Variations of Seismicity in the Avachinsky Gulf (Kamchatka, Russia)

Variations of seismic mode in the region of the Avachinsky Gulf (Kamchatka, Russia) are considered. Observed anomalies (seismic quiescence, the ring seismicity, reduction of the slope of the earthquake recurrence diagram) provide a basis to consider this region as a place of strong earthquake preparation. The Kamchatka regional catalogues of earthquakes between 1962–1995 were used in the analysis. A reduced seismicity rate is observed during 10 years in an area of 150 km × 60 km in size. During the last five years, in the vicinity of the area considered, earthquakes with M > 5 occurred three times more often than the average over thirty years. It is interpreted as ring seismicity. The block of 220 km × 220~km in size, including the quiescence zone, is characterized by a continuous decrease of the recurrence diagram slope, which has reached a minimum value for the last 33 years in this region.     

Seismotectonic regionalization of the Red Sea area and its application to seismic risk analysis

A seismological evaluation of the Red Sea margin is presented in this contribution based on the concept of seismotectonic regionalization. The geology and the tectonic structure are critically reviewed to define regions of homogeneous seismicity in the study area, and available seismicity data are implemented to estimate the seismic parameters of the region. The results of the study are applied to evaluate the seismic hazard of an offshore platform site.     

冈底斯中段林子宗火山岩岩石地球化学特征

广泛发育在冈底斯岩浆岩带中的林子宗火山岩及其与下伏地层间的区域不整合提供了印度-亚洲大陆碰撞的重要证据.谢通门地区的林子宗火山岩早期以中基性-中性岩为主,夹少量流纹质凝灰岩,晚期以流纹质火山岩为主.岩石学和地球化学研究表明,这套火山岩早期以钙碱性为主,带有较多陆缘火山岩特征,中期开始出现标志陆内活动的钾玄岩,晚期更多地显示了加厚陆壳条件下火山岩的特点,记录了由新特提斯俯冲消减末期过渡到印度-亚洲大陆碰撞的信息.中基性岩浆来源于俯冲带的地幔源区,长英质岩浆形成于加厚地壳的部分熔融.结合区域同位素年龄资料,可以认为林子宗火山岩中高钾流纹质火山岩是印度-亚洲大陆碰撞阶段陆壳缩短加压升温引起部分熔融的产物.     

Stratimagic地震相分析技术在川中GSM油气勘探中的应用

通过Stratimagic地震相分析技术的应用，明确了该区多种类型河道的沉积模式，预测了砂体的展布，对于四川盆地浅层砂岩油气勘探具有重要指导意义。     

Analysis of the institutional and social responses to the eruption and the lahars of Mount Pinatubo volcano from 1991 to 1998 (Central Luzon, Philippines)

Mount Pinatubo volcano erupted in June 1991 in the main island of Luzon belonging to the Philippines archipelago. Huge economic losses and population exodus have followed. This major crisis has been relayed with other crises due to rain-fed lahars which have been supplied with eruption deposits. These lahars have occurred every year since 1991 during the rainy season. They will probably last until 2005. After a brief presentation of the Philippine official response system to disasters, this paper draws up a critical analysis of the different kinds of institutional and social responses deployed to manage the different crisis and post-crisis phases of this event. Based on three viewpoints: from population, media and other actors, this analysis attempts to point out the strengths and weaknesses of the official management system, especially by studying the efficiency and the range of the solutions taken. So, it appears that the management of the June 1991 main crisis (eruption) was a success. On the other hand, difficulties have occurred with lahars risk management. Indeed, these lahars have obliged the authorities to protect and relocate thousands of people. In spite of persistent problems, the management system (monitoring/warning/evacuation) of lahar crises improves year after year. Failures appear especially within the rehabilitation program (protection/rehousing). Many direct (lack of means, preparedness, coordination, dialog, etc.) and indirect (politico-administrative, socio-economic, cultural contexts) factors come together to lock the wheels of the institutional response system. They defer the socio-economic start of this vital northern Philippines area. This revised version was published online in July 2006 with corrections to the Cover Date.     

