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AGU期刊一周Research Spotlight
AGU期刊一周Research Spotlight (Feb 22~Feb 28, 2018)
时间:2018年03月02日 10:39来源: 点击数:

I. Space & Planets

1. Elevated Heat Flow at Coronae on Venus

Enigmatic surface features on Venus called coronae are important for how Venus loses heat, and measurement of surface flexing around these features indicates higher heat flows than on Earth.

https://eos.org/editor-highlights/elevated-heat-flow-at-coronae-on-venus

2. Moon’s Magnetic Field May Magnetize Iron That Hits Its Surface

Scientists are using satellite data to study large impact basins on the surface of the Moon that contain magnetic anomalies.

https://eos.org/research-spotlights/moons-magnetic-field-may-magnetize-iron-that-hits-its-surface

II. Hazards & Disasters

1. Fiber-Optic Networks Can Be Used as Seismic Arrays

A new study repurposes telecommunications cables to harness sound from light. The method can accurately measure ground motion from distant earthquakes.

https://eos.org/research-spotlights/fiber-optic-networks-can-be-used-as-seismic-arrays

2. Drilling into a Future Earthquake

Researchers drill into a fault that is anticipated to rupture in coming decades to study fault structure and earthquake physics.

https://eos.org/research-spotlights/drilling-into-a-future-earthquake

III. Ocean Sciences

1. Tracking Deep-Earth Processes from Rapid Topographic Changes

Rapid elevation-rise in Turkey, tracked by marine sediments that now sit at 1.5 km in elevation, is linked to deep-Earth processes that can explain short-lived, extreme rates of topographic change.

https://eos.org/editor-highlights/tracking-deep-earth-processes-from-rapid-topographic-changes

2. New Postage Stamps Focus on Bioluminescent Marine Life

The stamps help draw attention to the wonders of creatures that generate their own light and to the environmental problems that threaten them in marine habitats, scientists say.

https://eos.org/articles/new-postage-stamps-focus-on-bioluminescent-marine-life

3. Shedding Light on the Southern Ocean Carbon Sink

One of the world’s largest carbon sinks is still poorly understood.

https://eos.org/research-spotlights/shedding-light-on-the-southern-ocean-carbon-sink

4. Calm Waters off Hawaii Harbor a “Nursery” of Sea Life

Ocean slicks—naturally occurring bands of smooth water—are home to an astounding diversity of fish larvae and other marine life, researchers show.

https://eos.org/articles/calm-waters-off-hawaii-harbor-a-nursery-of-sea-life

IV. Biogeosciences

1. One of World’s Oldest Animals Records Ocean Climate Change

Researchers probe millennia-old deep-ocean sponges for links between ocean nutrients and climate.

https://eos.org/research-spotlights/one-of-worlds-oldest-animals-records-ocean-climate-change

V. Geology & Geophysics

1. Climate Models Are Uncertain, but We Can Do Something About It

Model simulations of many climate phenomena remain highly uncertain despite scientific advances and huge amounts of data. Scientists must do more to tackle model uncertainty head-on.

https://eos.org/opinions/climate-models-are-uncertain-but-we-can-do-something-about-it

2. Drones in Geoscience Research: The Sky Is the Only Limit

Here are six ways that drones are making their way into geosciences research and industry through innovative applications.

https://eos.org/features/drones-in-geoscience-research-the-sky-is-the-only-limit

VI. Geophysical Research Letters

1. Ocean Chlorophyll as a Precursor of ENSO: An Earth System Modeling Study

Ocean chlorophyll concentration, a proxy for phytoplankton, is strongly influenced by internal ocean dynamics such as those associated with El Ni?o–Southern Oscillation (ENSO). Observations show that ocean chlorophyll responses to ENSO generally lead sea surface temperature (SST) responses in the equatorial Pacific. A long-term global Earth system model simulation incorporating marine biogeochemical processes also exhibits a preceding chlorophyll response. In contrast to simulated SST anomalies, which significantly lag the wind-driven subsurface heat response to ENSO, chlorophyll anomalies respond rapidly. Iron was found to be the key factor connecting the simulated surface chlorophyll anomalies to the subsurface ocean response. Westerly wind bursts decrease central Pacific chlorophyll by reducing iron supply through wind-driven thermocline deepening but increase western Pacific chlorophyll by enhancing the influx of coastal iron from the maritime continent. Our results mechanistically support the potential for chlorophyll-based indices to inform seasonal ENSO forecasts beyond previously identified SST-based indices.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL076077/full

