Carbon capture and storage (CCS) has the potential to signifiantly limit CO2 emissions to the atmosphere; however a leakage of CO2 from transport or storage could have environmental and safety implications. Monitoring of CCS storage is a further challenge, both to assure the public and, should leakage occur, to enable mitigation and verification. This chapter reviews the current state of knowledge regarding environmental sensitivities and monitoring and outlines the challenges for research over the next few years. The current hypothesis is that significantly large leaks would be required to cause noticeable damage in the ecosystem.

Magmas from SW Pacific back-arc basins have geochemical and isotopic signatures indicating variable mantle and subduction-derived components. Basalts from South Fiji Basin (SFB) are little influenced by subduction, but come from variably enriched mantle, resulting from mixing between enriched mantle, like FOZO, and depleted mantle, like DMM. The same components are present in the Havre Trough mantle, but Havre Trough basalts come from a mantle wedge to which a greater proportion of subduction-derived components are added. Their slab-derived components are isotopically similar to locally subducting sediment, with variable Sr and Pb from altered oceanic crust. Their compositional diversity correlates with morphology, previously described as contrasting Arc-type and Rift-type back-arc regimes. Geochemical modeling indicates that material is added as both supercritical fluids and slab melts below the back-arc, is locally distinct, and correlate with differences in the predicted slab-surface pressure and temperature conditions. Deeper slab surfaces correspond to higher-temperatures at a given distance from the volcanic front, but not necessarily with an increase in the amount of slab-derived material. Slab fluxes for rift-type basalts are consistent with predicted slab-surface temperatures at or below the water-saturated solidus. However, some are consistent with melting in equilibrium with residual rutile, zircon and monazite, so melting may have occurred by fluid fluxing of the slab surface, requiring external fluids from within the slab. Arc-type basalts are explained by thermal anomalies in the mantle wedge, which may correspond to locally hotter slab-surface temperatures and more fractionated slab-derived component signatures in their source.

We report new compositional and isotopic data for submarine lavas erupted on the Rumble V Ridge cross chain behind the Kermadec Arc at similar to 36 degrees S and for locally subducting sediment. In order to constrain cross-arc changes in the melt source, Havre Trough ambient mantle wedge isotope and trace element characteristics are interpreted from regional back-arc basalts that are relatively free of slab-derived components. They have MORB-like trace element concentrations and are isotopically "Pacific" but define greater heterogeneity in Pb-206/Pb-204 and Hf-176/Hf-177 than previously known within the Havre Trough. In contrast with the ambient mantle, all Rumble V Ridge lavas have trace element and isotopic characteristics consistent with subduction zone contributions despite their rear-arc setting but are less fluid-enriched than at the Kermadec volcanic front. A broad trend in Nd-Hf isotopic space and the correlation between Hf-176/Hf-177 and Hf concentration anomaly for Rumble V Ridge lavas is explained by across-arc changes in (1) the mantle wedge component, (2) the nature of the subduction component, and (3) the mass fraction of subduction components added. Samples from the distal cross chain tend to have lower Hf-176/Hf-177 at similar Nd-143/Nd-144 compared with samples closer to the arc, suggesting that a low-Hf-176/Hf-177 component is preferentially removed from the mantle wedge during trenchward advection. Isotope trends suggest that locally subducting sediment is the primary slab component for Rumble V Ridge magmas, but bulk mixing of ambient mantle with sediment or slab-derived fluids cannot account for cross-arc trace element ratios. Instead, cross-chain isotope and trace element characteristics are explained by the addition of 0.05%-2.0% sediment melts where trace zircon, monazite, and rutile are residual. The cross chain tracks an east to west increase in the mass fraction of a common subduction component. A particularly enriched subset of eastern basalts is interpreted as being derived from the addition of an even higher mass fraction of a different subduction component with greater apparent stability of refractory trace phases during sediment melting. An implication of this study is that both Nd and Hf can be mobile in sediment-rich subduction zones, but the relative mobility depends on the sediment composition and depth of melting, and the absolute mobility is small.

