本研究于2017年夏季在南沙珊瑚礁区采集了波纹钩鳞鲀样品, 通过特异性引物扩增波纹钩鳞鲀消化道中的线粒体细胞色素C氧化酶亚基Ⅰ(COⅠ)基因, 以高通量测序技术分析了其现场食物组成, 并测定了碳、氮稳定同位素以分析其营养级。研究结果显示, 波纹钩鳞鲀摄食的食物种类有13种, 分属于节肢动物门(Arthropoda)、脊索动物门(Chordata)和环节动物门(Annelida)。其中最主要的食物来源是节肢动物门扇蟹科的蟹类, 如滑面蟹(Etisus sp.)、Luniella pubescens、皱纹花瓣蟹(Liomera rugata)等, 分别占61.8%、6.7%和1.8%。鱼类也有一定的贡献, 占总食物序列的23.5%。同位素结果显示其营养级为3.71±0.07, 与分子检测的结果相符。研究结果表明波纹钩鳞鲀的主要食物是小型甲壳类动物以及植食性鹦嘴鱼, 这拓展了以往对波纹钩鳞鲀所扮演生态角色的认识。