Gempa Tsunami GMT SAC

Sugeng Pribadi ,  Nanang T. Puspito ,  Afnimar  and  Gunawan Ibrahim Abstract: The 25 October 2010 Mentawai earthquake has magnitude Mw 7.7 and shallow depth (12 km). Although the local people of Sikakap - the closed island near epicenter (78.33 km) only felt low shaking (II-III Mercally Intensity), it rised tsunami 7.4 m height causing casualties 447 people died. We suggested the phenomenon is the tsunami earthquake. Therefore we calculate the source mechanism by using W-phase method to determine its parameter. The result yield good value due to reference of GCMT solution with strike 340.3°, dip 8.3°, and slip 116.9°. The cross section diagram of hypocenter show the event located on the beginning of subduction. We obtain the values of seismic radiated energy  1.76×10 14  Nm, seismic moment 5.37×10 27  Nm, and its ratio is  Θ = −6.1  . It counted as the threshold of tsunami earthquake. The rupture process has long duration 82 s. The facts proved that the 2010 Mentawai as a tsunami e

Sugeng Pribadi 1,2 , Afnimar 3 , Nanang T. Puspito 3 & Gunawan Ibrahim 3 1 Tsunami Warning Information Division, Indonesian Meteorological Climatological and Geophysical Agency (BMKG), Jl. Angkasa I No.2, Jakarta13920 2 Graduate Student of Earth Sciences, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Jl. Ganesha 10, Bandung 40132 3 Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology (ITB), Jl. Ganesha 10, Bandung 40132 Email: sugengpribadimsc@gmail.com Abstract. We have characterized 27 earthquakes generate tsunamis in Indonesia from 1991 to 2012 based on source parameter analysis. It includes focal mechanism derived from W phase, the ratio ( Θ ) between seismic energy ( E ) and seismic moment ( M o ), moment magnitude ( M w ), rupture duration ( To ) and hypocenter distance to the trench. M ost of the earthquakes (24 events) are tsunamigenic earthquake with vari