Undersea Features Research Articles

Active deformation and volcanism offshore Campi Flegrei, Italy: new data from high-resolution seismic reflection profiles

The interpretation of high-resolution seismic reflection profiles permitted the identification of many geologic features in the inner shelf of Pozzuoli Bay. This area corresponds to the offshore of Campi Flegrei: a classically active volcanic area that experienced earthquakes and meter-scale vertical ground uplift before the 1538 Monte Nuovo eruption and in the period from 1970 to 1985. The detected undersea features include two small debris flows that are located in a submarine valley in the western part of Pozzuoli Bay. They may be the result of a pyroclastic flow and a pyroclastic surge that entered the sea. The younger debris flow in the uppermost marine deposits of Pozzuoli Bay formed during the 1538 Monte Nuovo eruption, and the older debris flow during the 3.8 ka-old Averno eruption. Other features detected by our survey are an undersea 8 m-high and 1 km-wide cryptodome, corresponding to a near-surface intrusion, located off Pozzuoli, that warped post-4 ka marine deposits. The interpretation of the cryptodome is based on seismic facies analysis, deformation geometry and correspondence to a magnetic high. It is suggested that this undersea dome formed during the uplift phases associated with the 1538 Monte Nuovo eruption and the two more recent bradyseismic crises of 1970–1972 and 1982–1984. Surface-breaking faults (with maximum vertical offset of 1 m) were recognized in very shallow waters near the coast of Pozzuoli. It is suggested that some of these faults were active during the 1982–1984 bradyseismic earthquake sequence.

Report on Axial Seamount (Undersea Features)

Report on Axial Seamount (Undersea Features)

Report on Axial Seamount (Undersea Features)

Report on Axial Seamount (Undersea Features)

Volcanism offshore of Vesuvius Volcano in Naples Bay

High-resolution seismic reflection data are used to identify structural features in Naples Bay near Vesuvius Volcano. Several buried seismic units with reflection-free interiors are probably volcanic deposits erupted during and since the formation of the breached crater of Monte Somma Volcano, which preceded the growth of Vesuvius. The presumed undersea volcanic deposits are limited in extent; thus, stratigraphic relationships cannot be established among them. Other features revealed by our data include (a) the warping of lowstand marine deposits by undersea cryptodomes located approximately 10 km from the summit of Vesuvius, (b) a succession of normal step faults that record seaward collapse of the volcano, and (c) a small undersea slump in the uppermost marine deposits of Naples Bay, which may be the result of nuee ardentes that entered the sea during a major eruption of Vesuvius in 1631. Detection of these undersea features illustrates some capabilities of making detailed seismic reflection profiles across undersea volcanoes.

Report on Unnamed (Undersea Features)

Report on Unnamed (Undersea Features)

Report on Unnamed (Undersea Features)

Report on Unnamed (Undersea Features)

Naming of undersea features

The Intergovernmental Oceanographic Commission (IOC), the International Hydrographic Organization (IHO), and the joint IOC/IHO Guiding Committee for the General Bathymetric Chart of the Oceans (GEBCO) have expressed considerable concern about the indiscriminate and unregulated naming of undersea features which often go into print without any close scrutiny. An author may not realize that the feature has a name already, maybe in another language, or that his terminology conflicts with established definitions.

The Roots and Development of the Canadian Permanent Committee on Geographical Names

AbstractThe Canadian Permanent Committee on Geographical Names traces its roots to a recommendation of land surveyors in 1888 and action by the federal government in 1897 to create the Geographic Board of Canada. Advisory committees have assisted the CPCGN with principles and procedures, undersea feature naming, alpine nomenclature, and toponymic research. The Committee has convened workshops on gazetteer production, language issues, data automation, and native names. It will continue to pursue field collection of toponyms and development of principles for standardizing toponyms and linking automated toponymic data bases

Editorial: Naming of undersea features

Editorial: Naming of undersea features

Report on Unnamed (Undersea Features)

Report on Unnamed (Undersea Features)

Undersea feature terminology, recommendations of the joint IHO/IOC guiding committee (GEBCO)

Undersea feature terminology, recommendations of the joint IHO/IOC guiding committee (GEBCO)

Bathymetry of the MODE-I region

Depth soundings before and during the Mid-Ocean Dynamics Experiment (MODE-I) are integrated to produce bathymetric charts of the MODE-I region at scales of 1:500,000 and 1:250,000. Seven undersea features are named. The southwestern portion of the Bermuda Rise is characterized by rugged bottom topography generally striking north-northeast to south-southwest. Southeast of the Blake Bahama Outer Ridge, a zone of morphology paralleling the regional contours of the lower continental rise and associated deeps along many of the steep slopes on the Bermuda Rise suggest that the submarine terrain may be influenced by erosion by bottom currents.