检索结果-南通市图书馆

The impact of crustal rheology on natural seismicity: Campi Flegrei caldera case study

Geoscience Frontiers 2019年第2期10卷 453-466页

作者： R.Castaldo L.D'Auria S.Pepe G.Solaro V.De Novellis P.Tizzani Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA)-Consiglio Nazionale delle Ricerche (CNR) Instituto Volcanológico de Canarias (INVOLCAN) Instituto Tecnológico y de Energías Renovables (ITER)

We analyze the crustal rheology beneath the active resurgent Campi Flegrei caldera(CFc) in Southern Italy by modelling the 3 D brittle-ductile(B/D) transition, based on available thermal, geological and geophysical data. Firstly, the thermal field in the conductive physical regime is modeled using a finite element method; based on an optimization tool, this method is applied to evaluate the location and dimensions of the deep thermal source beneath the caldera. A horizontally-extended thermal anomaly located at about 5000 m depth below sea level is identified beneath Pozzuoli Bay, a part of the CFc. The same isotherm is located at a depth of 20,000 m beyond the caldera. This indicates a higher horizontal temperature gradient in the caldera with respect to the surrounding area. Next, we utilize this thermal model to image the 3D rheological stratification of the shallow crust below the caldera with two different values of strain rates. Within the caldera, the B/D transitions with ε equal to 10^(-12) s^(-1) and 10^(-8) s^(-1) are located at 3000 m and 5000 m depths, respectively. Outside the caldera, the transition is very deep(15,000-20,000 m), seemingly uninfluenced by the thermal state of the CFc volcanism. Finally, we compare these results with the spatial distribution of earthquake hypocenters, Benioff strain release and b-value distribution to investigate the relationship between crustal rheology and seismicity characteristics. Our analysis reveals that the image of the B/D transition is in agreement with the distribution of earthquake hypocenters, constraining the potential seismogenic volume of the region. Our study demonstrates that knowledge of the rheological state of a volcanic system is an important element to interpret its dynamic, forecast future activity and improve evaluation of the associated seismic hazard.

关键词： Brittle-ductile transition Seismicity cut-off Geothermal measurements FE conductive thermal modelling Campi Flegrei caldera

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Modeling the multi-level plumbing system of the Changbaishan caldera from geochemical, mineralogical, Sr-Nd isotopic and integrated geophysical data

引用

Geoscience Frontiers 2021年第5期12卷 17-36页

作者： Jian Yi Pujun Wang Xuanlong Shan Guido Ventura Chengzhi Wu Jiannan Guo Pencheng Liu Jiahui Li College of Earth Science Jilin UniversityJianshe Street 2199Changchun 130061China Key Laboratory for Evolution of Past Life and Environment in Northeast Asia(Jilin University) Ministry of EducationChangchun 130026China Istituto Nazionale di Geofisica e Vulcanologia Via di Vigna Murata605Roma 00143Italy Istituto per lo Studio degli impatti Antropici e Sostenibilitàin ambiente marino(IAS) Capo Granitola(TP)91021Italy Changbai Mountain Tianchi Volcano Observatory Chibei DistrictAntu 133613China

Changbaishan,an intraplate volcano,is characterized by an approximately 6 km wide summit caldera and last erupted in *** experienced a period of unrest between 2002 and *** activity developed in three main stages,including shield volcano(basalts),cone-construction(trachyandesites to trachytes with minor basalts),and caldera-forming stages(trachytes to comendites).This last stage is associated with one of the more energetic eruptions of the last millennium on Earth,the 946 CE,VEI 7 Millennium Eruption(ME),which emitted over 100 km^(3) of *** to other active calderas,the plumbing system of Changbaishan and its evolution mechanisms remain poorly ***,we merge new whole-rock,glass,mineral,isotopic,and geobarometry data with geophysical data and present a model of the plumbing *** results show that the volcano is characterized by at least three main magma reservoirs at different depths:a basaltic reservoir at the Moho/lower crust depth,an intermediate reservoir at 10-15 km depth,and a shallower reservoir at 0.5-3 km *** shallower reservoir was involved in the ME eruption,which was triggered by a fresh trachytic melt entering a shallower reservoir where a comenditic magma was *** trachytes and comendites originate from fractional crystallization processes and minor assimilation of upper crust material,while the less evolved melts assimilate lower crust ***-eruptive magma mingling occurred during the ME eruption *** magma reservoirs of the caldera-forming stage partly reactivate those of the cone-construction *** depth of the magma storage zones is controlled by the layering of the *** plumbing system of Changbaishan is vertically extensive,with crystal mush reservoirs renewed by the replenishment of new trachytic to trachyandesitic magma from *** other volcanoes,evidence of a basaltic recharge is *** interpretation of the signals preceding possible future erupt

