Plate Tectonics Review from Valerie Nulisch Some Questions (C) 2017 by TEKS Resource System
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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. -
Kinematic Reconstruction of the Caribbean Region Since the Early Jurassic
Earth-Science Reviews 138 (2014) 102–136 Contents lists available at ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev Kinematic reconstruction of the Caribbean region since the Early Jurassic Lydian M. Boschman a,⁎, Douwe J.J. van Hinsbergen a, Trond H. Torsvik b,c,d, Wim Spakman a,b, James L. Pindell e,f a Department of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands b Center for Earth Evolution and Dynamics (CEED), University of Oslo, Sem Sælands vei 24, NO-0316 Oslo, Norway c Center for Geodynamics, Geological Survey of Norway (NGU), Leiv Eirikssons vei 39, 7491 Trondheim, Norway d School of Geosciences, University of the Witwatersrand, WITS 2050 Johannesburg, South Africa e Tectonic Analysis Ltd., Chestnut House, Duncton, West Sussex, GU28 OLH, England, UK f School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff CF10 3YE, UK article info abstract Article history: The Caribbean oceanic crust was formed west of the North and South American continents, probably from Late Received 4 December 2013 Jurassic through Early Cretaceous time. Its subsequent evolution has resulted from a complex tectonic history Accepted 9 August 2014 governed by the interplay of the North American, South American and (Paleo-)Pacific plates. During its entire Available online 23 August 2014 tectonic evolution, the Caribbean plate was largely surrounded by subduction and transform boundaries, and the oceanic crust has been overlain by the Caribbean Large Igneous Province (CLIP) since ~90 Ma. The consequent Keywords: absence of passive margins and measurable marine magnetic anomalies hampers a quantitative integration into GPlates Apparent Polar Wander Path the global circuit of plate motions. -
Shape of the Subducted Rivera and Cocos Plates in Southern Mexico
JOURNALOF GEOPHYSICAL RESEARCH, VOL. 100, NO. B7, PAGES 12,357-12,373, JULY 10, 1995 Shapeof the subductedRivera and Cocosplates in southern Mexico: Seismic and tectonicimplications Mario Pardo and Germdo Sufirez Insfitutode Geoffsica,Universidad Nacional Aut6noma de M6xico Abstract.The geometry of thesubducted Rivera and Cocos plates beneath the North American platein southernMexico was determined based on the accurately located hypocenters oflocal and te!eseismicearthquakes. The hypocenters ofthe teleseisms were relocated, and the focal depths of 21 eventswere constrainedusing a bodywave inversion scheme. The suductionin southern Mexicomay be approximated asa subhorizontalslabbounded atthe edges by the steep subduction geometryof theCocos plate beneath the Caribbean plate to the east and of theRivera plate beneath NorthAmerica to thewest. The dip of theinterplate contact geometry is constantto a depthof 30 kin,and lateral changes in thedip of thesubducted plate are only observed once it isdecoupled fromthe overriding plate. On thebasis of theseismicity, the focal mechanisms, and the geometry ofthe downgoing slab, southern Mexico may be segmented into four regions ß(1) theJalisco regionto thewest, where the Rivera plate subducts at a steepangle that resembles the geometry of theCocos plate beneath the Caribbean plate in CentralAmerica; (2) theMichoacan region, where thedip angleof theCocos plate decreases gradually toward the southeast, (3) theGuerrero-Oaxac.a region,bounded approximately by theonshore projection of theOrozco and O'Gorman -
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. -
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. -
Tectonic Setting & Generalized Geologic Maps of Washington And
on the Lea rs din e g ch E a . d e . g T e Tectonic Setting & Generalized Geologic Maps of Washington and Oregon The TO TLE Pict Earthquakes ure Frank D. Granshaw and Jenda Johnson, 2009 Volcanoes Tsunamis Geology1 Physical Geography Legend for Geography Relief map of Washington and Oregon showing Map colors correspond to vegetation Generalized geologic map of the Pacific Northwest. major cities, volcanoes, lakes and waterways. and surface types: (Circled numbers are the same as on Physical Geography legend) Greens—dense vegetation 1 Browns—grasslands and desert 1 A A Light gray to white—unvegetated alpine regions in the Cascade Range 2 2 Cities A Bellingham, WA N La Grande, OR B Seattle, WA O Baker, OR B I C Tacoma, WA P Ontario, OR B I D Olympia, WA B Bend, OR E Aberdeen, WA R Klamath Falls, OR C H C F Ellensberg, WA S Medford, OR E D 3 F G Yakima, WA T Coos Bay, OR D 3 H Wenatchee, WA U Newport, OR I Spokane, WA V Astoria ,OR G J Walla Walla, WA W Portland, OR G K Pasco, WA X Salem, OR K 4 4 5 L The Dalles, OR Y Eugene, OR 5 V V M Pendleton, OR J J Cascade Volcanoes M M L L W W 1 Mount Baker 6 Mount Hood 6 6 2 Glacier Peak 7 Mount Jeerson N N 3 Mount Rainier 8 Three Sisters 4 Mount St. Helens 9 Newberry Volcano X X 5 Mount Adams 10 Crater Lake O 7 7 Legend for Geology U U Igneous Rock 8 8 Q Q Y Y P Volcanic (Less than 1.6 million years) Volcanic (More than 1.6 million years) 9 9 Volcanic (Mostly 16.5- to 6-million- year-old flood basalts) T T Intrusive rock 10 Sedimentary and Metamorphic Rock 10 Unconsolidated sediment Sedimentary rock S Sedimentary & metamorphic rock R S R Metamorphic rock Physiographic Provinces2 Tectonics3 Map of major physiographic provinces in the Pacic Northwest. -
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. -
Earthquake Risk in Bangladesh