Geological Consequences of the Accretion of Benham Rise toNorthern Luzon, Philippines

Benham Rise is a large igneous province that has been accreted to the eastern seaboard of northern Lu-zon since Early Miocene. It started forming during the Eocene at a hotspot/mantle plume in the vicinity of the Central basin Spreading Center in the West Philippine Basin (CBSC) of the Philippine Sea Plate. Seafloor spreading from the CBSC and Parece Vela pushed Benham Rise towards Luzon. Eventually Benham Rise jammed against Luzon at the end of the Oligocene, with consequences that impacted on the geology of the Philippines which have been similarly noted in colli-sions of large igneous provinces in other areas. These are manifested as follows:     

东帝汶海槽断裂特征与构造演化模式

东帝汶海槽位于澳大利亚板块西北帝汶海与帝汶岛之间,晚中新世澳大利亚板块与东南亚班达岛弧碰撞引发了帝汶岛与帝汶海槽的构造变形,由于弧-陆碰撞过程的复杂性,帝汶海槽的变形时间与机制仍然存在较大争议。为约束帝汶海槽变形时间、探讨其演化过程,依据二维地震数据,对东帝汶海槽的断裂特征进行定量分析,并结合钻井与天然地震事件探讨弧-陆碰撞背景下帝汶海槽的构造演化模式。研究结果表明,晚中新世（约6 Ma）澳大利亚板块与班达岛弧碰撞,引发了帝汶岛的隆升与帝汶海槽的沉降,变形持续至晚上新世（约3 Ma）,形成现今帝汶海槽形态。现今澳大利亚板块与班达岛弧之间的相对运动速率已逐渐减小趋于停止,未来二者可能会以一个整体继续向北运动。     

菲律宾中部Cebu地区早白垩世高锶低钇中酸性岩 与铜金成矿

菲律宾群岛四周被现今仍活动的俯冲带所环绕,该区绝大多数的岩浆活动都与俯冲事件有关。白垩纪以来,该区岩浆活动十分活跃,在新生代达到顶峰,形成了一系列岩浆岩带。高锶低钇中酸性岩（Aidakite,埃达克岩）在菲律宾群岛有着广泛的分布（Jego et al., 2005）,主要集中在Luzon岛弧、Negros、Camiguin和Mindanao等地,主要产于新生代,这些新生代高锶低钇中酸性岩和相关的岩石也得到了广泛的研究。除了这些广泛分布的新生代高锶低钇中酸性岩以外,菲律宾地区还发育中生代高锶低钇中酸性岩,仅出现在菲律宾中部的Cebu岛,此外该区还发育一套早白垩世岛弧火山岩组合。火山岩组合锆石U-Pb年龄主要分布在126~118 Ma（Deng et al., 2015）;高锶低钇中酸性岩则主要为闪长岩,是该区Atlas大型斑岩铜矿的含矿岩体,前人研究显示其形成时代集中在109~108 Ma（Walther et al., 1981）,同样形成于早白垩世。然而对于其相应的地球化学研究还相当匮乏,关于其成因以及在早白垩世形成时所处的构造环境,都需要进一步的研究来加以限制。     

Early Cretaceous high-Mg adakites associated with Cu-Au mineralization in the Cebu Island,Central Philippines: Implication for partial melting of the paleo-Pacific Plate

Early Cretaceous arc volcanic rocks, diorite intrusions and an associated large porphyry deposit occur in the Cebu Island, Central Philippines. In this paper, we studied the diorite porphyries associated with Cu-Au mineralization in the Kansi region, where Early Cretaceous arc volcanic rocks are widely distributed. Zircon U-Pb age reveals that the diorites were formed at ca. 110 Ma, close to the formation age of Lutopan diorites in the famous Atlas porphyry Cu-Au deposit (109–101 Ma), and younger than those of the arc volcanics in this region (126–118 Ma). The Kansi diorites and Lutopan diorites are both calc-alkaline high-Mg adakites with high Sr/Y ratios. Their major elements define similar variation trends in Harker diagrams, suggesting that they were probably generated from a uniform source but experienced different degree of partial melting or fractional crystallization. The Kansi diorites are characterized by LREE enrichment, HREE depletion, no Eu negative anomaly, with enrichment of Pb, Sr, Zr and Hf and depletion of Nb, Ta, and Ti. They are probably generated by the partial melting of subducted oceanic crust, followed by a certain degree of mantle interaction and crustal contamination. The highly depleted Sr-Nd-Pb-Hf isotopes of the Kansi diorites are close to the Amami Plateau basalt and tonalite, indicating the dominance of a Pacific-type MORB in the source. The Cu-Au mineralization-related Kansi diorites are characterized by high oxygen fugacities more than ΔFMQ +2, indicating quite a good potential for porphyry Cu-Au mineralization in the region. Finally, in our tectonic model, the successive generation of arc volcanic rocks and adakites in the Cebu Island are responses to the subduction and rollback of the paleo-Pacific Plate to the proto-Philippine Sea Plate (PSP) in the Early Cretaceous.     

