IASPEI - Picture Gallery
IASPEI - Picture Gallery IASPEI - Picture Gallery
IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSW001 Oral Presentation 2396 Ancient subduction zone in the Sakhalin Island (the Sea of Okhotsk) Prof. Alexander Rodnikov Geophysical Center Russian Acadehy of Sciences IAVCEI In the Sea of Okhotsk in Eastern Sakhalin an ancient (Upper Cretaceous-Paleogene) subduction zone is distinguished. On the surface it is manifested by an ophiolite complex, which separates North Sakhalin oil and gas basin from Deryugin basin of the Sea of Okhotsk. This complex is represented with harzburgite, dunite, wehrlite, rodingite, gabbro and amphibolite forming ophiolite plates. It is supposed that 100 million years ago, the oceanic lithosphere of the Sea of Okhotsk subducted under Sakhalin, the eastern part of which was an andesite island arc. Behind andesite island arc, in western Sakhalin there was a back-arc basin where sandy clayey deposits accumulated in the Late Cretaceous- Paleogene, which subsequently formed the basement of Cenozoic North Sakhalin oil and gas basin. Approximately 10 15 million years ago subduction of the lithosphere of the Sea of Okhotsk apparently ceased. It is established that the Deryugin basin was formed at the place of ancient deep trench, and Sakhalin basin is located above the ancient (Late Cretaceous- Paleogene) subduction zone. So, the Late Cretaceous- Paleogene rocks of the North Sakhalin sedimentary basin formed in the conditions of back-arc basin may be favorable for generation, accumulation and conservation of hydrocarbons. Keywords: subduction zone, geodynamics, sakhalin
IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSW001 Oral Presentation 2397 Tomographic Inversion of Local P and S Data for Structure below the Toba Caldera Complex in North Sumatra Prof. Sri Widiyantoro Geophysics Bandung Institute of Technology IASPEI Wandono We have conducted a tomographic imaging for the Toba caldera, a 30 km x 90 km topographic depression, located in North Sumatra that represents one of the largest Quaternary calderas in the world. We estimate the 3D P- and S-wave velocity structures beneath the caldera complex using arrival time data of local earthquakes recorded by a 40-station seismic network which had been operated for 4 months (data by courtesy of a PASSCAL program) combined with data from a local network operated by BMG. The resulting tomographic images reveal the presence of pronounced low P and S velocity anomalies that are likely to map the distribution of magma within this subduction-related volcanic system. In the upper 10 km of crust the largest low-velocity region underlies a part of the great Sumatran fault and the southern part of the Toba depression and coincides with a gravity low centered over the regional uplift of a resurgent dome. The imaged low-velocity anomalies extending down to about 100 km depth may be related to the potency of a remaining supervolcano below the study region which will need further investigation. Keywords: toba caldera, tomography, supervolcano
- Page 675 and 676: IUGG XXIV General Assembly July 2-1
- Page 677 and 678: IUGG XXIV General Assembly July 2-1
- Page 679 and 680: IUGG XXIV General Assembly July 2-1
- Page 681 and 682: IUGG XXIV General Assembly July 2-1
- Page 683 and 684: IUGG XXIV General Assembly July 2-1
- Page 685 and 686: IUGG XXIV General Assembly July 2-1
- Page 687 and 688: IUGG XXIV General Assembly July 2-1
- Page 689 and 690: IUGG XXIV General Assembly July 2-1
- Page 691 and 692: IUGG XXIV General Assembly July 2-1
- Page 693 and 694: IUGG XXIV General Assembly July 2-1
- Page 695 and 696: IUGG XXIV General Assembly July 2-1
- Page 697 and 698: IUGG XXIV General Assembly July 2-1
- Page 699 and 700: IUGG XXIV General Assembly July 2-1
- Page 701 and 702: IUGG XXIV General Assembly July 2-1
- Page 703 and 704: IUGG XXIV General Assembly July 2-1
- Page 705 and 706: IUGG XXIV General Assembly July 2-1
- Page 707 and 708: IUGG XXIV General Assembly July 2-1
- Page 709 and 710: IUGG XXIV General Assembly July 2-1
- Page 711 and 712: IUGG XXIV General Assembly July 2-1
- Page 713 and 714: IUGG XXIV General Assembly July 2-1
- Page 715 and 716: IUGG XXIV General Assembly July 2-1
- Page 717 and 718: IUGG XXIV General Assembly July 2-1
- Page 719 and 720: IUGG XXIV General Assembly July 2-1
- Page 721 and 722: IUGG XXIV General Assembly July 2-1
- Page 723 and 724: IUGG XXIV General Assembly July 2-1
- Page 725: IUGG XXIV General Assembly July 2-1
- Page 729 and 730: IUGG XXIV General Assembly July 2-1
- Page 731 and 732: IUGG XXIV General Assembly July 2-1
- Page 733 and 734: IUGG XXIV General Assembly July 2-1
- Page 735 and 736: IUGG XXIV General Assembly July 2-1
- Page 737 and 738: IUGG XXIV General Assembly July 2-1
- Page 739 and 740: IUGG XXIV General Assembly July 2-1
- Page 741 and 742: IUGG XXIV General Assembly July 2-1
- Page 743 and 744: IUGG XXIV General Assembly July 2-1
- Page 745 and 746: IUGG XXIV General Assembly July 2-1
- Page 747 and 748: IUGG XXIV General Assembly July 2-1
- Page 749 and 750: IUGG XXIV General Assembly July 2-1
- Page 751 and 752: IUGG XXIV General Assembly July 2-1
- Page 753 and 754: IUGG XXIV General Assembly July 2-1
- Page 755 and 756: IUGG XXIV General Assembly July 2-1
- Page 757 and 758: IUGG XXIV General Assembly July 2-1
- Page 759: Published and Distributed by USMA 2
IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy<br />
(S) - <strong>IASPEI</strong> - International Association of Seismology and Physics of the Earth's<br />
Interior<br />
JSW001 Oral Presentation 2397<br />
Tomographic Inversion of Local P and S Data for Structure below the Toba<br />
Caldera Complex in North Sumatra<br />
Prof. Sri Widiyantoro<br />
Geophysics Bandung Institute of Technology <strong>IASPEI</strong><br />
Wandono<br />
We have conducted a tomographic imaging for the Toba caldera, a 30 km x 90 km topographic<br />
depression, located in North Sumatra that represents one of the largest Quaternary calderas in the<br />
world. We estimate the 3D P- and S-wave velocity structures beneath the caldera complex using arrival<br />
time data of local earthquakes recorded by a 40-station seismic network which had been operated for 4<br />
months (data by courtesy of a PASSCAL program) combined with data from a local network operated by<br />
BMG. The resulting tomographic images reveal the presence of pronounced low P and S velocity<br />
anomalies that are likely to map the distribution of magma within this subduction-related volcanic<br />
system. In the upper 10 km of crust the largest low-velocity region underlies a part of the great<br />
Sumatran fault and the southern part of the Toba depression and coincides with a gravity low centered<br />
over the regional uplift of a resurgent dome. The imaged low-velocity anomalies extending down to<br />
about 100 km depth may be related to the potency of a remaining supervolcano below the study region<br />
which will need further investigation.<br />
Keywords: toba caldera, tomography, supervolcano
Change language