Effects of the March 1964 Alaska Earthquake on Glaciers
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Effects on Hydrologic Regimen Glaciers r,FQLOGICA SURVFY PROFFSSIONA PAPER 544-D This page intentionally left blank THE ALASKA EARTHQUAKE, MARCH 27,1964: EFFECTS ON THE HYDROLOGIC REGIMEN Effects of the March 1964 Alaska Earthquake on Glaciers By AUSTIN POST GEOLOGICAL SURVEY PROFESSIONAL PAPER 544-D UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1967 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 45 cents THE ALASKA EARTHQUAKE SERIES The U.S. Geological Survey is publishing the results of investigations of the Alaska earthquake of March 27,1964, in a series of six Professional Papers. Professional Paper 544 describes the effect on hydrology. Other Professional Papers, some already published and some still in preparation, describe the effects of the earthquake on communities; the regional effects of the earthquakes; the effects on transporta tion, communications, and utilities; and the history of the field investigations and reconstruction effort. CONTENTS Page Pap;e Page Abstract ... D1 Earthquake-induced rockslide Changes m drainage and flow of Introduct.IQn 1 avalaniJhes on glaciers Con glacially fed rivers due tQ the Acknowledgments 2 Smaller avalantJhes TCon 1964 earthquake D33 Possible effects of earthquakes Allen Glacier_ . D21 Effects of the 1964 tectomc dis- . 6n glaciers. 2 Fickett Glacier_ _ _ . 21 placement.s on glaciers 34 Snow avalaMhmg .. 3 Unnamed glacier near Direct effects of the 1964 earih- Ice avalanching 5 Paguna Bay 21 quake on titial glaciers 36 Earthquake-intiuced roiJkslide Ro~Jkslide avalanches not asso Interpretatio11 of the data 36 avalaniJhes on glaciers 6 ciated with the 1964 earth Effect of avalanche-caused Sherman Glacier. 6 quake. _. 26 truckemng OTJ! the flow of Schwan Glacier .. 13 Avalanches before the 1964 gladers 36 Bermg and Steller Glaciers 13 earthquake._ 26 The earthquake-advance Martm River Glacier. 13 Rockshde avalaniJhes since theQry 37 Sioux Glacier 13 August 1964 26 Glacier surges 38 Smaller avalaniJhes . 21 General characteristics of the Summary anti conclusions 41 Saddlebag Glacier 21 larger rockslide avalaniJhes .. 31 References 41 ILLUSTRATIONS FIGURES Page Page Pa!'e 1. Map of sQuth-central Alas 10. S1Jhwan ·Glamer on August 18. Allen Glamer rockslide ava- ka vi 26, 1963 D14 lanche 1, August 25, 1965. D23 2. Head of Meares Glader, 11. Schwan Glader on August 19. Crulds Gleder, August 26, August 24, 1964 D4 25, 1964___ 15 1963.- 24 3. Cliffs on south side of Har 12. Map of rockslide avalanches 20 Childs Glacier, August 25, vard Glacier, August 24, in the W axell Ridge region, 1965.. 25 1964 ... 5 Fering anti Steller Gla- 21. Allen roiJkslide avalaMhe 4, 4. Honzoni,al profiles of roiJk ciers. _ _ _ HI August 25, 1965 27 slide avalaniJhes on gla 13. Map of roiJkslide avalaMhes 22. F.ockslide avalanche on Fair ciers. _ . - 7 on the Martin River an<:l weather Glacier, August 5. Map of rockslide avalanches western Steller Glaciers . _ 1 7 22, 1965.. 29 in the Sherman and Sad 14. Map of rollkslide avalanches 23 Map of rockslide avalaniJhe dlebag Glaciers area.. 8 and rockfalls m the Sioux, 011 Fairweather Glacier ' 30 6. RQIJkshde avalantJhe on Sher Johnson, and Miles Gla 24 RotJkslide avalanllhll on Net- man Glacier, August 25, mer region 18 land Glacier, August 29, 1965 .• 9 11). SiQux Glacier, August 26, 1964 32 7. Sherman Glacier, August 26, 1963 and August, 24, 1964. 19 25. Map showing relat10n of 1963 ________ ·-----·- 10 16. Saddlebag Glacier, August earthquake subsidence anti 8. Sherman Glacier, August 24, 26, 1963 anti August 25, uplift to glaciers _ 35 1964. ··-- 11 1965 20 26. Observed glacier surges smre 9. Map of rockslide avalanche 17. Map of rockslide avalanllhes 1936 in Alaska and western on Schwan Glacier. 12 on Allen Glacier_ _ _ _ _ 22 Canada. 40 TABL~JS Pap;e I. Snow avalaMhes on large glaciers near the epiceni,er of the 1964 earthquake D4 2. Earth'luake-mduceti rockshde avalaniJhes 6 3. Rockshde avalanche deposits on glaciers since 11}45 and pnor to 1964 earthquake 26 4. Rockslide avalanr,hes more recent than 1964 earthquake 26 5. Late August levels of glamllr-dammed lakes m the Chugach and Kenai Mountams, 19RO 65 33 6 Changes in termmi of tidewater glaciers in the Chugallh and Kenai Mount.ams, 1960 65 31) 7. Lengths anti times of sudden movement of glaciers observed by Tarr and Martin llfter the 1899 earth quake 39 v 138° 0 50 100 MILES 0 50 100 KILOMETERS 0 F Yakutat G U L F ALASKA EXPLANATION ~Bagley All enD Icefields and glaciers Limit of cracking of alluvial deposits Epicenter of 1964 earthquake Glacier areas shown as figures and photographs in this report FIGURE 1.