HR: 0800h
AN: U11B-0834 [Abstracts]
TI: Seismic cascades in advance and after 26 December 2004 Sumatra-Andaman and other
mega-earthquakes
AU: Romashkova, L
EM: lina@mitp.ru
AF: International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Russian Academy of
Sciences, 79-2 Warshavskoye Shosse, Moscow, 117556
Russian Federation
AU: Nekrasova, A
EM: nastia@mitp.ru
AF: International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Russian Academy of
Sciences, 79-2 Warshavskoye Shosse, Moscow, 117556
Russian Federation
AU: * Kossobokov, V
EM: volodya@mitp.ru
AF: International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Russian Academy of
Sciences, 79-2 Warshavskoye Shosse, Moscow, 117556
Russian Federation
AU: * Kossobokov, V
EM: volodya@mitp.ru
AF: Institute de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252
France
AB:
Regular features of discrete cascades of fractures are generally observed both in Nature and laboratory. Specifically, an
understanding of seismic process in terms of dynamics of a hierarchical system of blocks-and-faults and deterministic chaos,
has already led to reproducible intermediate-term middle-range earthquake prediction technique that passed statistical
significance testing in forward application, 1992-present. The 26 December 2004 mega-earthquake is the first indication that
the algorithm, designed for prediction of M8.0+ earthquakes and tested in applications aimed at smaller target events down to
M5.5+ in Italy, can be rescaled for prediction of mega-earthquakes of M9.0+. The event is not a full verification although
supported by case histories of the other mega-earthquakes of the 20th century (Kamchatka, 1952; Andreanoff Islands, 1957;
Chile, 1960; and Alaska, 1964). The analysis of seismic sequences within space-time of long-, intermediate-, and short-term
scales evidence consecutive stages of inverse cascading of seismic activity to the great shock and direct cascading of
aftershocks. The first may reflect coalescence of instabilities at the approach of a catastrophe, while the second indicates
a certain state of readjustments in the system after it.
In the case of 26 December 2004 event the inverse cascade could be related to a stepwise rise of seismic rate excited by the
great 04 June 2000 (off-shore southern Sumatra) and the major 02 November 2002 (off-shore northern Sumatra) earthquakes. The
direct cascade of aftershocks is characterized with a constant daily rate of above 250 events in the first 46 hours that has
changed abruptly to a constant rate of about 27 events and remained the same until the swarm activity in the Andaman Sea back
arc started on January 26 and burst out 500 magnitude 4 or larger quakes by January 28. Right after that the rate of
aftershocks dropped to another near constant value of 11 per day through February, then to about 6 through March right to the
time of 28 March 2004 Nias Mw8.7 mega-earthquake and its aftershocks. The spatial cascade of ruptures ended with 10 April
2005 strong magnitude 6.7 earthquake to the south of the mega-ones. We compare the observed seismic dynamics prior to and
after the other mega-earthquakes, which demonstrate common features of predictability and diverse behavior in course
second-order phase transitions in the complex non-linear system of the Earth lithospheric blocks-and-faults.
DE: 3238 Prediction (3245, 4263)
DE: 3252 Spatial analysis (0500)
DE: 3270 Time series analysis (1872, 4277, 4475)
DE: 7209 Earthquake dynamics (1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Union [U]
MN: Fall Meeting 2005