Numerical modelling of coastal inundation from Cascadia Subduction Zone tsunamis and implications for coastal communities on western Vancouver Island,Canada

Natural Hazards - In the present study, numerical simulations were conducted to estimate the spatio-temporal characteristics of tsunami inundation for municipalities on Vancouver Island, Canada, as...     

Tsunami hazard evaluation for Kuwait and Arabian Gulf due to Makran Subduction Zone and Subaerial landslides

Given the recent historical disastrous tsunamis and the knowledge that the Arabian Gulf (AG) is tectonically active, this study aimed to evaluate tsunami hazards in Kuwait from both submarine earthquakes and subaerial landslides. Despite the low or unknown tsunami risks that impose potential threats to the coastal area’s infrastructures and population of Kuwait, such an investigation is important to sustain the economy and safety of life. This study focused on tsunamis generated by submarine earthquakes with earthquake magnitudes (M _w ) of 8.3–9.0 along the Makran Subduction Zone (MSZ) and subaerial landslides with volumes of 0.75–2.0 km³ from six sources along the Iranian coast inside the AG and one source at the Gulf entrance in Oman. The level of tsunami hazards associated with these tsunamigenic sources was evaluated using numerical modeling. Tsunami model was applied to conduct a numerical tsunami simulation and predict tsunami propagation. For landslide sources, a two-layer model was proposed to solve nonlinear longwave equations within two interfacing layers with appropriate kinematic and dynamic boundary conditions. Threat level maps along the coasts of the AG and Kuwait were developed to illustrate the impacts of potential tsunamis triggered by submarine earthquakes of different scales and subaerial landslides at different sources. GEBCO 30 arc-second grid data and others were used as bathymetry and topography data for numerical modeling. Earthquakes of M _w 8.3 and M _w 8.6 along the MSZ had low and considerable impacts, respectively, at the Gulf entrance, but negligible impacts on Kuwait. An earthquake of M _w 9.0 had a remarkable impact for the entire Gulf region and generated a maximum tsunami amplitude of up to 0.5 m along the Kuwaiti coastline 12 h after the earthquake. In the case of landslides inside the AG, the majority impact occurred locally near the sources. The landslide source opposite to Kuwait Bay generated the maximum tsunami amplitudes reaching 0.3 m inside Kuwait Bay and 1.8 m along the southern coasts of Kuwait.

     

Tsunami hazard evaluation for Kuwait and Arabian Gulf due to Makran Subduction Zone and Subaerial landslides

This paper explores the ways that Mongolian pastoral-nomadic herders and supporting aid organizations anticipate, interpret, and respond to dzud, a form of winter storm that prevents livestock grazing and often results in large-scale herd deaths. Analysis is drawn from organizational reports, government speeches, and mass media that have been collected to give a complex, multi-faceted understanding of the collection, distribution, and interpretation of data pertaining to the social and scientific construction of this natural hazard. Using critical discourse analysis, this study asks how herder perspectives and needs have been incorporated into reports and action plans of international development organizations. The collected documents provide insight into the ways that knowledge is constructed, disseminated and valued among policy makers, development planners and herders. Additionally, the findings indicate disagreement between stakeholders as to when to declare a national emergency, and how to best help herders respond to the increasing frequency of dzud. While some organizations rely on traditional recovery mechanisms, others have turned to technological solutions, all aiming to assist herders in adequately responding to and recovering from one dzud before another occurs. From the analysis of policy proposals, this study aims to understand and inform the ways that international development programs, government officials, and herders work to preserve pasturelands and herding lifestyles threatened by dzud.     

俯冲带研究进展与问题

自从板块构造理论出现以来,俯冲带的相关研究工作就一直方兴未艾。通过对俯冲带的分类、俯冲的动力机制、俯冲带与地震的关系、俯冲带中的流体与岩浆作用以及俯冲带成矿等方面进行综合阐述,介绍了在目前科技水平下对俯冲带研究所取得的一些成果。同时也指出了俯冲带研究中的不足之处以及我国在俯冲带研究中的优缺点。     

