(Supplement S1) Volcanic ash layer description and thickness analysis from different DSDP, ODP and IODP Holes

Ocean drilling provides a global record of deposits throughout the oceans. An international collaborative ocean research programme was established in 1966, and the International Ocean Discovery Program (IODP) is the most recent manifestation of this. During each expedition a large amount of data are generated and collected by the shipboard science team. It could be suggested that due to the different staff and objectives during each expedition there would be significant variations in the consistency of data recorded in the shipboard visual core descriptions (VCDs). Use of shipboard VCD data in a global study of volcanism through time required the ground truthing of VCD data, to assess the consistency of ash layer reporting and to identify the amount of under/over recording of volcanic ash layers in cores. Approximately 1400 ash layers in DSDP, ODP, IODP and JAMSTEC cores were examined and it was found that on average 70-75% of recorded volcanic ash layers were present as described, an average of 17-20% were over recorded and 10-15% were under recorded. A number of factors could contribute to this variability, such as VCD format, lack of time for shipboard sampling of every ash layer, significant ash layer colour changes since time of coring, or differences in VCD recording and volcanic ash layer identification and description schemes between expeditions. These findings are important and will allow greater confidence in further studies based on data compiled from shipboard VCDs

VOLCORE_2021 - a 2021 update of the global database of visible tephra layers sampled by ocean drilling

VOLCORE_2021 is an update on the original VOLCORE data released in 2020. Change notes are listed within the VOLCORE_2021 data file. A major update is the new merged Layers-Holes-AgeDepth sheet, enabling easier manipulation of the data. The VOLCORE (Volcanic Core Records) database is a collection of 34,696 visible tephra (volcanic ash and associated products) occurrences reported in the initial reports volumes of all of the Deep Sea Drilling Project (DSDP; 1966-1983), the Ocean Drilling Program (ODP; 1983-2003), the Integrated Ocean Drilling Program (IODP; 2003-2013) and the International Ocean Discovery Program (IODP; 2013-present) up to and including IODP Expedition 381. The combined international drilling programmes (OD) have locations with global coverage. Cored tephra layers and tephra-bearing sediments span timescales from recent to ~150 million years in age. This database is a collection of information about reported visible tephra layers entirely or predominantly composed of volcanic ash. Data include the depth below sea floor, tephra thickness, location, and any reported comments. An approximate age was estimated for most (29,493) of the tephra layers using available age-depth models. The database can be applied to tephrochronology, volcanology, geochemistry, studies of sediment transport and palaeoclimatology

VOLCORE - a global database of visible tephra layers sampled by ocean drilling

The VOLCORE (Volcanic Core Records) database is a collection of 34,696 visible tephra (volcanic ash and associated products) occurrences reported in the initial reports volumes of all of the Deep Sea Drilling Project (DSDP; 1966-1983), the Ocean Drilling Program (ODP; 1983-2003), the Integrated Ocean Drilling Program (IODP; 2003-2013) and the International Ocean Discovery Program (IODP; 2013-present) up to and including IODP Expedition 381. The combined international drilling programmes (OD) have locations with global coverage. Cored tephra layers and tephra-bearing sediments span timescales from recent to ~150 million years in age. This database is a collection of information about reported visible tephra layers entirely or predominantly composed of volcanic ash. Data include the depth below sea floor, tephra thickness, location, and any reported comments. An approximate age was estimated for most (29,493) of the tephra layers using available age-depth models. The database can be applied to tephrochronology, volcanology, geochemistry, studies of sediment transport and palaeoclimatology

Quantifying uncertainties in marine volcanic ash layer records from ocean drilling cores

Ocean drilling provides a global record of deposits throughout the oceans. An international collaborative ocean research programme was established in 1966, and the International Ocean Discovery Program (IODP) is the most recent manifestation of this. During each expedition a large amount of data are generated and collected by the shipboard science team. It could be suggested that due to the different staff and objectives during each expedition there would be significant variations in the consistency of data recorded in the shipboard visual core descriptions (VCDs). Use of shipboard VCD data in a global study of volcanism through time required the ground truthing of VCD data, to assess the consistency of ash layer reporting and to identify the amount of under/over recording of volcanic ash layers in cores. Approximately 1400 ash layers in DSDP, ODP, IODP and JAMSTEC cores were examined and it was found that on average 70-75% of recorded volcanic ash layers were present as described, an average of 17-20% were over recorded and 10-15% were under recorded. A number of factors could contribute to this variability, such as VCD format, lack of time for shipboard sampling of every ash layer, significant ash layer colour changes since time of coring, or differences in VCD recording and volcanic ash layer identification and description schemes between expeditions. These findings are important and will allow greater confidence in further studies based on data compiled from shipboard VCDs.</p

