CATASTROPHISM - VERY LARGE TSUNAMIS ON TONGA

I AM ALWAYS RUNNING ACROSS DEPICTIONS OF VERY LARGE CATASTROPHIC EVENTS THAT CANNOT BE EXPLAINED BY ANY OTHER THAN A CATASTROPHIST.

THIS ONE PARALLELS A LARGE TSUNAMI THAT SWEPT THE PACIFIC SIDE OF AUSTRALIA AND CAST EXTREMELY LARGE BOULDERS VERY FAR INLAND AND AT LARGE ELEVATIONS.

IOHANI WOLFGRAMM PREACHED TO THE PEOPLE OF TONGA THAT THEY WOULD ONE DAY REAP A VERY LARGE WAVE BECAUSE OF THE WICKEDNESS OF HIS PEOPLE. I BELIEVE THAT DAY IS VERY NEAR AT HAND. HERE IS AN ACCOUNT OF A PREVIOUS HIT:



Geology; February 2009; v. 37; no. 2; p. 131-134; DOI: 10.1130/G25277A.1
© 2009 Geological Society of America

Huge erratic boulders in Tonga deposited by a prehistoric tsunami
Cliff Frohlich1,*, Matthew J. Hornbach1, Frederick W. Taylor1, Chuan-Chou Shen2, 'Apai Moala3, Allan E. Morton4 and Jens Kruger5

1 Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78758-4445, USA
2 Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan, Republic of China
3 Geology Section, Ministry of Lands, Survey, and Natural Resources, Nuku'alofa, Tonga
4 343 Harvard Avenue, Rexburg, Idaho 83440, USA
5 SOPAC, South Pacific Islands Applied Geoscience Commission, Nabua, Fiji Islands

Correspondence: *E-mail: cliff@ig.utexas.edu.

Along some coastlines there are erratic boulders apparently emplaced by tsunamis or cyclonic storms; evaluating their origin and time of emplacement places constraints on the frequency, severity, and location of coastal hazards. Seven such large coral limestone boulders are present near Fahefa village on Tongatapu Island, southwest Pacific, apparently emplaced by a prehistoric tsunami. These boulders are 10–20 m above sea level and above any possible source, and all are 100–400 m from the present shoreline. Coral 230Th ages indicate that the limestone formed during the last interglacial sea-level highstand, ca. 120–130 ka. The largest boulder is ~20 times more massive than any reported boulders emplaced by historically documented storms and may be the largest known tsunami or storm erratic worldwide situated above its source. We performed computer simulations to assess whether tsunamis produced by earthquakes, undersea landslides, or volcanoes could emplace the boulders. The simulations indicate that either volcanic flank collapse along the Tofua arc ~30–40 km to the southwest or undersea landslides on the submarine slopes of Tongatapu could be responsible. Either could explain why these boulders are not widespread on Tongatapu, and instead occur in a localized group along the western coast. This study demonstrates that small (<1 km3) submarine slope failures sometimes generate locally large tsunamis. The Fahefa boulders are in a well-studied and well-populated area, yet were unknown to the scientific community until recently; this suggests that systematic searches elsewhere for erratic boulders and other tsunami deposits might provide new information for assessing the size and extent of prehistoric tsunamis.