Subduction of the Juan de Fuca and Gorda plates beneath western North America

presents a paradox; despite the fact that there is good evidence of 3 to 4 cm/yr of

ongoing convergence, there is a remarkable paucity of either historic or instrumentally

recorded shallow subduction earthquakes. Steady aseismic slip along the entire

Cascadia subduction zone provides one explanation for this seismic quiescence.

However, the Cascadia subduction zone shares many features, including temporal

quiescence, with other subduction zones that have experienced very large shallow

subduction earthquakes (Heaton and Kanamori, 1984). Yet, there is no

direct geologic or historical evidence presently available to confirm that great

shallow subduction earthquakes have occurred along the coast of Washington,

Oregon, and northern California. However, there are reports describing Indian

legends of great sea-level disturbances that may be related to large nearby earthquakes.

In this letter, we briefly review the history of exploration and settlement of

this region by nonnative people and then discuss legends from Indians in northern

Washington and northern California

Heaton, Thomas H.

Snavely, Parke D., Jr.

Caltech Authors - Main

Bulletin of the Seismological Society of America, Vol. 75, No. 5, pp. 1455-1460, October 1985 
POSSIBLE TSUNAMI ALONG THE NORTHWESTERN COAST OF THE 
UNITED STATES INFERRED FROM INDIAN TRADITIONS 
BY THOMAS H. HEATON AND PARKED. SNAVELY, JR. 
Subduction of the Juan de Fuca and Gorda plates beneath western North America 
presents a paradox; despite the fact that there is good evidence of 3 to 4 cm/yr of 
ongoing convergence, there is a remarkable paucity of either historic or instrumen- 
tally recorded shallow subduction earthquakes. Steady aseismic slip along the entire 
Cascadia subduction zone provides one explanation for this seismic quiescence. 
However, the Cascadia subduction zone shares many features, including temporal 
quiescence, with other subduction zones that have experienced very large shallow 
subduction earthquakes (Heaton and Kanamori, 1984). Yet, there is no 
direct geologic or historical evidence presently available to confirm that great 
shallow subduction earthquakes have occurred along the coast of Washington, 
Oregon, and northern California. However, there are reports describing Indian 
legends of great sea-level disturbances that may be related to large nearby earth- 
quakes. In this letter, we briefly review the history of exploration and settlement of
this region by nonnative people and then discuss legends from Indians in northern 
Washington and northern California. 
The coastline of Washington was first explored by Captain Bruno Heceta of 
Spain in 1775, and a Spanish settlement was briefly occupied (5 months) in 1792 
at Neah Bay (see Figure 2). This coastline was also explored by Captain James 
Cook (England) in 1778 and Captain Robert Gray (United States) in 1792. Fur 
trading settlements were established by Canadians in 1810 and 1811 at Spokane, 
Astoria, and Fort Okanogan. Permanent, but sparse, settlement of the region 
persisted until the 1850's when a major wave of immigration occurred. 
It seems certain that great coastal subduction earthquakes have not occurred 
since the 1850's and highly probable that they have not occurred since the 1790's. 
However, Judge James Swan has reported curious Indian "traditions" that suggest 
effects that could have resulted from a great shallow subduction earthquake. Swan 
was a renowned student of Indian lore, writing several fascinating accounts of his 
experiences with coastal Indians from Washington, Oregon, and British Columbia 
during the 1850's through 1870's (Swan, 1857, 1868, 1874). 
The following excerpts are from Swan's 1868 publication, "The Indians of Cape 
Flattery." Although it is useful to study a large quantity of Swan's writings in order 
to better understand the context of the "traditions" of a large sea-level disturbance, 
the first excerpt indicates Swan's impressions of the reliability of Indian legends. 