2. Contemporary Deformation of the North China Plain From Global Positioning System Data

The North China Plain (NCP) is a region with high level of seismic hazard. Previous Global Positioning System measurements, however, have shown a near absence of present-day crustal deformation. Using updated Global Positioning System data covering three blocks of the eastern China, we discover that interseismic deformation in the NCP takes place in an ~1,100 km wide left-lateral shear zone of roughly east-west orientation. The 6.0 ± 1.3 mm/yr interseismic left-lateral shear over the NCP results in contemporary deformation that is eventually accommodated by earthquake ruptures of right-lateral strike-slip along the north-northeast trending faults and anticlockwise block rotates. We suggest that rapid eastward motion of the rigid South China block, with respect to the rigid Amurian block, has created a left-lateral shear couple to twist the nonrigid NCP to form the contemporary deformation.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL076599/full

3. Spatiotemporal Patterns of Precipitation-Modulated Landslide Deformation From Independent Component Analysis of InSAR Time Series

Long-term landslide deformation is disruptive and costly in urbanized environments. We rely on TerraSAR-X satellite images (2009–2014) and an improved data processing algorithm (SqueeSAR?) to produce an exceptionally dense Interferometric Synthetic Aperture Radar ground deformation time series for the San Francisco East Bay Hills. Independent and principal component analyses of the time series reveal four distinct spatial and temporal surface deformation patterns in the area around Blakemont landslide, which we relate to different geomechanical processes. Two components of time-dependent landslide deformation isolate continuous motion and motion driven by precipitation-modulated pore pressure changes controlled by annual seasonal cycles and multiyear drought conditions. Two components capturing more widespread seasonal deformation separate precipitation-modulated soil swelling from annual cycles that may be related to groundwater level changes and thermal expansion of buildings. High-resolution characterization of landslide response to precipitation is a first step toward improved hazard forecasting.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL075950/full

4. Northern Galápagos Corals Reveal Twentieth Century Warming in the Eastern Tropical Pacific

Models and observations disagree regarding sea surface temperature (SST) trends in the eastern tropical Pacific. We present a new Sr/Ca-SST record that spans 1940–2010 from two Wolf Island corals (northern Galápagos). Trend analysis of the Wolf record shows significant warming on multiple timescales, which is also present in several other records and gridded instrumental products. Together, these data sets suggest that most of the eastern tropical Pacific has warmed over the twentieth century. In contrast, recent decades have been characterized by warming during boreal spring and summer (especially north of the equator), and subtropical cooling during boreal fall and winter (especially south of the equator). These SST trends are consistent with the effects of radiative forcing, mitigated by cooling due to wind forcing during boreal winter, as well as intensified upwelling and a strengthened Equatorial Undercurrent.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL075323/full

5. Tidal Triggering of Microearthquakes Over an Eruption Cycle at 9°50'N East Pacific Rise

Studies have found that earthquake timing often correlates with tides at mid-ocean ridges and some terrestrial settings. Studies have also suggested that tidal triggering may preferentially happen when a region is critically stressed, making it a potential tool to forecast earthquakes and volcanic eruptions. We examine tidal triggering of ~100,000 microearthquakes near 9°50'N East Pacific Rise recorded between October 2003 and January 2007, which encompasses an eruption in January 2006. This allows us to look at how tidal triggering signal varies over an eruption cycle to examine its utility as a forecasting tool. We find that tidal triggering signal is strong but does not vary systematically in the 2+ years leading up to the eruption. However, tidal triggering signal disappears immediately posteruption. Our findings suggest that tidal triggering variation may not be useful for forecasting mid-ocean ridge eruptions over a 2+ year timescale but might be useful over a longer timescale.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL076497/full

