Content uploaded by Max Semenovich Barash
Author content
All content in this area was uploaded by Max Semenovich Barash on Mar 20, 2014
Content may be subject to copyright.
Oceanology; Vol. 42, No. 5, 2002, pp. 677-681. Translated from Okeanologiya, Vol. 42, No. 5, 2002, pp. 709-713.
Original Russian Text Copyright © 2002 by Kuzin, Barash.
English Translation Copyright © 2002 by MAIK "Nauka /Interperiodica " (Russia).
-
..
’ ■■ — MARINE GEO LOGY
.............
.......
=
A Possible Mechanism for the Ferromanganese Nodules
“Floating” in the Near Equatorial Part of the Pacific Ocean
I. P. Kuzin and M. S. Barash
Shirshov Institute o f Oceanology, Russian Academy of Sciences, Moscow, Russia
Received July 4, 2001
Abstract—In this paper we apply the mechanism of a near-bottom tsunami in the open ocean to explain the
paradoxical location of massive ferromanganese nodules at the surface of sediments of different ages. These
tsunamis are generated by the strongest (M > 7.5) earthquakes in the Central American seismic zone and prop
agate in the near-bottom water layer (3000-5000 m). Their amplitudes are equal to 0.8-3.0 cm, while the veloc
ities reach 180 m/s. Such perturbations of the water layer are able to cause not only the erosion of the sediments
but also the transport (rolling, overturning) of ferromanganese nodules over the ocean bottom. As a result, they
can be located at the surface of sediments of various ages. This confirms our supposition about the mechanism
of “floating” of massive ferromanganese nodules. Previously, in order to solve the problem mentioned above,
we used the mechanism of the Raylpigh waves, which are excited by the strongest (M > 7.5) earthquakes in
Central America. However, an analysis of the amplitudes of the Rayleigh waves showed that, at distances of
3300-5400 km from the seismic zone, these amplitudes are very small (about 0.5 mm). Therefore, they are able
to cause erosion at a rate up to 50 m/My by mechanical forcing on the sediments. However, the Rayleigh waves
are not able to move ferromanganese nodules because of their small scale (0.5 mm) as compared to the size of
the nodules (5-10 cm). Hence, the mechanism of a near-bottom tsunami is preferable for explaining the effect
of nodule “floating.”
INTRODUCTION
In our previous article [13], we considered a possi
ble mechanism of the influence of the Rayleigh surface
waves in the Central American zone on the bottom sed
iments in the Clarion-Clipperton province during the
strongest earthquakes (M > 7.5). This formulation of
the problem was conditioned, first of all, by the impos
sibility to explain the existing correlation between the
unconsolidated sediments and ferromanganese nodules
(erosional cut and “floating” of the nodules) using the
previously considered mechanisms. They include
(a) long-term periods when no sediments are accumu
lated; (b) regional erosion of the Tertiary sediments and
accumulation of ferromanganese nodules as residual
elements; (c) the effect of the bottom shaking under the
forcing of the seismic waves from the strongest earth
quakes; (d) microflux of geogases; (e) bioturbation and
extrusion of nodules to the surface of the floor by
benthic organisms; (f) rheological properties of the sed
iments; and (g) hydrodynamics of the density-stratified
bottom water layers [2, 4, 19]. All these mechanisms
cannot explain the facts of erosion of Tertiary sedi
ments 34—80 m thick and the location of the denser
ancient (mainly Oligocene) ferromanganese nodules
(density about 2.0 g/cm3) [11] at the surface of the sed
iments of different ages up to recent ones (the density
of the consolidated sediments is about 1.2 g/cm3 [12]).
