Geodynamics and Earthquakes

LECTURER
Prof. Carlo Doglioni

University La Sapienza, Rome

DATE: 28th August 2018
TIME: 11:15 – 12:15 am
LOCATION: Rigoni Stern Institute, Asiago

Abstract

The mechanisms driving plate motion and the Earth’s geodynamics are still not entirely clarified. Lithospheric volumes recycled at subduction zones or emerging at rift zones

testify mantle convection. The cooling of the planet and the related density gradients are invoked to explain mantle convection either driven from the hot interior or from the

cooler outer boundary layer. In this paper we summarize a number of evidence supporting generalized asymmetries along the plate boundaries that point to a polarization

of plate tectonics. W-directed slabs provide two to three times larger volumes to the mantle with respect to the opposite E- or NE-directed subduction zones. W-directed slabs are deeper and steeper, usually characterized by down-dip compression. Moreover, they show a shallow decollement and low elevated accretionary prism, a steep regional monocline with a deep trench or foredeep, a backarc basin with high heat flow and positive gravity anomaly. Conversely directed subduction zones show antithetic signatures and no similar backarc basin. Rift zones also show an asymmetry, e.g., faster Vs in the western lithosphere and a slightly deeper bathymetry with respect to the eastern flank. These evidences can be linked to the westward drift of the lithosphere relative to the underlying mantle and may explain the differences among subduction and rift zones as a function of their geographic polarity with respect to the “tectonic equator.” Therefore also mantle convection and plate motion should be polarized. All this supports a general tuning of the Earth’s geodynamics and mantle convection by astronomical forces. The horizontal component of the solid Earth tide is energizing the system, providing a force able to shift horizontally the lithosphere toward the “west”. Earthquakes develop at plate boundaries where there are velocity gradients determined by viscosity gradients in the low-velocity zone at the lithosphere base. Along diverging polate boundaries the energy that forms during the interseismic period (hundreds of years) in the shallow crust (e.g., down to 20 km) is gravitational, whereas along transcurrent and contractional plate boundaries is mainly elastic. This difference determines a different evolution of the deformation during the coseismic stage, i.e., the earthquake. The different phenomenologies in the opposite tectonic settings should provide different seismic precursors that have to be systematically monitored in order to arrive to predict earthquakes in the future.

 

 

Education

1975-1981      B.S. and Dr. in Geology, Ferrara University

 

Major Activities

 

1981-1983 Assistant at the University of Ferrara

1983-1984 Post-Doc at the University of Basel (CH)

1983-1992 Researcher at the University of Ferrara

1992-1994 Associate professor University of Bari

1994-1997 Full Professor University of Basilicata

1997-Present Full Professor of Geodynamics, Sapienza University – Roma

2016-Present President Istituto Nazionale di Geofisica e Vulcanologia

 

Honors and Awards

 

1986               Dal Piaz Award of the Italian Geological Society

1994               Distinguished Lecturer of the AAPG, US tour

2004               Spendiarov Award of the Russian Academy of Sciences, 32° IGC

2005               Distinguished Lecturer of the AAPG, Europe tour

2005               Member of the Academia Europaea

2006               Member of the Istituto Lombardo di Scienze Lettere ed Arti

2007               Member of the Istituto Veneto di Scienze Lettere ed Arti

2009               Alfred Wegener Award, European Association of Geoscientists and Engineers

2009               Member of the Accademia dei Lincei

2009               Premio Sapienza Ricerca

2009               Premio Bellunesi nel Mondo

2011               Member of the Accademia Nazionale delle Scienze, detta dei XL

2013               Premio SS Vittore e Corona, Feltre

2014               Member of the European Academy of Sciences and Arts

2015               Honorary Professor of Chinese Geosciences University, Beijing

2016               Member of the Accademia delle Scienze di Torino

 

Research Interests

Geodynamics, Earthquakes, plate tectonics

 

  • Polarized Plate Tectonics, Carlo Doglioni*,1, Giuliano Panzax,{ *Dipartimento di Scienze della Terra, Università La Sapienza, Roma, Italy
  • Normal fault earthquakes or graviquakes, C. Doglioni1,2, E. Carminati1,2, P. Petricca & F. Riguzzi
  • Can Earth’s rotation and tidal despinning drive plate tectonics?, Federica Riguzzi, Giuliano Panza, Peter Varga, Carlo Doglioni.

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