Hydrothermal Alteration and Fluid Geochemistry of the Tongonan Geothermal Field, Philippines

Abstract: The alteration mineralogy, the present-day fluid chemistry, and some fluid inclusion data are used to make inferences on the chemical changes that have occurred in the fluids during the history of the Tongonan Geothermal Field. Thermal activity in the Tongonan area began in the Miocene when emplacement of many plutons forming a batholith contact metamorphosed the overlying volcanics to hornblende hornfels assemblages. In the early Pliocene, when tectonic uplift occurred along the Philippine Fault, about 2 mole % of mainly carbon dioxide and sulfur gas was released to a geothermal fluid and condensed in groundwater with geothermal steam. The condensate intensely altered the reservoir rock and formed an acid mineral assemblage, which was overprinted by a later, lower temperature, neutral-pH assemblage. Some chlorite, epidote and illite in the reservoir rock formed at temperatures up to 100°C lower than present-day temperatures possibly during the Plio-Pleistocene uplift period, i.e., the system was heating up. The assemblage garnet-anhydrite formed in fractures from a condensate after the gas had nearly completely separated from the deep, CO₂-rich fluid during vigorous boiling possibly during hydrothermal eruptions. The output of gas to the geothermal fluid decreased, while the salinity (10,000 mg/kg or - 2 wt% NaCl) and the temperature of the geothermal fluid remained nearly constant throughout the Quaternary. When this neutral-pH, alkali chloride fluid boiled, it initially precipitated albite or epidote on the rims then anhydrite at the center of fractures at high temperatures (-250–300°C). At lower temperatures (-150–250°C), adularia or wairakite and later calcite were deposited as the proportion of gas in the steam condensate increased. The origin of solutes is also discussed.     

菲律宾迪纳伽特岛铬铁矿地质特征简介

通过对菲律宾棉兰老岛北端的迪纳伽特岛铬铁矿进行考察,介绍菲律宾共和国铬铁矿的分布概况,迪纳伽特岛铬铁矿资源的类型、分布、规模等情况,并将收集到的当地矿山建设外部条件及投资环境作简介,对该地区感兴趣的投资者可以起到参考和了解的作用。     

鄂尔多斯盆地石炭纪中央古隆起形成机制

将鄂尔多斯盆地简化为受南北挤压的等厚各向同性弹性薄板模型进行应力—应变场数值模拟,力图揭示鄂尔多斯地区石炭纪出现的细腰状中央古隆起的形成机制。模拟中Z轴方向应变(εz)正值区对应于盆地内部的隆起区,zε正等值线形态对应于隆起形态;单轴挤压条件下,εz正等值线总会呈现沿应力轴方向延伸的细腰状形态;点作用力产生的zε正等值线范围局限,而线作用力产生的εz正值区分布较广。模拟结果表明鄂尔多斯盆地石炭纪细腰状隆起是在南北边界受挤压条件下,应力—应变在盆地内部传递过程中所必然出现的结果,南北向点作用力比南北向线作用力产生的zε等值线形态更接近于鄂尔多斯盆地中央古隆起形态;点作用力可能代表了石炭纪微板块间的点碰撞或者弧—陆碰撞。     

Analysis of crustal deformation in Luzon, Philippines using geodetic observations and earthquake focal mechanisms

