Incipient
axial collapse of the Main Cordillera and strain partitioning
gradient between the central and Patagonian Andes, Lago Laja,
Chile | Daniel Melnick , François
Charlet et al.
Lago Laja is a late Quaternary volcanic-dammed lake located
near the drainage divide of the south central Andes. Field observations,
lake reflection seismic profiles, bathymetry, and remote sensing
data reveal an active fault system that runs parallel to the
volcanic arc along the axis of the Main Cordillera, the Lago
Laja fault system (LLFS). Normal faults of this extensional
system cut late Pleistocene volcanics, <7.1 ka still water
lacustrine sediments, 6.3 ka pyroclastic deposits, and Holocene
alluvial fans. We divide the LLFS in three segments on the basis
of fault geometry, width, and slip magnitude. | More |
Deformation
and permeability of aggregated soft earth materials | C.
G. Eggers, M. Berli et al
This study develops a framework for modeling
deformation of individual pores in elastoviscoplastic earth
material accounting for the effects of evolving pore size and
shape on material hydraulic permeability. We describe the velocity
field of a fluid within deforming pores of hypotrochoidal cross-sectional
areas as a function of remote stress or deformation and elastoviscoplastic
material properties using finite element analysis. We find that
pore permeability decreases with increasing stress and deformation.
Pore cross-sectional areas are mainly reduced in size while
the shape remains constant.
More...
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Predicting
Solar Cycle 24 and beyond | Mark A. Clilverd, Ellen Clarke
et al
We use a model for sunspot number using low-frequency solar
oscillations, with periods 22, 53, 88, 106, 213, and 420 years
modulating the 11-year Schwabe cycle, to predict the peak sunspot
number of cycle 24 and for future cycles, including the period
around 2100 A.D. We extend the earlier work of Damon and Jirikowic
(1992) by adding a further long-period component of 420 years.
Typically, the standard deviation between the model and the
peak sunspot number in each solar cycle from 1750 to 1970 is
±34. The peak sunspot prediction for cycles 21, 22, and
23 agree with the observed sunspot activity levels within the
error estimate. Our peak sunspot prediction for cycle 24 is
significantly smaller than cycle 23, with peak sunspot numbers
predicted to be 42 ± 34. These predictions suggest that
a period of quiet solar activity is expected, lasting until
~2030, with less disruption to satellite orbits, satellite lifetimes,
and power distribution grids and lower risk of spacecraft failures
and radiation dose to astronauts. Our model also predicts a
recovery during the middle of the century to more typical solar
activity cycles with peak sunspot numbers around 120. | More |
Evidence
in support of the climate change-Atlantic hurricane hypothesis
| James B. Elsner
The power of Atlantic tropical cyclones is rising rather dramatically
and the increase is correlated with an increase in the late
summer/early fall sea surface temperature over the North Atlantic.
A debate concerns the nature of these increases with some studies
attributing them to a natural climate fluctuation, known as
the Atlantic Multidecadal Oscillation (AMO), and others suggesting
climate change related to anthropogenic increases in radiative
forcing from greenhouse-gases. Here tests for causality using
the global mean near-surface air temperature (GT) and Atlantic
sea surface temperature (SST) records during the Atlantic hurricane
season are applied. Results show that GT is useful in predicting
Atlantic SST, but not the other way around. Thus GT "causes"
SST providing additional evidence in support of the climate
change hypothesis. Results have serious implications for life
and property throughout the Caribbean, Mexico, and portions
of the United States. | More |