-Map of south-central Alaska showing the major glaciers and icefields and the epicenter of the March 27 earthquake. VI THE ALASKA EARTHQUAKE, MARCH 27,1964: EFFECTS ON THE HYDROLOGIC REGIMEN EFFECTS OF THE MARCH a964 ALASKA EARTHQUAKE ON GLACIERS By Austin Post ABSTRACT The 1964 Alaska earthquake occurred occurring in the Copper River region scale dynamic response of any glacier in a region where there are many 160 kilometers east of the epicenter. to earthquake shaking or avalanche hundreds of glaciers, large and small. Some of these amlanches traveled sev- loading was found in either the Chugach Aerial photographic investigations in- eral kilometers at low gradients; com- or Kenai Mountains 16 months after dicate that no snow and ice avalanches pressed air may have provided a lubri- the 1964 earthquake, nor was there any of large size occurred on glaciers despite cating layer. If long-term changes in evidence of surges (rapid advances) as the violent shaking. Rockslide ava- glaciers due to tectonic changes in alti- postulated by the Earthquake-Advance lanches extended onto the glaciers in tude and slope occur, they will probably Theory of !L'arr and Martin. many localities, seven very large ones be very small. No evidence of large- INTRODUCTION Alaskan glaciers are of such size Most rivers in this area derive a The author conducted aerial- and number that they influence the part of their flow from glaciers, photographic investiga1;ions on climate, streamflow, and works of and, for many major streams, such glaciers in northwestern North man in many parts of the State. as the Matanuska and Copper America from 1960 to 1963 under Their influence is especially im- Rivers, glacier melt provides a grants from the National Science portant in the region most strongly substantial part of their summer Foundation. This project was runoff. Although it is primarily administered by the University of affected by the Alaska earthquake the glacial rivers that affect works Washington, Seattle, P. E. Church of March 27,1964, where about 20 of man in the State, in a few places being principal investigator. percent of the land area is covered the glaciers themselves are near Practically all of the larger gla- by ice (fig. 1). North, east, and transportation routes or facilities. ciers in Alaska were examined and west of the epicenter, the Chugach Changes in glaciers resulting from their various features noted. More Mountains are covered with ap- earthquakes thus may have eco- than 2,000 oblique and vertical proximately 6,500 km2 (square nomic as well as scientific interest. photographs were taken each year. kilometer) of icefields and snow- The 1964 earthquake was one of These observations and pictures filled valleys from which more the strongest ever recorded in provide detailed information than a dozen major and hundreds North America. Tectonic dis- about the glaciers before the earth- of s m a 1 1e r glaciers descend. placements occurred over a larger quake occurred. Southwest of the epicenter the area than has previously been ob- The U.S. Geological Survey Sargent and Harding Icefields served (Plafker, 1965a; Plafker continued these studies in 1964 and Mayo, 1965). The area in and 1965 as part of n broader and other glaciers cover approxi- which cracking occurred in allu- program of investigation of the mately 4,200 krn2 in the Kenai vial deposits is considered the relation of glaciers to climate and Mountains. East of the Copper probable limit of the area where the role of glaciers in the hy- River, the Bagley Icefield con- noticeable effects on glaciers might drologic cycle. Mark F. Meier tains some 10,400 km2 of glaciers. be expected (fig. 1). directed this program. Dl D2 ALASKA EARTHQUAKE, MARCH 27, 196:4 By comparing photographs m o r a i n e s, superglacial photographs were furnished the taken before and after the earth- streams and lakes. author by George Plafker of the quake, the immediate effects on Glacier termini-position, Geological Survey and Troy glaciers can be analyzed. The configuration, and relative P6w6 of the University of data available make it possible activity. Alaska, John Sater of the Arctic to determine what changes have Iceberg discharge of tidal Institute of North America, and occurred in other years in the glaciers. W. 0. Field of the American shaken area. Changes in regions Outlet and marginal streams, Geographical Society. John R. where earthquake shaking did not and glacier-dammed lakes. Reid of the University of North take place were also analyzed. Terminal and lateral mo- Dakota, Colin Bull of the Ohio Studies were conducted in late rainos, trimlinw, and bar- State University, Institute of August and in September, the ren zones. Polar Studies, Samuel Tuthill of time when the seasonal snow In addition, a careful search was Muskingum College, Ohio, fur- cover on glacier ice is at a mini- made during the 1964 and 1965 nished information regarding mum.