We utilize regional GPS velocities from Luzon, Philippines, with focal mechanism data from the Harvard Centroid Moment Tensor (CMT) Catalog, to constrain tectonic deformation in the complex plate boundary zone between the Philippine Sea Plate and Eurasia (the Sundaland block). Processed satellite imagery and digital elevation models are used with existing gravity anomaly, seismicity, and geologic maps to define a suite of six elastic blocks. Geodetic and focal mechanism data are inverted simultaneously to estimate plate rotations and fault-locking parameters for each of the tectonic blocks and faults comprising Luzon. Major tectonic structures that were found to absorb the plate convergence include the Manila Trench (20–100 mm yr^− 1) and East Luzon Trough ( 9–15 mm yr^− 1)/Philippine Trench ( 29–34 mm yr^− 1), which accommodate eastward and westward subduction beneath Luzon, respectively; the left-lateral strike-slip Philippine Fault ( 20–40 mm yr^− 1), and its northward extensions, the Northern Cordillera Fault ( 17–37 mm yr^− 1 transtension), and the Digdig Fault ( 17–27 mm yr^− 1 transpression). The Macolod Corridor, a zone of active volcanism, crustal thinning, extension, and extensive normal and strike-slip faulting in southwestern Luzon, is associated with left-lateral, transtensional slip of  5–10 mm yr^− 1. The Marikina Fault, which separates the Central Luzon block from the Southwestern Luzon block, reveals  10–12 mm yr^− 1 of left-lateral transpression. Our analysis suggests that much of the Philippine Fault and associated splays are locked to partly coupled, while the Manila and Philippine trenches appear to be poorly coupled. Luzon is best characterized as a tectonically active plate boundary zone, comprising six mobile elastic tectonic blocks between two active subduction zones. The Philippine Fault and associated intra-arc faults accommodate much of the trench-parallel component of relative plate motion.     

南海东北部台湾浅滩陆坡的浊流沉积物波的发育及其成因的构造控制

南海东北部马尼拉海沟发育有面积达35 000 km2的、壮观的沉积物波波域,水深2 600～4 100 m。基于波域的特征、区域分布、物质组成等,判断其为重力流成因。该波域于1.2 Ma开始起动,从而形成了和下伏平行反射截然不同的波状反射,二者之间为沉积物波的起动面。该波域的发育史受控于台湾造山运动的发育史,吕宋岛弧在北西西向运动的菲律宾海板块的携带下,于6.5 Ma左右和欧亚大陆边缘发生斜向弧—陆碰撞,碰撞焦点持续向南转移,于1.2 Ma左右转移至台湾南部,造成台湾南部的物理剥蚀、乃至向毗邻深水的碎屑供应急剧增加,改变了深水沉积动力学状态,浊流活动的强度和频率极大加强,从而开始了该波域的起动和发育。该沉积物波的发育和台湾造山运动构成了完美的构造活动和沉积响应关系。     

Devonian supra-subduction zone setting for the Princhester and Northumberland Serpentinites: implications for the tectonic evolution of the northern New England Orogen

