Geologic Considerations for Redevelopment Planning of Managua, Nicaragua, Foilowing the 1972 Earthquake GEOLOGICAL SURVEY PROFESSIONAL PAPER 914 Prepared in cooperation with the Government of Nicaragua and the Agency for International Development, U.S. Department of State Geologic Considerations for Redevelopment Planning of Managua, Nicaragua, Following the 1972 Earthquake By HENRY R. SCHMOLL, RICHARD D. KRUSHENSKY, and ERNEST DOBROVOLNY GEOLOGICAL SURVEY PROFESSIONAL PAPER 914 Prepared in cooperation with the Government of Nicaragua and the Agency for International Development, U.S. Department of State The geologic framework of the area around Managua provides the basis for identifying potential geologic hazards that should be considered in redeveloping the city UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1975 UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Schmoll, Henry R. Geologic considerations for redevelopment planning of Managua, Nicaragua, following the 1972 earthquake. (Geological Survey Professional Paper 914) Includes bibliographical references. Supt. of Docs. No.: I 19.16:914 1. Seismology-Nicaragua-Managua (Dept.) 2. Volcanism-Nicaragua-Managua (Dept.) 3. Sediments (Geology)-Nicaragua­ Managua (Dept.) l. Krushensky, R. D., joint author. II. Dobrovolny, Ernest, 1912- joint author. III. United States. Agency for International Development. IV. Title: Geologic considerations for redevelopment planning of Managua, Nicaragua ... V. Series: United States Geological Survey Professional Paper 914. QE535.2.N5S35 624'.151'097285 75-619060 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock Number 024-001-02709-7 CONTENTS Page Page Abstract ........................................................................................... .. Physical characteristics of geologic materials-Con. Introduction .................................................................................... .. l Alluvium.................................................................................... 11 Geologic setting ............................................................................... 3 Soil............................................................................................. 12 Volcanism ....................................................................................... .. 3 Summary.................................................................................... 12 Centers of volcanic eruptions .................................................. .. 3 Faults and other linear geologic features......................................... 12 Masaya .............................................................................. .. 3 Linear features in the Managua area........................................ 14 Apoyeque .......................................................................... .. 5 Tiscapa set.......................................................................... 15 Asososca, Tiscapa, and the Nejapa-Ticomo collapse Las Nubes set...................................................................... 17 pits and associated cones .............................................. .. 6 Nejapa-Tipitapa set............................................................ 18 Talpetas-Miraflores ........................................................... 7 Cofradi~ set......................................................................... 19 Chronologie relationship of volcanic deposits ........................ 7 Northwest-trending sets...................................................... 19 Historical and present volcanic activity in Nicaragua ............ 8 Major lineaments in Nicaragua................................................ 20 Possible future volcanic activity .............................................. .. 8 Summary.................................................................................... 21 Physical characteristics of geologic materials ................................ .. 9 Conclusions....................................................................................... 21 Loose tephra ............................................................................ .. 9 Recommendations............................................................................. 21 Partly indurated volcanic mudflow and ash-flow deposits .... .. 10 References cited................................................................................. 22 Hard volcanic rock .................................................................. .. 11 ILLUSTRATIONS Page PLATE l. Map of Nicaragua showing lineaments and other featur~s seen on side-looking imagery .......................................................... In pocket FIGURE l. Sketch map showing approximate extent of deposits from various volcanic centers..................................................................... 2 2. Sketch map of southern Nicaragua, showing physiographic provinces and geologic units.......................................................... 4 3. Schematic and composite stratigraphic column illustrating the kinds and complexity of deposits in the Managua area........... 7 4. Same schematic and composite stratigraphic column as shown in figure 3, with the materials according to physical character- istics and, in part, mode of deposition..................................................................................................................................... 9 5. Map of the Managua area showing faults, other linear geologic features, and damage zone........................................................ 13 6. Diagram showing approximate orientation of sets of linear geologic features in Nicaragua and surrounding areas.................. 14 7. Map of the Managua area showing zones dominated by sets of linear geologic features............................................................... 15 8. Map of Managua and vicinity, showing location of faults and fractures that developed during the 1972 earthquake................ 16 TABLES Page TABLE l. Grain-size distribution and selected distribution parameters for three samples of partly indurated mudflow or ash-flow deposits.. 10 2. Selected physical properties for two samples of partly indurated mudflow or ash-flow deposits.................................................. 10 III GEOLOGIC CONSIDERATIONS FOR REDEVELOPMENT PLANNING OF MANAGUA, NICARAGUA, FOLLOWING THE 1972 EARTHQUAKE By HENRY R. ScHMOLL, RICHARD D. KRUSHENSKY, and ERNEST DoBROVOLNY ABSTRACT This report is the result of a 3-week reconnaissance field A brief reconnaissance investigation of the geology in the vicinity of investigation in an area that extends roughly from Managua, Nicaragua, was undertaken by the U.S. Geological Survey at Mateare on the west to Tipitapa on the east, and from Lake the request of the Agency for International Development, U.S. Depart­ ment of State. The objective was to determine whether any areas within Managua south to the Cordillera del Pacifico and the about 15 km of the present city are better suited than others as sites for Masaya caldera (fig. I); this area will be referred to as the reconstruction, taking into consideration volcanism, geologic materials Managua area. Fieldwork involved (I) study and mapping and structures, and seismicity. of volcanic centers and their associated deposits, (2) study During the time that man has inhabited the area, several metres of of the physical properties of these deposits, and (3) study materials from four volcanic centers have been deposited in the vicinity of and mapping of faults and other linear geologic features. Managua. These deposits include lava flows, mudflows, ash flows, and ash falls. Volcanic activity continues today; widespread and destructive A major part of the study was a review of all available deposition of volcanic materials similar to that of the past can occur at geologic reports concerning the December I972 earth­ any time. quake, most of which were only in manuscript form. Also Most of the materials underlying the Managua area range from loose or poorly consolidated pyroclastic deposits to partly indurated mudflow used were an unpublished report and associated maps and ash-flow deposits; lava flows, alluvium, and soil are dominant in prepared by the Parsons Corp., Marshall and Stevens, Inc., only small areas. The partly indurated deposits are widespread and have and International Aero Service Corp. ( I972) under sufficient strength and stiffness to provide adequate foundations in most contract to Catastro e lnventario de Recursos Naturales. places; these characteristics are not likely to be altered by seismic shock. The'existing geologic literature was examined and is cited Linear geologic features, including faults, fractures, and lineaments, are present throughout the Managua area; they can be grouped, on the throughout the present report. basis of orientation, into seven sets, most of which are directly related to Colored aerial photography of the Managua area at the regional geologic structure. Faulting has occurred during the last various scales was furnished by the National Aeronautics 10,000 years along nearly all these trends; faulting and concomitant and Space Administration; black-and-white aerial pho­ seismic activity, with varying frequency and magnitude along different tography of the city, at scales of I:7,000 and l:IO,OOO, was trends, can be expected to continue. We