"Cannery Row" is well known from the novel of the same name written by John Steinbeck in 1994. It historically extends back to the early 1940's when sardines were being heavily fished in Monterey Bay and an extensive network of canneries were established in Monterey. To support these canneries and the fishing vessels delivering fish to the shore-based processing facilities, an extensive network of seabed infrastructure was developed. Once the fisheries collapsed, the canneries shut down and the "Row" became derelict with the seabed infrastructure left to deteriorate in place. Today the row has been revitalized by an invigorating tourist industry brought to the peninsula with the establishment of the Monterey Bay Aquarium (MBA) nearly 40 years ago. New seabed infrastructure was constructed to support the aquatic exhibits of the MBA but unlike the previous canneries' infrastructure, this infrastructure was constructed with the conservation of the unique and spectacular nearshore marine environment in mind. Using modern geophysical instrumentations consisting of Multi-Beam Echosounder (MBES) and 3.5 kHz Compressed High Intensity Radar Pulse (CHIRP) sub-bottom profiling systems we mapped the seafloor geology, imaged abandoned and present-day seabed infrastructure, and characterized the benthic habitats. From this mapping effort we were able to assess the artifacts of the seafloor and illustrate how modern seafloor processes such as sediment transport is altering the infrastructure. Much of the abandoned submarine infrastructure provides hard substrate within a dynamic unconsolidated sand bottom that is habitat for encrusting and sessile organisms, contributing to the diversity and complexity of the marine ecosystem of the area. In addition, a prominent granodiorite exposure upon which the dynamic sand onlaps is prime holdfast foundation for kelp that in turn provides habitat for fish. Although not pristine, the impacts of previous industrial disturbances and anthropogenic impacts are now well mitigated with the area set aside as a natural reserve and educational center piece within the Monterey Bay National Marine Sanctuary.

Abstract A compilation of offshore and island geologic, marine acoustic, and seafloor sampling data for the Channel Islands National Park was used to construct geologic and potential marine benthic habitat maps of selected areas around various Channel Islands. For this investigation, we focused on three offshore areas around Santa Rosa Island (the north-central area west of Carrington Point, an area off and west of East Point, and an area off and west of South Point), and most of the shelf area around Santa Barbara Island. The maps represent the most detailed offshore mapping in the region to date, and they provide insights into the geology and potential benthic habitats in the area that can be used to manage marine biological and other resources. The geology of the offshore areas is essentially an extension of the Tertiary geologic formations that have been mapped on the islands, but locally covered by deposits of Quaternary marine sediments. Structures in the north-central part of Santa Rosa Island and in the northeastern part of Santa Barbara Island appear to represent the most active regional tectonic processes, while the areas in the southern parts of Santa Barbara Island appear more passive, with few well-defined faults. The first potential marine benthic habitat maps for the Channel Islands National Park are presented here, and they illustrate that diverse and favorable habitats exist. For example, the extensive areas of rugose, differentially eroded bedrock outcrops on the midshelf seafloor of the islands provide good habitats for demersal rockfish (Sebastes spp.), and rock outcrops in the nearshore areas provide hold-fasts for kelp, which can provide habitat for larval and young-of-the-year rockfish. Although true habitat is not well known in the areas studied, the potential habitat maps provide an effective management tool that can be used to protect and conserve the most promising probable habitats.

The geology and structure of the Cleft Segment of the Southern Juan de Fuca Ridge (JdFR) have been examined using high‐resolution mapping systems, observations by remotely operated vehicle (ROV), ROV‐mounted magnetometer, and the geochemical analysis of recovered lavas. Bathymetric mapping using multibeam (EM300) coupled with in situ observations that focused on near‐axis and flank regions provides a detailed picture of 0 to 400 ka upper crust created at the southern terminus of the JdFR. A total of 53 rock cores and 276 precisely located rock or glass samples were collected during three cruises that included sixteen ROV dives. Our observations of the seafloor during these dives suggest that many of the unfaulted and extensive lava flows that comprise and/or cap the prominent ridges that flank the axial valley emanate from ridge parallel faults and fissures that formed in the highly tectonized zone that forms the walls of the axial valley. The geochemically evolved and heterogeneous nature of these near‐axis and flank eruptions is consistent with an origin within the cooler distal edges of a crustal magma chamber or mush zone. In contrast, the most recent axial eruptions are more primitive (higher MgO), chemically homogeneous lobate, sheet, and massive flows that generate a distinct magnetic high over the axial valley. We suggest that the syntectonic capping volcanics observed off‐axis were erupted from near‐axis and flank fissures and created a thickened extrusive layer as suggested by the magnetic and seismic data. This model suggests that many of the lavas that comprise the elevated ridges that bound the axial valley of the Cleft Segment were erupted during the collapse of a magmatic cycle not during the robust phase that established a new magmatic cycle.