大陆俯冲带的深部流体及变质化学地球动力学——以苏鲁超高压变质带为例

通过苏鲁超高压变质带的岩石学、矿物化学、地球化学和年代学研究,在大陆俯冲带深部流体与变质化学地球动力学方面取得了重要的创新性成果。研究证明大陆俯冲带的深部流体是高氧逸度、富硅酸盐的超临界流体,揭示出超高压变质极端条件下的流体－矿物(岩石)相互作用可以导致不活动元素发生溶解和迁移,可以导致金红石的Nb/Ta之间发生强烈的分异,提出俯冲到地幔深处的超高压榴辉岩是地球内部“隐藏”的超球粒陨石Nb/Ta比值的物质源区,与低球粒陨石Nb/Ta比值的物质源区大陆地壳和亏损地幔在化学成分上形成互补。     

Structure of the Subduction Zone and Volcanism in Kamchatka

Doklady Earth Sciences - The correlation of the parameters of a subducted plate with the volcanism is studied. The north-to-south increase in the age of a slab controls the dip angle, the slab...     

Iranshahr Blueschists as Results of Subduction of the Neotethys Inner Makran Oceanic Crust, SE Iran

<正>The Makran accretionary prism is one of the most extensive subduction accretions on Earth.It is characterized by intense folding,thrust faulting and dislocation of the Cenozoic units consisted of sedimentary,igneous and metamorphic rocks.It is located in the southeast of Iran and southwest of Pakistan.Rock     

Discrete Element Modeling of a Subduction Zone with a Seafloor Irregularity and its Impact on the Seismic Cycle

Seafloor irregularities influence rupture behavior along the subducting slab and in the overriding plate, thus affecting earthquake cycles. Whether seafloor irregularities increase the likelihood of large earthquakes in a subduction zone remains contested, partially due to focus put either on fault development or on rupture pattern. Here, we simulate a subducting slab with a seafloor irregularity and the resulting deformation pattern of the overriding plate using the discrete element method. Our simulations illustrate the rupture along three major fault systems: megathrust, splay and backthrust faults. Our results show different rupture dimensions of earthquake events varying from tens to ca. 140 km. Our results suggest that the recurrence interval of megathrust events with rupture length of ca. 100 km is ca. 140 years, which is overall comparable to the paleoseismic records at the Mentawai area of the Sumatran zone. We further propose the coseismic slip amounts decrease and interseismic slip amounts increase from the surface downwards gradually.     

New record of coralline algae from the Holocene sediments of Agatti Island,Lakshadweep, India

The present paper examines the coralline algal assemblage recovered from the Holocene sediments of Agatti Island, Lakshadweep, India. The assemblage comprises nine species of coralline algae which include Amphiroa fragilisma, Lithophyllum nitorum, Lithophyllum incrustans, Lithoporella melobesioids, Spongites sp., Porolithon craspedium, Aethesolithon problematicum, Clathromorphum parcum, Melobesoideae gen. et spec. indet. Clathromorphum parcumis an endophytic coralline alga reported for the first time from the Indian subcontinent. Out of these, seven species belong to the family Corallinaceae and the two represent the family Hapalidiaceae of the class Rhodophyceae. Coralline algal association of this area is dominated by Lithophylloideae, Melobesioideae and Mastophoroideae which include encrusting to fragmented growth forms. The associated branching corals are well developed and adapted to shallow, warm water, low turbid, protected lagoonal environment.     

阿留申俯冲带几何学特征及运动学成因模式

阿留申俯冲带位于环太平洋俯冲带最北端,是东太平洋型俯冲和西太平洋俯冲的过渡区域。该俯冲带火山岛弧距离海沟的距离从东向西逐渐增大,而形成地球上独特的岛弧火山链与海沟V字型斜交的现象。这一现象的运动学成因目前并没有统一的认识。本文通过对阿留申俯冲带几何形态数据、运动学数据进行整理分析,尝试运用构造赤道理论探讨该现象形成的运动学背景。阿留申俯冲带的几何学数据表明:从俯冲带东段(175°E)至俯冲带西段(155°W),火山岛弧距俯冲海沟的距离从80 km增加至250 km。与此同时,俯冲板片的倾角由60°减小至30°。板块的运动学分析表明:相对北美板块,太平洋板块的东段的运动矢量为48 mm/a,向北运动;逐渐转变为西段的78mm/a,向西北方向运动。相对于软流圈,太平洋板块的运动方向没有改变,始终向西北方向运动,速率向西逐渐增加。因此,在俯冲带的东段太平洋板块的绝对运动方向和相对运动方向存在30°左右的夹角,而这个夹角在西段几乎不存在。太平洋板块的绝对运动方向和相对运动方向之间的夹角不同,会导致软流圈对俯冲板片的反作用力差异,从而形成不同的俯冲角度和俯冲带宽度。太平洋板块相对北美板块和相对地幔的速度方向夹角的变化被认为是引起阿留申火山弧与海沟"V"字型斜交的运动学成因。     

