Japan Geoscience Union Meeting 2014

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Oral

Symbol H (Human Geosciences) » H-DS Disaster geosciences

[H-DS27_1AM1] Tsunami and its Forecast

Thu. May 1, 2014 9:00 AM - 10:45 AM 418 (4F)

Convener:*Yutaka Hayashi(Meteorological Research Institute), Erick Mas(International Research Institute of Disaster Science), Toshitaka Baba(Japan Agency for Marine-Earth Science and Technology), Chair:Erick Mas(International Research Institute of Disaster Science), Masami Okada(Meteorological Research Institute)

10:30 AM - 10:45 AM

[HDS27-P05_PG] The 24 September 2013 tsunami in the Makran region, northwestern Indian Ocean

3-min talk in an oral session

Mohammad HEIDARZADEH1, *Kenji SATAKE1 (1.Earthquake Research Institute (ERI), The University of Tokyo)

Keywords:Northwestern Indian Ocean, Tsunami, Makran subduction zone, Landslide, Spectral analysis, Numerical modeling

Tsunami waves were observed in the northwestern Indian Ocean following the Mw 7.7 Pakistan inland earthquake on 24 September 2013. We analyze eleven tide gauge records as well as one DART record of this tsunami and perform numerical modeling of tsunami. The tsunami registered a maximum wave height of 109 cm in Qurayat tide gauge station (Oman). Spectral analysis showed that the most governing period of the tsunami waves was around 12 min though wavelet analysis showed that parts of the tsunami energy were partitioned into other period bands of 7 and 16 min. Distribution of aftershocks in the region showed that all of them were located inland indicating that the tsunami was generated by submarine geological phenomena triggered by the earthquake. Tsunami backward ray tracing showed that the tsunami source was possibly located at offshore Jiwani (Pakistan) and the tsunami was most likely generated immediately after the main shock. Tsunami modeling assuming a pile-up structure at the location of the new island was not successful in reproducing the observed sea level records. A landslide source with a length of about 15-20 km, a thickness of 100-150 m located at 61.72oE and 24.60oN seems capable of fairly reproducing the observed sea level records. This event was the second tsunami recorded in the Makran region since 1945, and may be evidence for hazards from landslide-generated waves following seismic activities.