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Glacial Rebound and Plate Spreading: Results from the First Countrywide GPS Observations in Iceland
Geophys. J. Int. (2009) 177, 691–716 doi: 10.1111/j.1365-246X.2008.04059.x Glacial rebound and plate spreading: results from the first countrywide GPS observations in Iceland ∗ T. Arnad´ ottir,´ 1 B. Lund,2 W. Jiang,1 H. Geirsson,3 H. Bjornsson,¨ 4 P. Einarsson4 and T. Sigurdsson5 1Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, IS-101 Reykjav´ık, Iceland. E-mail: [email protected] 2Department of Earth Sciences, Uppsala University, Villavagen¨ 16, 752 36 Uppsala, Sweden 3Physics Department, Icelandic Meteorological Office, Reykjav´ık, Iceland 4Institute of Earth Sciences, University of Iceland, IS-101 Reykjav´ık, Iceland 5National Land Survey of Iceland, Akranes, Iceland Downloaded from https://academic.oup.com/gji/article/177/2/691/2023257 by guest on 30 September 2021 Accepted 2008 December 10. Received 2008 December 5; in original form 2008 June 12 SUMMARY Iceland is one of the few places on Earth where a divergent plate boundary can be observed on land. Direct observations of crustal deformation for the whole country are available for the first time from nationwide Global Positioning System (GPS) campaigns in 1993 and 2004. The plate spreading across the island is imaged by the horizontal velocity field and high uplift rates (≥10 mm yr−1) are observed over a large part of central and southeastern Iceland. Several earthquakes, volcanic intrusions and eruptions occurred during the time spanned by the measurements, causing local disturbances of the deformation field. After correcting for the largest earthquakes during the observation period, we calculate the strain rate field and find that the main feature of the field is the extension across the rift zones, subparallel to the direction of plate motion. -
Iceland Is Cool: an Origin for the Iceland Volcanic Province in the Remelting of Subducted Iapetus Slabs at Normal Mantle Temperatures
Iceland is cool: An origin for the Iceland volcanic province in the remelting of subducted Iapetus slabs at normal mantle temperatures G. R. Foulger§1 & Don L. Anderson¶ §Department of Geological Sciences, University of Durham, Science Laboratories, South Rd., Durham, DH1 3LE, U.K. ¶California Institute of Technology, Seismological Laboratory, MC 252-21, Pasadena, CA 91125, U. S. A. Abstract The time-progressive volcanic track, high temperatures, and lower-mantle seismic anomaly predicted by the plume hypothesis are not observed in the Iceland region. A model that fits the observations better attributes the enhanced magmatism there to the extraction of melt from a region of upper mantle that is at relatively normal temperature but more fertile than average. The source of this fertility is subducted Iapetus oceanic crust trapped in the Caledonian suture where it is crossed by the mid-Atlantic ridge. The extraction of enhanced volumes of melt at this locality on the spreading ridge has built a zone of unusually thick crust that traverses the whole north Atlantic. Trace amounts of partial melt throughout the upper mantle are a consequence of the more fusible petrology and can explain the seismic anomaly beneath Iceland and the north Atlantic without the need to appeal to very high temperatures. The Iceland region has persistently been characterised by complex jigsaw tectonics involving migrating spreading ridges, microplates, oblique spreading and local variations in the spreading direction. This may result from residual structural complexities in the region, inherited from the Caledonian suture, coupled with the influence of the very thick crust that must rift in order to accommodate spreading-ridge extension. -
Plate Tectonics Review from Valerie Nulisch Some Questions (C) 2017 by TEKS Resource System
