DOCSLIB.ORG

The Giles County, Virginia, Seismic Zone Seismological Results and Geological Interpretations

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Giles County, Virginia, Seismic Zone Seismological Results and Geological Interpretations THE GILES COUNTY, VIRGINIA, SEISMIC ZONE SEISMOLOGICAL RESULTS AND GEOLOGICAL INTERPRETATIONS U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1355 Landsat multispectral image showing Giles County, Virginia, and surroundings. Image number 2654-15090-7, taken November 6,1976. The solid circle locates Pearisburg, Virginia, seat of Giles County and the presumed epicenter of the earthquake of May 31,1897. Cover designed by Norma J. Maes THE GILES COUNTY, VIRGINIA, SEISMIC ZONE SEISMOLOGICAL RESULTS AND GEOLOGICAL INTERPRETATIONS Angel's Rest promontory (center foreground, elevation 3633 ft [1107 m] above sea level) of Pearis Mountain with the town of Pearisburg and the New River (elevation 1581 ft [482 m] above sea level) at its base. View is toward the southwest. This mountain was erroneously reported to have cracked during the May 31, 1897, earthquake centered in the vicinity. The Narrows seismograph station (code: NAV) is located in Mill Creek Valley, this side of Sentinel Point promontory extending to the right (north). Refer to Narrows, Virginia-West Virginia 7.5 minute topographic map for details. The Giles County, Virginia, Seismic Zone Seismological Results and Geological Interpretations By G. A. BOLLINGER and RUSSELL L. WHEELER U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1355 A description of a newly recognized seismogenic zone, .^sn%. with contributions towards evaluation of ;fflL ^\!*L*_^ :: its seismic hazard /<«///F Q !w UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1988 DEPARTMENT OF THE INTERIOR DONALD PAUL HODEL, Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging-in-Publication Data Bollinger, G. A. The Giles County, Virginia seismic zone. (U.S. Geological Survey professional paper ; 1355) "A description of a newly recognized seismogenic zone, with contributions towards evaluation of its seismic hazard." Bibliography: p. Supt. of Docs no.: I 19.16:1355 1. Seismology Virginia Giles County. 2. Faults (Geology) Virginia Giles County. I. Wheeler, Russell L. II. Title. III. Series. QE535.2.U6B63 1989 551.2'2'09755782 88-600018 For sale by the Books and Open-File Reports Section, U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Page Abstract ........................................... 1 Types of faults potentially responsible for the Giles County Introduction ....................................... 1 seismic zone Continued Terminology .................................... 4 Atlantic normal faults ............................ 43 Geologic setting ................................. 5 Other fault types ................................ 44 Introduction ................................. 5 Summary ....................................... 44 Stratigraphy and structure .................... 7 State of stress in the Giles County, Virginia, locale ...... 45 Independence of seismogem'c and exposed structure 8 Introduction .................................... 45 Seismicity of the Giles County, Virginia, locale .......... 9 Stress orientations ............................... 45 Network monitoring program ...................... 9 Criteria used to select data ........................ 47 Analysis of network events from January 1978 through Results ........................................ 49 December 1980 ................................ 14 Consistency with focal mechanisms ................. 51 Tests of the seismic zone ...................... 14 Summary ....................................... 53 Fault area ................................... 18 Conclusions ........................................ 53 Focal mechanism studies ......................... 22 General observations ............................. 53 Types of faults potentially responsible for the Giles County Specific statements .............................. 54 seismic zone ...................................... 26 Future work needed for hazard zoning ................. 54 Introduction .................................... 26 Acknowledgments ................................... 57 Crustal properties and seismicity .................. 26 References cited .................................... 57 Grenville orogeny ................................ 27 Appendixes ........................................ 69 lapetan normal faults ............................ 