High resolution multibeam (EM300 and SEABEAM) data of the Southern Havre Trough (SHT), combined with observations and sample collections from the submersible Shinkai6500 and deep-tow camera, are used to develop a model for the evolution and magmatism of this backarc system. The Havre Trough and the associated Kermadec Arc are the product of westward subduction at the Pacific-Australian plate boundary. Detailed studies focus on newly discovered features including a seamount (Saito Seamount) and a deep graben (Ngatoroirangi Rift, >4000 m water depth floored with a constructional axial volcanic ridge >5 km in length and in excess of 200 m high), both of which are characterised by pillow and lobate flows estimated at <20,000 years old based on sediment cover, high reflectivity and thin Mn crusts on recovered glassy olivine basalts and basaltic andesites. Elongate volcanic ridges at 35 degrees 15'S and 34 degrees 30'S, and backarc seamounts (35 degrees 30'S, 178 degrees 30'E) occur at the eastern margin of the SHT. Similar seafloor morphology is observed in the central and western portions of the basin, suggesting that recent volcanism may be broadly distributed across the backarc. Mass balance modelling indicates a maximum crustal thickness of similar to 11 km to <6 km, similar to estimates of crustal thickness in the Lau Basin to the north. Given such high crustal attenuation and extensive backarc mafic magmatism within deep SHT rifts, we propose that the SHT is in an incipient phase of distributed and "disorganised" oceanic crustal accretion in multiple, ephemeral, and short but deep (>4000 m) spreading systems. These discontinuous spreading systems are characterised by failed rifts, rift segmentation, and propagation. Successive episodes of magmatic intrusion into thinned faulted arc basement results in defocused asymmetrical accretion. Cross-arc volcanic chains, isolated volcanoes and underlying basement plateaus are interpreted to represent a "cap" of recent extrusives. However, they may also be composed entirely of newly accreted crust and the spatially extensive basement fabric of elongated volcanic ridges may be the surface expression of pervasive dike intrusion that has thoroughly penetrated and essentially replaced the original arc crust with newly accreted intrusives. (C) 2009 Elsevier B.V. All rights reserved.

The “Graveyard seamounts” comprise a complex of 28 small volcanic edifices covering about 140 km2 on the northern flank of the Chatham Rise, an oceanic plateau that extends several hundred kilometers east of New Zealand. The features are associated with widely distributed Late Cenozoic volcanism that created a number of clusters of small intraplate volcanoes in the area. They have various volcanic forms, including cones, summit craters, and lateral dike ridges. Typically, each seamount is between 100 and 400 m high, rising from basal water depths of 1050–1200 m to summit depths of 750–1000 m. Bottom-current flows of 10–20 cm s-1 produce basal scour moats at all the seamounts.

Repeated multibeam bathymetric surveys at Monowai Cone, a shallow submarine basaltic volcano and part of the Monowai Volcanic Center in the northern Kermadec arc, were conducted in 1998, 2004, and 2007. These surveys document dramatic depth changes at the volcano including negative changes up to −176 m from two sector collapses and positive changes up to +138 m from volcanic reconstruction near the summit and debris avalanche deposits downslope of the slide scars. One sector collapse occurred on the SE slope between 1998 and 2004 with a volume of ∼0.09 km3, and another occurred on the SW slope between 2004 and 2007 with a volume of ∼0.04 km3. The volume of positive depth change due to addition of volcanic material by eruption is of the same order: ∼0.05 km3 between 1998 and 2004 and ∼0.06 km3 between 2004 and 2007. During these time intervals, monitoring by the Polynesian Seismic Network detected frequent T wave swarms at Monowai, indicative of explosive eruptive activity every few months. An unusual T wave swarm on 24 May 2002 was previously interpreted as the collapse event between the 1998 and 2004 surveys, but no similarly anomalous T waves were detected between 2004 and 2007, probably because the Polynesian Seismic Network stations were acoustically shadowed from the second slide event. We interpret that the sector collapses on Monowai are caused by the unstable loading of fragmental erupted material on the summit and steep upper slopes of the volcano (>20°). Moreover, there appears to be a cyclic pattern in which recurrent eruptions oversteepen the cone and periodically lead to collapse events that transport volcaniclastic material downslope to the lower apron of the volcano. Volumetric rate calculations suggest that these two processes may be more or less in equilibrium. The repeated collapses at Monowai are relatively modest in volume (involving only 0.1–0.5% of the edifice volume), have occurred much more frequently than is estimated for larger debris avalanches at subaerial volcanoes, and may be characteristic of how persistently active shallow submarine arc volcanoes grow.