Plate Tectonics Review from Valerie Nulisch Some questions (c) 2017 by TEKS Resource System. Some questions (c) 2017 by Region 10 Educational Service Center. Some questions (c) 2017 by Progress Testing. Page 2 GO ON A student wanted to make a model of the Earth. The student decided to cut a giant Styrofoam ball in half and paint the layers on it to show their thickness. 1 Which model below best represents the layers of the Earth? A B C D Page 3 GO ON 2 A student is building a model of the layers of the Earth. Which material would best represent the crust? F Grouping of magnetic balls G Styrofoam packing pellets H Bag of shredded paper J Thin layer of graham crackers 3 Your teacher has asked you to make a model of the interior of the Earth. In your model, how do the thicknesses of the lithosphere and crust compare? A The lithosphere is thinner than the crust. B The lithosphere is exactly the same thickness as the crust. C The lithosphere is thicker than the crust. D The lithosphere is thicker than the oceanic crust, but thinner than the continental crust. 4 Sequence the layers of the Earth in order from the exterior surface to the interior center. F Lithosphere, mantle, inner core, outer core, crust, asthenosphere G Inner core, outer core, mantle, asthenosphere, lithosphere, crust H Crust, mantle, outer core, inner core, asthenosphere, lithosphere J Crust, lithosphere, asthenosphere, mantle, outer core, inner core Page 4 GO ON 5 The tectonic plate labeled A in the diagram is the A Eurasian Plate B Indo-Australian Plate C Pacific Plate D African Plate Page 5 GO ON 6 The tectonic plate labeled B in the diagram is the — F Eurasian Plate G Indo-Australian Plate H Pacific Plate J North American Plate Page 6 GO ON Directions: The map below shows Earth's tectonic plates; six of them are numbered. -
The Geology of England – Critical Examples of Earth History – an Overview
The Geology of England – critical examples of Earth history – an overview Mark A. Woods*, Jonathan R. Lee British Geological Survey, Environmental Science Centre, Keyworth, Nottingham, NG12 5GG *Corresponding Author: Mark A. Woods, email: [email protected] Abstract Over the past one billion years, England has experienced a remarkable geological journey. At times it has formed part of ancient volcanic island arcs, mountain ranges and arid deserts; lain beneath deep oceans, shallow tropical seas, extensive coal swamps and vast ice sheets; been inhabited by the earliest complex life forms, dinosaurs, and finally, witnessed the evolution of humans to a level where they now utilise and change the natural environment to meet their societal and economic needs. Evidence of this journey is recorded in the landscape and the rocks and sediments beneath our feet, and this article provides an overview of these events and the themed contributions to this Special Issue of Proceedings of the Geologists’ Association, which focuses on ‘The Geology of England – critical examples of Earth History’. Rather than being a stratigraphic account of English geology, this paper and the Special Issue attempts to place the Geology of England within the broader context of key ‘shifts’ and ‘tipping points’ that have occurred during Earth History. 1. Introduction England, together with the wider British Isles, is blessed with huge diversity of geology, reflected by the variety of natural landscapes and abundant geological resources that have underpinned economic growth during and since the Industrial Revolution. Industrialisation provided a practical impetus for better understanding the nature and pattern of the geological record, reflected by the publication in 1815 of the first geological map of Britain by William Smith (Winchester, 2001), and in 1835 by the founding of a national geological survey. -
Japan Geoscience Union Meeting 2009 Presentation List
Japan Geoscience Union Meeting 2009 Presentation List A002: (Advances in Earth & Planetary Science) oral 201A 5/17, 9:45–10:20, *A002-001, Science of small bodies opened by Hayabusa Akira Fujiwara 5/17, 10:20–10:55, *A002-002, What has the lunar explorer ''Kaguya'' seen ? Junichi Haruyama 5/17, 10:55–11:30, *A002-003, Planetary Explorations of Japan: Past, current, and future Takehiko Satoh A003: (Geoscience Education and Outreach) oral 301A 5/17, 9:00–9:02, Introductory talk -outreach activity for primary school students 5/17, 9:02–9:14, A003-001, Learning of geological formation for pupils by Geological Museum: Part (3) Explanation of geological formation Shiro Tamanyu, Rie Morijiri, Yuki Sawada 5/17, 9:14-9:26, A003-002 YUREO: an analog experiment equipment for earthquake induced landslide Youhei Suzuki, Shintaro Hayashi, Shuichi Sasaki 5/17, 9:26-9:38, A003-003 Learning of 'geological formation' for elementary schoolchildren by the Geological Museum, AIST: Overview and Drawing worksheets Rie Morijiri, Yuki Sawada, Shiro Tamanyu 5/17, 9:38-9:50, A003-004 Collaborative educational activities with schools in the Geological Museum and Geological Survey of Japan Yuki Sawada, Rie Morijiri, Shiro Tamanyu, other 5/17, 9:50-10:02, A003-005 What did the Schoolchildren's Summer Course in Seismology and Volcanology left 400 participants something? Kazuyuki Nakagawa 5/17, 10:02-10:14, A003-006 The seacret of Kyoto : The 9th Schoolchildren's Summer Course inSeismology and Volcanology Akiko Sato, Akira Sangawa, Kazuyuki Nakagawa Working group for -