28 A. A note on microseismic levels for the Virginia Poly­ lapetus Ocean ............................... 28 technic Institute Seismic Network, by Matthew Gravity maps and the lapetan continental edge ... 28 Sibol ..................................... 70 Area of expected occurrence of lapetan normal faults 33 B. Determination of a duration magnitude relationship Southeastward extent of lapetan normal faults 33 for the Virginia Polytechnic Institute Seismic Net­ Northwestward extent of lapetan normal faults 35 work, by Marc Viret and G. A. Bollinger ....... 72 Summary ................................... 37 C. Velocity model test for Giles County locale, by D. A. Allegheny thrust-load faults ....................... 37 Carts and G. A. Bollinger .................... 76 A testable deduction from the thrust-load hypothesis 37 D. Statistical tests of the Giles County seismic zone, by Stratigraphic tests ........................... 39 R. L. Wheeler .............................. 78 Structural tests .............................. 42 E. Statistical tests of the composite focal mechanism Summary ................................... 43 solution, by R. L. Wheeler ................... 85 ILLUSTRATIONS FIGURE 1. Intensity maps for the 1897 Giles County, Va., earthquake ............................................... 2 2. Map showing the Virginia Polytechnic Institute Seismic Network ......................................... 6 3. Sketch summarizing the stratigraphy of the central and southern Appalachians in and near Giles County, Va. ... 7 4. Magnification curves for the seismographs comprising the Giles County subnetwork of the Virginia Polytechnic Institute Seismic Network ................................................................................ 10 5. Sample seismograms for a microearthquake ............................................................ 11 6. Maps showing capability for detection and location of hypothetical microearthquakes by any 5 stations of the Virginia Polytechnic Institute Seismic Network ............................................................. 12 7. Maps showing capability for detection and location of hypothetical microearthquakes by any 15 stations of the Virginia Polytechnic Institute Seismic Network ............................................................. 13 8. Maps showing 90-percent confidence location ellipses .................................................... 15 9. Epicenter map for microearthquakes located by data from the Giles County, Va., subnetwork ................. 16 10. Map showing a comparison of actual blast locations with those calculated using data from the Giles County, Va., subnet­ work .......................................................................................... 18 11. Epicenter map for microearthquakes located by data from the Giles County, Va., subnetwork and for felt earthquakes relocated by J. W. Dewey and D. W. Gordon ........................................................ 20 12. The 18 epicenters scaled according to magnitude ........................................................ 21 13. Section showing vertical distribution of the hypocenters projected perpendicularly into a northwest-striking plane B-B' .......................................................................................... 22 VI CONTENTS FIGURE 14. Section showing vertical distribution of the hypocenters that define the seismic zone projected perpendicularly into a northeast-striking plane A-A '................................................................... 23 15. Vertical sections showing definition of possible fault-plane areas ........................................... 24 16. Provisional composite focal-mechanism solution for events in the Giles County, Va., seismic zone .............. 25 17. Index map showing locations of some structures and other features named in the text ........................ 29 18. Eastward gravity rise in parts of central and southern Appalachians near Giles County, Va., locale ............. 30 19. Positions of eastward gravity rise in wavelength-filtered Bouguer anomaly fields ............................ 32 20. Sketch illustrating interpretation of wavelengths of gravity anomalies in terms of the depths of the sources of the anomalies ...................................................................................... 33 21. Relationship of the eastward rise in Bouguer gravity field to the western edge of Mesozoic extension in central and southern Appalachians ........................................................................... 