关键词： Changbaishan volcano caldera Plumbing system Triggering mechanism Storage depth

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Typology of Natural Hazards and Assessment of Associated Risks in the Mount Bambouto caldera(Cameroon Line,West Cameroon)

引用

Acta Geologica Sinica(English Edition) 2009年第5期83卷 1008-1016页

作者： Ghislain T.ZANGMO Armand D.KAGOU David G.NKOUATHIO Pierre WANDJI Department of Earth Science Faculty of ScienceUniversity of DschangCameroon Laboratory of Geology High Teacher Training SchoolUniversity of Yaounde ICameroon

Mount Bambouto is a polygenic stratovolcano of the Cameroon Volcanic Line, built between 21 Ma and 4.5 Ma. It is situated approximately 200 km NE of Mount Cameroon, between 09° 55＇ and 10°15＇ longitude east and, 05°25＇ and 05°50＇ latitude north. The volcano covers an area of 500 km^2 and culminates at 2740 m at Meletan dome and bears a collapsed caldera at the summit （13 × 8 km）. Mount Bambouto is characterized by several natural hazards of different origins： meteorological, such as landslides and rock falls; anthropogenic, such as bushfires, tribal wars and deforestation; and volcanological, such as volcanic eruption. The thematic map shows that 55-60% of the caldera has high probability of occurrence of mass movement. The caldera has a high population density （3000 inhabitants）, which increases the level of risk, evaluated at approximately $US3.8 million for patrimony, 3000 civilian deaths and destruction of biodiversity.

关键词： caldera hazard risk assessment Mount Bambouto Cameroon Line

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study of Multi-Origin Hazards and Assessment of Associated Risks in the Lefo caldera (Bamenda Volcano, Cameroon Line)

引用

International Journal of Geosciences 2014年第11期5卷 1300-1314页

作者： Zangmo Tefogoum Ghislain Nkouathio David Guimolaire Kagou Dongmo Armand Gountie Dedzo Merlin Kamgang Pierre Department of Earth Sciences Faculty of Sciences University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Sciences University of Dschang Dschang Cameroon Department of Life and Earth Science High Teacher Training College University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Science University of Yaounde 1 Yaounde Cameroon

The Bamenda Volcano (BV) (2621 m) is a stratovolcano situated in the Cameroon Line (CL). BV includes Mount Lefo (2534 m) which is situated on its southern slopes and contains one elliptical caldera (3 × 4 km). This caldera is propitious to farming and breeding activity. Despite these profitable assets, Lefo caldera (LC) is an amphitheater of the occurrence of multi-origin hazards that have direct or indirect impacts on the biodiversity and human patrimony. The most present hazards are those of meteorological origin. Numerous combined factors (steepest slopes, heavy rainfalls, weathered state of volcanic products…) rule these hazards. These factors gave rise to the occurrence of landslides, gullies erosion and rock falls which occur precisely on caldera northern and eastern rims. Hazards of anthropogenic origin are based on the destruction of the vegetation cover by the population for dealing, firewood and building issues. Moreover, during the breeding activity, the cattle covers the caldera throughout the day;this unevens the topography and destroys the meadow. Hazards of volcanological origin are not yet occurring in LC;but the recent Lake Monoun (1984) and Nyos (1986) CO2 eruptions, mount Cameroon eruptions (1999 and 2000) and mount Oku Lake event (2011) which are close to the BV and, the age of 0 Myr of basalt, constitutes a subject of controversy toward the reactivation of the Cameroonian hotspot faults. The assessment of risks in LC was based on the average income of breeding activity and house investment. The economy of LC is valued at about US$527472.527. The level of such risk will be important in case of loss of human beings and the destruction of geomorphosites’ values. In order to reduce the level of looses in this zone, hazard and risks maps are provided in this paper as well as some recommendations.