俯冲带岩浆弧安山岩的成因研究进展

安山岩是俯冲带岩浆弧中重要的岩石类型,其成因至今仍是国际地质学界研究的热点之一.根据安山岩分布的地质背景,岩浆弧安山岩可以简单划分为陆弧安山岩和洋弧安山岩,二者在化学成分和空间分布等方面存在明显差异.自20世纪20年代末以来,大量的研究成果丰富了人们对岩浆弧安山岩成因的认识,逐渐将其归纳为玄武质岩浆输入和安山质岩浆输入2种模型.玄武质岩浆输入模型认为形成岩浆弧安山岩的初始岩浆成分为玄武质,强调分离结晶、同化混染和岩浆混合等壳内过程;而安山质岩浆输入模型认为地幔源区可以直接形成安山质熔体,强调俯冲板片来源的流体/熔体—地幔橄榄岩的交代反应和沉积物底辟等壳下过程.虽然岩浆弧安山岩的成因研究取得了一定的进展,但每一个模型都有亟待完善之处.地幔交代岩的实验岩石学研究、安山岩与大陆地壳形成与演化间的关系、理论计算和模拟的应用等都是未来需要研究的领域.     

Mapping of Interplate Coupling in the Kamchatka Subduction Zone from Variations in the Earthquake Size Distribution

Doklady Earth Sciences - The geometry of supposed coupling zones in the Kamchatka subduction zone is determined by the earthquake size distribution based on ealier revealed relationship between its...     

The Formation and Evolution of Uvarovite in UHP Serpentinite and Rodingite and its Constraints on Chromium Mobility in the Oceanic Subduction Zone

The uvarovite-andradite and uvarovite-andradite-grossular solid-solution series are rare in nature. The discovery of uvarovite-andradite in serpentinite and rodingite from the ultra-high pressure (UHP) metamorphic belt in southwestern Tianshan provided an opportunity to investigate its behavior in the subduction zone. Uvarovite (defined as chromium-garnet) from serpentinite is homogeneous in a single grain, covering compositions in the uvarovite-andradite solid solution series of Adr58–66Uv33–41, with few grossular components. Uvarovite from rodingites contain various Cr2O3 contents (1.7–17.9 wt%) and mineral compositions being in the range of Adr21–31Uv41–50Grs22–37, Adr52–90Uv5–25Grs0–21 and Adr19–67Uv3–63Grs13–42. Discontinuous chemical variation of uvarovite from core to rim indicates that uvarovite formed by consuming andradite and chromite, which could provide Ca, Cr, Al and Fe. Raman signals of water were identified for uvarovite from both serpentinite and rodingite, with high water content in uvarovite from serpentinite. The high pressure mineral assemblage, as well as the association with perovskite, indicated that the studied uvarovite from serpentinite and rodingite was formed through high pressure metamorphism, during the subduction zone serpentinization and rodingitization. High alkaline and highly reduced fluids released from serpentinization or rodingitization in the oceanic subduction zone promote the mobility of chromium and enable its long-distance migration.     

Preface: Deep Carbon Cycle and Abiotic Methane in the Subduction Zone

<正>Two kinds of carbon cycle on Earth have been recognized: surface short-term and deep long-term carbon cycles(Berner, 2003; Zhang et al., 2017). Over the years, the surface short-term carbon cycle has been attracted extensive attention because of their significance implications in the study of environmental changes of human beings. Recently,     

