| Abstract: | The Hengill region in SW Iceland is an unstable ridge-ridge-transform triple junction between an active and a waning segment of the mid-Atlantic spreading center and a transform that is transgressing southward. The triple junction contains active and extinct spreading segments and a widespread geothermal area. We evaluated shear-wave birefringence for locally recorded upper-crustal earthquakes using an array of 30 three-component digital seismographs. Fast-polarization directions, ??, are mostly NE to NNE, subparallel to the spreading axis and probably caused by fissures and microcracks related to spreading. However, there is significant variability in ?? throughout the array. The lag from fast to slow S is not proportional to earthquake depth (ray length), being scattered at all depths. The average wave-speed difference between qS1 and qS2 in the upper 2-5 km of the crust is 2-5%. Our results suggest considerable heterogeneity or strong S scattering. |
| Genre: | Article |
| ProdID: | 70018542 |
| Citation Author: | Evans, J. R.; Foulger, G. R.; Julian, B. R.; Miller, A. D. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | 458 |
| Citation Issue: | 5 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Geophysical Research Letters |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | 4 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Crustal shear-wave splitting from local earthquakes in the Hengill triple junction, southwest Iceland; 1996; Article; Journal; Geophysical Research Letters; Evans, J. R.; Foulger, G. R.; Julian, B. R.; Miller, A. D. |
| Citation Start Page: | 455 |
| Citation Volume: | 23 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Crustal shear-wave splitting from local earthquakes in the Hengill triple junction, southwest Iceland; 1996; Article; Journal; Geophysical Research Letters; Evans, J. R.; Foulger, G. R.; Julian, B. R.; Miller, A. D. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
| Publisher: | |
