Investigating the Magma System of the Active Rabaul Caldera

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The specific investigations of this project include a three-dimensional study of the P-wave velocity structure of Rabaul Caldera which identifies a large magma body in the under the central area of the caldera that is the likely source for the recent historic eruption. Using P arrival time data from both natural earthquakes and explosions from the Rabaul Earthquake Location and Caldera Structure (RELACS) experiment, we were able to image a low-velocity body in the body of the caldera that is the likely a large magma body (Tanimura and Mori).During the course of this study a great (Mw8.0) earthquake occurred on the transform fault east of Rabaul in the New Ireland area (Weitin-Kamdaru fault). The earthquake caused strong shaking in Rabaul and Kokopo, along with a 1 m tsunami in Rabaul Harbour. On New Ireland, which is very sparsely populated, there were observed surface offsets of the fault as large as 5.5 m. We wrote reports about the 2000 New Ireland Earthquake with a description of the earthquake (Itikarai) and a study of the earthquake source and subsequent triggering of two subsequent large earthquakes along the New Britain trench (Park and Mori).