I.Climate Change
1. Microfossils Illuminate Ancient Ocean Currents
Researchers use dissolved silicon concentrations to map out how currents may have changed millennia ago in the Pacific.
https://eos.org/research-spotlights/microfossils-illuminate-ancient-ocean-currents
2. Volcanic Woes May Have Contributed to Ancient Egypt’s Fall
Ice cores and ancient river records suggest that volcanic eruptions may have reduced the flow of the Nile River. Failures of the Nile floods that usually irrigated Egypt’s farms could have fed social unrest.
https://eos.org/articles/volcanic-woes-may-have-contributed-to-ancient-egypts-fall
II. Hazards & Disasters
1. Probing Magma Reservoirs to Improve Volcano Forecasts
The roots of volcanoes remain enigmatic, largely because geophysical and petrological models remain rudimentary. Scientific drilling and exploration can help.
https://eos.org/features/probing-magma-reservoirs-to-improve-volcano-forecasts
2. Polluted Lakes in Disguise
Clear lake water under highly polluted conditions might necessitate a rethink of water management policies and pollutant mitigation.
https://eos.org/articles/polluted-lakes-in-disguise
III. Geochemistry, Mineralogy, Volcanology
1. New Frontiers and Technologies in Submarine Volcanism Research
AGU Chapman Conference on Submarine Volcanism: New Approaches and Research Frontier; Hobart, Tasmania, Australia, 29 January to 3 February 2017
https://eos.org/meeting-reports/new-frontiers-and-technologies-in-submarine-volcanism-research
2. How to Trigger a Massive Earthquake
Humans may be to blame for California’s second-largest 20th century earthquake, and a team of seismologists has now proposed how that could have happened.
https://eos.org/articles/how-to-trigger-a-massive-earthquake
IV.Geology & Geophysics
1. Larsen Receives 2017 Luna B. Leopold Young Scientist Award
Isaac Larsen will receive the 2017 Luna B. Leopold Young Scientist Award at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. The award recognizes a young scientist for “a significant and outstanding contribution that advances the field of Earth and planetary surface processes.”
https://eos.org/agu-news/larsen-receives-2017-luna-b-leopold-young-scientist-award
2. Church Receives 2017 G. K. Gilbert Award
Michael Church will receive the 2017 G. K. Gilbert Award in Surface Processes at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. The award recognizes a scientist who has made “a single significant advance or sustained significant contributions to the field of Earth and planetary surface processes” and “also promoted an environment of unselfish cooperation in research and the inclusion of young scientists into the field.”
https://eos.org/agu-news/church-receives-2017-g-k-gilbert-award
3. Lenaerts Receives 2017 Cryosphere Early Career Award
Jan Lenaerts will receive the 2017 Cryosphere Early Career Award at the 2017 American Geophysical Fall Meeting, to be held 11–15 December in New Orleans, La. The award is for “a significant contribution to cryospheric science and technology.”
https://eos.org/agu-news/lenaerts-receives-2017-cryosphere-early-career-award
4. Czimczik Receives 2017 Sulzman Award for Excellence in Education and Mentoring
Claudia Czimczik will receive the 2017 Sulzman Award for Excellence in Education and Mentoring at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. The award is given to “one mid-career female scientist…for significant contributions as a role model and mentor for the next generation of biogeoscientists.”
V.Space & Planets
1. Geologic Map of Europa Highlights Targets for Future Exploration
The first such map of the icy moon puts its strange surface features into perspective.
https://eos.org/articles/geologic-map-of-europa-highlights-targets-for-future-exploration
2. Can Large Electric Fields Power Jupiter’s X-ray Auroras?
Electric fields with megavolt potentials in Jupiter’s polar region accelerate particles to 100 times more energy than Earth’s typical auroral particles, a new study finds.
