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Geodynamics of tha Wadati-Benioff zone earthquakes: The 2004 Sumatra earthquake and other great earthquakes
Language
English
Obiettivo Specifico
3.3. Geodinamica e struttura dell'interno della Terra
Status
Published
JCR Journal
N/A or not JCR
Peer review journal
Yes
Title of the book
Issue/vol(year)
1/46 (2007)
Publisher
University of Mexico
Pages (printed)
19-50
Issued date
March 2007
Alternative Location
Abstract
The displacement of the Earth’s instantaneous rotation pole – observed at ASI of Matera, Italy – the seismic data (USGS)
in the two days following the main shock, the high frequency P-wave radiation, the geomorphologic data, and the satellite data of
uplift/subsidence of the coasts (IGG) converge toward a new interpretation of the Great Sumatran earthquake (TU=26 December
2004 - 00h 58m, Lat=3.3°N, Lon=95.8°E, H=10 km, M=9.3) based on the second conjugate – nearly vertical – CMT fault plane
solution. In a non-double-couple treatment that considers non-negligible non-elastic contributions to the earthquake phenomena,
only a nearly vertical fault can explain both high values of seismic moment and the ≈3.0 mas (≈10 cm) polhody displacement
toward an azimuth exactly opposite to the epicentre azimuth.
Case-histories of great earthquakes are then reviewed to highlight the overall analogies. The similarity of the vertical
displacements shown by these earthquakes (Chile 1960, Alaska 1964, …) leads to a common interpretation necessitating resort
to a prevailing uprising of lithospheric material. This interpretation is supported by the inspection of the irregularities of the
hypocentre distribution along the Wadati-Benioff zones. Moreover, in the case of great South American earthquakes, a volcanic
eruptions-earthquakes correlation is clearly recognisable.
A thorough revision of the pure elastic rebound model of great earthquakes occurrence and a complete overcoming of the
large scale subduction concept is then needed.
in the two days following the main shock, the high frequency P-wave radiation, the geomorphologic data, and the satellite data of
uplift/subsidence of the coasts (IGG) converge toward a new interpretation of the Great Sumatran earthquake (TU=26 December
2004 - 00h 58m, Lat=3.3°N, Lon=95.8°E, H=10 km, M=9.3) based on the second conjugate – nearly vertical – CMT fault plane
solution. In a non-double-couple treatment that considers non-negligible non-elastic contributions to the earthquake phenomena,
only a nearly vertical fault can explain both high values of seismic moment and the ≈3.0 mas (≈10 cm) polhody displacement
toward an azimuth exactly opposite to the epicentre azimuth.
Case-histories of great earthquakes are then reviewed to highlight the overall analogies. The similarity of the vertical
displacements shown by these earthquakes (Chile 1960, Alaska 1964, …) leads to a common interpretation necessitating resort
to a prevailing uprising of lithospheric material. This interpretation is supported by the inspection of the irregularities of the
hypocentre distribution along the Wadati-Benioff zones. Moreover, in the case of great South American earthquakes, a volcanic
eruptions-earthquakes correlation is clearly recognisable.
A thorough revision of the pure elastic rebound model of great earthquakes occurrence and a complete overcoming of the
large scale subduction concept is then needed.
Type
article
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