292 research outputs found
Forecasting the path of a laterally propagating dike
An important aspect of eruption forecasting is predicting the path of propagating dikes. We show how lateral dike propagation can be forecast using the minimum potential energy principle. We compare theory to observed propagation paths of dikes originating at the BĂĄrĂ°arbunga volcano, Iceland, in 2014 and 1996, by developing a probability distribution for the most likely propagation path. The observed propagation paths agree well with the model prediction. We ïŹnd that topography is very important for the model, and our preferred forecasting model considers its inïŹuence on the potential energy change of the crust and magma. We tested the inïŹuence of topography by running the model assuming no topography and found that the path of the 2014 dike could not be hindcasted. The results suggest that lateral dike propagation is governed not only by deviatoric stresses but also by pressure gradients and gravitational potential energy. Furthermore, the model predicts the formation of curved dikes around cone-shaped structures without the assumption of a local deviatoric stress ïŹeld. We suggest that a likely eruption site for a laterally propagating dike is in topographic lows. The method presented here is simple and computationally feasible. Our results indicate that this kind of a model can be applied to mitigate volcanic hazards in regions where the tectonic setting promotes formation of laterally propagating vertical intrusive sheets
Upper- and mid-mantle interaction between the Samoan plume and the Tonga-Kermadec slabs
Mantle plumes are thought to play a key role in transferring heat from the core\u2013mantle
boundary to the lithosphere, where it can significantly influence plate tectonics. On impinging
on the lithosphere at spreading ridges or in intra-plate settings, mantle plumes may generate
hotspots, large igneous provinces and hence considerable dynamic topography. However, the
active role of mantle plumes on subducting slabs remains poorly understood. Here we show
that the stagnation at 660 km and fastest trench retreat of the Tonga slab in Southwestern
Pacific are consistent with an interaction with the Samoan plume and the Hikurangi plateau.
Our findings are based on comparisons between 3D anisotropic tomography images and 3D
petrological-thermo-mechanical models, which self-consistently explain several unique
features of the Fiji\u2013Tonga region. We identify four possible slip systems of bridgmanite in the
lower mantle that reconcile the observed seismic anisotropy beneath the Tonga slab
(VSH4VSV) with thermo-mechanical calculations
A Simple Bias Correction in Linear Regression for Quantitative Trait Association Under Two-Tail Extreme Selection
Selective genotyping can increase power in quantitative trait association. One example of selective genotyping is two-tail extreme selection, but simple linear regression analysis gives a biased genetic effect estimate. Here, we present a simple correction for the bias
Deformation of the North American plate interior from a decade of continuous GPS measurements
A megathrust earthquake cycle model for Northeast Japan: bridging the mismatch between geological uplift and geodetic subsidence
Technical design of the phase I Mu3e experiment
The Mu3e experiment aims to find or exclude the lepton flavour violating decay at branching fractions above . A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of . We present an overview of all aspects of the technical design and expected performance of the phase I Mu3e detector. The high rate of up to muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements
Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake
The 2011 Tohoku-oki (Mw 9.1) earthquake is so far the best-observed megathrust rupture, which allowed the collection of unprecedented offshore data. The joint inversion of tsunami waveforms (DART buoys, bottom pressure sensors, coastal wave gauges, and GPS-buoys) and static geodetic data (onshore GPS, seafloor displacements obtained by a GPS/acoustic combination technique), allows us to retrieve the slip distribution on a non-planar fault. We show that the inclusion of near-source data is necessary to image the details of slip pattern (maximum slip ~48â
m, up to ~35â
m close to the Japan trench), which generated the large and shallow seafloor coseismic deformations and the devastating inundation of the Japanese coast. We investigate the relation between the spatial distribution of previously inferred interseismic coupling and coseismic slip and we highlight the importance of seafloor geodetic measurements to constrain the interseismic coupling, which is one of the key-elements for long-term earthquake and tsunami hazard assessment
Astrometry and geodesy with radio interferometry: experiments, models, results
Summarizes current status of radio interferometry at radio frequencies
between Earth-based receivers, for astrometric and geodetic applications.
Emphasizes theoretical models of VLBI observables that are required to extract
results at the present accuracy levels of 1 cm and 1 nanoradian. Highlights the
achievements of VLBI during the past two decades in reference frames, Earth
orientation, atmospheric effects on microwave propagation, and relativity.Comment: 83 pages, 19 Postscript figures. To be published in Rev. Mod. Phys.,
Vol. 70, Oct. 199
Triggering of the 2014 M_w7.3 Papanoa earthquake by a slow slip event in Guerrero, Mexico
Since their discovery two decades ago, slow slip events have been shown to play an important role in accommodating strain in subduction zones. However, the physical mechanisms that generate slow slip and the relationships with earthquakes are unclear. Slow slip events have been recorded in the Guerrero segment of the CocosâNorth America subduction zone. Here we use inversion of position time series recorded by a continuous GPS network to reconstruct the evolution of aseismic slip on the subduction interface of the Guerrero segment. We find that a slow slip event began in February 2014, two months before the magnitude (M_w) 7.3 Papanoa earthquake on 18 April. The slow slip event initiated in a region adjacent to the earthquake hypocentre and extended into the vicinity of the seismogenic zone. This spatio-temporal proximity strongly suggests that the Papanoa earthquake was triggered by the ongoing slow slip event. We demonstrate that the triggering mechanism could be either static stress increases in the hypocentral region, as revealed by Coulomb stress modelling, or enhanced weakening of the earthquake hypocentral area by the slow slip. We also show that the plate interface in the Guerrero area is highly coupled between slow slip events, and that most of the accumulated strain is released aseismically during the slow slip episodes
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