High-resolution seafloor and sub-surface data were acquired as part of a site survey in Iskenderun Bay, SE Turkey to characterize the geohazards at the location of the proposed drilling site. A 3km×3km geophysical study reveals a pockmark field which trends NE and NNE, similar to the trend of major fault systems in the area. The pockmarks, with an average diameter of 35m, reach their highest density in the northern part of the detailed survey area, with 13features/km2. Acoustic anomalies in the seismic records (acoustic turbidity, blanking, enhanced reflectors) below the proposed drilling site indicated potential shallow gas beneath it. The local seismic anomalies (amplitude and frequency) parallel to stratigraphy were assigned a low gas risk. As a result of the active neotectonics in the area, the pockmark field presented a potential hazard for drilling at the original location. The geohazard study resulted in moving the proposed drilling site eastward to an area of fewer pockmarks, less sub-surface seismic anomalies, and thus a location interpreted as a lower geohazard environment.

High-resolution swath bathymetry and backscatter data from the Santa Barbara basin reveal a distinct assemblage of morphologic and sedimentologic features characteristic of the tectonically active setting of the basin. Such characteristics include the north–south asymmetry of the basin, the presence of an intra-basinal structural and morphologic high, extensive mass wasting, and fields of mounds and pockmarks. The north–south asymmetry of the basin and the increased abundance of slope failure along the northern basin slope likely reflect higher rates of tectonic shortening and sediment accumulation along the northern basin margin. High sedimentation rates lead to high pore water content of the sediment which, in combination with seismic shaking, may explain the abundance of mass wasting features even on shallowly inclined lower basin slopes. Mounds and pockmarks are the surface expression of locally extensive fluid seepage which we interpret to be driven by a combination of high sedimentation rates, a high organic content of sediment, and anoxic bottom water conditions during extended periods in Neogene and Quaternary times. During ROV dives we observed active fluid seepage to have occurred preferentially on the shelf and on a structural and topographic high, presumably due to structural focusing of migrating formation fluids. The preferred alignment of some pockmarks along faults is consistent with structurally controlled expulsion of formation fluids from underlying Neogene units. Despite the high tectonic activity of the basin, fault scarps are rare and only observed in areas of low sediment accumulation on the shelf and on topographic highs. Mass balance considerations suggest that sedimentation rates averaged over interseismic time scales are too high and scarp growth rates too low for scarps to be characteristic features of the basin floor. Long-term sediment accumulation rates that account for the effect of sediment compaction are low enough, however, to lead to long-wavelength surface expressions of the most active faults.

The California (USA) margin includes two different tectonic regimes: subduction north of the Mendocino Triple Junction and translation south. Both margins include seeps, and their distribution can be inferred using seafloor bathymetry and backscatter as well as subsurface seismic data. Anomalous bathymetric and backscatter features related to fluid expulsion include headless submarine canyons, fault zones, anticlines, pockmarks, and mud volcanoes. Anomalous backscatter may be caused by authigenic carbonate (related to the bacterial oxidation of methane) or cold seep clams—both have an impedance and roughness that may be higher than the surrounding seafloor. Remote-operated vehicle (ROV) dives to such suspect seep sites document the presence of extensive authigenic carbonate, areally restricted cold seep communities, carpets of chemoautotrophic bacteria, and bubbling gas. Our operations in the Monterey Bay, on the translational California margin, and the Eel River basin, on the convergent margin, indicate that bathymetric and backscatter maps of the seafloor, if sufficiently high resolution, can be used to map seep sites, and that the distribution of such seeps can be used to constrain subsurface conduits of fluid flow. ROVs, due to their combination of visualization, propulsion, manipulation, sonar, and navigation, provide an excellent platform for ground-truthing, mapping, and sampling seafloor seeps.

Evidence of active and dormant fluid seepage in the Santa Barbara Basin is observed as active venting of gas and oil, bacterial mats, precipitates of authigenic carbonate, and mud and tar volcanoes. Fluid seepage occurs preferentially in the proximity to faults and faulted anticlines, and to slump scarps. Seepage next to faults and anticlines indicates that hydrocarbon migration and pore fluid expulsion is controlled structurally, with faults acting as preferred conduits for fluid flow across units of low matrix permeability.