36 22. Approximate orientations of Giles County, Va., seismic zone and of central and southern Appalachian thrust structures 38 23. Permian and Pennsylvanian stratigraphy of West Virginia coal fields ...................................... 40 24. Distributional patterns of Pennsylvanian units in West Virginia and parts of adjacent States .................. 41 25. Orientations of maximum horizontal compressive stresses ................................................ 46 26. Orientation distributions of measurements of greatest horizontal compressive stress .......................... 50 27. Consistency of in situ stress orientation with orientation deduced from composite
Load more

Recommended publications
  • Nureg/Cr-7238
    NUREG/CR-7238 Guidance Document: Conducting Paleoliquefaction Studies for Earthquake Source Characterization Office of Nuclear Regulatory Research AVAILABILITY OF REFERENCE MATERIALS IN NRC PUBLICATIONS NRC Reference Material Non-N RC Reference Material As of November 1999, you may electronically access Documents available from public and special technical NUREG-series publications and other NRC records at libraries include all open literature items, such as books, the NRC's Public Electronic Reading Room at journal articles, transactions, Federal Register notices, http://www. nrc. gov/reading-rm.html. Publicly released Federal and State legislation, and congressional reports. records include, to name a few, NUREG-series Such documents as theses, dissertations, foreign reports publications; Federal Register notices; applicant, and translations, and non-NRC conference proceedings licensee, and vendor documents and correspondence; may be purchased from their sponsoring organization. NRC correspondence and internal memoranda; bulletins Copies of industry codes and standards used in a and information notices; inspection and investigative substantive manner in the NRC regulatory process are reports; licensee event reports; and Commission papers maintained at- and their attachments. The NRC Technical Library NRC publications in the NUREG series, NRC Two White Flint North regulations, and Title 10, "Energy," in the Code of 11545 Rockville Pike Federal Regulations may also be purchased from one Rockville, MD 20852-2738 of these two sources. These standards are available in the library for reference 1. The Superintendent of Documents use by the public. Codes and standards are usually U.S. Government Publishing Office copyrighted and may be purchased from the originating Washington, DC 20402-0001 organization or, if they are American National Standards, from- Internet: http://bookstore.gpo.gov Telephone: American National Standards Institute 1-866-512-1800 11 West 42nd Street Fax: (202) 512-2104 New York, NY 10036-8002 http://www.ansi.org 2.
    [Show full text]
  • Skempton's Poroelastic Relaxation
    Datashare 129 Skempton’s poroelastic relaxation: The mechanism that accounts for the distribution of pore pressure and exhumation-related fractures in black shale of the Appalachian Basin Terry Engelder and Rose-Anna Behr AAPG Bulletin, v. 105, no. 4 (April 2021), pp. 669–694 Copyright ©2021. The American Association of Petroleum Geologists. All rights reserved. EXPLANATIONS FOR TABLE 2: In an expansion of work by Sheldon (1912) on COMPARATIVE TERMINOLOGIES FROM the Appalachian Plateau, east-northeast fractures were SELECTED JOINT STUDIES IN THE mapped across a region large enough to sample rocks APPALACHIAN BASIN through a 20° swing of the Appalachian oroclinal bend (Parker, 1942). Parker (1942) relabeled the strike fi The rst depictions of Appalachian Basin fractures joints in Sheldon (1912) as set III (accompanying paper were in wood block prints by Sarah Hall as they appear Table 2 and in this Datashare). This was necessary ’ in her husband s paper from the geological survey of because the azimuth of these set III joints (i.e., the east- the fourth district of New York (Hall, 1843). A print northeast set) did not follow around the oroclinal of Taughannock Falls cascading over the Geneseo bend as defined by fold axes. Parker (1942, p. 406) black shale a few kilometers north of Ithaca, New York, writes, “Their different character and constant strike shows two major joint sets that are not quite orthogonal. over the whole region point definitely to an indepen- The artist even captured a hint of lithological control dent origin, perhaps simultaneous or perhaps much of the black shale on joint development.
