Joint inversion study using tsunami waveforms and InSAR data provides a new way to understand the magnitude and spatial extent of subduction zone earthquakes. A great earthquake (Mw 8.5) occurred on 12 September 2007 off the west coast of Bengkulu, Indonesia. The tsunami generated by the event was recorded by tide gauge stations around the Indian Ocean and by two bottom‐pressure sensors in the deep sea. The ground surface displacements produced by the earthquake on Pagai Islands and on Sumatra Island were observed by Interferometric Synthetic Aperture Radar (InSAR). We estimated the slip distribution of the earthquake by joint inversion incorporating a spatial smoothness constraint, using tsunami waveforms and InSAR data. The total released seismic moment calculated from the slip distribution is 6.7 × 1021 N m (Mw 8.5), consistent with the seismic moment of the Global CMT solution, 6.71 × 1021 N m. The maximum observed tsunami heights along the coast of Bengkulu agree with those computed from the slip distribution. The slip amount of the 2007 earthquake is smaller than the amount of potential slip that has been accumulated since after the 1797 and 1833 events. The premise is that, averaged over long periods of time, the entire fault must slip equal amounts. Therefore the 2007 great earthquake could be followed by several great earthquakes that will rupture the plate interface until the potential slip that has been accumulated is completely released.

Abstract. On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements.The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS) (Rudloff et al., 2009) combines GPS technology and ocean bottom pressure (OBP) measurements. Especially for nearfield installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information.The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

Rencana pembangunan breakwater merupakan bagian dari 8 tahap pembangunan Dermaga Lantamal III Pondokdayung di Tanjungpriok Jakarta. Dalam pembangunan breakwater dan perencanaan pemeliharaan pelabuhan perlu dilaksanakan analisa sedimentasi mengenai laju sedimentasi dan pola transpor sedimen. Penentuan laju sedimentasi dan analisa transpor sedimen pada saat pembangunan breakwater perlu ditinjau terlebih dahulu dari analisa kondisi sekarang, sehingga penelitian ini dilaksanakan dengan tiga tahap : (1) penghitungan selisih volume dan selisih kedalaman pada titik – titik di setiap segmen yang telah ditentukan berdasarkan tiga buah Lembar Lukis Teliti (LLT) tahun 1993, 2001, dan 2009; (2) melaksanakan simulasi pemodelan numerik dengan menggunakan software SMS 9.0 pada kondisi saat ini yang di bandingkan dengan penghitungan manual berdasarkan LLT dan hasil penghitungan Dishidros berdasarkan data survei tahun 2009; dan (3) melaksanakan pemodelan numerik simulasi breakwater sesuai siteplan dari Disfaslanal. Penghitungan selisih volume sedimen di lokasi penelitian sesuai area hitungan menunjukkan terjadi erosi dengan erosi rata – rata 4679,807 m3 per tahun. Begitu pula dengan penghitungan selisih kedalaman menunjukkan terjadi penurunan permukaan dasar laut dengan penurunan kedalaman rata – rata 0,006 meter per tahun. Berdasarkan penghitungan data lapangan sedimen suspensi rata – rata 0,0227 gr/ltr, deposisi antara 2,5 sampai dengan 7,5 cm per tahun. Sedangkan berdasarkan hasil analisa model sedimen suspensi rata –rata 0,182 gr/l, deposisi 3,6 cm per tahun. Pada model simulasi breakwater sedimen suspensi rata – rata 0,052 gr/ltr, deposisi di perairan 3,41 cm per tahun, di dalam kolam dermaga dan di pintu masuk kolam dermaga masing – masing 3,32 cm per tahun dan 2,46 cm per tahun. Pada musim Timur pembangunan breakwater memberikan dampak sedimentasi yang cukup rendah, namun pada musim Barat dengan meninjau pola arus yang terjadi sedimentasi cenderung akan lebih tinggi.