History, Traditions, Etc.--The history of this tribe (Makah), as far as 
their knowledge extends, is a confused mass of fables, legends, myths, and 
allegories. Nothing that they can state prior to the existence of a few 
generations back is clear or wholly to be relied upon. There are a few 
prominent events that have been remembered as having occurred; but the 
detail is confused, and it is very rare that two Indians tell the same story 
alike, unless it may be some wild and improbable legend, like the fairy 
tales related in nurseries, which are remembered in after life. A notable 
instance of this unreliability is in their version of the account of the 
1455 
1456 LETTERS TO THE EDITOR 
Spanish settlement attempted at Neeah Bay by Lieut. Quimper, in 1792 
by order of the commandant of the Spanish forces at Nootka. All they 
really know about it, is that they have been told by their fathers that the 
Spaniards were here, and they can point out the locality where yet may be 
found pieces of tile used by the Spaniards in building. But although that 
occurrence was only seventy-three y ars ago, there is but one man living 
in the tribe who remembers the circumstances, and he is in his dotage. 
Almost every Indian I have questioned upon the subject gives a different 
version of the detail. Now, as they cannot relate correctly matters given in 
our history, and of a comparatively recent date, but little dependence can 
be placed upon the tales of their origin, which are interesting only for their 
fabulous and superstitious nature. 
More recent events, such as the murder of the crews of the ship Boston, 
in 1803, and of the Tonquin, in 1811, and the captivity of Jewett among 
the Nootkans, they remember hearing about, and relate with tolerable 
accuracy. As events recede in years, however, they become obscured with 
legends and fables, so that the truth is exceedingly difficult to discover. 
Keeping these strong caveats in mind, we now reprint Swan's (1868) account of 
Indian "traditions" of a great sea level disturbance along the coast of Washington. 
Geographic locations of tribes and places mentioned in this account are shown in 
Figures I and 2 (modern spelling of some words may differ from that in the account). 
In addition, the word, Makah, is used by eastern inland Indians and nonnative 
people; the word, Classet, is used by northern Coastal Indians, and the word 
Kwenaitchechat is used by Cape Flattery Indians (Makahs). All of these words have 
the same meaning: "people who live on a point of land projecting into the sea (i.e. 
Cape Flattery)." 
The only tradition that I have heard respecting any migratory movement 
among the Makahs, is relative to a deluge or flood which occurred many 
years ago, but seems to have been local, and to have had no connection 
with the Noachic deluge which they know nothing about, as a casual visitor 
might suppose they did, on hearing them relate the story of their flood. 
This I give as stated to me by an intelligent chief; and the statement was 
repeated on different occasions by several others, with a slight variation in 
detail. 
"A long time ago," said by informant, "but not at a very remote period, 
the water of the Pacific flowed through what is now the swamp and prairie 
between Waatch village and Neeah Bay, making an island of Cape Flattery. 
The water suddenly receded leaving Neeah Bay perfectly dry. It was four 
days reaching its lowest ebb, and then rose again without any waves or 
breakers, till it had submerged the Cape, and in fact the whole country, 
excepting the tops of the mountains at Clyoquot. The water on its rise 
became very warm, and as it came up to the houses, those who had canoes 
put their effects into them, and floated off with the current, which set very 
strongly to the north. Some drifted one way, some another; and when the 
waters assumed their accustomed level, a portion of the tribe found 
themselves beyond Nootka, where their descendants now reside, and are 
known by the same name as the Makahs in Classett, or Kwenaitchechat. 
Many canoes came down in the trees and were destroyed, and numerous 