俯冲带楔体中逆冲构造的形成及演化：构造物理模拟实验研究

通过交换不同的边界条件来进行构造物理模拟，重塑及研究岩石圈中各种构造现象发生及发展的过程与机制，并与自然界中存在的构造现象进行对比，是构造物理模拟所具有的独特优越性。实验以俯冲带楔体中及其底部逆冲断层形成过程中的几何学、运动学的研究为主题，以底部摩擦强度（俯冲片与传送带间的摩擦）及插入厚度的变化为边界条件进行的。实验证实了俯冲带中楔体底部及其下部俯冲片中存在的构造底侵作用；底部不同的摩擦强度与不同的插入厚度对楔体前缘、内部及底部逆冲构造的形成演化及其组合形式有如下影响：（１）楔体前缘逆冲断层系之间的间距随底部摩擦强度增强而加大；（２）当底部摩擦强度大时，楔体前缘逆冲叠瓦扇构造表现出一种前导主叠瓦扇（Ｌｅａｄｉｎｇｎｉｍｂｒｉｃａｔｅｆａｎ），反之则显示尾（Ｔｒａｉｌｉｎｇ）叠瓦扇组合特点；（３）插入厚度对楔体内部的反向逆冲构造的形成及演化具明显的影响。     

Ancient and Modern Subduction Zone Contributions to the Mantle Sources of Lavas from the Lassen Region of California Inferred from Lu-Hf Isotopic Systematics

Hafnium isotopic compositions have been determined on a suiteof calc-alkaline and high-alumina-olivine tholeiitic lavas fromthe Lassen region of California and are used, in conjunctionwith previously published mineralogical, geochemical, and isotopicdata, to constrain their petrogenesis. Positive correlationbetween     

中国东部新生代玄武岩记录古太平洋俯冲带壳幔相互作用

大陆玄武岩通常具有与洋岛玄武岩相似的地球化学成分,其中含有显著的壳源组分.对于洋岛玄武岩来说,虽然其中的壳源组分归咎于深俯冲大洋板片的再循环,但是对板片俯冲过程中的壳幔相互作用缺乏研究.对于大陆玄武岩来说,由于其形成与特定大洋板片在大陆边缘之下的俯冲有关,可以用来确定古大洋板片俯冲的地壳物质再循环.本文总结了我们对中国东部新生代玄武岩所进行的一系列地球化学研究,结果记录了古太平洋板片俯冲析出流体对地幔楔的化学交代作用.这些大陆玄武岩普遍具有与洋岛玄武岩类似的地球化学成分,在微量元素组成上表现为富集LILE和LREE、亏损HREE,但是不亏损HFSE的分布特点,在放射成因同位素组成上表现为亏损至弱富集的Sr-Nd同位素组成.在排除地壳混染效应之后,这些玄武岩的地球化学特征可以由其地幔源区中壳源组分的性质来解释.俯冲大洋地壳部分熔融产生的熔体提供了地幔源区中的壳源组分,其中包括洋壳镁铁质火成岩、海底沉积物和大陆下地壳三种组分.华北和华南新生代大陆玄武岩在Pb同位素组成上存在显著差异,反映它们地幔源区中的壳源组分有所区别.中国东部新生代玄武岩的地幔源区是古太平洋板片于中生代俯冲至亚欧大陆东部之下时,在>200 km的俯冲带深度发生壳幔相互作用的产物.在新生代期间,随着俯冲太平洋板片的回卷引起的中国东部大陆岩石圈拉张和软流圈地幔上涌,那些交代成因的地幔源区发生部分熔融,形成了现今所见的新生代玄武岩.      

Multistage Metamorphic Evolution and P-T-t Path of High-T Eclogite from the North Dabie Complex Zone during Continental Subduction and Exhumation

正Objective High-T eclogites from the North Dabie complex zone(NDZ),central China underwent a complex metamorphic evolution involved in ultrahigh-pressure(UHP)and highpressure eclogite-facies metamorphism,and subsequent     

A Large Transpression Zone at the South Margin of the East Kunlun Mountains and Oblique Subduction

1. Introduction The East Kunlun terrane lying in northern Qinghai-Tibetan Plateau is a Caledonian-Indosinian composite orogenic belt. South of the terrance is the Baryan Hara-Songgan (Songpan-Garze) terrane, which is an Indosinian orogenic belt. Between the two terrances is the boundary of Indosinian 搒outh margin of the East Kunlun?(western Datan-eastern Datan-A抧yemaqen) convergent belt extended about 1200 km. On the north side of the convergent belt, the southern East Kunlun terra…