    [Show full text]
  • High-Resolution Spatial and Temporal Analysis of the Aftershock Sequence of the 23 August 2011 Mw 5.8 Mineral, Virginia, Earthquake
    High-Resolution Spatial and Temporal Analysis of the Aftershock Sequence of the 23 August 2011 Mw 5.8 Mineral, Virginia, Earthquake Author: Stephen Glenn Hilfiker Persistent link: http://hdl.handle.net/2345/bc-ir:107179 This work is posted on eScholarship@BC, Boston College University Libraries. Boston College Electronic Thesis or Dissertation, 2016 Copyright is held by the author. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (http:// creativecommons.org/licenses/by-nc-nd/4.0). Boston College The Graduate School of Arts and Sciences Department of Earth and Environmental Sciences HIGH-RESOLUTION SPATIAL AND TEMPORAL ANALYSIS OF THE AFTERSHOCK SEQUENCE OF THE 23 AUGUST 2011 Mw 5.8 MINERAL, VIRGINIA, EARTHQUAKE a thesis by STEPHEN GLENN HILFIKER submitted in partial fulfillment of the requirements for the degree of Master of Science August 2016 © copyright by STEPHEN GLENN HILFIKER 2016 High-Resolution Spatial and Temporal Analysis of the Aftershock Sequence of the 23 August 2011 Mw 5.8 Mineral, Virginia, Earthquake Stephen G. Hilfiker John E. Ebel ABSTRACT Studies of aftershock sequences in the Central Virginia Seismic Zone (CVSZ) provide critical details of the subsurface geologic structures responsible for past and (possibly) future earthquakes in an intraplate setting. The 23 August 2011 MW 5.8 Mineral, Virginia, earthquake, the largest magnitude event recorded in the CVSZ, caused widespread damage and generated a lengthy and well-recorded aftershock sequence. Over 1600 aftershocks were recorded using a dense network of seismometers in the four months following the mainshock, offering the unique opportunity to study the fault structure responsible for the post-main event seismicity.
    [Show full text]
  • Source Zones, Recurrence Rates, and Time Histories for Earthquakes Affecting Kentucky (KTC-96-4)
    Commonwealth of Kentucky fred N. Mudge Transportation Cabinet Paul E. Patton Secretary of Transportation Frankfort, Kentucky 40622 Governor August 14, 1996 Mr. Paul Toussaint Division Administrator Federal Highway Administration 330 West Broadway Frankfort, KY 40602 Dear Mr. Toussaint: Subject: IMPLEMENTATION STATEMENT KYHPR 94-155, Evaluation and Analysis of Innovative Concepts for Bridge Seismic Retrofit This report is the first of three reports for the above referenced study. The objective of this study was to develop earthquake time histories for use in the design of transportation facilities throughout the commonwealth. In order to achieve this objective, the following tasks were defined: 1. definition and evaluation of earthquakes in seismic zones that have the potential to generate damaging ground motions in Kentucky, 2. specification of the source characteristics, accounting for the spreading and attenuation of the ground motions to the top-of-the-bedrock at sites in Kentucky, and 3. determination of seismic zoning maps for the commonwealth based on peak­ particle accelerations, response spectra, and time histories. These tasks have been addressed in the report entitled Source Zones, Recurrence Rates, and Time Histories for Earthquakes Affecting Kentucky (KTC-96-4). Seismic input data (time histories, response spectra, and surface accelerations) were generated for all counties in KENTUCKY TRANSPORTATION CABINET "PROVlDE A SAFE, EFFICIENT, ENVIRONMENTALLY SOUND, AND FISCALLY RESPONSIBLE TRANSPORTATION SYSTEM WHICH PROMOTES ECONOMIC GROWTH AND ENHANCES THE QUAUTY OF LIFE IN KENTUCKY:' "AN EQUAL OPPORTUNITY EMPLOYER M/F/D" Kentucky and have been included in this report. It should be noted that the seismic data is generated at the county seat and not at the county centroid.
