1,215 research outputs found
The case of the 2005 Kashmir earthquake
The use of Very High Resolution (VHR) satellite
panchromatic image is nowadays an effective tool to
detect and investigate surface effects of natural disasters.
We specifically examined the capabilities of VHR images
to analyse earthquake features and detect changes based on
the combination of visual inspection and automatic classification
tools. In particular, we have used Quickbird (0.6m
spatial resolution) images for detecting the three main coseismic
surface features: damages, ruptures and landslides.
The present approach has been applied to the 8 October 2005,
Mw7.6 Kashmir, Pakistan, earthquake. We have focused our
study in and around the main urban areas hit by the above
earthquake specifically at Muzaffarabad and Balakot towns.
The automatic classification techniques provided the best results
wherever dealing with the damage to man-made structures
and landslides. On the other hand, the visual inspection
method demonstrated in addressing the identification of
rupture traces and associated features. The synoptic view
(concerning landslide, more than 190 millions of pixels have
been automatically classified), the spatiotemporal sampling
and the fast automatic damage detection using satellite images
provided a reliable contribution to the prompt response
during natural disaster and for the evaluation of seismic hazard
as well
Characterization of active fault scarps from LiDAR data: a case 1 study from Central 2 Apennines (Italy)
A high resolution DEM (1 ms spacing) derived from an airborne LiDAR campaign was
11 used in an attempt to characterize the structural and erosive elements of the geometry of the Pettino 12 fault, a seismogenic normal fault in Central Apennines (Italy). Four 90- to 280 m -long fault scarp 13 segments were selected and the surface between the base and the top of the scarps was analyzed 14 through the statistical analysis of the following DEM-derived parameters: altitude, height of the 15 fault scarp, distance along strike, slope and aspect. The results identify slopes of up to 40° in faults 16 lower reaches interpreted as fresh faces, 34° up the faces. The Pettino fault maximum long slipe17 rate (0.6-1.1 mm/yr) was estimated from the scarp heights, which are up to 12 and 19 m in the 18 selected four segments, and the age (ca. 18 ka) of the last glacial erosional phase in the area. The 19 combined analysis of the DEM-derived parameters allow us to (a) define aspects of 3D scarp 20 geometry, (b) decipher its geomorphological significance, and (c) estimate the long-term slip rate
Normal faults and thrusts re-activated by deep fluids: the 6 April 2009 Mw 6.3 L’Aquila earthquake, central Italy.
On April 6 2009, a Mw=6.3 earthquake occurred in the central Apennines (Italy) damaging L’Aquila city and the surrounding country. We relocate the October 2008-April 6 2009 foreshocks and about 2000 aftershocks occurred between April 6 and April 30 2009, by applying a double-difference technique and determine the stress field from focal mechanisms. The events concentrate in the upper 15 km of the crust. Three main NW-SE to NNW-SSE striking, 30°-45° and 80°-90° dipping faults activate during the seismic sequence. Among these, a normal fault and a thrust were re-activated with dip-slip movements in response to NE-SW extension. The structural maturity of the seismogenic fault system is lower than that displayed by other systems in southern Apennines, because of the lower strain rate of the central sector of the chain with respect to the southern one. VP/VS increases progressively from October 2008 to the April 6 2009 mainshock occurrence along a NW-SE strike due to an increment in pore fluid pressure along the fault planes. Pore pressure diffusion controls the space-time evolution of aftershocks. A hydraulic diffusivity of 80 m2/s and a seismogenic permeability of about 10-12 m2 suggest the involvement of gas-rich (CO2) fluids within a highly fractured medium. Suprahydrostatic, high fluid pressure (about 200 MPa at 10 km of depth) within overpressurized traps, bounded by pre-existing structural and/or lithological discontinuities at the lower-upper crust boundary, are required to activate the April 2009 sequence. Traps are the storage zone of CO2-rich fluids uprising from the underlying, about 20 km deep, metasomatized mantle wedge. These traps easily occur in extensional regimes like in the axial sector of Apennines, but are difficult to form in strike-slip regimes, where sub-vertical faults may cross the entire crust. In the Apennines, fluids may activate faults responsible for earthquakes up to Mw=5-6. Deep fluids more than tectonic stress may control the seismotectogenesis of accretionary wedges
Exploring quantum quasicrystal patterns: a variational study
We study the emergence of quasicrystal configurations produced purely by
quantum fluctuations in the ground-state phase diagram of interacting bosonic
systems. By using a variational mean-field approach, we determine the relevant
features of the pair interaction potential that stabilize such quasicrystalline
states in two dimensions. Unlike their classical counterpart, in which the
interplay between only two wave vectors determines the resulting symmetries of
the solutions, the quantum picture relates in a more complex way to the
instabilities of the excitation spectrum. Moreover, the quantum quasicrystal
patterns are found to emerge as the ground state with no need of moderate
thermal fluctuations. The study extends to the exploration of the excitation
properties and the possible existence of super-quasicrystals, i.e.
supersolid-like quasicrystalline states in which the long-range non-periodic
density profile coexist with a non-zero superfluid fraction. Our calculations
show that, in an intermediate region between the homogeneous superfluid and the
normal quasicrystal phases, these exotic states indeed exist at zero
temperature. Comparison with full numerical simulations provides a solid
verification of the variational approach adopted in this work.Comment: 10 pages, 6 Figure
HIV Protease Inhibitors: Advances in Therapy and Adverse Reactions, Including Metabolic Complications
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90068/1/phco.19.4.281.30937.pd
Mantle wedge dynamics vs crustal seismicity in the Apennines (Italy)
In the Apennines subduction (Italy), earthquakes mainly occur within overriding
plate, along the chain axis. The events concentrate in the upper 15 km of the crust above the
mantle wedge and focal solutions indicate normal faulting. In the foreland, the seismogenic
volume affects the upper 35 km of the crust. Focal solutions indicate prevailing reverse faulting
in the northern foreland and strike-slip faulting in the southern one. The deepening of the
seismogenic volume from the chain axis to the foreland follows the deepening of the Moho and
isotherms. The seismicity above the mantle wedge is associated with uplift of the chain axial
zone, volcanism, high CO2 flux, and extension. The upward pushing of the asthenospheric mantle
and the mantle-derived, CO2-rich fluids trapped within the crust below the chain axis causes this
seismicity. All these features indicate that the axial zone of Apennines is affected by early rifting
processes. In northern Italy, the widespread and deeper seismicity in the foreland reflects active
accretion processes. In the southern foreland, the observed dextral strike-slip faulting and the lack
of reverse focal solutions suggest that accretion processes are not active at present. In our
interpretation of the Apennines subduction, the shallower seismicity of the overriding plate is due
to the dynamics (uprising and eastward migration) of the asthenospheric wedge
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