In the solution of the problem on the relations
between the sediments and ferromanganese nodules,
we focused, first of all, on the data of sufficiently strong
shocks of the earth’s surface under the influence of
the Rayleigh waves during the strongest earthquakes
(M ~ 8.5). It is known that during the Lisbon (1775),
Assam (1950), and Alaska (1964) earthquakes, notable
vibrations of the ground were observed at distances of
4000 to 8000 km [6, 18] during the propagation of the
Rayleigh waves. It is natural to suppose that similar
shocks are manifested at the ocean bottom in the Clar
ion-Clipperton province during the strongest earth
quakes in Central America at distances from 3300 to
4300 km from the closest experimental study area and
4300-5400 from the most remote one (see Fig. 3 in [13]).
In order to study the possible amplitudes of the
ocean bottom vibrations, we used the records of
200 earthquakes at seismic stations in Petropavlovsk-
Kamchatskii and Severo-Kurilsk with M = 6.0-8.2
from different seismically active zones in the Pacific
Ocean at distances from 580 to 9200 km [13]. It was
found that at distances of 3300-4300 km and
4300-5400 km the amplitude of the vertical oscilla
tions in the Rayleigh waves during earthquakes with
M = 7.5-8.2 reaches 0.4-0.5 mm. This means that,
when a benthic storm begins under the influence of the
Rayleigh waves caused by one of those earthquakes,
the surface layer of unconsolidated sediment, accumu
lated over a period of 200-250 to 400-500 years, could
be washed out [2, 19].
An estimate of the recurrence of the earthquakes of
the magnitude groups 7.5-7.9, 8.0-8.4, and greater
than 8.5 on the basis of the data available [17,24] leads
678 KUZIN, BARASH
Fig. 1. Schematic of a near-bottom tsunami recording dur
ing the earthquake on March 14, 1979, near the Mexican
coast (according to [20]). (a) Position of the pressure gauge
(P) and the epicentral гопе of the earthquake with a magni
tude M = 7.6 (hatched area); (b) sea level record of the near
bottom tsunami generated by the earthquake on March 14,
1979. E is the moment of arrival of the body waves; T is the
moment of arrival of the tsunami wave. The amplitude of
the record equal to 1 cm corresponds to a pressure change
of 100 Pa. TTie high-frequency component of the oscilla
tions with a period of 2-4 min and amplitude of 0.1 cm cor
responds to the Rayleigh surface waves.
as to the conclusion that over 1000 years about
20 earthquakes with such amplitudes can occur. By
decreasing the possible amplitude 1.6-2.0 times (to
increase the probability of such vibrations), we obtain
in estimate of the sediment erosion of about 5 mm for
1000 years. If we assume that the beginning of the ero
sion started 17 My BP, the erosional cut should be equal
to 85 m. At a rate of the sediment accumulation equal
to 1.5 mm in one thousand years, the layer of the sedi
ments accumulated during this period would be equal
to 25 m. In this case, the erosion would be equal to
60 m. This is comparable with the mean estimate of the
jrosional cut [2, 19]. In the latter paper it is shown,
however, that it is likely that the period of erosion of the
Tertiary sediments in the Clarion-Clipperton study
areas does not exceed 1 My (more precisely,
0.9-0.7 My). In this case, the mechanism of the sedi
ment erosion gives a value of the erosional cut that is
underestimated 7-16 times. It should be added that the
small (up to 0.5 mm) amplitudes of the ocean bottom
vibrations during the propagation of the Rayleigh
waves cannot explain the displacement of massive
ferromanganese nodules to the surface of the uncon
solidated sediments of different ages up to the recent
ones.
Taking into account that the Rayleigh surface waves
mechanism cannot be used for the explanation of the
erosional cut of unconsolidated sediments and, even
more, it cannot be used to explain the problem of the
ferromanganese nodules, we applied for the first time
the mechanism of a near-bottom tsunami to solve this
problem. We are analyzing the tsunamis generated by
strong earthquakes and propagating in the bottom layer
in the open ocean.
ANALYSIS OF THE TSUNAMI DATA
It is known that the majority of the tsunamis (up to
80%) are excited by the strongest earthquakes with
M > 7; that is, they have a seismic origin [8]. According
to the data available over the past 450 years
(1537-1979), about 55 events of the tsunami type and
similar ones (high tidal waves, storm flooding, etc.)
occurred during such earthquakes in the Central Amer
ican seismic active zone [15, 16]. According to the data
from [22], the possible magnitudes values M of 7.0-8.3
were determined for half of the known earthquakes.