    [Show full text]
  • Data for Quaternary Faults, Liquefaction Features, and Possible Tectonic Features in the Central and Eastern United States, East of the Rocky Mountain Front
    U.S. Department of the Interior U.S. Geological Survey Data for Quaternary faults, liquefaction features, and possible tectonic features in the Central and Eastern United States, east of the Rocky Mountain front By Anthony J. Crone and Russell L. Wheeler Open-File Report 00-260 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards nor with the North American Stratigraphic Code. Any use of trade names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. 2000 Contents Abstract........................................................................................................................................1 Introduction..................................................................................................................................2 Strategy for Quaternary fault map and database .......................................................................10 Synopsis of Quaternary faulting and liquefaction features in the Central and Eastern United States..........................................................................................................................................14 Overview of Quaternary faults and liquefaction features.......................................................14 Discussion...............................................................................................................................15 Summary.................................................................................................................................18
    [Show full text]
  • 1 1 2 3 4 5 the MAGIC Experiment: a Combined Seismic And
    1 2 3 4 5 6 The MAGIC experiment: A combined seismic and magnetotelluric deployment to 7 investigate the structure, dynamics, and evolution of the central Appalachians 8 9 Maureen D. Long1*, Margaret H. Benoit2, Rob L. Evans3, John C. Aragon1,4, James Elsenbeck3,5 10 11 12 1Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, CT, 13 06520, USA. 14 2National Science Foundation, 2415 Eisenhower Ave., Alexandria, VA, 22314, USA. 15 3Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Clark 263, 16 MS 22, Woods Hole, MA, 02543, USA. 17 4Now at: Earthquake Science Center, U.S. Geological Survey, 345 Middlefield Rd., MS 977, 18 Menlo Park, CA, 94025, USA. 19 5Now at: Lincoln Laboratories, Massachusetts Institute of Technology, 244 Wood St., Lexington, 20 MA, 02421, USA. 21 22 23 Revised manuscript submitted to the Data Mine section of Seismological Research Letters 24 25 26 27 28 29 *Corresponding author. Email: [email protected] 30 31 32 33 34 35 36 37 38 1 39 ABSTRACT 40 The eastern margin of North America has undergone multiple episodes of orogenesis and 41 rifting, yielding the surface geology and topography visible today. It is poorly known how the crust 42 and mantle lithosphere have responded to these tectonic forces, and how geologic units preserved 43 at the surface relate to deeper structures. The eastern North American margin has undergone 44 significant post-rift evolution since the breakup of Pangea, as evidenced by the presence of young 45 (Eocene) volcanic rocks in western Virginia and eastern West Virginia and by the apparently recent 46 rejuvenation of Appalachian topography.
    [Show full text]
  • Annual Report for Fiscal Year 2017
    This report covers the National Earthquake Hazards Reduction Program (NEHRP or Program) activities during fiscal year (FY) 2017. It is submitted to the Congress by the Interagency Coordinating Committee on Earthquake Hazards Reduction (Interagency Coordinating Committee), as required by the Earthquake Hazards Reduction Act of 1977 (Public Law 95-124, 42 U.S.C. 7701 et. seq.), as amended by the National Earthquake Hazards Reduction Program Reauthorization Act of 2004 (Public Law 108-360). The members of the Interagency Coordinating Committee are as follows: Chair Dr. Walter Copan Under Secretary of Commerce for Standards and Technology and Director National Institute of Standards and Technology U.S. Department of Commerce Mr. Peter Gaynor Acting Administrator Federal Emergency Management Agency U.S. Department of Homeland Security Dr. France A. Córdova Director National Science Foundation Mr. John Michael “Mick” Mulvaney Director Office of Management and Budget Executive Office of the President Dr. Kelvin Droegemeier Assistant to the President for Science and Technology and Director Office of Science and Technology Policy Executive Office of the President Dr. James F. Reilly II Director U.S. Geological Survey U.S. Department of the Interior Disclaimer: Certain trade names or company products may be identified in this document to describe a procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by any of the agencies represented on the Interagency Coordinating Committee on Earthquake Hazards Reduction, nor does it imply that the trade names or company products are necessarily the best available for the purpose. Table of Contents Executive Summary ..................................................................................................................................... i Section 1 – Introduction .............................................................................................................................