A set of interactive computer animations of acoustic phenomena was created using the Java-based PHYSics appLETS (or physlets) developed at Davidson College [Christian and Belloni, 2001]. These animations allow the user to adjust certain parameters of a modeled system and view—in real time—the corresponding change in the physical behavior of the system. Because the animations are accessed via the web and can run on any computer (using Java), students can work with them in many different settings. The goal is to help students with limited math skills who enroll in PHYS103 ‘‘Physics of Musical Sound’’ at Central Washington University develop an intuitive understanding of basic acoustic phenomena and to assist them in applying quantitative reasoning to predict the behavior of musical systems. These newly-created acoustics and vibration physlets will be used for the first time during the Spring term, 2007, in the PHYS103 course taught by the author. Students will be given a quiz before and after working with the physlets on various topics to assess the effectiveness of this pedagogical tool.

New multibeam mapping and whole-rock geochemistry establish the first order definition of the modem submarine Kermadec arc between 30 degrees and 35 degrees S. Twenty-two volcanoes with basal diameters > 5 km are newly discovered or fully-mapped for the first time; Giggenbacb, Macauley, Havre, Haungaroa, Kuiwai, Ngatoroirangi, Sonne, Kibblewhite and Yokosuka. For each large volcano, edifice morphology and structure, surficial deposits, lava fields, distribution of sector collapses, and lava compositions are determined. Macauley and Havre are large silicic intra-oceanic caldera complexes. For both, concentric ridges on the outer flanks are interpreted as recording mega-bedforms associated with pyroclastic density flows and edifice foundering. Other stratovolcanoes reveal complex histories, with repeated cycles of tectonically controlled construction and sector collapse, extensive basaltic flow fields, and the development of summit craters and/or small nested calderas.Combined with existing data for the southernmost arc segment, we provide an overview of the spatial distribution and magmatic heterogeneity along similar to 780 km of the Kermadec arc at 30 degrees-36 degrees 30' S. Coincident changes in arc elevation and lava composition define three volcano-tectonic segments. A central deeper segment at 32 degrees 20'-34 degrees 10' S has basement elevations of > 3200 m water-depth, and relatively simple stratovolcanoes dominated by low-K series, basalt-basaltic andesite. In contrast, the adjoining arc segments have higher basement elevations (typically < 2500 in water-depth), multi-vent volcanic centres including caldera complexes, and erupt sub-equal proportions of dacite and basalt-basaltic andesite. The association of silicic magmas with higher basement elevations (and hence thicker crust), coupled with significant inter- and intra-volcano heterogeneity of the silicic lavas, but not the mafic lavas, is interpreted as evidence for dehydration melting of the sub-arc crust. Conversely, the crust beneath the deeper arc segments is thinner, initially cooler, and has not yet reached the thermal requirements for anatexis. Silicic calderas with diameters > 3 km coincide with the shallower arc segments. The dominant mode of large caldera formation is interpreted as mass-discharge pyroclastic eruption with syn-eruptive collapse. Hence, the shallower arc segments are characterized by both the generation of volatile-enriched magmas from crustal melting and a reduced hydrostatic load, allowing magma vesiculation and fragmentation to initiate and sustain pyroclastic eruptions. Proposed initiation parameters for submarine pyroclastic eruptions are water-depths < 1000 m, magmas with 5-6 wt.% water and > 70 wt.% SiO2, and a high discharge rate. (c) 2005 Elsevier B.V. All rights reserved.