STUDENT VERSION Earthquake Risk in Bangladesh PASSAGE ONE Background A major earthquake can destroy any town. Imagine the damage it could do to a huge city, where millions of people live in poorly made buildings. Now imagine this city is also threatened by natural hazards like flooding and rising sea levels. These are the dangers that face Dhaka, the capital of Bangladesh. Scientists predict a major earthquake in the region. It’s been more than 100 years since the last one so Dhaka is not prepared. Today, a team of scientists is investigating the active geology behind earthquakes in Bangladesh. The project is led by Michael Steckler and Leonardo Seeber from Columbia University’s Lamont-Doherty Earth Observatory, and includes international and local scientists. These scientists represent a range of specialties, such as seismology (earthquakes), structural geology (rocks and tectonic forces), and the center sedimentology (sediments and past environments). Together, they of the action Bangladesh is a country in South Asia are studying the country’s past and present geological events — bordered by India, Bhutan, and Myanmar. It sits on the Bay of Bengal and its capital from shifting faults to changing river patterns — to help people in city, Dhaka, is located in the Bengal Delta. ©AMNH / Google Earth Bangladesh prepare for the next major earthquake. nepal bhutan bangladesh china dhaka myanmar india thailand laos cambodia amnh.org/education/bangladesh © 2013 American Museum of Natural History. All Rights Reserved. Page 1 Earthquake Risk STUDENT VERSION in Bangladesh CONTINUED Background Bangladesh: A Land of Extremes Bangladesh is a small country in south Asia. -
Tectonics and Magmatism in Turkey and the Surrounding Area Geological Society Special Publications Series Editors
Tectonics and Magmatism in Turkey and the Surrounding Area Geological Society Special Publications Series Editors A. J. HARTLEY R. E. HOLDSWORTH A. C. MORTON M. S. STOKER Special Publication reviewing procedures The Society makes every effort to ensure that the scientific and production quality of its books matches that of its journals. Since 1997, all book proposals have been refereed by specialist reviewers as well as by the Society's Publications Committee. If the referees identify weaknesses in the proposal, these must be addressed before the proposal is accepted. Once the book is accepted, the Society has a team of series editors (listed above) who ensure that the volume editors follow strict guidelines on refereeing and quality control. We insist that individual papers can only be accepted after satisfactory review by two independent referees. The questions on the review forms are similar to those for Journal of the Geological Society. The referees' forms and comments must be available to the Society's series editors on request. Although many of the books result from meetings, the editors are expected to commission papers that were not presented at the meeting to ensure that the book provides a balanced coverage of the subject. Being accepted for presentation at the meeting does not guarantee inclusion in the book. Geological Society Special Publications are included in the ISI Science Citation Index, but they do not have an impact factor, the latter being applicable only to journals. More information about submitting a proposal and producing a Special Publication can be found on the Society's web site: www.geolsoc.org.uk. -
Plate Tectonics
Plate tectonics tive motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative move- ment of the plates typically varies from zero to 100 mm annually.[2] Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This predic- The tectonic plates of the world were mapped in the second half of the 20th century. tion of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some sup- porters) propose gradual shrinking (contraction) or grad- ual expansion of the globe.[3] Tectonic plates are able to move because the Earth’s lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topog- raphy and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative im- portance of each of these factors and their relationship to each other is unclear, and still the subject of much debate. -
Investigation 2: How Do We Recognize Plate Boundaries? Assessment
Investigation 2: How do we recognize plate boundaries? Assessment Answer the questions below in complete sentences. 1. What major plate lies west of the North American plate? The major plate west of the North American plate is the Pacific plate. 2. What plate lies northeast of the North American plate? The plate NE of the North American plate is the Eurasian plate. 3. What plate borders the North American plate to the southeast? The plate that borders the North American plate to the southeast is the African plate. 4. Which three plates border the North American plate to the south? The Caribbean, Cocos, and South American plates border the North American plate to the south. 5. What plate borders the North American plate in the U.S. Pacific Northwest? The plate that borders the North American plate in the U.S. Pacific Northwest is the Juan de Fuca Plate. 6. How are earthquakes and volcanoes related to plate boundaries? Earthquake clusters occur on or very near plate boundaries. Volcanoes occur about 100 kilometers away from a plate boundary in the overriding plate. 7. What kind of plate boundary separates the North American and Eurasian plates? A divergent plate boundary separates the North American and Eurasian plates. Copyright © 2012 Environmental Literacy and Inquiry Working Group at Lehigh University Investigation 2: Assessment 2 8. What kind of plate boundary separates the North American and Pacific plates at 31˚ latitude, -115˚ longitude? A transform plate boundary separates the North American and Pacific plates at 31˚ latitude, -115˚ longitude. 9. What kind of plate boundary separates the North American and Pacific plates at 55˚ latitude, -160˚ longitude? A convergent plate boundary separates the North American and Pacific plates at 55˚ latitude, -160˚ longitude.