| Abstract: | An array of 14 biaxial shallow-borehole tiltmeters (at 10-7 radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (>10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake. |
| Genre: | Article |
| ProdID: | 70011055 |
| Citation Author: | Johnston, M. J. S.; Mortensen, C. E. |
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| Citation End Page: | 1034 |
| Citation Issue: | 4168 |
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| Citation Language: | English |
| Citation Larger Work Title: | Science |
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| Citation Number Of Pages: | 4 |
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| Citation Search Results Text: | Tilt precursors before earthquakes on the San Andreas fault, California; 1974; Article; Journal; Science; Johnston, M. J. S.; Mortensen, C. E. |
| Citation Start Page: | 1031 |
| Citation Volume: | 186 |
| Citation Year: | 1974 |
| Type: | citation/reference |
| Text: | Tilt precursors before earthquakes on the San Andreas fault, California; 1974; Article; Journal; Science; Johnston, M. J. S.; Mortensen, C. E. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 1 Jan 1974 00:00 -0600 |
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