    [Show full text]
  • 88 Annual Meeting of the Eastern Section of the Seismological
    88th Annual Meeting of the Eastern Section of the Seismological Society of America October 23-26th, 2016 Reston, VA 88th Annual Meeting of the Eastern Section of the Seismological Society of America Acknowledgements The work of many people made this meeting possible and we are grateful for their contributions. These people include: Field Trip Leaders: J. Wright Horton, Jr., Steven Schindler, Terrence Paret Banquet Guest Speaker: Terrence Paret Abstract Submission and Registration: Bo Orloff, Sissy Stone, Nan Broadbent, SSA main office Budget and planning: Charles Scharnberger from the Eastern Section of SSA Graphic Design and Webmaster: Bo Orloff Jesuit Seismological Society Award Committee. Past meeting organizers, especially Steven Jaume, Chris Cramer, and Maurice Lamontagne. Many thanks to all the session chairs! Thomas Pratt, Oliver Boyd, and Christine Goulet Planning Committee Chairs Many thanks to our generous sponsors: 2 88th Annual Meeting of the Eastern Section of the Seismological Society of America General Information Meeting Theme: The 2016 Eastern Section meeting is titled “From the Mantle to the Surface” and is a joint meeting with the Pacific Earthquake Engineering Research (PEER) Center’s Next Generation Attenuation-East (NGA- East) project. It will include a combination of geophysical studies being carried out using the USArray and other ground-motion data in the eastern United States. Special sessions include crust and mantle studies utilizing USArray, studies of central and eastern U.S. faults, seismicity and ground motions, and the Next Generation Attenuation Project for Central and Eastern North America—NGA-East. NGA-East Special Session (Wednesday 8:30-12:00): The Next Generation Attenuation project for Central and Eastern North America (CENA), NGA-East, is a major multi-disciplinary project coordinated by the PEER.
    [Show full text]
  • Joint Loading Configurations Inferred from Propagation Paths
    Journal of Structural Geology 21 (1999) 1637±1652 www.elsevier.nl/locate/jstrugeo Joint interaction with embedded concretions: joint loading con®gurations inferred from propagation paths David T. McConaughy 1, Terry Engelder* Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA Received 16 December 1997; accepted 18 May 1999 Abstract The interaction between propagating joints and embedded concretions in a Devonian black shale near Seneca Lake, NY, permits identi®cation of the loading con®gurations responsible for two joint sets of dierent ages striking at nearly the same orientation. The earlier set consists of systematic joints cut by later Alleghanian joints of the Appalachian Plateau. The later set consists of non-systematic curving cross joints that abut these same Alleghanian joints. Field evidence shows that concretions functioned as sti inclusions in a compliant black shale. As a consequence of this elastic contrast, local perturbations in the remote stress ®eld persisted around the concretions during burial, tectonic deformation, and exhumation. These stress perturbations in¯uenced joint propagation paths of both joint sets. Our conclusions about loading con®gurations are based on ®nite-element modeling of the eect of the local stress perturbation on concretion-modi®ed joint propagation. Modeling shows that the local stress perturbation from a thermoelastic loading was responsible for de¯ecting cross joints away from concretions in a curved propagation path near the concretion. This load con®guration also led to arrest of cross joints before they penetrated the shale±concretion interface. At greater distances from the concretion, the propagation path of cross joints was controlled by the contemporary tectonic stress ®eld.
    [Show full text]
  • New Paleontology Gallery Exhibit Soon to Open
    The Newsletter of the Calvert Marine Museum Fossil Club Volume 22 .Number 4 D~cember2007 New Paleontology Gallery Exhibit Soon to Open ... After years of planning and months of construction and installation, a new exhibit, nearing its birth now graces' the entrance, to our Paleontology Gallery. Designed by Exhibits Curator, James Langley, this superb addition to the Museum was made possible through funding from a CMM's resident artist, Tim Scheirer National Parks Service begins to apply the spiral Earth-history Gateways Grant and the time-line to the wall. Rachel Reese, Clarissa and Lincoln Dryden another member of the CMM Exhibit's Endowment for Department, completed the computer Paleontology. CMM Fossil graphic work. The new exhibit will also Club members donated feature video presentations, some of the fossils on geoanimations, and computer terminals for display. in depth information about thefossils. Tommy Younger (left) and Skip The mural includes cast replicas. It Edwards crafted the jewel-like is my desir.e to gradually replace armature that holds an original most of the casts with original oreodont skull now on display. Scalae Naturae ... fossils as donations and/or funds become available. CALVERT MARINE MUSEUM www.calvertmarinemuseum.com '~The Ecphora December 2007 Deinosuchus: Another Maryland "SuperCroc" Figure 2 shows life drawings of crocodile and alligator heads, at approximately the same scale as By: George F. Klein Figure 1. You will note the width of the alligator's head compared to that of the crocodile. In terms of skull width, Deinosuchus resembles an alligator Deinosuchus was a large crocodilian that more than a crocodile.