Geology and Petroleum Systems of the Eastern Meseta and Atlas Domains of Morocco
258 Paper 22 Geology and petroleum systems of the Eastern Meseta and Atlas Domains of Morocco FATIMA CHARRAT\ MOHAMAD ELALTI\ MoHO HAMIDI M. NOR2, NG TONG SAN2, SUPIAN SUNTEK2 AND TJIA, H.D.2 10ttice National de Recherches et d'Exploitations Petrolieres Rabat, Maghreb 2PETRONAS Carigali, Tower 1, Petronas Twin Towers 50088 Kuala Lumpur, Malaysia Morocco (Maghreb), located in Northwest Africa, has three main structural domains: The (a) RifDomain, the (b) Atlas Domain comprising two different structural regions, the relatively stable eastern and western Meseta, (characterized by mildly deformed Mesozoic strata) and the active Middle-High Atlas Belts, where the Meso Cenozoic section was highly folded during the Alpine orogeny; and finally, the (c) Sahara-Anti Atlas Domain at the south, marks the stable margin of the West African Craton. The eastern Meseta, with the Middle and the High Atlas chains (Atlas Domain ss.) is the objective of our study; it extends eastward through Algeria. The Middle Atlas and the High Atlas tectonic belts frame the Meseta. The Cambrian marine transgression over the northwestern African continental platform allowed deposition of shales, silts and sands over a faulted land surface. Folding at the Late Cambrian generated an irregular angular unconformity with the Ordovician sequence. This sequence, dominantly argillaceous at the beginning, ended with a regressive phase of glacio-marine sedimentation that developed coarse sandstones and micro-conglomerate. Volcanic eruptions caused localised metamorphism. The Ordovician ended with regression due to the emergence of the area (Taconic phase). Glacio-eustatism followed, leading to the widespread Silurian deposits of graptolite bearing black clays in shallow marine, confined (euxinic) troughs. -
Alpine Orogeny the Geologic Development of the Mediterranean
Alpine Orogeny The geologic development of the Mediterranean region is driven by the Alpine-Himalayan orogeny, a suturing of Gondwana-derived terranes with the Eurasion craton. In broad terms, this is a Mesozoic and Cenozoic convergent zone that extends from the Spain to Southeastern Asia and may extend along the southwest Pacific as far as New Zealand (Rosenbaum and Lister, 2002). The Alpine orogeny was caused by the convergence of the African and European plates (Frisch, 1979; Tricart, 1984; Haas et al., 1995) with peak collisional phases occurring at different times: Cretaceous in the Eastern Alps and Tertiary in the Western Alps (Schmid et al., 2004). Note: prior to the opening of the Paleotethys sea, the Variscan orogenic belt developed in central Europe then the Laurussian and Gondwana converged in the Devonian and Late Carboniferous. Although the location of the suture Extent of the Alpine-Himalayan orogenic belt is not clear, the orogenic belt was extensive, (Rosenbaum and Lister, 2002). running from the Bohemian Massif to the Alpine-Carpathian-Dinarides belt (). The Paleotethys sea existed in the Triassic but closed in the early Mesozoic due to convergence along the Cimmerian (and Indosinian) suture zone. The Paleotethys (or Tethys I) has been described as a wedge- shaped ocean that opened to the east, separating Eurasia from Africa, India, and Australia (Laurasia and Gondwana). Very little evidence of the Paleotethys exists today which has caused some to question its existence (Meyerhoff and Eremenko, 1976) The Tethys opened as Pangea broke up in the Early Jurassic and Africa moved east relative to Europe. -
Azores and Iceland
