TY - JOUR
T1 - Geodetic constraints for the mechanism of Anatahan eruption of May 2003
AU - Watanabe, Tsuyoshi
AU - Tabei, Takao
AU - Matsushima, Takeshi
AU - Kato, Teruyuki
AU - Nakada, Setsuya
AU - Yoshimoto, Mitsuhiro
AU - Chong, Raymon
AU - Camacho, Juan Takai
N1 - Funding Information:
The authors thank the staff of the Emergency Management Office of the Northern Mariana Islands for their corporation in making field observations. Initial GPS data at Anatahan were obtained by J. Beavan and his colleagues. Comments by G. S. Mattioli and an anonymous reviewer helped improve the manuscript. Some figures were created with using Generic Mapping Tools ( Wessel and Smith, 1995 ). The research was supported by Grant-in-Aid for Scientific Research No.14380200 from the Japan Society for the Promotion of Science.
PY - 2005/8/15
Y1 - 2005/8/15
N2 - Anatahan Island is located at the southern end of the Mariana volcanic chain. On May 10, 2003, the eastern crater of the island erupted for the first time in recorded history. The Plinian eruption column reached an altitude as high as 13 km on May 11, and a thick layer of ash covered the island. The eruptive activity continued to June 2003, but most of the erupted material was expelled during the first week. The volcanic activity declined in the second half of 2003, but resumed in April 2004. In order to determine crustal deformation associated with the eruption, we conducted GPS measurements in July 2003 at a benchmark (ANAT) located approximately 7 km west-northwest of the active crater, where GPS campaign measurements had been repeated four times since 1992. In the period from January to July 2003 during the eruption, significant subsidence - as much as 21 cm - was detected, but horizontal movement was negligible. We began taking continuous GPS measurements at the same site in July 2003 to monitor the transient deformation that was probably associated with magma migration. To assess the spatial extent of the deformation more accurately, we established another permanent GPS site (ANA2) at a site approximately 3 km from the active crater in the northeastern part of the island in January 2004. The coordinates of this time series at ANAT probably show a change in trends at the beginning of 2004. Another subsidence of 2.8 cm and a westward motion of 2.1 cm were estimated to have occurred in the period from July to December 2003. This was followed by an uplift of 5.2 cm and movement in an eastward direction of 1.0 cm in the period from January to June 2004. We developed three preliminarily models of inflation/deflation sources for three different time periods. During the period from January to July 2003, a deformation source was located beneath the ANAT site and acted as a deflation source. Considering the gap in the GPS time series and errors in data (especially after July 2003), we expected that the deformation sources were located beneath the western part of Anatahan Island and not below the active crater.
AB - Anatahan Island is located at the southern end of the Mariana volcanic chain. On May 10, 2003, the eastern crater of the island erupted for the first time in recorded history. The Plinian eruption column reached an altitude as high as 13 km on May 11, and a thick layer of ash covered the island. The eruptive activity continued to June 2003, but most of the erupted material was expelled during the first week. The volcanic activity declined in the second half of 2003, but resumed in April 2004. In order to determine crustal deformation associated with the eruption, we conducted GPS measurements in July 2003 at a benchmark (ANAT) located approximately 7 km west-northwest of the active crater, where GPS campaign measurements had been repeated four times since 1992. In the period from January to July 2003 during the eruption, significant subsidence - as much as 21 cm - was detected, but horizontal movement was negligible. We began taking continuous GPS measurements at the same site in July 2003 to monitor the transient deformation that was probably associated with magma migration. To assess the spatial extent of the deformation more accurately, we established another permanent GPS site (ANA2) at a site approximately 3 km from the active crater in the northeastern part of the island in January 2004. The coordinates of this time series at ANAT probably show a change in trends at the beginning of 2004. Another subsidence of 2.8 cm and a westward motion of 2.1 cm were estimated to have occurred in the period from July to December 2003. This was followed by an uplift of 5.2 cm and movement in an eastward direction of 1.0 cm in the period from January to June 2004. We developed three preliminarily models of inflation/deflation sources for three different time periods. During the period from January to July 2003, a deformation source was located beneath the ANAT site and acted as a deflation source. Considering the gap in the GPS time series and errors in data (especially after July 2003), we expected that the deformation sources were located beneath the western part of Anatahan Island and not below the active crater.
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U2 - 10.1016/j.jvolgeores.2004.11.033
DO - 10.1016/j.jvolgeores.2004.11.033
M3 - Article
AN - SCOPUS:23844538248
SN - 0377-0273
VL - 146
SP - 77
EP - 85
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
IS - 1-3 SPEC. ISS.
ER -