Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Oceans”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
USGS2010

Update on geographic spread of invasive lionfishes ( Pterois volitans [Linnaeus, 1758] and P. miles [Bennett, 1828]) in the Western North Atlantic Ocean, Caribbean Sea and Gulf of Mexico

The Indo-Pacific lionfishes ( Pterois volitans [Linnaeus, 1758] and P. miles [Bennett, 1828]: Family Scorpaenidae) are the first nonnative marine fishes to establish in the Western North Atlantic/Caribbean region. The chronology of the invasion was reported last year (Schofield 2009) using records from the US Geological Survey's Nonindigenous Aquatic Species database. This article provides an update of lionfish geographic spread (as of October 2010) and predictions of future range.

Aquatic Invasions↗
USGS1997

Deep-ocean field test of methane hydrate formation from a remotely operated vehicle

We have observed the process of formation of clathrate hydrates of methane in experiments conducted on the remotely operated vehicle (ROY) Ventana in the deep waters of Monterey Bay. A tank of methane gas, acrylic tubes containing seawater, and seawater plus various types of sediment were carried down on Ventana to a depth of 910 m where methane gas was injected at the base of the acrylic tubes by bubble stream. Prior calculations had shown that the local hydrographic conditions gave an upper limit of 525 m for the P-T boundary defining methane hydrate formation or dissociation at this site, and thus our experiment took place well within the stability range for this reaction to occur. Hydrate formation in free sea-water occurred within minutes as a buoyant mass of translucent hydrate formed at the gas-water interface. In a coarse sand matrix the Filling of the pore spaces with hydrate turned the sand column into a solidified block, which gas pressure soon lifted and ruptured. In a fine-grained black mud the gas flow carved out flow channels, the walls of which became coated and then filled with hydrate in larger discrete masses. Our experiment shows that hydrate formation is rapid in natural seawater, that sediment type strongly influences the patterns of hydrate formation, and that the use of ROV technologies permits the synthesis of large amounts of hydrate material in natural systems under a variety of conditions so that fundamental research on the stability and growth of these substances is possible.

Geology↗
USGS1997

Five new species of jawfishes ( Opistognathus : Opistognathidae) from the western Atlantic Ocean

Synonymies, diagnoses, descriptions, illustrations, and spot distribution maps are given for ten species of Opistognathus, including all western Atlantic species that have a cirrus on their anterior nostrils. Three deep-water species lacking nasal cirri are also treated, including O. leprocarus n. sp. (Bahamas and Lesser Antilles), O. melachasme (Yucatan), and O. nothus n. sp. (North Carolina, Gulf of Mexico and Cuba); the latter two species were originally thought to represent different sexes of the same species. The O. macrognathus species group is diagnosed primarily by having sexually dimorphic jaws and sexually dichromatic maxillary markings, and includes the eastern Pacific O. scops and the following five western Atlantic species: O. macrognathus (Florida, Gulf of Mexico, and Bahamas to northern South America), O. brasiliensis n. sp. (southern Brazil), O. cuverii (southern Brazil), O. robinsi n. sp. (South Carolina, Florida, Bahamas, and Gulf of Mexico), and O. signatus n. sp. (Nicaragua, Panama, and northern South America). Opistognathus robinsi and O. signatus are very similar morphologically and here recognized as allopatric sister-species but the possibility exists that their disjunct continental distributions may be a collecting artifact. The broadly distributed and shallow-water species Opistognathus whitehurstii and O. maxillosus are superficially similar to some members of the O. macrognathus species group, including having cirri on their anterior nostrils, but differ most obviously in having non-sexually dimorphic jaws and more numerous cephalic sensory pores. An identification key is provided for all known western Atlantic species of Opistognathus.

Bulletin of Marine Science↗
USGS2009

International year of planet earth 7. Oceans, submarine land-slides and consequent tsunamis in Canada

Canada has the longest coastline and largest continental margin of any nation in the World. As a result, it is more likely than other nations to experience marine geohazards such as submarine landslides and consequent tsunamis. Coastal landslides represent a specific threat because of their possible proximity to societal infrastructure and high tsunami potential; they occur without warning and with little time lag between failure and tsunami impact. Continental margin landslides are common in the geologic record but rare on human timescales. Some ancient submarine landslides are massive but more recent events indicate that even relatively small slides on continental margins can generate devastating tsunamis. Tsunami impact can occur hundreds of km away from the source event, and with less than 2 hours warning. Identification of high-potential submarine landslide regions, combined with an understanding of landslide and tsunami processes and sophisticated tsunami propagation models, are required to identify areas at high risk of impact.

Geoscience Canada↗
USGS2009

NOAA/West coast and Alaska Tsunami warning center Atlantic Ocean response criteria

West Coast/Alaska Tsunami Warning Center (WCATWC) response criteria for earthquakesoccurring in the Atlantic and Caribbean basins are presented. Initial warning center decisions are based on an earthquake's location, magnitude, depth, distance from coastal locations, and precomputed threat estimates based on tsunami models computed from similar events. The new criteria will help limit the geographical extent of warnings and advisories to threatened regions, and complement the new operational tsunami product suite. Criteria are set for tsunamis generated by earthquakes, which are by far the main cause of tsunami generation (either directly through sea floor displacement or indirectly by triggering of sub-sea landslides).The new criteria require development of a threat data base which sets warning or advisory zones based on location, magnitude, and pre-computed tsunami models. The models determine coastal tsunami amplitudes based on likely tsunami source parameters for a given event. Based on the computed amplitude, warning and advisory zones are pre-set.

Science of Tsunami Hazards↗