Authigenic carbonate associated with modern `cold seep' biological communities and their extinct analogues exhibit a broad range in stable isotope and mineral composition within the limited geographic area of Monterey Bay. Although such variations in ancient samples have been used to infer differing tectonic settings, these carbonates all formed within a faulted continental margin environment and chemical variations reflect local differences in the sources and flux of carbon to sediment pore fluids. The slow seepage of fluid, and with it dissolved carbon, along the transform-faulted continental margin results in discrete areas of enhanced microbial sulfate reduction, oxidation of methane from both biogenic and thermogenic origins, as well as the active precipitation of both high-Mg calcite (HMC) and dolomite. The authigenic carbonates include semicontinuous pavements of shallow cemented sediments surrounding benthic communities; circular or pipe-like `chimneys' interpreted as cemented conduits formed as a result of methane gas expulsion; centimeter- to meter-scale rings, doughnuts or slabs winnowed from variable depths within sediments; and carbonate veins (ankerite or calcite) or cements in faulted basement rocks draped with bacterial mat. Abundant pyrite framboids, preferentially filling the tests of the benthic foraminifer Uvigerina peregrina and characteristic of the HMC-bearing samples, are products of a zone of shallow microbial sulfate reduction, a process fundamental to the nourishment of the chemosynthetic cold seep communities. Sites on a sedimented ridge west of the San Gregorio Fault Zone have carbon isotopic values between −35 and −56‰ that are strongly influenced by carbon derived from methane. The higher values of δ18O (more enriched in 18O) are found closer to the active fault zone. Carbonates from sites within the San Gregorio Fault Zone or from Monterey Canyon floor exposures of Miocene sediments have carbon isotope values between −7 and −26‰ that are mixtures of sedimentary organic carbon and microbially oxidized hydrocarbons from organic-rich, petroleum source rocks. Dolomite-bearing samples are more enriched in both 18O and 13C. Bulk carbonate samples with heavier 18O (δ18O>3.5‰) result from the abundance of authigenic dolomite and low temperatures of formation. Local destabilization of clathrates might also create pore fluids that are more enriched in both 13C and 18O.

Remotely operated vehicle (ROV)-based mapping of tectonic features, zones of anomalous reflectivity, and geomorphic targets in Monterey Bay, California, demonstrates the regional abundance of fluid expulsion along the active transform margin between the Pacific and North American plates. Cold seeps-extant communities characterized by chemosynthetic bivalves, bacterial mats, and rare tubeworms-are the surface manifestations of present-day fluid expulsion of sulfide- and methane-rich fluids, whereas slabs, veins, and chimneys of authigenic carbonate represent regions of either dormant methane-rich fluid expulsion, or areas where the present rate of flow is too low to support chemosynthetic fauna. We have found both active and dormant fluid seepage along fault zones, at the surface expression of mud volcanoes, on organic-rich or permeable substrate, and within headless canyons across a wide range of depths within Monterey Bay. The fluid egress at these sites may be driven by a combination of (1) pore-space reduction caused by rapid sedimentation and/or tectonic compaction related to residual Pacific-North America compression, and (2) increased buoyancy due to a decrease in pore-fluid density related to diagenesis and/or catagenesis at depth. Although provocative, the relationship between topographically driven aquifer discharge and sea-floor fluid expulsion remains speculative for Monterey Bay. The widespread distribution of fluid expulsion features controlled by a variety of conduits in Monterey Bay implies that cold seeps may be common features on translational margins.

Fluid flow out of the seafloor offshore Monterey Bay region is extensive. To date 16 major active and ancient, or dormant, seep sites have been identified and many of these sites are composed of smaller sites too numerous to map at a regional scale. These seeps have been identified by the presence of chemosynthetic communities that are primarily composed of chemoautotrophic organisms or by carbonate deposition and buildups. Of the 17 identified sites, 9 active cold seep sites support living chemosynthethic communities. Seven major dormant seep sites have been identified based upon the presence of carbonate deposits or buildups.

The U.S. Environmental Protection Agency (EPA) is responsible for ocean disposal site designations under the provisions of Section 102 of the Marine Protection, Research and Sanctuaries Act (MPRSA). EPA Region IX led a multiagency (federal and state) effort to designate an ocean dredged material disposal site for the San Francisco Bay region. Geophysical and oceanographic studies were conducted on the continental slope west of the Farallon Islands. Data collected on the continental slope complements data collected previously on the continental shelf off San Francisco. The types of data collected range from sediment samples to marine bird and mammal counts. These data were the basis for evaluating alternative sites for ocean disposal site designation. Geographic information systems (GIS) technology is allowing researchers and managers to integrate these diverse data types into relational thematic coverages. Development of these thematic maps into two‐dimensional and three‐dimensional images enhances visual and spatial analysis and allows assessment of potential environmental impacts for monitoring of the designated San Francisco deep ocean disposal site (SF‐DODS). Using GIS in conjunction with scientific visualization can augment the spatial and temporal dimensions of environmental data sets and assist decision makers.

Core OO99-21 contains an as yet chronologically unbounded record of sedimentation in the upper reaches of Monterey Canyon. Through a careful analysis of the sedimentary structures, variations in grain size, differences in mineralogy, and sediment carbon content of the core, it is possible to determine the nature of sedimentation in this part of the canyon. Characterizing the sediment throughout the core is an important step to understanding the environmental mechanisms responsible for deposition in the near-shore Canyon head. Several techniques have been used to log the core's physical characteristics, including Gamma Ray (GRAPE), photographs, XRD mineralogy, and Total Carbon content. Sedimentation of fine silts and clays appears to dominate in the head of Monterey Canyon with occasional high energy events inputting coarser material into the system.