521 research outputs found
Mattia Damiani (1705–1776), poet and scientist in eighteenth century Tuscany
Mattia Damiani da Volterra (1705–1776), “renowned Doctor,” was the author
in 1754 of a collection of scientifi c poems, Le Muse Fisiche (The Physical Muses) on
two subjects: Newtonian physics and the plurality of the worlds. Damiani’s interest
in science was precocious, but even at that, it was superimposed on his studies in
jurisprudence completed in Pisa in 1726. In 2003, Damiani’s lost text, De Hygrometris
et eorum defectibus disputatio (Disputation about hygrometers and their defects),
which was printed in 1726 in Pisa, was brought to light. It characterizes him as a
young scientist who refl ected upon the properties and limits of laboratory instruments
and on nascent aspects of climatology. In this Disputation, a delightful amalgamation
of scientifi c and humanistic literature is pursued. A discussion of the properties
and limits of contemporary hygrometers and a comparison of the Cartesian and
Newtonian hypotheses about cloud formations are interspersed with quotations of
verses on natural phenomena, mostly from poems of the classic age—a prelude to
the author’s future involvement in writing scientifi c verses. The poetry of Damiani,
which often shows a musicality comparable to that of the poet Giacomo Leopardi
(1798–1837), deserves to be recognized and saved from oblivion. Especially remarkable
is the implicit “multimedia” project of a union among science, poetry, theater,
and music. The rediscovered Disputation about hygrometers opens a new window on
the personages involved and on the evolution of meteorological concepts in Europe in
the context of the then-new Galilean and Newtonian physics
The vague volcano-seismic clock of the South American Pacific margin
During his trip on the Beagle, Charles Darwin
wrote about the eruptions associated with the Concepci´on
earthquake of 1835. A later survey by Lorenzo Casertano,
following the great 1960 Chilean earthquake, identified some
unclear evidence of a link between eruptions and the seismic
event, although some reservations were also raised. Using
data available in 2006 in the Smithsonian Institution
Catalogue of volcanic eruptions, Scalera revealed grounded
evidence that South-American Wadati-Benioff zone earthquakes
of magnitudes greater than 8.4 are associated with
an increased rate of volcanic eruptions, but it was still impossible
to determine a causal link between the two phenomena.
An average return period of about 50 yr was deducible
from the data for the time window 1800–1999. After
2006, the Smithsonian Institution’s effort to improve our
knowledge of this region has greatly increased the completeness
of the catalogue, adding the eruptions from the 2000–
2010 interval, together with 50% more new entries in the
list of Andean volcanoes. The great Chilean Maule earthquake
of 27 February 2010 (M = 8.8), occurring exactly five
decades after the 1960 event, provided an occasion to reanalyse
this updated database. The results suggest a preferential
causal eruptions-earthquake relationship, but additional future
volcano-seismic events should be studied to arrive at
a definitive conclusion, within the perspective of using this
phenomenon for Civil Protection. The possible correlation of
South American volcano-seismic events with the Markowitz
oscillation of the Polar Motion is another good reason for
trying to establish an integrated geodynamic explanation
Great and old earthquakes against great and old paradigms ? paradoxes, historical roots, alternative answers
International audienceThe similarity of the vertical displacements shown by case-history extreme-magnitude earthquakes are scrutinised (Chile 1960, Alaska 1964, Sumatra 2004, ...). A common interpretation ? an uprising of lithospheric material ? can be found, which is supported by the irregularities of the hypocentres distribution along the Wadati-Benioff zones. In the case of major South American earthquakes, a volcanic eruptions-earthquakes correlation is recognisable. Further support to this interpretation is the displacement of the Earth's instantaneous rotation pole ? ?3.0 mas (?10 cm), observed at ASI of Matera, Italy ? the seismic data (USGS) in the two days following the main shock, the geomorphologic data, and the satellite data of uplift/subsidence of the coasts (IGG) make possible a new interpretation of the Great Sumatran earthquake (26 December 2004) based on the second conjugate ? nearly vertical ? CMT fault plane solution. All this converges toward different causes of seismogenetic processes, strongly supporting a deep origin of disturbances, fluxes of materials leading to more or less sudden movements of masses, and phase changes, which lead to either earthquakes or silent-slow events in Wadati-Benioff zones. A reinterpretation of the geodynamics of the active margins and mountain building is proposed with a heuristic model that does not resort to large-scale subduction, but only to isostatic uplift of deep material intruding between two decoupling plates in a tensional environment. Concomitant phase changes toward less-packed lattice and buoyancy effect caused by the Clapeyron slope can help the extrusion of material over the m.s.l., constituting an orogenic process. The phenomena expected to occur in the model directly and harmoniously contribute to the building up of the surface geophysical and geomorphological features of the orogenic zones
Coriolis effect as cause of East-West Earth's asymmetry
The different slope of the Wadati-Benioff zones oriented towards east and west is considered a main asymmetry of the Earth's globe. Under the Americas they have angles of about 30o, while under the Pacific east coasts (Asia, Japan) the
angles are steeper. In the framework of plate tectonics geodynamics the cause of this
difference can be identified in the tidal drag that would cause a global shift of the
lithosphere towards west. But this solution has been many times criticized on the
basis of the irrelevance of the tidal forces with respect to viscous friction. Instead,
it is possible to show that in a different framework, in which sudden extrusions of
mantle materials occur by local phase change toward a more unpacked lattice, the
value of the Coriolis fictitious force can rise of several magnitude orders, becoming
the main cause of the east-west asymmetry of the Wadati-Benioff zones, which might
be ascribed entirely to internal causes of the planet (its rotation and geodynamics)
and not to external causes (influence of other celestial bodies). Some astrogeodetic
clues supporting the new geodynamic scenario are scrutinized
La cartografia a raggio variabile – nascita e prospettive di una disciplina sperimentale
non disponibil
Is large scale subduction made unlikely by the mediterranean deep seismicity?
