The August and October 1968 East Rift Eruptions of Kilauea Volcano, Hawaii by DALLAS B
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The August and October 1968 East Rift Eruptions of Kilauea Volcano, Hawaii By DALLAS B. JACKSON, DONALD A. SWANSON, ROBERTY. KOYANAGI, and THOl\1AS L. WRIGHT GEOLC)GICAL SURVEY PROFESSIONAL PAPER 890 UNITED STATES GOVERNMENT PRINTING OFFICE.WAS HI NGTON: 197 5 UNITED STATES DEPARTMENT OF THE INTERIOR JAI\-IES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director First printing 1975 Second printing 1983 For sale by the Distribution Branch, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22.304 CONTENTS Page Page Abstract ________ _______ _________ ____ ______ __ ____ ____ __ ____ 1 August 1968 eruptiun-Coutinued Introduction __ ____ __________ __ __ __ ______ __ _ ___ __ ______ __ ___ 1 Volume of deformation compared with volume of Acknowledgments ----------------------------------- _____ 2 erupted lava _______________________________________ 21 Events preceding the August 1968 eruption ________________ 3 Rate of magma tran.-;fer ___ _________ __ __ ____ ______ 21 August 1968 eruption_______________________________________ 3 Events between the August and October 1968 eruptions ______ 22 Setting ---------------------------------------------- 3 October 1968 eruption __ ______________________________ 22 Narrative ofthe eruption ------------------------------ 4 Setting ~--------------------------------------------- 22 Ground cracking -------------------------------------- 8 Narrative of the eruption _____ _____ ___________ __ __ _ __ __ 22 Seismicity ____ __ ______ __ ____ __ _ _____ __ ____ __ ____ __ __ ___ 9 Area and volume estimates ---------------------------- __ 24 Summit deformation ---------------------------------- 10 Ground cracking ___________ __ ___ ________ _ ___ __ ___ __ ___ 24 Tilt and vertical displacements ____________________ 10 Seismicity ______ __ _ _ __ __ __ ___ _ __ ____ __ __ _ _ __ _ __ __ _____ __ 25 Horizontal displacements and strains ______________ 13 Summit deformation _____ ______________________ 26 Deformation of the upper east rift zone__________________ 14 Deformation of the upper east rift zune between August and October ___________ ___________ 27 A vertical displacement and tilt model for the summit 15 Petrography and chemistry of tne October 1968 lava _ 29 A vertical displacement dike model for the upper Magma reservoir in the Makaopuhi area________________ 30 east rift zone----------------------------------------- 17 Net ground deformation July to October 1968 ______ ________ 31 Petrography and chemistry of the August 1968 lava ____ 19 References cited ________________________________________ 32 ILLUSTRATIONS Page FIGURE 1. Index map of summit area of Kilauea Volcano and parts of east rift zone and Koae fault system showing vents and lava flows of the August and October 1968 eruptions and epicenters of earthquakes associated with the August eruption -- 2 2. Record of components of tilt at Uwekahuna vault from August 1967 to February 1969 ______________________ ----- 3 3. Graph showing cumulative dilatation between July 1966 and October 1968 in main part of Kilauea Caldera --- ---- 4 4. Map showing tilt and vertical ground displacements, June 4-6 to July 15, 1968 ___________________ -------- ---------- 4 5. Graph showing seismicity and tilt associated with the August eruption and first 6 days of the October eruption ------ 5 6. Photograph showing lava lake in Hiiaka Crater, 0840 August 22 -------------------------- --- -- ----- -------------- 6 7. Photograph showing nearly drained lava lake in Hiiaka Crater, 1400 August 22------------------------------------ 6 8. Photograph showing tree mold and lava-coated boulders on slope ofHiiaka Crater--------------------------- ----- 7 9. Aerial photograph showing fume from vents 3 and 2 and right-offset en echelon arrangement of fissures ------------ 7 10. Photograph showing spatter-draped branches ofohia tree at vent 3 ------------------------------------------------ 7 11. Photograph showing fissure covered by welded spatter at vent 4 ---------------------- --------------------------- 8 12-18. Maps showing: 12. Location of cracks that opened during August 1968 eruption ________________________ ----------------------------- 8 13. Ground tilt and vertical ground displacement for August 1968 eruption _______ ------------------------------- 10 14. Change in tilt before and during August 1968 eruption __________________________________ ---------------- ----- 12 15. Change in length ofgeodimeter lines for August 1968 Eruption ------------------------------------------------ 13 16. Horizontal displacement for August 1968 eruption ----------------------------------------------------------- 14 17. Dilatational strain for August 1968 eruption ----------------------------------------- -- ---------- -- ------ --- 14 18. Possible horizontal displacement near site of August 1968 eruption _________ ---------------------------------- 15 19-25. Graphs showing: 19. Measured vertical displacement and tilt compared with point-source elastic model ----------------------------- 16 20. Observed tilt data fitted to theoretical tilt curve with a theoretical maximum tilt of 60 microradians -------- 16 21. Measured tilt and vertical displacement compared with vertical line-source elastic model ----------------------- 17 22. Measured vertical displacement compared with model for small spherical thrust-pressure source ---------- 17 23. Theoretical vertical displacement curves calculated by the finite-element method for dikes dipping 60°, 75°, and 9~ ----------------------------------------------------------------------------------------------- 18 24. Finite-element curves for dikes dipping 75o and 90° matched to vertical ground displacements along the Escape andAinahouRoads ----------------------------------------------------------------------------- 18 25. Residual vertical displacement across east rift zone derived by subtracting theoretical displacements for ver- tical dike from adjusted data of figure 24B --------------------------------------------------------------- 19 III IV CONTENTS Page FIGURE 26. Photograph showing tree molds near vent B, October 1968 eruption ------------------------------------------- 23 27. Diagram showing periods of activity at selected vents of October 1968 eruption ______________ ------------------ 23 28. Photograph of lava pouring underground in Napau Crater, October 14, 1968 ------------------------------------ 24 29. Photograph of lava flow south of ventE cut by graben -------------------------------------------------------- 25 30-3 7. Maps showing: 30. Epicentral distribution of selected earthquakes for four intervals before and during October 1968 eruption ---- 26 31. Ground tilt changes at summit of Kilauea during October 1968 eruption--------------------------------------- 28 32. Vertical ground displacement and tilt from August 26-29 to October 9-10, 1968 ------------------------------- 29 33. Horizontal displacement between August 23-24 and October 10-15, 1968 ______________________ --~--------------- 30 34. Dilatational strain between August 23-24 and October 10-15, 1968 ------------------------------------------- 31 35. Vertical displacement and tilt between July 15 and October 9-10, 1968 ---------------------------------------- 32 36. Horizontal displacement between July 22-24 and October 10-15, 1968 ------------------------------------------ 33 37. Dilatational strain between July 22-24 and October 10-15, 1968__________________________ ____ __ __ __ __ __ __ __ __ 33 TABLES Page TABLE 1. Time of eruption and drainback, and volume and rate of lava extruded, from the seven major vent areas of the August 1968 eruption ---------------------------------------------------------------------------------------------- 6 2. Chemical analyses of lava from the August and October 1968 eruptions of Kilauea Volcano_________________________ 20 3. Modal analyses of spatter and glassy flow skins of August 1968 eruption _____________________ _____________________ 20 4. Locations of key seismic stations used in establishing the epicenter and hypocenter locations in figure 30 __________ 25 5. Modal analyses of spatter samples from October 1968 eruption ---------------------------------- _________________ 30 METRIC-ENGLISH EQUIVALENTS Metric unit English equivalent Metric unit English equivalent Length Specific combinations-Continued millimetre ( mm) 0.089H7 inch (in) litre per second (1/s) .0353 cubic foot per second metre (m) :t28 feet (ft) cubic metre per second kilometre (km) .62 mile (mi) per square kilometre [ (ma;s) /km2J Hl.47 eubic feet per second per Area square mile [ (ft3/s) /mi21 metre per day (m/d) feet per day (hydraulic square metre (m2) 10.76 square feet (ft2) conductivity) (ft/d) square kilometre (km~) .386 square mile (mi2) metre per kilometre hectare ( ha) 2.47 acres (m/km) :1.28 feet per mile (ft/mi) kilometre per hour Volume (km/h) .9113 foot per second (ft/s) metre per second (m/s) :::.28 feet per second metre squared per day cubic centimetre ( cm'1) 0.061 cubic inch (ina) litre (l) 61.0:{ cubic inches (m2jd) 10.764 feet squared per day (ft2/d) cubic metre (m3) 3G.31 cubic feet (ft3) (transmissivity) cubic metre .00081 acre-foot (acre-ft) cubic metre per second cubic hectometre (hma) =~10.7 acre-feet (m3js) 22.826 million gallons per day litre 2.11;{ pints (pt) (Mgal/d) litre 1.06 quarts (qt) cubic metre per minute litre .26 gallon (gal) (m3/min) = 264.2 gallons per minute (gal/min) cubic metre .00026 million gallons (:Mgal or litre per second (1/s) 15.85 gallons per minute 106 gal) litre per second per