Brothers volcano, which is part of the active Kermadec arc, northeast of New Zealand, forms an elongate edifice 13 km long by 8 km across that strikes northwest-southeast. The volcano has a caldera with a basal diameter of ~3 km and a floor at 1,850 m below sea level, surrounded by 290- to 530-m-high walls. A volcanic cone of dacite rises 350 m from the caldera floor and partially coalesces with the southern caldera wall. Three hydrothermal sites have been located: on the northwest caldera wall, on the southeast caldera wall, and on the dacite cone. Multiple hydrothermal plumes rise ~750 m through the water column upward from the caldera floor, originating from the northwest caldera walls and atop the cone, itself host to three separate vent fields (summit, upper flank, northeast flank). In 1999, the cone site had plumes with relatively high concentrations of gas with a ΔpH of −0.27 relative to seawater (proxy for CO2 + S gases), dissolved H2S up to 4,250 nM, high concentrations of particulate Cu (up to 3.4 nM), total dissolvable Fe (up to 4,720 nM), total dissolvable Mn (up to 260 nM) and Fe/Mn values of 4.4 to 18.2. By 2002, plumes from the summit vent field had much lower particulate Cu (0.3 nM), total dissolvable Fe (175 nM), and Fe/Mn values of 0.8 but similar ΔpH (−0.22) and higher H2S (7,000 nM). The 1999 plume results are consistent with a magmatic fluid component with the concentration of Fe suggesting direct exsolution of a liquid brine, whereas the much lower concentrations of metals but higher overall gas contents in the 2002 plumes likely reflect subsea-floor phase separation. Plumes above the northwest caldera site are chemically distinct, and their compositions have not changed over the same 3-year interval. They have less CO2 (ΔpH of −0.09), no detectable H2S, total dissolved Fe of 955 nM, total dissolved Mn of 150 nM, and Fe/Mn of 6.4. An overall increase in 3He/4He values in the plumes from R/RA = 6.1 in 1999 to 7.2 in 2002 is further consistent with a magmatic pulse perturbing the system. The northwest caldera site is host to at least two large areas (~600 m by at least 50 m) of chimneys and sub-cropping massive sulfide. One deposit is partially buried by sediment near the caldera rim at ~1,450 m, whereas the other crops out along narrow, fault-bounded ledges between ~1,600 and 1,650 m. Camera tows imaged active 1- to 2-m-high black smoker chimneys in the deeper zone together with numerous 1- to 5-m-high inactive spires, abundant sulfide talus, partially buried massive sulfides, and hydrothermally altered volcanic rocks. 210Pb/226Ra dating of one chimney gives an age of 27 ± 6 years; 226Ra/Ba dating of other mineralization indicates ages up to 1,200 years. Formation temperatures derived from Δ34Ssulfate-sulfide mineral pairs are 245° to 295° for the northwest caldera site, 225° to 260°C for the southeast caldera and ~260° to 305°C for the cone. Fluid inclusion gas data suggest subsea-floor phase separation occurred at the northwest caldera site. Alteration minerals identified include silicates, silica polymorphs, sulfates, sulfides, Fe and Mn oxide and/or oxyhydroxides, and native sulfur, which are consistent with precipitation at a range of temperatures from fluids of different compositions. An advanced argillic assemblage of illite + amorphous silica + natroalunite + pyrite + native S at the cone site, the occurrence of chalcocite + covellite + bornite + iss + chalcopyrite + pyrite in sulfide samples from the southeast caldera site, and veins of enargite in a rhyodacitic sample from the northwest caldera site are indicative of high-sulfidation conditions similar to those of subaerial magmatic-hydrothermal systems. The northwest caldera vent site is a long-lived hydrothermal system that is today dominated by evolved sea-water but has had episodic injections of magmatic fluid. The southeast caldera site represents the main upflow of a relatively well established magmatic-hydrothermal system on the sea floor where sulfide-rich chimneys are extant. The cone site is a nascent magmatic-hydrothermal system where crack zones localize upwelling acidic waters. Each of these different vent sites represents diverse parts of an evolving hydrothermal system, any one of which may be typical of submarine volcanic arcs.

An extensive ferromanganese nodule field adjacent to the Campbell Plateau in the Southwest Pacific Ocean forms beneath the Deep Western Boundary Current (DWBC) and Antarctic Circumpolar Current (ACC). West of c. 174°E, between 59 and 48°S, the field is inferred to be 300–500 km wide, but east of 174°E, where the currents impinge on the eastern slope of the Campbell Plateau, the field narrows from c. 200 km at 55°S to c. 120 km at 49°S. This coincides with deflection of current flow eastward, and consequent reduction in bottom-current velocity and eddy kinetic energy. Based on seafloor photographs, dredge samples, and 3.5 kHz profile data, five principal nodule facies form broadly parallel zones eastwards from the lowermost Campbell escarpment. These are defined based on location, presumed nodule genesis, and seafloor nodule density: (1) slope hydrogenous, high-density (SHH); (2) abyssal diagenetic/hydrogenous, low-density (ADHL); (3) abyssal hydrogenous, high-density (AHH); (4) abyssal diagenetic, high-density (ADH); and (5) abyssal diagenetic, low-density (ADL). Several nodule morphotypes are identified including distinctive discoidal forms with overgrowths possibly resulting from overcrowding and partial sediment burial. Seafloor abundance, surficial textures, and chemistry indicate a predominantly hydrogenous nodule growth and very low net sedimentation beneath the core of the DWBC. Increasing Mn, Ni, and Cu contents, and decreasing detrital silicate contents from core to rim, reflect intensifying abyssal DWBC circulation since c. 6 Ma. Because of the DWBC’s high velocity, the nodules provide no record of an increasing terrigenous bedload from New Zealand since c. 3 Ma. However, in regions of reduced flow velocity eastwards from the main DWBC pathway, relatively higher sedimentation rates prevail, and nodules have a higher diagenetic component.