However, we cannot use this information directly
because it is related to the manifestation of tsunamis
near the coast and, using these data, it is difficult to esti
mate the motion of the near-bottom layer in the open
ocean. Only after near-bottom tsunamis were recorded
in the 1970s-1980s far from the coastline using the
pressure gauges did it become possible to use this infor
mation in the solution of the problem of the interaction
between the sediments and ferromanganese nodules on
the basis of observations in the Clarion-Clipperton
province.
At present, at least four records of near-bottom tsu
namis are known to be related to the following earth
quakes: (a) in the Central American seismically active
zone near the Mexican coast on March 14,1979, M = 7.6;
(b) in the south Kuril zone near Shikotan Island on Feb
ruary 23, 1980, M = 7.0; (c) and (d) in the Gulf of
Alaska on November 14, 1987, and March 6, 1988,
M = 7.6 in both cases.
The first record was obtained at a point south of the
California Peninsula during an earthquake in the Petat-
lan town region (Mexico) with a focal depth equal to
20 km. The pressure gauge was located at a depth of
3210 m at a distance of 980 km (8.8°) from the epicen
ter. The tsunami record had a multiphase character.
Along with the main maximum 8 mm (double ampli
tude 1.6 cm), four other maxima can be distinguished
with amplitudes from 6.5 to 3 mm and periods of oscil
lations from 15 to 45 min (figure) [20]. The time of the
tsunami wave propagation is 1 h 28 min, which corre
sponds to a velocity of 670Jcm/h or 186 m/s. This value
OCEANOLOGY Vol. 42 No. 5 2002
A POSSIBLE MECHANISM FOR THE FERROMANGANESE NODULES “FLOATING” 679
is close to the estimate 638 km/h or 177 m/s obtained
from the relation V = JgH, where g = 9.79 m/s2 is the
acceleration due to gravity at a latitude of 22° N and H
is the ocean depth in meters. Taking into account the
periods of the oscillations and the velocity of the tsu
nami wave propagation, its length can be estimated as
170-500 km.
The second record of a near-bottom tsunami was
made by a group of researchers headed by
S.L. Solov’ev over the shelf of Shikotan Island (depth
133 m) during an earthquake with M = 7.0 and a focus
located 30-40 km under the upper part of the continen
tal slope of the Kuril-Kamchatka Trench, depth con
tour 800 m [9]. The amplitude of the first, the greatest
wave, was equal to 3.5 cm (double amplitude 7 cm); its
period was 18 min. Over approximately 10 h after the
arrival of the first wave, about 11 maxima with a
decreasing amplitude from 2-3 to 1.75-1.50 cm and
periods of 11-24 min (most frequently 17 min) were
observed. In 15 min, the wave covered a distance of
33 km from the epicenter, which corresponds to a
velocity greater than 130 km/h or about 37 m/s (wave
lengths 24-52 km).
Near-bottom tsunamis from the earthquakes in the
Gulf of Alaska with focal depths of 10 km were
recorded at two points: (a) south of Kodiak Island at a
depth of 5 km; (b) southwest of Vancouver Island,
ocean depth 3 km. In 1987, during the earthquake at the
point closest to the epicenter south of Kodiak Island
(A ~ 970 km or 8.7°), the amplitude of the tsunami
reached 1 cm, while in a more remote one southwest of
Vancouver Island (A ~ 1730 km or 15.6°), the amplitude
reached 1.7 cm [21]. During the earthquake in 1988, the
amplitudes of the tsunamis at the same points were
equal to 2.6 cm (A ~ 900 km or 8.1°) and 2.9 cm
(A ~ 1520 km or 13.7°), respectively. In the latter case,
the tsunami records both in the California and South
Kuril regions had a multiphase character (five maxima
with amplitudes from 2.9 to 2.0 cm) [23]. Unfortu
nately, the lack of a time reference on the tsunami
record in 1988 (the tsunami record of 1987 is not pub
lished) does not allow us to determine the velocity of
the wave propagation and the periods of the main and
subsequent tsunami pulses.