The Princhester Serpentinite of the Marlborough terrane of the northern New England Orogen is a remnant of upper mantle peridotite that was partially melted at an oceanic spreading centre at 562 Ma, and subsequently interacted with Late Devonian island arc basalts in an intra-oceanic supra-subduction zone (SSZ) setting. The full range of rare-earth element (REE) contents, including U-shaped patterns, can be explained by a single process of reaction of partially melted, depleted peridotite with Late Devonian calc-alkaline and island arc tholeiite magmas by equilibrium porous flow, fractionating the REE by a chromatographic column effect. The Northumberland Serpentinite on South Island of the Percy Group has similar REE and high field strength element (HFSE) contents to the most depleted samples of the Princhester Serpentinite, supporting a common origin. However, spinel compositions suggest that the Northumberland Serpentinite interacted with boninitic magmas. The REE and mineral geochemistry indicates that the Princhester and Northumberland Serpentinites both represent part of the mantle component of a disrupted SSZ ophiolite. The ophiolite is considered to have formed above an east-dipping subduction zone, based on the geochemistry of Devonian island arc basalts between Mt Morgan and Monto, which include compositions identical to dykes and gabbroic blocks within the Princhester Serpentinite. Blockage of the subduction zone by collision with the Australian continent during the Late Devonian led to slab breakoff and the reversal of subduction direction, trapping the Late Devonian ophiolite in a forearc position. Its location, in a forearc setting above a growing accretionary wedge, conforms to the definition of a Cordilleran-type ophiolite. This interpretation is consistent with current views that most ophiolites are formed from young, hot and thin oceanic lithosphere at forearc, intra-arc and backarc spreading centres in a SSZ setting, and that emplacement follows genesis by 10 million years or less. Late Devonian crustal growth may have been widespread in the New England Orogen, because the disrupted ophiolite assemblage of the Yarras complex in the southern New England Orogen is probably of this age. Extensional tectonism at the end of the Carboniferous dismembered the Princhester – Northumberland ophiolite, removed the crustal section, and produced windows of accretionary wedge rocks within the fragmented ophiolite. The Princhester Serpentinite, together with fault slices of metasedimentary rocks, was thrust westward as a flat sheet over folded strata of the Yarrol Forearc Basin by a Late Permian out-of-sequence thrust during the Hunter – Bowen Orogeny, completing the emplacement of the Marlborough terrane. The Princhester and Northumberland Serpentinites could have been displaced by strike-slip movement along the Stanage Fault Zone or an equivalent structure. There is no record in the northern New England Orogen of SSZ ophiolites and volcanic arc deposits of Cambrian age, as exposed along the Peel Fault. Partial melting of the Princhester Serpentinite at an oceanic spreading centre at 562 Ma, recorded by mafic intrusives displaying N-MORB chemistry, was an earlier event that was outboard of any Early Paleozoic subduction zone along the margin of the Australian continent, and cannot be regarded as representing the early history of the New England Orogen. It is possible that the formation of intra-oceanic arcs in latest Silurian and Devonian time was the first tectonic event common to both the southern and northern New England Orogen.     

Characterization of the proto-Philippine Sea Plate:Evidence from the emplaced oceanic lithospheric fragments along eastern Philippines

The proto-Philippine Sea Plate(pPSP)has been proposed by several authors to account for the origin of the Mesozoic supra-subduction ophiolites along the Philippine archipelago.In this paper,a comprehensive review of the ophiolites in the eastern portion of the Philippines is undertaken.Available data on the geology,ages and geochemical signatures of the oceanic lithospheric fragments in Luzon(Isabela,Lagonoy in Camarines Norte,and Rapu-Rapu island),Central Philippines(Samar,Tacloban,Malitbog and Southeast Bohol),and eastern Mindanao(Dinagat and Pujada)are presented.Characteristics of the Halmahera Ophiolite to the south of the Philippines are also reviewed for comparison.Nearly all of the crust-mantle sequences preserved along the eastern Philippines share Early to Late Cretaceous ages.The geochemical signatures of mantle and crustal sections reflect both mid-oceanic ridge and suprasubduction signatures.Although paleomagnetic information is currently limited to the Samar Ophiolite,results indicate a near-equatorial Mesozoic supra-subduction zone origin.In general,correlation of the crust-mantle sequences along the eastern edge of the Philippines reveal that they likely are fragments of the Mesozoic pPSP.     

Public perception of climate change and disaster preparedness: Evidence from the Philippines

The Philippines is highly susceptible to both geophysical and climate-related disasters. This article explores Filipinos knowledge and perception of climate change and their association with what action Filipinos take to prepare for rapid onset natural hazards such as typhoons. Data for this study were collected from a nationally representative random survey of 5,184 adults conducted between March and April of 2017. Filipinos self-report relatively low levels of knowledge of climate change and cited increased temperatures, shifts in seasons, and heavier rains as the most likely consequences. Levels of disaster preparedness in the Philippines differ widely by region. Although most Filipinos perceive that natural hazards are a risk to them, only a third of Filipinos undertake measures to prepare for disasters. Filipinos who perceive climate-related changes directly impacting their households report taking greater action to prepare for disasters. Filipinos who believe they have been directly impacted by climate-related changes are also more likely to prepare for disasters, take planning actions, and undertake material actions to prepare, such as dwelling improvements. Other factors associated with disaster preparedness include gender, membership in an association, wealth, risk perception, and prior exposure to and losses due to disasters. The findings imply that, while posing different challenges and requiring different responses, adaptation to climate change and disaster preparedness are inherently associated and potentially mutually reinforcing. Policies and programs would arguably benefit from a more unified intervention framework that links climate change adaptation and disaster preparedness.     