13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2369 A COMPARATIVE STUDY ON STRONG GROUND MOTION IN TWO VOLCANIC ENVIRONMENTS: AZORES AND ICELAND Carlos S. OLIVEIRA1, Ragnar SIGBJÖRNSSON2, Simon ÓLAFSSON3 SUMMARY The objective of this paper is to present the main results of a comparative study of strong ground motion on the Azores and Iceland. These islands are a super-structural part of the Mid Atlantic Ridge, which marks the boundary between the North-American Plate and the Eurasian Plate and creates a north-south oriented belt of seismic and volcanic activity. The tectonic environments are described and compared emphasising the similarities in the geological structure, including surface geology and its effects on strong ground motion. Furthermore, the seismicity of the Azores and Iceland is compared based on earthquake catalogues using statistical analysis. The strong-motion networks on the islands are described along with the strong-motion data used in the subsequent analysis. The strong-motion data are compared using statistical analysis. The main emphasis is put on attenuation of strong-motion data, characterised by root mean square acceleration and peak ground acceleration. The attenuation is also compared to some of the common attenuation relationships, used by the engineering community in Europe and America. The main findings are that there are significant similarities between the tectonic environments of the Azores and Iceland. Furthermore, the similarities found in seismicity are statistically significant. The attenuation is characterised by rapid decay with increasing distance and high acceleration in the near source area. It is found that the same ground motion estimation models can be applied on the Azores and in Iceland. -
Stress Orientations in the Nankai Trough Constrained Using Seismic and Aseismic Slip
RESEARCH ARTICLE Stress Orientations in the Nankai Trough Constrained 10.1029/2020JB019841 Using Seismic and Aseismic Slip Key Points: Tyler J. Newton1 and Amanda M. Thomas1 • Stress inversions of slow slip events imply the presence of intrinsically 1Department of Earth Sciences, University of Oregon, Eugene, OR, USA weak fault materials • The strength of the megathrust is similar to its surroundings in SSE source regions Abstract The strength of subduction thrust faults is key to understanding seismogenesis at the • Slow fault slip accommodates a large provenance of Earth's largest earthquakes. Earthquake focal mechanisms are routinely inverted to fraction of the total seismic moment constrain the stress state at seismogenic depths. However, on some megathrusts, deformation is in the Nankai Trough accommodated by both earthquakes and types of slow fault slip. We employ focal mechanisms of short‐term Supporting Information: slow slip events (SSEs), a type of slow fault slip, and earthquakes in a regional stress inversion to investigate • Supporting Information S1 the stress state of the Nankai Trough megathrust and interpret the results in the context of regional • Figure S1 tectonics Previous studies using earthquake‐only stress inversions found principal stress orientations in this • Figure S2 • Figure S3 region that are incompatible with thrust faulting on the megathrust. When both SSEs and earthquakes are • Figure S4 considered, the stress state of the central and eastern Nankai Trough megathrust is well oriented for thrust • Figure S5 faulting. Our results suggest that slow fault slip source regions may appear to have misoriented stress fields if slow fault slip constitutes a substantial proportion of fault slip and the stress field is not well constrained by earthquakes. -
Plate Tectonics Passport
What is plate tectonics? The Earth is made up of four layers: inner core, outer core, mantle and crust (the outermost layer where we are!). The Earth’s crust is made up of oceanic crust and continental crust. The crust and uppermost part of the mantle are broken up into pieces called plates, which slowly move around on top of the rest of the mantle. The meeting points between the plates are called plate boundaries and there are three main types: Divergent boundaries (constructive) are where plates are moving away from each other. New crust is created between the two plates. Convergent boundaries (destructive) are where plates are moving towards each other. Old crust is either dragged down into the mantle at a subduction zone or pushed upwards to form mountain ranges. Transform boundaries (conservative) are where are plates are moving past each other. Can you find an example of each type of tectonic plate boundary on the map? Divergent boundary: Convergent boundary: Transform boundary: What do you notice about the location of most of the Earth’s volcanoes? P.1 Iceland Iceland lies on the Mid Atlantic Ridge, a divergent plate boundary where the North American Plate and the Eurasian Plate are moving away from each other. As the plates pull apart, molten rock or magma rises up and erupts as lava creating new ocean crust. Volcanic activity formed the island about 16 million years ago and volcanoes continue to form, erupt and shape Iceland’s landscape today. The island is covered with more than 100 volcanoes - some are extinct, but about 30 are currently active. -