    [Show full text]
  • Earthquake Hazard Studies in the Northeastern United States
    THE LAMONT COOPERATIVE SEISMIC NETWORK AND THE ADVANCED NATIONAL SEISMIC SYSTEM: EARTHQUAKE HAZARD STUDIES IN THE NORTHEASTERN UNITED STATES. Annual Project Summary October 01, 2003 - September 30, 2004 External Grant Award Number: 04HQAG-0115 Won-Young Kim Lamont-Doherty Earth Observatory of Columbia University Palisades, NY 10964, USA Tel: 845-365-8387, Fax: 845-365-8150 E-mail: [email protected] URL: <http://www.ldeo.columbia.edu/LCSN> Program Element: Element II. Research on Earthquake Occurrence and Effects Key Words: Wave Propagation, Regional Seismic Hazards and Real-time earthquake information Investigations undertaken The operation of the Lamont-Doherty Cooperative Seismographic Network (LCSN) to mon- itor earthquakes in the northeastern United States is supported under this award. The goal of the project is to compile a complete earthquake catalog for this region to assess the earthquake haz- ards, and to study the causes of the earthquakes in the region. The LCSN now operates 40 seis- mographic stations in seven states: Connecticut, Delaware, Maryland, New Jersey, New York, Pennsylvania and Vermont. During October 2003 through September 2004, scientists and staff at the Lamont-Doherty Earth Observatory of Columbia University (LDEO) satisfactorily carried out three main objectives of the project: 1) continued seismic monitoring for improved delineation and evaluation of hazards associated with earthquakes in the Northeastern United States, 2) im- proved real-time data exchange between regional networks and the USNSN for development of an Advanced National Seismic System (ANSS) and expanded earthquake reporting capabilities, and 3) promoted effective dissemination of earthquake data and information. A significant amount of associated research effort was related to determining seismic mo- ment tensor and focal depth of small to moderate-sized earthquakes in the eastern United States by using three-component, broadband seismic waveform data.
    [Show full text]
  • Unraveling the Central Appalachian Fold-Thrust Belt, Pennsylvania: the Power of Sequentially Restored Balanced Cross Sections for a Blind Fold-Thrust Belt
    Unraveling the central Appalachian fold-thrust belt, Pennsylvania: The power of sequentially restored balanced cross sections for a blind fold-thrust belt Peter B. Sak1, Nadine McQuarrie2,*, Benjamin P. Oliver2,*, Natasha Lavdovsky2, and Margaret S. Jackson1,* 1Department of Earth Sciences, Dickinson College, Carlisle, Pennsylvania 17013, USA 2Department of Geosciences, Princeton University, Princeton, New Jersey 08540, USA ABSTRACT Anticlinorium, the northernmost structure of example of a blind thrust system. At its north- the fold-thrust belt that cuts upsection from ernmost end, the fold-thrust belt sweeps east- We present a kinematic model for the the Cambrian Waynesboro Formation to the ward, creating the broad arc of the Pennsylvania sequential development of the Appalachian Silurian Salina décollement. Because the fault salient (Fig. 1). Although previous research in fold-thrust belt (eastern U.S.) across a clas- that cores the Nittany Anticlinorium can only the central Appalachians has made considerable sic transect through the Pennsylvania salient. facilitate 10 km of shortening on the plateau, progress toward quantifying how shortening New map and strain data are used to create an early history of Appalachian Plateau LPS is distributed among microscopic (e.g., Smart a balanced geologic cross section from the in Silurian and younger rocks is required to et al., 1997; Thorbjornsen and Dunne, 1997), southern edge of the Valley and Ridge Prov- balance the section. We propose that the addi- mesoscopic (e.g., Smart et al., 1997; Hogan
    [Show full text]