Thus, concluding the discussion of the data on near
bottom tsunami, we have to note the following. First,
unlike the surface waves generating vibrations of the
bottom and indirectly influencing the near-bottom
water layer, the perturbation during a tsunami is gener
ated in the boundary water layer. As this takes place, the
perturbations related to the same magnitude of the
earthquake at comparable distances from the source
exceed the amplitude of oscillations in the surface
waves by at least one order of magnitude (8 mm as
opposed to 0.8 mm, according to [13]). This excess can
be as high as 20-40 times at distances about 15°
(according to [ 13], the displacement associated with the
Rayleigh waves at M = 7.5-7.9 is equal to approxi
mately 0.75 mm, while in the records during the earth
quakes in the Gulf of Alaska they were equal to
1.7-2.9 cm).
Second, in the case of a tsunami, the perturbations in
the bottom water layer propagate at a very high speed
as compared to the usual currents, not less than
650-750 km/h (see above and also [6]) or 180-210 m/s.
Both factors should facilitate an intensive influence of
the bottom tsunami on the sediment^ and ferromanga
nese nodules on the ocean bottom.
From the consideration of the previous information
it follows that to solve this problem we can take the tsu
nami records during the earthquakes in the Gulf of
Alaska at a point southwest of Vancouver Island
(13.7°-15.6°) as a first approximation of the initial data,
extrapolating them to the distances corresponding to the
remoteness of the study areas 2 (30°-39°) and 1 (41°-49°)
in the Clarion-Clipperton province from the Central
American seismically active zone. We assume that the
minimum amplitude of a tsunami oscillation is 8 mm
taking into account the wave decay due to the respec
tive 2.0- to 2.7- and 2.8- to 3.4-fold excess in the epi-
central distances to study areas 2 and 1 compared to
those observed during the recording of these waves.
This possibility is taken into account by the choice of
the initial amplitude of the tsunami, which is
2.1-3.6 times smaller than that observed in the experi
ment (8 mm as opposed to 1.7-2.9 cm as shown above).
It is noteworthy that, according to the available data,
tsunami waves are characterized by a weak decay as the
coefficient of turbulent viscosity in the bottom bound
ary layer is constant. Only in a more complex model of
turbulence should the decay of a tsunami increase [10].
Another important factor in the choice of the bottom
tsunami as the source conditioning the observed ero
sion of the sediments and transport of ferromanganese
nodules to the surface of the present sediments is the
estimate of the tsunami recurrence. It is known that not
every earthquake with a magnitude M > 7 is accompa
nied by a tsunami. For example, as follows from the
above-mentioned data, of 55 events of tsunami type in
Central America that occurred during the last 450 years
(1537-1979) [15, 16], only about 17 events fit the pro
portion of clearly manifested tsunamis after a thorough
analysis. According to [22], from 27 determinations of
the earthquake magnitudes, the overwhelming majority
falls in the M ranges 7.0-7.4 and 7.5-7.9 (11 determi
nations in each range). Only two clearly manifested tsu
namis are related to the first group. It is noted in many
publications dedicated to the study of tsunamis that
many factors influence the generation of a tsunami dur
ing a strong earthquake: the mechanism of the focus
(the most effective is the displacement with an upward
motion— the piston mechanism); the depth of the focus
(the maximum amplitudes of tsunamis correspond to a
depth of the source equal to 10 km) [1, 8, 14, and oth
ers]; and the depth of the basin where tsunami is gener
ated (approximately 1300 m) [7].