lives were lost. The water was four days regaining its accustomed level." 
LETTERS TO THE EDITOR 1457 
The same tradition was related to be by the Kwilleyutes, who stated that 
a portion of that tribe made their way to the region in the vicinity of Port 
Townsend, where their descendants are known as the Chemakum tribe. I 
have also received the same tradition from the Chemakum Indians, who 
claim to have originally sprung from the Kwilleyutes. There is no doubt in 
my mind of the truth of this tradition. The Waatch prairie shows conclu- 
sively that the water of the Pacific once flowed through it; and on cutting 
through the turf at any place between Neeah Bay and Waatch, the whole 
50 ° 
45 ° 
4A 
3A / 
4A 
"% ~,~ ".° 
"% 
 :f,2 -.. Makah 
IA 3A ' - . ay  
3A 
Chemokum 
• Ind lon$ 
2 / _ j j  
• ~ ; 
2A J / / I /  / : . _ ! ~ 2, 
Mendocmo F..Z. L ". ( • 
40 ° t J i i - - i -  ~- - i - - - -x~ i t I 
-130  ° -125  o 
FIG. 1. Approximate location of Indian tribes and place names mentioned in this report. Approximate 
locations of sea-floor magnetic lineations and Quaternary volcanoes (triangles) are also shown. 
substratum is found to be pure beach sand. In some places the turf is not 
more than a foot thick; at others the alluvial deposit is two or three feet. 
As this portion of the country shows conclusive vidence of volcanic 
action, there is every reason to believe that there was a gradual depression 
and subsequent upheaval of the earth's crust, which made the waters rise 
and recede as the Indians stated. Fossil remains of whales are said by the 
Indians to be found around a lake near Clyoquot, which were possibly 
deposited at the time of this flood. I have not seen these remains, but I 
1458 LETTERS TO THE EDITOR 
o +i +!++++i~+~++ii+++++il + 
"~.  c . , .  + + 
++ • 
. . . .  +. .+ ,,,.,,,,,m,,. %,,-~++ 
I ' 
(: ... +~++I 
" I I  
- / 
m 
-+  j 
J 
O 
I I  
+;  - ~+++ .... 
- ; +, 
~') ++ + I 
++ 
26 
IS 
| '...S lC R ¥/ 
q 
+/  
,% 
- .+~. 
T I 
i 
' y :+~ s 
i / 
F IG .  2.  Topographic map of the Cape Flattery region (U.S. Geological Survey Cape Flattery Quad- 
rangle, 15-rain series). 
have been told of their existence by so many different Indians who 
professed to have seen them, that I think the story probably correct. The 
Indians do no think they got there by means of the flood, but that, as 
before stated, they are the remains of the feasts of the T'hlukloots, or 
thunder bird, who carried the whales there in his claws, and devoured them 
LETTERS TO THE EDITOR 1459 
at his leisure. With the single exception of this legend of the flood, I have 
never learned from them that they have any tradition respecting the tribe 
coming to or going from the place where they now reside, and this is the 
only one which they relate of ancient times that is corroborated by 
geological or other evidence. 
Could this be an account of a great tsunami? Although there are many features 
of this report that seem exaggerated, apparently Swan was convinced that some 
remarkable sea-level disturbance had occurred. He clearly segregates this report 
from the majority of legends which he feels are of a more mythical nature. The 
words, "a long time ago, but not at a very remote period," indicate that the alleged 
disturbance predates the lifetimes of the reporting Indians, but was not to be 
confused with an ancient ime which was associated with the great majority of their 
mythical legends. 
If this is an account of an ancient sunami, then what can be deduced about its 
nature and origin? Great tsunamis may have periods of tens of minutes to hours, 
but 4 days is without percedent. If we are to believe that this is an account of a 
through the years. If the event is real, then it is apparent that the effects must have 
been substantial. However, it seems incredulous that any tsunami could have 
overtopped the entire Cape Flattery region since the highest elevation of the cape 
exceeds 400 m. Furthermore, one is hard pressed to explain why the water would 
become warm. Nevertheless, the description of water receding from Neah Bay and 