Active Faults and Neotectonics in Japan1) Atsumasa OKADA2) And
第 四 紀 研 究 (The Quaternary Research) 30 (2) p. 161-174 July 1991 Active Faults and Neotectonics in Japan1) Atsumasa OKADA2) and Yasutaka IKEDA3) Wereview in this paperthe recent trend ofactive fault studies in Japan. The JapaneseIslands, includingthe continentalshelves and slopessurrounding them, form an activetectonic belt. The overalldistribution and regional characteristics of Quaternary faults have recently been clarified, and are nowbeing supplemented in detail. Some topics, including the studies of active faults on shallow sea and lake bottoms, the geomorphicand structural evolution of and the surface defromationassociated with thrust faults, and the excavationof active faults with or without historic activity, are also reviewed. brief review, see RESEARCH GROUP FOR ACTIVE I. Introduction FAULTS, 1980b). The earlier edition has The Japanese Islands, including the continen- provided basic data for earthquake prediction tal shelves and slopes surrounding them, form an research and earthquake-disaster-prevention active tectonic belt delineated on the southeast planning. This book was extensively revised in by oceanic subduction systems along the north- 1991, introducing the mass of new data obtained west rim of the Pacific Ocean. Being closely in the past decade. Active faults were mapped related to this physiographic setting, tectonic for the Japanese Islands and adjacent sea features such as Quaternary faults, folds, and bottoms, to a uniform standard, and compiled associated tectonic landforms develop in and into a set of sheet maps (originally on a scale around the islands. Studies on the neotectonics 1:200,000) with an inventory of faults for each or recent crustal movements have been sheet map. Two smaller-scale compiled maps conducted mainly by geodetic, seismological, of active faults (1:3,000,000 and 1:1,000,000) were geomorphological and geological methods. -
Earthquake Risk Transfer for Greece
Earthquake Risk Transfer for Greece Overview Figure 59. Hash circles represent current Earling undercover regions. Greece is located at the complex boundary zone in the eastern Mediterranean between the African Plate and the Eurasian Plate. The northern part of Greece lies on the Eurasian Plate while the southern part lies on the Aegean Sea Plate. The Aegean Sea Plate is moving southwestward with respect to the Eurasian Plate at about 30 mm/yr while the African Plate is subducting northwards beneath the Aegean Sea Plate at a rate of about 40 mm/yr. The northern plate boundary is a relatively 64 Earling Natural Risk Transfer Platform More; https://acircularworld.com diffuse divergent boundary while the southern convergent boundary forms the Hellenic arc. These two plate boundaries give rise to two contrasting tectonic styles, extension on east-west trending fault zones with strike-slip tectonics on SW-NE trending fault zones throughout west and central Greece, Peloponnese and the northern Aegean and contractional in the southern Aegean, continuing around to the Ionian islands. The south Aegean is the location of the volcanic arc and is characterized by extension. To the east of Crete along the Hellenic Arc, strike-slip tectonics with some extension become important. Earling can issue accurate earthquake preparedness alert especially for North of Greece. EPA Effect on Greece Insurance Loss Longterm Loss Millions $3,500 $1,300 $130 $600 Total Loss Insured Loss EPA Effect Figure 60. EPA effect on Sep 7, 1999, Greece earthquake (Higgins, 2016). 65 Earling Natural Risk Transfer Platform More; https://acircularworld.com EPA Effect on Greece Insurance Penetration Rate 38% 36% 33% 30% 28% 25% 23% 21% 17% 18% 15% 13% 2020 2021 2022 2023 2024 Figure 61.