680 KUZIN, BARASH
However, up to the present, the reason why during
earthquakes of the same magnitude tsunamis are gener
ated in some cases and are not generated in others is
still not known. The solution of this problem goes
beyond the scope of this study; however, it is necessary
to note the following. As mentioned above, at the earth
quakes with M > 7.5, tsunamis are generated in 80% of
the cases [8]. We can assume 50% as the lower limit.
Then, based on the recurrence of the earthquakes with
M = 7.5-8.5 considered above, we can expect that over
1000 years, 10 tsunamis (but not 20) with an amplitude
of at least 8 mm can be generated. In this case, the total
erosion of the sediments over 1000 years will be
80 mm. Extrapolating this estimate over 1 My, we get
an erosional cut of the sediment layer equal to 80 m. It
follows from this that the observed erosional cut in the
study areas 1 and 2 in the Clarion-Clipperton province
could appear within 0.42-1 My. This conclusion agrees
with the results of [19].
As for the problem of the location of ancient ferro
manganese nodules over the recent sediments, their
“floating” or maintenance at the surface of the bottom
is possible when they are displaced (overturned, rolled)
under the influence of a near-bottom tsunami with
amplitudes at least the sizes of the nodules (5-10 cm).
In the light of the data considered above, this possibility
seems quite feasible.
Thus, from the example of study areas in the Clar
ion-Clipperton province, we can conclude that near
bottom tsunamis caused by the earthquakes with
M = 7.5-8.5 from the Central American seismically
active zone are the most applicable mechanism explain
ing the features of the interaction between the sedimen
tary layer and ferromanganese nodules. We have to
admit that there is an uncertainty with the generation
and recurrence of tsunamis for earthquakes with
M = 7.5-8.5 which can cause doubt about the reliabil
ity of the estimates of the washout of the bottom sedi
ments in the study areas mentioned above. However,
the influence of near-bottom tsunamis on the relations
between the sediments and ferromanganese nodules is
beyond doubt. A similar conclusion can be reached for
other ferromanganese nodule provinces in the Pacific
Ocean taking into account the high seismicity of its
margins. At the same time, we cannot neglect the influ
ence of strong benthic currents in certain regions, for
example, in the province near Antarctica where seismic
activity is low (see Fig. 1 in [13]).
DISCUSSION OF THE RESULTS
In the case of a near-bottom tsunami in the open
ocean generated by an earthquake with M > 7.5, the
intensity of the influence in the water column near the
bottom of an individual event at comparable distances
increases from 10 to 20-40 times (the amplitude of the
perturbation is equal to 8-29 mm as opposed to 0.5 mm
in the Rayleigh waves).
If we assume that the recurrence of the tsunamis is
two times smaller than the recurrence of the earth
quakes with M = 7.5-8.5 and the minimum washout
during each near-bottom tsunami is equal to 8 mm
(which is 32 times or 1.5 order of magnitude greater
than under the influence of the Rayleigh waves), the
total erosional cut would be equal to 80 mm after
1000 years or 80 m after 1 My. Then, the washout of the
unconsolidated Tertiary sediments in the study areas
mentioned above could be formed during the last
0.42-1 My. This estimate agrees with the estimate
made from the stratigraphic data in [19].
In the case when we choose a tsunami to solve this
problem, besides the differences in the value of the per
turbation compared to the Rayleigh surface waves,
there are differences in the origin of forcing. In the
former case, the bottom water layer plays a passive role.
The perturbations propagate at a very high velocity of
about 3.6 km/s in a solid medium covered by unconsol
idated sediments. The forcing has a short-wave charac
ter (the period is about 18 s on average, the wavelength
is 65 km) and relatively short duration (about 5 min;
see, for example, [5]). In the case of a tsunami, the per
turbation spreads in the water layer with an amplitude
that is 10-40 times greater than the displacement of the
bottom under the Rayleigh wave forcing. The velocity
of the tsunami wave propagation is approximately
20 times smaller than that of a Rayleigh wave, but it is,
however, much greater than the velocities of the usual
oceanic currents (180 m/s and greater). The forcing has
a long-wave character (the periods are 15-45 min, the
wavelength is 170-500 km) and significantly greater
duration, from two and more hours, according to [20],
to 11 h, according to [9]. The significant amplitude of
perturbations, a velocity greater than the velocity of the
usual oceanic currents, and the long duration of forcing
should facilitate not only the washout of the sediments
but also the transportation (overturning, rolling) of fer
romanganese nodules. As a result, they can be located
over sediments of different ages including the recent
ones.