关键词： Hazards Risk Anthropogenic Activities Lefo caldera

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Socio-Economic Impact of Land Use and Land Cover Change on the Inhabitants of Mount Bambouto caldera of the Western Highlands of Cameroon

引用

Advances in Remote Sensing 2018年第1期7卷 25-45页

作者： Formeluh Abraham Toh Tsi Evaristus Angwafo Lawrence Monah Ndam Mvondo Ze Antoine Department of Forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Fundamental Science Higher Technical Teacher Training College (HTTTC) University of Bamenda Bambili Cameroon Department of Botany and Plant Physiology University of Buea Buea South West Region Cameroon Department of International Environmental and Agricultural Science Faculty of Agriculture Tokyo University of Agriculture and Technology Tokyo Japan Department of Soil Science Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon

This work assessed the impact of land use and land cover (LULC) change on the socio-economic conditions of the inhabitants in the Mount Bambouto caldera from 1980-2016. To achieve this, three time series satellite images;Landsat Thematic Mapper (TM) (1980), Landsat Enhanced Thematic Mapper (ETM) (2001), and Landsat 8 Operational Land Imager (OLI) (2016) scenes were employed to investigate the changes in LULC. The use of satellite images was supplemented with individual interviews, discussions with focus groups and key informants, and direct field observations. Five categories of LULC classes were identified namely: thick woody vegetation (natural forest and oil palms), light vegetation (croplands), savannah (grasslands), buildings (settlements), and bare grounds. The results showed that between 1980 and 2016, croplands, buildings and bare lands increased by 4%, 0.43% and 5.7% respectively while savannah/grassland and natural forest decreased by 4.4% and 5.8% respectively. Household survey revealed soil fertility decline and lack of credit schemes to be major constraints to crop production. Many religious holidays contribute to seasonal food shortages and the community faces a host of socio-economic and institutional challenges. Consequently, majority of house-holds are destitute, live in abject poverty;which is an indication of the need for interventions by government and other development stakeholders to tackle the problems of soil fertility, land use change and food insecurity.

关键词： Land Use Land Cover Landsat Bambouto caldera Socioeconomic Impact Soil Fertility Cameroon

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Typology of Natural Hazards and Assessment of Associated Risks in the Mount Bambouto caldera(Cameroon Line,West-Cameroun)

引用

地学前缘 2009年第S1期16卷 66-66页

作者： Zangmo Tefogoum Ghislain Kagou Dongmo Armand Nkouathio David Guimolaire Wandji Pierre Department of Earth Science University of Dschang Laboratory of Geology ENSUniversity of Yaounde IB.P.47 Yaounde

Mount Bambouto is a polygenic stratovolcano of the Cameroon Volcanic Line,built between 21 Ma and 4.5 Ma(Nkouathio et al.,2008).It is situated at about 200 km NE of mount Cameroon,at 09°55′and 10°15′East and,05°25′and 05°50′*** volcano covers an area of 500 Km^2 and culminates at 2740 m at Meletan hill and bears a collapsed elliptical caldera at the summit(13×8 km).Mount

关键词： Cameroon Line Mount Bambouto caldera hazards risks

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

caldera公司收购SCO OpenServer产品线Linux走向高端

每周电脑报

引用

每周电脑报 2000年第33期 32-32页

Linux厂商caldera系统公司8月表示已经同意购买SCO的两个分公司,并组成一个新的公司。caldera公司称即将组建的新公司将获得SCO公司的服务器软件和专业服务分部的资产,并且将获得SCO公司OpenServer产品线的独家发行权。分析家指出,Cald... 详细信息

Linux厂商caldera系统公司8月表示已经同意购买SCO的两个分公司,并组成一个新的公司。caldera公司称即将组建的新公司将获得SCO公司的服务器软件和专业服务分部的资产,并且将获得SCO公司OpenServer产品线的独家发行权。分析家指出,caldera公司的收购行动宣告了Unix独立的时代的终结。独立的Unix系统正在有力地向Linux转变,下出多少时间,Linux系统将具有Unix系统的高端特性。在合同条款中,caldera系统公司将联合收购的Professional Services分部组

关键词：产品线公司收购企业收购 caldera SCO OpenServer Linux

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

caldera免费提供操作系统

每周电脑报

引用

每周电脑报 1997年第7期 17-17页

caldera公司近期发布了OpenDOS操作系统,这个产品通过Internet向非商业用户及教育界的用户免费提供。同时,3月份caldera公司将通过网络发布OpenDOS的核心部分源代码。 OpenDOS的二进制代码,是基于DOS 7技术之上的,这些技术是去年该公司... 详细信息

caldera公司近期发布了OpenDOS操作系统,这个产品通过Internet向非商业用户及教育界的用户免费提供。同时,3月份caldera公司将通过网络发布OpenDOS的核心部分源代码。 OpenDOS的二进制代码,是基于DOS 7技术之上的,这些技术是去年该公司从Novell公司处获得的,可以支持所有基于DOS的应用程序。通过Internet让用户获得二进制代码和源代

关键词：操作系统计算机系统二进制代码源代码 caldera

来源：

同方期刊数据库评论