6. Hekla Volcano, Iceland, in the 20th Century: Lava Volumes, Production Rates, and Effusion Rates

Lava flow thicknesses, volumes, and effusion rates provide essential information for understanding the behavior of eruptions and their associated deformation signals. Preeruption and posteruption elevation models were generated from historical stereo photographs to produce the lava flow thickness maps for the last five eruptions at Hekla volcano, Iceland. These results provide precise estimation of lava bulk volumes: V1947–1948 = 0.742 ± 0.138 km3, V1970 = 0.205 ± 0.012 km3, V1980–1981 = 0.169 ± 0.016 km3, V1991 = 0.241 ± 0.019 km3, and V2000 = 0.095 ± 0.005 km3 and reveal variable production rate through the 20th century. These new volumes improve the linear correlation between erupted volume and coeruption tilt change, indicating that tilt may be used to determine eruption volume. During eruptions the active vents migrate 325–480 m downhill, suggesting rough excess pressures of 8–12 MPa and that the gradient of this excess pressure increases from 0.4 to 11 Pa s?1during the 20th century. We suggest that this is related to increased resistance along the eruptive conduit.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL076887/full

VII. AGU Blogs

1. How Democracies Die, by Steven Levitsky and Daniel Ziblatt

The authors of this essential study are both scholars at Harvard University. They specialize in studying the decay of democratic governments and societies, one in century-ago Europe, and the other in half-century-ago years ago Latin America. They spell out the structure of authoritarian takeover across these different contexts, and then turn to our situation in 21st century America. This book could not be more timely, more relevant, or more essential. I implore you to consume it.

https://blogs.agu.org/mountainbeltway/2018/02/26/democracies-die-steven-levitsky-daniel-ziblatt/

2. Friday fold: some Google Earth views of Namibia

In preparing last week’s Friday fold, I did some browsing around in Google Earth in northwestern Namibia, at the intersection between the Kaoko and Damara deformational belts. Man, it’s incredible there. Check out some of the folds you can see from space:

https://blogs.agu.org/mountainbeltway/2018/02/23/friday-fold-google-earth-views-namibia/

3. Monday Geology Picture: Airplane View of Table Mountain

Yesterday morning I flew back to Cape Town after a business trip. I arrived a little after 7 am and was treated to a stunning view of Table Mountain and Lion’s Head as I flew in. I’m sharing a picture I snapped of that view as this week’s geology picture.

https://blogs.agu.org/georneys/2018/02/26/monday-geology-picture-airplane-view-table-mountain/

4. An emerging crisis? Valley blocking landslides in the Papua New Guinea highlands

The Mw=7.5 earthquake in Papua New Guinea has generated remarkably little international publicity.  I noted shortly after the earthquake that landslides are likely to be a significant problem given the nature of the earthquake and the topography.  Information is slowly emerging now, and this is increasingly looking like a potential crisis to me.  The best data so far has been posted on the Facebook Page of Bernard James McQueen, who appears to be a helicopter pilot (?) from New Zealand, working in Papua New Guinea.  He has posted a series of images and two videos – check them out, they make deeply alarming viewing.

https://blogs.agu.org/landslideblog/2018/02/28/papua-new-guinea-crisis/

5. An update on landslides from the Mw=7.5 Papua New Guinea earthquake

Information is slowly emerging regarding the impacts of landslides from the Mw=7.5 Papua New Guinea earthquake.  Unfortunately the area remains too cloudy to allow useful optical band satellite imagery to be obtained by Planet Labs, but I will keep an eye on this over the coming days.  Meanwhile media reports suggest that landslides may have been a significant factor – that is not a surprise in an upland area.  The most informative report that I have seen today is from the Post Courier, which indicates at least 31 fatalities, a large proportion of which may have been from landslides.

https://blogs.agu.org/landslideblog/2018/02/27/papua-new-guinea-earthquake-2/



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