then returning in a strong current is clearly suggestive of a tsunami. 
If this is a tsunami description, could the sea wave have originated from a great 
earthquake at a distant location? Since there is no mention of any ground shaking, 
this might be a logical conclusion. However, large historical earthquakes along the 
Pacific rim have not generated large tsunamis at Neah Bay. The Mw 9.2 Alaskan 
earthquake in 1964 caused a tsunami of only about 1.3 m at Neah Bay (Cloud and 
Scott, 1972). Furthermore, the story indicates that Cape Flattery was an island 
before this legendary event. This may be plausible since a low marshy area between 
Waatch and Neah Bay is the only thing that currently prevents Cape Flattery from 
being an island. If there was permanent uplift of the Waatch lowland associated 
with the event described in the legend, then crustal deformation associated with a 
nearby subduction earthquake could explain the uplift. However, this and any other 
conjectures about the significance of this legend are purely speculative. There are 
enough inconsistencies in the legend that one must seriously consider the interpre- 
tation that this Indian tradition may be entirely fictional. Nevertheless, it is 
noteworthy that such a report exists for a region for which there is growing con- 
cern that large subduction earthquakes and subsequent tsunamis may be a real 
possibility. 
We have mentioned this report by Swan to several colleagues and this resulted 
in the rediscovery of other Indian legends of earthquake activity along the north- 
western coastal United States. Gary Carver (Department ofGeology, Humbolt State 
University, Arcata, California) informed us of myths of the Yurok Indians in which 
earthquakes seem to play a prominent role. These myths were recorded by A. L. 
Kroeber (1976) between 1900 and 1907. Yurok Indians inhabited the region that 
roughly coincides with Redwood National Park in northernmost coastal California 
(see Figure 1). According to Yurok mythology, the god, Earthquake, was a very 
powerful being that ran over the earth, shaking and tearing the ground, breaking 
trees, and disturbing the rivers and ocean. However, the Yurok stories are very 
1460 LETTERS TO THE EDITOR 
allegorical and seem to be correctly classified as myths. We do not reproduce these 
myths here since they are somewhat lengthy, difficult o interpret, and their factual 
basis is unknown. 
CONCLUSIONS 
We thank Gary Carver for generously providing materials relating to Yurok 
Indian mythology. We also thank Joseph Ziony and Robert Wallace for thoughtful 
reviews of the manuscript. This work is supported, in part, by the U.S. Nuclear 
Regulatory Commission. 
REFERENCES 
Cloud, W. K. and N. H. Scott (1982). Distribution ofintensity, in The Great Alaska Earthquake o/1964, 
Seismology and Geodesy, National Academy of Sciences, Washington, D.C., 65-108. 
Heaton, T. H. and H. Kanamori (1984). Seismic potential ssociated with subduction i the northwestern 
United States, Bull. Seism. Soc. Am. 74, 933-941. 
Kroeber, A. L. (1976). Yurok Myths, University of California Press, Berkeley, California, 488 pp. 
Swan, J. G.-(1857). The Northwest Coast, Harper and Brothers, Publishers, New York, 435 pp. 
Swan, J. G. (1868). The Indians of Cape Flattery, at the entrance to the straight of Juan de Fuca, 
Washington Territory, Smithsonian Contributions To Knowledge, 220, 108 pp. 
Swan, J. G. {1874). The Haidah Indians, of the Queen Charlotte Islands, British Colombia, Smithsonian 
Contributions To Knowledge, 267, 25 pp. 
U.S. GEOLOGICAL SURVEY 
SEISMOLOGICAL LABORATORY 
CALIFORNIA INSTITUTE OF TECHNOLOGY 
PASADENA, CALIFORNIA 91125 (T.H.) 
U.S. GEOLOGICAL SURVEY 
345 MIDDLEFIELD ROAD 
MENLO PARK, CALIFORNIA 94025 (P.S.) 
Manuscript received 8May 1985 


Possible tsunami along the northwestern coast of the United States inferred from Indian traditions

https://authors.library.caltech.edu/36389/1/1455.full.pdf

Possible tsunami along the northwestern coast of the United States inferred from Indian traditions

Abstract

Similar works

Full text

Available Versions

Caltech Authors - Main