Frequency of large volcanic eruptions over the past 200 000 years

Volcanic eruptions are the dominant cause of natural variability in climate forcing on timescales up to multidecadal. Large volcanic eruptions lead to global-scale climate effects and influence the carbon cycle on long timescales. However, estimating the frequency of eruptions is challenging. Here we assess the frequency at which eruptions with particular deposition fluxes are observed in the EPICA Dome C ice core over the last 200 kyr. Using S isotope analysis we confirm that most of the largest peaks recorded at Dome C are from stratospheric eruptions. The cumulative frequency through 200 kyr is close to linear, suggesting an approximately constant rate of eruptions. There is no evidence for an increase in the rate of events recorded in Antarctica at either of the last two deglaciations. Millennial variability is at the level expected from recording small numbers of eruptions, while multimillennial variability may be partly due to changes in transport efficiency through the Brewer–Dobson circulation. Our record of events with sulfate deposition rates &gt; 20 and &gt;50 mg m−2 contains 678 and 75 eruptions, respectively, over the last 200 kyr. Calibration with data on historic eruptions and analysis of a global Quaternary dataset of terrestrial eruptions indicates that sulfate peaks with deposition rates &gt; 20 and &gt;50 mg m−2 correspond to explosive eruptions of magnitude ≥ 6.5 and ≥7, respectively. The largest recorded eruption deposited just over 300 mg m−2

High-resolution sulfur isotopic composition measurements of volcanic sulfate from Toba candidate eruptions preserved in EDML and EDC Antarctic ice cores

Multiple peaks in sulfate concentration in ice cores have been identified as potential candidates for the ~74 ka Toba supereruption. The sulfur isotopic composition of sulfate preserved in two EPICA Antarctic ice cores, EDML and EDC, for 11 of the candidates has been analysed at high temporal resolution for mass-independent fractionation (MIF) using multi-collector inductively coupled plasma mass spectrometry. S-MIF signals preserved in volcanic sulfate are indicative of stratospheric eruptions due to sulfur aerosols being exposed to ultraviolet radiation when erupted into and above the ozone layer and subsequently undergoing photochemical reactions. Sulfur aerosols in the stratosphere will have longer residence times than those in the troposphere and will scatter incoming solar radiation. This data set includes the eruption, sample type, depths, ages (using the AICC2012 age model), sulfate concentration (determined by ion chromatography) and isotopic composition data (δ34S, δ33S, Δ33S) and their associated errors

Unique prospective cohort study : rheumatic heart disease (RHD) and pregnancy

Background: An increased cardiac workload in pregnancy can unmask undiagnosed RHD and exacerbate clinical symptoms in women with RHD. Pregnant women with mechanical heart valves who require therapeutic anticoagulation throughout pregnancy; women with mitral or aortic stenosis; or with severe RHD, are at particular risk. There is a paucity of clinical research about RHD in pregnancy with most recommendations based on generic studies of severe disease in non-pregnant adults or women with congenital cardiac disease. A two-year study of the prevalence, management and outcomes of RHD in pregnancy across Australia and New Zealand has commenced as part of the Australasian Maternity Outcomes Surveillance System (AMOSS), a bi-national surveillance/research system of rare or serious conditions in pregnancy, childbirth and the post natal period. In New Zealand, AMOSS is run under the auspices of the Perinatal and Maternal Mortality Review Committee (PMMRC). Methods: We have developed a prospective cohort study to identify and collect data from every pregnant woman with RHD presenting at one of 300 maternity units in Australia and New Zealand. The content of the extensive data collection tools includes RHD history, clinical changes over the duration of the pregnancy, echocardiographic findings, anticoagulation regimens and delivery and neonatal outcomes. Results: In the initial six months of data collection we have been notified of 40 cases suggesting that 60–80 cases may be identified annually in New Zealand. Conclusion: This prospective cohort study allows a unique opportunity to gather information of maternal and infant outcomes in this serious condition