(M
7.5) Central American Earthquakes on the Sedimentary Formations within the Clarion
Clipperton Province
I. P. Kuzin and M. S. Barash
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
Received May 28, 2001
Abstract—During the expeditionary studies of the sedimentary cover at two test sites within the Clarion–Clip-
perton Province, an erosional cut of the Tertiary sediments was observed and paradoxical bedding of massive
ancient manganese nodules over the sediment surface of different ages right up to the recent ones was recog-
nized. The explanations available for the observed pattern are essentially qualitative and are not supported by
sufficient argumentation. We proposed a new approach considering the mechanical impact of the Rayleigh
waves generated by the strongest (M 
7.5) earthquakes within the nearest Central American seismic active
region on the sediments. This approach is based on the data on the ground oscillations on land that were excited
by the Rayleigh waves of selected catastrophic earthquakes (Lisbon, 1775; Assam, 1950; and Alaskan, 1964).
These oscillations were observed at epicentral distances from 2000–4000 to 8000 km. The mechanism consid-
ered is realistic and allows one to use quantitative characteristics of the Rayleigh wave oscillations for the expla-
nation of their mechanical impact on the sediments. The study of the Rayleigh wave amplitudes was carried out
using about 200 records of earthquakes with M = 6.0–8.2 at distances of 560–9200 km obtained at the Petro-
pavlovsk-Kamchatskii and Severo-Kuril’sk seismic stations. For the analysis, we used the waves arriving from
various seismically active regions of the Pacific Ocean. The close seismotectonic and seismic analogy between
the Kuril–Kamchatka and Central American segments of the Pacific belt allows us to apply the data recorded
in the former region for studies of the same phenomena in the latter area. Then, at distances between the test
sites and the seismically active Central American region of 3000–5400 km, the amplitudes of the Rayleigh
waves reach about 0.5 mm. These values are large enough to explain the “seismological erosion” of the sedi-
ments; however, they are insufficient for displacement of manganese nodules because of their large size (from
3–5 to 10 cm). For explanation of the nodule displacement, another mechanism is required.
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