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http://hdl.handle.net/10136/220
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| Title: | Analysis of a recent swarm activity along the Hot Springs-Montosa fault near Socorro, NM |
| Authors: | Petrilla, Cecilia C. |
| Issue Date: | 14-Jan-2009 |
| Abstract: | Socorro, New Mexico is located within the geologically complex, central segment of the Rio Grande rift. A mid-crustal magma body is known to exist at depth and most microearthquake activity in the Socorro area occurs in swarms.
HYPO71 solutions for swarm activity during September, 1985 and April-May, 1986 indicate focal depth activity between 7.00 and 14.00 km with peak activity between 9.00 and 9.50 km. Statistical error analysis for 41 A/A and A/B events from the April-May, 1986 swarm indicate the standard deviation error in depth determinations resulting from errors inherent in reading analog recordings is equivalent to the uncertainty in focal depth (ERZ) as determined by HYPO71.
Epicenters for the September, 1985 and April-May, 1986 swarms and a magnitude 3.4 event on August 16, 1985 are located near the Hot Springs-Montosa strike-slip fault zone. The well-constrained composite fault plane solution for the April-May, 1986 swarm very possible indicates left-lateral, strike-slip movement along this fault. Analysis of the poorly constrained fault plane solutions for the August 16, 1985 event and for the September, 1985 swarm may provide supporting evidence for activity along the fault.
Focal mechanism analysis for a swarm of April 21, 1987, located near the Hot Springs-Montosa fault, but south of the September, 1985 and April-May, 1986 swarms, indicates normal faulting.
The strike-slip focal mechanism and a change in the orientations of the T axes near the Hot Springs-Montosa fault may combine to indicate that the geologic stress field in the Socorro area has changed. |
| URI: | http://hdl.handle.net/10136/220 |
| Appears in Collections: | Independent Studies
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| Petrilla, Cecilia C..pdf | | 29068Kb | Adobe PDF | View/Open |
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