It is noteworthy that the estimate of the erosional cut
of the Tertiary sediments based on the data on natural
tsunamis is not indisputable due to the uncertainty
related to the recurrence of tsunamis. However, the
influence of a near-bottom tsunami on the sediment
layer and ferromanganese nodules is beyond doubt. It is
likely that it is the real source of the observed relations
between the sediments and nodules in the study areas in
the Clarion-Clipperton province as well as in the other
provinces with a high concentration of ferromanganese
nodules close to highly seismic zones considered in the
previous article.
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research, project no. 01-05-64263.
OCEANOLOGY Vol. 42 No. 5 2002
A POSSIBLE MECHANISM FOR THE FERROMANGANESE NODULES “FLOATING” 681
REFERENCES
1. Alekseev, A.S. and Gusyakov, V.K., On the Estimation of
the Tsunami Hazard from Underwater Earthquakes,
Trudy 27-go Mezhdunarodnogo geologicheskogo kon-
gressa (Trans. 27th Int. Geological Congress), Moscow,
1984, vol. 6, pp. 127-133.
2. Barash, M.S., Kruglikova, S.B., and Mukhina, V.V., On
the Stratigraphy of the Cenozoic Deposits in Two Test
Areas in the Clarion-Clipperton Province (Pacific
Ocean), Okeanologiya, 1993, vol. 33, no. 2,
pp. 276-283.
3. Barash, M.S. and Kruglikova, S.B., Age of the Radi-
olaria from the Ferromanganese Nodules of Clarion-
Clipperton Province (Pacific Ocean) and the Problem of
Their “Non-sinking,” Okeanologiya, 1994, vol. 34,
no. 6, pp. 890-904.
4. Barash, M.S., Kruglikova, S.B., and Mukhina, V.V.,
Stratigraphic Features of the Sedimentary Formations of
the Clarion-Clipperton Province (Eastern Equatorial
Pacific), Okeanologiya, vol. 40, no. 3, pp. 424-433.
5. Bolt, В., Vglubinakh Zemli (Within the Earth’s Interior),
Moscow: Mir, 1984.
6. Bolt, B.A., Horn, W.L., Macdonald, G.A., and
Scott, R.F., Geological Hazards, Heidelberg: Springer,
1977. Translated under the title Geologicheskie stikhii,
Moscow: Mir, 1978.
7. Gusyakov, V.K., On the Relation of the Tsunami Hazard
from Underwater Earthquakes to the Conditions of Sed
imentation on the Sea Floor, Problemy seismichnosti
Dal’nego Vostoka (Problem of Seismicity of the Far
East), Petropavlovsk-Kamchatski: 2000, pp. 46-64.
8. Dotsenko, S.F. and Solov’ev, S.L., On the Role of the
Residual Displacements of the Ocean Floor in the
Tsunami Generation by Underwater Earthquakes,
Okeanologiya, 1995, vol. 35, no. 1, pp. 25-31.
9. Dykhan, B.D., Zhak, V.M., Kulikov, E.A., et al, The
First Tsunami Registration in the Ocean (Tsunami on
February 23, 1980 off South Kuril Islands), Dokl. Akad.
NaukSSSR, 1981, vol. 257, no. 5, pp. 1088-1092.
10. Klevannyi, K.A. and Pelinovskii, E.N., Dissipation of
Tsunamis in the Near-Bottom Boundary Layer: A Model
with a Constant Exchange Coefficient, Issledovaniya
tsunami (Tsunami Studies), Moscow: Mezhduvedom-
stvennyi geofiz. komitet, 1986, no. 1, pp. 80-88.
