USGS Professional Paper 544-E, Text

The Alaska Eoarthquake March 27, 1964 Effects on Hydrologic Regimen Seismic Seiches GEOLOGICAL SURVEY PROFESSIONAL PARER 544-E This page intentionally left blank lll~~~lill'iiiiifiifilll~llll3 1819 00086467 4 THE ALASKA EARTHQUAKE, MARCH 27, 1964: EFFECTS ON THE HYDROLOGIC REGIMEN Seismic Seiches From the March 1964 Alaska Earthquake By ARTHUR McGARR and ROBERT C. VORHIS An interpretation of the continental distribution of seiches from the earthquake GEOLOGICAL SURVEY PROFESSIONAL PAPER 544-E ; 14 r APR 111991 AUG 15 1968 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1968 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 THE ALASKA EARTHQUAKE SERIES The U.S. Geological Survey is publishing the re sults of investigations of the Alaska earthquake of March 27, 1964, in a series of six Professional Papers. Professional Paper 544 describes the effects of the earthquake on the hydrologic regimen. Other chap ters in this volume describe the effects of the earth quake on the hydrology of south-central Alaska, the Anchorage area, areas outside Alaska, and the effects on glaciers. Other Professional Papers in the series describe the history of the field investigations and reconstruction; the effects of the earthquake on communities; the regional effects of the earthquake; and the effects on transportation, utilities, and communications This page intentionally left blank CONTENTS Page Page Page Abstract ____________________ _ E1 Location and nature of the Interpretation of seiche distri Introduction _________________ _ 1 seiches-Continued bution-Continued Purposes of the study _______ _ 2 Geographic distribution _____ _ Ell Relation to seismic surface Definition of terms_ -- ______ _ 2 Hydrodynamic factors ______ _ 12 waves__________________ E15 Previous studies of seismic Interpretation of seiche distri- Radiation pattern_________ 15 seiches __________________ _ 3 bution __________________ _ 13 Distance from epicenter____ 15 Sources of data ___ --- ______ _ 3 Relation to geologic features_ 13 Lateral refraction. ___ ----- 16 Acknowledgments __________ _ 4 Sediment thickness ______ _ 13 Local crustal structure_____ 18 General theoretical background_ 5 Thrust faults ____________ _ Irregular structures_________ 19 Location and nature of the 13 seiches __________________ _ 7 Basins, arches, and domes __ 14 Seiches and seismic intensity_ 20 Seiche data ________________ _ 7 Edge of overlaps _________ _ 14 Conclusions and recommenda- Gaging stations, instruments, Rocky Mountain system __ _ 14 tions_____________________ 22 and their records _______ _ 10 Miscellaneous areas _______ _ 15 References.__________________ 23 ILLUSTRATIONS PLATE 1. Map of the conterminous United States and southern Canada showing occurrence of seiches from the Alaska earthquake and their relation to major tectonic features------------------------------------------------------------ In pocket FIGURES Page 1. The coordinate system applied to a theoretical water body and seiches of the first, third, and fifth modes _____________________________ ----------------- E6 2-5. Records: 2. The largest seiche recorded on a stream in each of eight States __________ _ 9 3. Some large seismic seiches on reservoirs _________________________ ------ 9 4. Three types of bubble-gage records of Alaska earthquake seiches _______ -- 10 5. Seiche effects of Alaska earthquake on stage and flow, Miami area, Florida_ 10 6-8. Maps: 6. Map of conterminous United States showing seiche density by State and by river basin---------------------------------------------------- 11 7. Maximum horizontal acceleration at stations of the World-wide Standard Seismograph Network in the United States calculated for two aftershocks of the Alaska earthquake _______________________________ ---------- 16 8. Phase-velocity distribution of 20-second Rayleigh waves in North America_ 17 9. Amplification of Rayleigh-wave displacements in low-rigidity sediment over- lying high-rigidity rock, (A) for 15- and (B) for 8-second period waves _____ _ 18 10. Variation in amplitude of surface horizontal acceleration as a function of "layer" shear wave velocity, for 6- and 10-second period Rayleigh waves __________ _ 20 11. Alaska earthquake seiches plotted on the intensity map of the Missouri earth quake of October 21, 1965--------------------------------------------- 21 v TABLES Page 1. Summary of 859 seismic effects from the Alaska earthquake on surface-water bodies throughout the world_____________________________________________ E7 2. First-, third-, and fifth-order modes, in seconds, for seiches on water bodies with selected widths and depths_- __________ - __ -_- ________ -_- __ - _____ -_-----_- 12 3. Seismic effects