Feedback Between Dike Intrusions, Opening in the Deep Rift Zones, and Flank Motion, Suggested by the Numerical Modeling of Geodetic Data Spanning 1993-1997 at Kilauea Volcano
Abstract
Interferometric Synthetic Aperture Radar (InSAR) from the JERS-1 satellite reveals a maximum of 30 cm of line-of-sight displacement occurring near Makaopuhi Crater associated with an intrusion in the middle East Rift Zone (ERZ) at Kilauea in 1993. Using a 3D-Mixed Boundary Element Method, the best-fit model for the deformation signal is a subvertical shallow dike. Although the dike did not rupture the surface, the magnitude of opening and location near Makaopuhi Crater are similar to other recent eruptive intrusions at Kilauea, like the 1997 and 2011 events. Our modeled dike also dips steeply to the south (away from the rift zone), which is a feature of all models of recent ERZ dike intrusions, as well as dikes exposed by erosion in inactive Hawaiian volcanoes. The modeled volume for the 1993 dike is 7.4 × 106 m3, which is small in comparison to the 1997, 2007, and 2011 dikes, but larger than the 1999 intrusion. In addition, a post-intrusion JERS-1 interferogram spanning 1993-1997 was analyzed. Our best fit numerical model for this 4-year period consists of opening of the deep rift zones (extending 3-8.5 km depth) by about 0.5 m triggering slip on a sub-horizontal detachment fault connected to the seaward side of the vertical deep rift zones. Using a static stress changes analysis, we classify the 1993 dike intrusion as a passive intrusion, similar to those that occurred in 1997 and 1999. The persistent deep rifting and seaward sliding of the south flank along the décollement creates a high tensile-stress region in the shallow part of the ERZ that leads to failure of the crust above the deep rift zones, allowing "opportunistic" dike intrusions in the region. Passive intrusions make forecasting difficult, because they are not necessarily preceded by inflation or increase in seismicity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V43J0270W
- Keywords:
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- 8499 General or miscellaneous;
- VOLCANOLOGY