11. Kozlov, S.A., Physical Properties of the Ferromanganese
Oxide Ores of the Pacific Ocean, Geologiya okeanov i
morel Tez■ dokl. XIII Mezhdunar. shkoly morskoi
geologii (Geology of Seas and Oceans. 13th Interna
tional School on Marine Geology, Abstracts of Papers),
Moscow: Institute of Oceanology, Russian Academy of
Sciences, 1999, vol. II, pp. 114-115.
12. Kondratenko, A.V. and Shilov, V.V., Engineering-Geo
logical Stratification of the Central and Eastern Zones of
the Clarion-Clipperton Ore Field, Geologiya okeanov i
morei. Tez. dokl. XIII Mezhdunar. shkoly morskoi
geologii (Geology of Seas and Oceans. 13th Interna
tional School on Marine Geology, Abstracts of Papers),
Moscow: Institute of Oceanology, Russian Academy of
Sciences, 1999, vol. II, pp. 116-117.
13. Kuzin, I.P. and Barash, M.S., On the Action of the Ray
leigh Waves from the Strongest (M > 7.5) Earthquakes of
Central America on the Sedimentary Formations of the
Clarion-Clipperton Province, Okeanologiya, vol. 42,
no. 4.
14. Solov’ev, S.L., Seismic Conditions of Tsunami Genera
tion, Doctoral (Phys.-Mathematical.) Dissertation,
Moscow: Institute of Physics of the Earth, Russian
Academy of Sciences, 1970.
15. Solov’ev, S.L. and Go, Ch.N., Katalog tsunami na vos-
tochnom poberezh 'e Tikhogo okeana (Catalogue of the
Tsuiiamis on the Eastern Coast of the Pacific Ocean),
Moscow: Nauka, 1975.
16. Solov’ev, S.L., Go, Ch.N., and Kim, Kh.S., Katalog tsu
nami v Tikhom okeane 1969-1982 gg (Catalogue of the
Tsunamis in the Pacific Ocean in 1969-1982), Moscow:
Mezhduved. Geofiz. Komitet, 1986.
17. Fedotov, S.A., On the Seismic Cycle, Possibilities of
Quantitative Seismic Zonation, and Long-Term Seismic
Forecast, Seismicheskoe raionirovanie SSSR (Seismic
Zonation of the USSR), Moscow: Nauka, 1968,
pp. 121-150.
18. Aby, G., The Earthquakes. Translated under the title
Zemletryaseniya, Moscow: Nedra, 1982.
19. Barash, M.S. and Kruglikova, S.B., Age of Manganese
Nodules of the Clarion-Clipperton Province and the
Problem of Nodule Maintenance at the Sediment Sur
face, PACON Proceed., Honolulu, Hawaii: PACON
International, 2000, pp. 220-230.
20. Filloux, J.H., Tsunami Recorded on the Open Ocean
Floor, Geophys. Res. Lett., 1982, vol. 9, no. 1, pp. 25-28.
21. Gonzalez, F.I., Bernard, E.N., and ЕЫе, M.C., Deep
Ocean Measurements of Three Alaskan Tsunamis, Pro
ceed. Intern. Tsunami Symposium, July 31-August 1,
1989, Novosibirsk: 1990, p. 216.
22. Gutenberg, B. and Richter, C.F., Seismicity of the Earth
and Associated Phenomena, New Jersey, Princeton
Univ. Press, 1954.
23. Milburn, H.B. and Bernard, E.N., Deep Ocean Tsunami
Observations, Workshop on Scientific Uses of Undersea
Cables. Jan. 30-Feb. 1,1990, Honolulu. Hawaii, Wash
ington, D.C.: 1990, pp. 69-73.
24. Newmark, N.M. and Rosenblueth, E., Fundamentals o f
Earthquake Engineering, Englewood Cliffs, New Jer
sey: Prentice-Hall, 1971, pp. 247-266.