of the Alaska earthquake at surface-water gages________________ 25 VI THE ALASKA EARTHQUAKE, MARCH 27, 1964: EFFECTS ON THE HYDROLOGIC REGIMEN SEISMIC SEICHES FROM THE MARCH 1964 ALASKA EARTHQUAKE 1 By Arthur McGarr, Lamont Geological Observatory of Columbia University, Palisades, N.Y., and Robert C. Vorhis, U.S. Geological Survey ABSTRACT Seismic seiches caused by the Alaska that the distribution of seiches is related For example, the Rocky Mountains pro earthquake of March 27, 1964, were to the amplitude distribution of short vided a wave guide along which seiches recorded at more than 850 surface period seismic surface waves. These were more numerous than in areas to water gaging stations in North America waves have their greatest horizontal either side. In North America, neither and at 4 in Australia. In the United acceleration when their periods range direction nor distance from the epicenter States, including Alaska and Hawaii, from 5 to 15 seconds. Similarly, the had any apparent effect on the distribu 763 of 6,435 gages registered seiches. water bodies on which seiches were re tion of seiches. Nearly all the seismic seiches were corded have low-order modes whose Where 8eismic surface waves propa recorded at teleseismic distance. This periods of oscillation also range from 5 gated into an area with thicker sediment, is the first time such far-distant effects to 15 seconds. the horizontal acceleration increased have been reported from surface-water Several factors seem to control the about in proportion to the increasing bodies in North America. The densest distribution of seiches. The most im thickness of the sediment. In the Mis occurrence of seiches was in States portant is variations of thickness of low sissippi Embayment however, where the bordering the Gulf of Mexico. rigidity sediments. This factor caused waves emerged from high rigidity crust The seiches were recorded on bodies the abundance of seiches in the Gulf into the sediment, the horizontal accele of water having a wide range in depth, Coast area and along the edge of sedi ration increased near the edge of the width, and rate of flow. In a region con mentary overlaps. Major tectonic fea embayment but decreased in the central taining many bodies of water, seiche tures such as thrust faults, basins, arches, part and formed a shadow zone. distribution is more dependent on geo and domes seem to control seismic Because both seiches and seismic in logic and seismic factors than on hydro waves and thus affect the distribution tensity depend on the horizontal accelera dynamic ones. The concept that seiches of seiches. Lateral refraction of seismic tion from surface waves, the distribution are caused by the horizontal accelera surface waves due to variations in local of seiches may be used to map the tion of water by seismic surface waves phase-velocity values was responsible for seismic intensity that can be expected has been extended in this paper to show increase in seiche density in certain areas. from future local earthquakes. INTRODUCTION Seismic waves from the Alaska water bodies to oscillate at many quake seiches from his colleagues earthquake of March 28, 1964,2 places throughout North America. in the U.S. Geological Survey and were so powerful that they caused Those oscillations, or seismic from other hydrologic organiza seiches, were recorded at hundreds tions both in North America and of surface-water gaging stations throughout the world. The replies although they had rarely been identified most locations where 1 Lamont Geological Observatory Contribution 1070. reported following previous earth seiches were recorded. In the 2 The date and time of an earthquake can be given quakes and, when reported, had United States, of all gages which either as local or Greenwich time. In and near the epicentral region, it is customary to give the local received little study. Local reports could have recorded a seiche at time, snch as 5:36p.m. A.s.t. on March 27, 1964, for of numerous seiches resulting from the time of the Alaska earthquake, the Alaska earthquake. In studies of a worldwide nature, the date and time of an earthquake are the Alaska earthquake prompted slightly more than 10 percent did. usually given in Greenwich time. Thus, the Alaska one of the authors, Vorhis, to Factors other than the nature of earthquake occurred at 03:36 on March 28, 1964, G.c.t. request records of Alaska earth- the recording installation and the El E2 ALASKA EARTHQUAKE, MARCH 27, 1964 geometry of the water body seem In a sense, the three types of in application to water waves is to have controlled the pattern of struments provide complementary shown in figure 1.

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