Public perception of climate change and disaster preparedness: Evidence from the Philippines

The Philippines is highly susceptible to both geophysical and climate-related disasters. This article explores Filipinos knowledge and perception of climate change and their association with what action Filipinos take to prepare for rapid onset natural hazards such as typhoons. Data for this study were collected from a nationally representative random survey of 5,184 adults conducted between March and April of 2017. Filipinos self-report relatively low levels of knowledge of climate change and cited increased temperatures, shifts in seasons, and heavier rains as the most likely consequences. Levels of disaster preparedness in the Philippines differ widely by region. Although most Filipinos perceive that natural hazards are a risk to them, only a third of Filipinos undertake measures to prepare for disasters. Filipinos who perceive climate-related changes directly impacting their households report taking greater action to prepare for disasters. Filipinos who believe they have been directly impacted by climate-related changes are also more likely to prepare for disasters, take planning actions, and undertake material actions to prepare, such as dwelling improvements. Other factors associated with disaster preparedness include gender, membership in an association, wealth, risk perception, and prior exposure to and losses due to disasters. The findings imply that, while posing different challenges and requiring different responses, adaptation to climate change and disaster preparedness are inherently associated and potentially mutually reinforcing. Policies and programs would arguably benefit from a more unified intervention framework that links climate change adaptation and disaster preparedness.     

Public perception of climate change and disaster preparedness: Evidence from the Philippines

The Philippines is highly susceptible to both geophysical and climate-related disasters. This article explores Filipinos knowledge and perception of climate change and their association with what action Filipinos take to prepare for rapid onset natural hazards such as typhoons. Data for this study were collected from a nationally representative random survey of 5,184 adults conducted between March and April of 2017. Filipinos self-report relatively low levels of knowledge of climate change and cited increased temperatures, shifts in seasons, and heavier rains as the most likely consequences. Levels of disaster preparedness in the Philippines differ widely by region. Although most Filipinos perceive that natural hazards are a risk to them, only a third of Filipinos undertake measures to prepare for disasters. Filipinos who perceive climate-related changes directly impacting their households report taking greater action to prepare for disasters. Filipinos who believe they have been directly impacted by climate-related changes are also more likely to prepare for disasters, take planning actions, and undertake material actions to prepare, such as dwelling improvements. Other factors associated with disaster preparedness include gender, membership in an association, wealth, risk perception, and prior exposure to and losses due to disasters. The findings imply that, while posing different challenges and requiring different responses, adaptation to climate change and disaster preparedness are inherently associated and potentially mutually reinforcing. Policies and programs would arguably benefit from a more unified intervention framework that links climate change adaptation and disaster preparedness.     

Public perception of climate change and disaster preparedness: Evidence from the Philippines

The Philippines is highly susceptible to both geophysical and climate-related disasters. This article explores Filipinos knowledge and perception of climate change and their association with what action Filipinos take to prepare for rapid onset natural hazards such as typhoons. Data for this study were collected from a nationally representative random survey of 5,184 adults conducted between March and April of 2017. Filipinos self-report relatively low levels of knowledge of climate change and cited increased temperatures, shifts in seasons, and heavier rains as the most likely consequences. Levels of disaster preparedness in the Philippines differ widely by region. Although most Filipinos perceive that natural hazards are a risk to them, only a third of Filipinos undertake measures to prepare for disasters. Filipinos who perceive climate-related changes directly impacting their households report taking greater action to prepare for disasters. Filipinos who believe they have been directly impacted by climate-related changes are also more likely to prepare for disasters, take planning actions, and undertake material actions to prepare, such as dwelling improvements. Other factors associated with disaster preparedness include gender, membership in an association, wealth, risk perception, and prior exposure to and losses due to disasters. The findings imply that, while posing different challenges and requiring different responses, adaptation to climate change and disaster preparedness are inherently associated and potentially mutually reinforcing. Policies and programs would arguably benefit from a more unified intervention framework that links climate change adaptation and disaster preparedness.