Age determination of paleotsunami sediment from Lombok Island, Indonesia, and surrounding area has been carried out using the 210 Pb method in BATAN Jakarta. The basic theory of this method assumes that weathering of ...Age determination of paleotsunami sediment from Lombok Island, Indonesia, and surrounding area has been carried out using the 210 Pb method in BATAN Jakarta. The basic theory of this method assumes that weathering of sediments, including paleotsunami sediments, will result in 210 Pb enrichment. The principle of this method is to calculate 210 Pb contents accumulation in a particular sedimentation interval from the surface to the deeper buried sediments. The results are then converted into age or depositional time in years ago unit. The dating results from the paleotsunami sediments of the Gawah Pudak（S8°46’2.91’’, E115°56’34.23’’） and Gili Trawangan areas（S8°21’1.38’’, E116°2’36.6’’） indicate the Gawah Pudak sediments were deposited 37 years ago（c. in 1977）and 22 years ago（c. in 1992）. Three paleotsunami sediments from Gili Trawangan were deposited 149 years ago（c. in 1865）, 117 years ago（c. in 1897） and 42 years ago（c. in 1972）. These results are then compared to the available Indonesian earthquake catalogue data. This study reveals that paleotsunami sediments around Lombok Islands, from older to younger, were caused by the 1857 earthquake（epicentre in Bali Sea; M7; S8°00’09.45’’,E115°29’56.41’’）, 1897 earthquake（epicentre in Flores Sea;M5.5; S6°47’59.62’’, E120°48’03.5’’ or Sulu Sea earthquake; M8.5; 70 km NW of Basilan Island）, the 1975 earthquake（Nusa Tenggara; S10°6’16.61’’, E123°48’09.39’’）, 1977 earthquake（in Waingapu, Sumba; M8.0;S11°5’39.34’’, E118°27’50.86’’） and the 1992 earthquake（Flores; M7.8; S8°28’52.11’’, E121°53’44.3’’）.展开更多
In this study,we simulated the transport of a large coralline boulder on southern Ishigaki Island of the Sakishima Islands,Japan,to evaluate local paleotsunami size in comparison to a well-known historical event(the 1...In this study,we simulated the transport of a large coralline boulder on southern Ishigaki Island of the Sakishima Islands,Japan,to evaluate local paleotsunami size in comparison to a well-known historical event(the 1771 Meiwa tsunami).According to the geological evidence,the boulder was deposited at 10 m elevation by two paleo-tsunami events.We assumed two types of fault models and eight dislocations for each fault.Then we investigated whether there are any combinations of the fault models that can satisfy the movement of the boulder from its presumed initial position to the present position by two tsunamis.Results show that several combinations of tsunami source models can satisfy the geological constraints.展开更多
文摘Age determination of paleotsunami sediment from Lombok Island, Indonesia, and surrounding area has been carried out using the 210 Pb method in BATAN Jakarta. The basic theory of this method assumes that weathering of sediments, including paleotsunami sediments, will result in 210 Pb enrichment. The principle of this method is to calculate 210 Pb contents accumulation in a particular sedimentation interval from the surface to the deeper buried sediments. The results are then converted into age or depositional time in years ago unit. The dating results from the paleotsunami sediments of the Gawah Pudak（S8°46’2.91’’, E115°56’34.23’’） and Gili Trawangan areas（S8°21’1.38’’, E116°2’36.6’’） indicate the Gawah Pudak sediments were deposited 37 years ago（c. in 1977）and 22 years ago（c. in 1992）. Three paleotsunami sediments from Gili Trawangan were deposited 149 years ago（c. in 1865）, 117 years ago（c. in 1897） and 42 years ago（c. in 1972）. These results are then compared to the available Indonesian earthquake catalogue data. This study reveals that paleotsunami sediments around Lombok Islands, from older to younger, were caused by the 1857 earthquake（epicentre in Bali Sea; M7; S8°00’09.45’’,E115°29’56.41’’）, 1897 earthquake（epicentre in Flores Sea;M5.5; S6°47’59.62’’, E120°48’03.5’’ or Sulu Sea earthquake; M8.5; 70 km NW of Basilan Island）, the 1975 earthquake（Nusa Tenggara; S10°6’16.61’’, E123°48’09.39’’）, 1977 earthquake（in Waingapu, Sumba; M8.0;S11°5’39.34’’, E118°27’50.86’’） and the 1992 earthquake（Flores; M7.8; S8°28’52.11’’, E121°53’44.3’’）.
基金supported by Grants-in-Aid from the Japanese Ministry of Education,Culture,Sports,Science,and Technology to Goto(23684041)a Grant-in-Aids from the Japan Society for the Promotion of Science(22241042,26242033)from IRIDeS,Tohoku University to Imamura.
文摘In this study,we simulated the transport of a large coralline boulder on southern Ishigaki Island of the Sakishima Islands,Japan,to evaluate local paleotsunami size in comparison to a well-known historical event(the 1771 Meiwa tsunami).According to the geological evidence,the boulder was deposited at 10 m elevation by two paleo-tsunami events.We assumed two types of fault models and eight dislocations for each fault.Then we investigated whether there are any combinations of the fault models that can satisfy the movement of the boulder from its presumed initial position to the present position by two tsunamis.Results show that several combinations of tsunami source models can satisfy the geological constraints.