The deep seismicity in the Mediterranean region does not have the pattern that the alleged convergence of Africa and Eurasia should produce. Often, where subduction slabs and Wadati-Benioff zones should be present – showing intermediate and deep hypocenters – only shallow intracrustal seismicity is detected. Most geoscientists admit, without a valid explanation, that in this region subduction occurs largely aseismically.
Inspection of South Tyrrhenian, Aegean and South Carpathian deep foci zones makes clear that these isolated narrow plumes (or clusters, filaments) of hypocentres cannot be sites of active subduction but that they are related to uplift of deep mantle material. Their presence under actively rising part of orogens – besides many additional clues coming from a number of different fields –leads to a unified interpretation of the involved phenomena, and to a new interpretation of the orogenic processes and fold belt building. The evidence points to vertical displacements of materials as the main process responsible for deep earthquakes, volcanic phenomena and orogenesis.
Several tens of km of overthrusts and underthrusts should not be mistaken for large-scale subduction, and the limit of 50-70 km (the roots of an orogen) should be considered the maximum depth of occurrence of metamorphism. Into these limits of depth, the nonlithostatic overpressures due to the surfaceward mantle flow, the association of fluids, extreme magnitude earthquakes and deviatoric stress can be the causes both of those metamorphosed facies (until now presumed to come from depth up to 200 km) and of a shallower than supposed synthesis of biogenic and abiogenic hydrocarbons
If Space is Material, What Inertia Should Be? - Rediscovering a Dismissed Awareness of Ernst Mach
The ”Mach’s Principle” has beenconsidered for more than a century as the highest
expression of the philosophical rationality of the western world, but it is possible to
proof that it is built on a unstable ground and with uncomplete assumptions. With a great
intellectual honesty, Ernst Mach showed in his works some awareness of the incompleteness
of his reasoning about inertia. Moreover the Mach Principle is often misinterpreted by
scientific community with an illegitimate extrapolation of the Mach words
Roots of modern geodynamical views in Schiaparelli's thought – The volcano-seismic correlation events on the Andes
The reflections of Schiaparelli in the branch of astronomy more extensively
involved with the geophysics and geology was influential on the progress of Earth sciences,
contributing to unprejudiced forms of reasoning about the evolution of our planet.
Today some new factual evidence and interpretations of the phenomena linked to a volcanoseismic
correlation and to a progressive shift of the Earth’s rotation poles through geological
time find their roots in the geoedynamical examples published in 1893 and 1891 by
Schiaparelli. If a possible synchronicity of a volcano-seismic correlation – peculiar for the
South American Pacific Margin – with features of the Markowitz oscillation of the secular
Polar Motion will be confirmed by comparison of a longer series of Polar Motion data and
volcano-seismic events (average return period of 40-50 years), we would reasonably be in
the presence of a phenomenon that puts in communication the Earth’s surface with its deeper
interior (core-mantle boundary) and that should be directly linked to a slow asymmetrical
expansion of the Earth
The geodinamic meaning of the deep earthquakes: First clues for a global perspective for fold belts?
Abstract: Earthquakes are not uniformly distributed either along mountain belts and arcs or in depth. The zones in which the deeper earthquakes originate are shown, and their regional and global context is examined. The characteristic inhomogeneous pattern is inspected in the Italian region as well on a Mediterranean and global scale. A possible reinterpretation of global tectonics is proposed with non-collisional orogenic processes – involving global expansion, rifting, isostasy, surfaceward flow of deep material, gravitational spreading, and phase changes
The geodynamic meaning of the deep earthquakes: First clues for a global perspective for fold-belts?
Earthquakes are not uniformly distributed either along mountain belts and arcs or in depth. The zones in which the deeper earthquakes originate are shown, and their regional and global context is examined. The characteristic inhomogeneous pattern is inspected in the Italian region as well on Mediterranean and global scale. A possible reinterpretation of global tectonics is proposed with non-collisional orogenic processes – involving global expansion, rifting, isostasy, surfaceward flow of deep material, gravitational spreading, and phase changes. The associated model of evolution of an orogen does not resort to large scale subduction. The model – with the right modifications for the local different situations – could apply to the evolution of the Italian and world orogens
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