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MONITORING AND FORECAST

SS Sumatra, Indonesia

SITUATION IN SS SUMATRA AFTER EARTHQUAKES IN THE ISLAND PAGAI-SELATAN of 25 October 2010, Ms = 7.3.

The earthquake of October 25, 2010, occurred in the SS Sumatra, in the boundary region of the northern and southern sub-systems. It was expected and predicted in the northern subsystem. This earthquake has confirmed the unusual nature of the previous earthquakes of 30.09.2009 and 06.04.2010. In the next 3 months in the Mentawai Islands west of Sumatra may occur catastrophic earthquake with M=8.5 and the deadly tsunami. /October 28, 2010/

FORECAST OF EARTHQUAKES WITH Ms ≥ 7.8 in the SS Sumatra. Earthquake on Oct. 25, 2010 in the west of Sumatra, near the island of Pagai Selatan ☼, on the magnitude and focal mechanism, we have ranked as earthquake-indicators. It confirmed the unusual nature of the previous two earthquakes of 30.09.2009, M7.3 and 06.04.2010, M7.7 (B and C in Fig.1), (see Communication on 02.10.2009 and the Communication dated April 20, 2010). There has been predicted that in Zone A (near the Mentawai Islands - Siberut and Sipura and offshore from Padang) is being prepared and expected a catastrophic earthquake with M=8.5. It was also noted that the atypical earthquake will help and can accelerate the preparation of this catastrophe". In September, the Bulletin 003, we predicted that the immediate danger here is from November 2010 to January 2011, when the track will cross the region of instability.

By Oct. 25 track very close to the zone of instability of the catastrophic earthquake. Earthquake ☼ raised track and a few have removed him from the zone of instability. Under this scenario, the danger of a catastrophic earthquake M8.5 in Zone A is removed in time to mid-2012.

But if an earthquake on Oct. 25, 2010 is the result of unusual earthquakes of 30.09.2009, M7.3 and 06.04.2010, M7.7, which is likely, then the situation changes. Earthquake 09.30.2009 partially lifted the accumulated stress in the SS Sumatra due to the lateral narrowing subducting Australian plate beneath Sumatra, the earthquake 06.04.2010 leveled stress state in the hub area of contact plates and microplates in northern Sumatra, and earthquake 25.10.2010 again restored to a dangerous level partially relieved stress in the SS Sumatra. In the language of entropy, this means that the track remained at dangerous levels near the zone of instability.

So with this interpretation, the forecast earthquake remain in force: with November 2010 to January 2011, in Zone A (Fig.1) can occur catastrophic earthquake M8.5. The earthquake will lead to the formation of powerful tsunami waves from 5 to 10 m in the Indian Ocean. The earthquake coincides with the rupture of historical earthquakes in 1797, Mw=8.7 west of Sumatra, near the Mentawai Islands - Siberut and Sipura. Now the probability of strong earthquakes with M≥7.8 in the SS Sumatra P=15.57% (on the entropy of Pw=26.35%, and the cumulative energy Pk=59.10%) (Fig.2). In September it was 12% (25%, 49%).

Subsystems North and South of Sumatra. Prediction of earthquakes with 7.3<Ms<7.8. Earthquake ☼ occurred on the border of North and South subsystems with magnitudes near the threshold. The distribution of aftershocks (Fig.3) and the energy we have ranked her to earthquake-indicators for the subsystem North of Sumatra (Fig.1). In September, the Bulletin 003, we predicted that in the North sub-system has a shortage of earthquake-indicator energy, and that in the coming months, the trigger for expected catastrophe may be an earthquake with M=7.0. The earthquake 25.10.2010 is expected earthquake-indicator, which will more than fill the existing shortage of energy in the subsystem. Monitoring in the northern subsystem confirms the above mentioned training of catastrophic earthquake. The probability of strong earthquake has jumped by 4% and is now equal to P=39% (Pw=48%, Pk=80%). Forecasts for the South subsystem has not changed. The southern part of Sumatra in the coming years until 2015 will be seismically in a safe condition.