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Report on Udintsev Transform (Undersea Features) — December 1990

Bulletin of the Global Volcanism Network, vol. 15, no. 12 (December 1990)
Managing Editor: Lindsay McClelland.

Udintsev Transform (Undersea Features) T-waves near Udintsev Fracture Zone/Pacific-Antarctic Rise junction

Please cite this report as:

Global Volcanism Program, 1990. Report on Udintsev Transform (Undersea Features) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:12. Smithsonian Institution.

Udintsev Transform

Undersea Features

56.153°S, 143.373°W; summit elev. -5700 m

All times are local (unless otherwise noted)

RSP stations detected acoustic signals (T-waves) from 42 seismic events between 29 October and 1 November, and 523 on 15-19 November. The strongest shocks reached mb 5.3 on 29 October at 0643 GMT and 1 November at 0157 GMT. Preliminary WWSSN epicenter determinations were at 55.96°S, 143.20°W and 55.979°S, 143.15°W, with latitude uncertainties of ± 23 and 16 km, respectively. The located events occurred along a young, seismically active portion of the Udintsev Fracture Zone (Molnar and others, 1975) near its intersection with the Pacific-Antarctic Ridge (figure 1). Talandier notes that "it is possible that this crisis is linked to volcanic activity." Bathymetric data for this region are very limited, and seismic stations are distant, with WWSSN detection thresholds of about M 5.

Figure (see Caption) Figure 1. Computer-generated bathymetric map of a portion of the S-central Pacific, showing the Eltanin and Udintsev Fracture Zone systems, and the prominent seamount at about 53.9°S, 140.3°W in the epicentral area of the March 1991 swarm. Contour interval, 200 m. Courtesy of the U.S. Naval Research Laboratory.

Reference. Molnar, P., Atwater, T., Mammerickx, J., and Smith, S.M., 1975, Magnetic anomalies, bathymetry and the tectonic evolution of the south Pacific since the Late Cretaceous: Geophysical Journal of the Royal Astronomical Society, v. 40, p. 383-420.

Geologic Background. Acoustic signals (T-waves) from a seismic swarm were detected in 1990 from a source along the Udintsev fracture zone at about 143 deg W, along the segment that corresponds with the Pacific-Antarctic Ridge (Global Volcanism Network Bulletin, 1990). The seismicity may have been linked to volcanic activity.

Information Contacts: J. Talandier, LDG Tahiti; E. Bergman, NEIC.