https://eos.org/research-spotlights/can-large-electric-fields-power-jupiters-x-ray-auroras
VI.Geophysical Research Letters
1. Organic Condensation and Particle Growth to CCN Sizes in the Summertime Marine Arctic is Driven by Materials More Semivolatile Than at Continental Sites
Ship-based aerosol measurements in the summertime Arctic indicate elevated concentrations of ultrafine particles with occasional growth to cloud condensation nuclei (CCN) sizes. Focusing on one episode with two continuously growing modes, growth occurs faster for a large, preexisting mode (dp ≈ 90 nm) than for a smaller nucleation mode (dp ≈ 20 nm). We use microphysical modeling to show that growth is largely via organic condensation. Unlike results for midlatitude forested regions, most of these condensing species behave as semivolatile organics, as lower volatility organics would lead to faster growth of the smaller mode. The magnitude of the CCN hygroscopicity parameter for the growing particles, ~0.1, is also consistent with organic species constituting a large fraction of the particle composition. Mixing ratios of common aerosol growth precursors, such as isoprene and sulfur dioxide, are not elevated during the episode, indicating that an unidentified aerosol growth precursor is present in this high-latitude marine environment.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075671/full
2. Rivers and Floodplains as Key Components of Global Terrestrial Water Storage Variability
This study quantifies the contribution of rivers and floodplains to terrestrial water storage (TWS) variability. We use state-of-the-art models to simulate land surface processes and river dynamics and to separate TWS into its main components. Based on a proposed impact index, we show that surface water storage (SWS) contributes 8% of TWS variability globally, but that contribution differs widely among climate zones. Changes in SWS are a principal component of TWS variability in the tropics, where major rivers flow over arid regions and at high latitudes. SWS accounts for ~22–27% of TWS variability in both the Amazon and Nile Basins. Changes in SWS are negligible in the Western U.S., Northern Africa, Middle East, and central Asia. Based on comparisons with Gravity Recovery and Climate Experiment-based TWS, we conclude that accounting for SWS improves simulated TWS in most of South America, Africa, and Southern Asia, confirming that SWS is a key component of TWS variability.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL074684/full
3. On the Short-term Grounding Zone Dynamics of Pine Island Glacier, West Antarctica, Observed With COSMO-SkyMed Interferometric Data
Using radar satellite data from the Italian COSMO-SkyMed (CSK) constellation and the German TanDEM-X formation, we present comprehensive measurements of the biweekly grounding line dynamics of Pine Island Glacier, West Antarctica, from August to December 2015. The 1 day repeat cycle of CSK reveals tidally induced, grounding line migration on the scale of kilometers and extensive seawater intrusion within the grounding zone, which significantly exceeds that predicted for a stiff bed but are consistent with that calculated for a deformable bed. The deformable bed also explains the continuous draining/filling of subglacial lakes proximal to the grounding line. After correction for oceanic tides, we estimate a retreat rate for 2011–2015 of 0.3 km/yr at the glacier center and 0.5 km/yr on the sides, which is 3 times slower than for 1994–2011 (1.2 km/yr at the center). We attribute the decrease in retreat rate to colder ocean conditions in 2012–2013 relative to 2000–2011.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL074320/full
4. Lower Mantle Substructure Embedded in the Farallon Plate: The Hess Conjugate
The morphologies of subducted remnants in the lower mantle are essential to our understanding of the history of plate tectonism. Here we image a high-velocity slab-like (HVSL) anomaly beneath the southeastern U.S. using waveforms from five deep earthquakes beneath South America recorded by the USArray. In addition to travel time anomalies, the multipathing of S and ScS phases at different distances are used to constrain the HVSL model. We jointly invert S and ScS traveltimes, amplitudes, and waveform complexities to produce a best fitting block model characterized by a rectangular shape with a 2.5% S wave velocity increase and tapered edges. While the Farallon slab is expected to dip primarily eastward, the HVSL structure apparently dips 40° to 50° to the SE and appears to be related to the eclogitized Hess conjugate.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075032/full
5. Strong SH-to-Love Wave Scattering off the Southern California Continental Borderland
Seismic scattering is commonly observed and results from wave propagation in heterogeneous medium. Yet deterministic characterization of scatterers associated with lateral heterogeneities remains challenging. In this study, we analyze broadband waveforms recorded by the Southern California Seismic Network and observe strongly scattered Love waves following the arrival of teleseismic SH wave. These scattered Love waves travel approximately in the same (azimuthal) direction as the incident SH wave at a dominant period of ~10 s but at an apparent velocity of ~3.6 km/s as compared to the ~11 km/s for the SH wave. Back projection suggests that this strong scattering is associated with pronounced bathymetric relief in the Southern California Continental Borderland, in particular the Patton Escarpment. Finite-difference simulations using a simplified 2-D bathymetric and crustal model are able to predict the arrival times and amplitudes of major scatterers. The modeling suggests a relatively low shear wave velocity in the Continental Borderland.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075213/full
VII. AGU Blogs
1. The Tanjung Bungah landslide: a very challenging site
In Malaysia, the fall out from the Tanjung Bungah landslide, which killed 11 construction workers in Penang on Saturday, continues unabated. The Penang State Government is reported to have stated that the cause of the landslide was human error. That may be true, but it is far from clear as to what this means. Was there a failure to understand the ground conditions properly? Or was the slope design incorrect? Or was there a failure to construct to the agreed design? Errors can occur at any stage; often there are multiple small elements. It is also important to emphasise that human error does not necessarily mean that someone was negligent (although this is sometimes the case).
http://blogs.agu.org/landslideblog/2017/10/24/tanjung-bungah-landslide-1/
2. Tanjung Bungah: a major construction site landslide in Malaysia that killed 11 people
A landslide at a construction site at Tanjung Bungah, which is a suburb of George Town in Penang in NW Malaysia, on Saturday killed 11 site workers. The slide, which occurred at the construction site for two 49 storey residential towers, is known to have killed workers from Indonesia, Bangladesh, Myanmar and Pakistan, as well as the site supervisor from Malaysia.
http://blogs.agu.org/landslideblog/2017/10/23/tanjung-bungah-1/
3.Glacier Retreat Generating New Islands List
Climate change has been driving the recession of glaciers and ice sheets, which in turn has been changing our maps. One notable category of physical geographic features indicative of the change due to the retreat is the formation of new islands. Below is a list of new islands that this blog has identified and reported. This is not a comprehensive list of all islands that have been formed.
4. Wolves a defining part of Alaska landscape
The wolf tracks appeared as they always do, as a surprise.
On a day between fall and winter, with the leaves fallen and browning but the ground not yet hard, I was walking with my dog and an a.m. radio. We were descending a four-wheeler trail on a hillside 20 miles from the nearest town, Minto.
http://blogs.agu.org/thefield/2017/10/19/wolves-defining-part-alaska-landscape/
