HR: 0800h
AN: V21D-0656    [Abstracts]
TI: Ground deformation from dike development
AU: * Song, J
EM: jsong@usgs.gov
AF: Institute of Geology, China Earthquake Administration, Dewai Qijiahuozi, Beijing, 100029 China
AU: * Song, J
EM: jsong@usgs.gov
AF: Research Center of Geophysics Exploration, China Earthquake Administration, 104 Wenhua Road, Zhenzhou, 450003 China
AU: * Song, J
EM: jsong@usgs.gov
AF: Now at U S Geological Survey, 384 Woods Hole Road, Woods Hole, MA 02543 United States
AU: Liu, G
EM: bost1@263.net
AF: Institute of Geology, China Earthquake Administration, Dewai Qijiahuozi, Beijing, 100029 China
AU: Zhang, X
EM: xkzhang@public2.zz.ha.cn
AF: Research Center of Geophysics Exploration, China Earthquake Administration, 104 Wenhua Road, Zhenzhou, 450003 China
AB: We investigate the relationship between ground deformation from dike emplacement and geometries using analytical models. We used the free surface half space model of Coulomb 2.5. We varied four basic dike parameters: dip, depth of the top, depth of the bottom, and thickness of dilation. We present cross-sections to illustrate temporal vertical deformation. In vertical dike (dip 90o) models, vertical ground deformation increases while the dike develops upward, and the deformation pattern is symmetric about the dike, forming two peaks at both sides of the dike where the lateral extent of surface vertical deformation increases as the dike develops. For a non-vertical dike, vertical deformation is asymmetric about the dike and extends further laterally when compared to the vertical case. Deformation amplitude is greater as well. Surface expression is negligible when the depth of dike bottom is > 6km. Vertical deformation reaches 0 and is downward at the location where the dike will open on the surface. For models with dikes dipping > 45°, along a perpendicular bisector starting from center of the dike vertical deformation decreases on the dipping side of the dike to negative values and then back to positive values, forming a second peak. In models with dikes with dip less than 45°, vertical deformation is negative after the initial decrease near the dike location. Finally, vertical deformation increases when the thickness of dike dilation increases. These models can help guide the initial interpretation of leveling observations made in volcanic areas.
DE: 8419 Volcano monitoring (7280)
DE: 8434 Magma migration and fragmentation
DE: 8486 Field relationships (1090, 3690)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005