Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases
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| Formato: | Artículo científico |
| Lenguaje: | en |
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Universidad Nacional Autónoma de México
2005
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| _version_ | 1876440599144431616 |
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| author | Marta Galindo |
| author_facet | Marta Galindo |
| contents | Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases Marta Galindo Arturo Iglesias Luis F. Terán José L. Barreda Carlos Coba Raúl W. Valenzuela Javier F. Pacheco Ciencias de la Tierra Test T phases Pacific ocean Socorro Island Ban Treaty (CTBT) We carried out a seismic survey and installed five portable, broadband seismometers in the southeastern corner of SocorroIsland during June 1999. Power spectral densities for all five sites were relatively noisy when compared to reference curvesaround the world. Power spectral densities remain constant regardless of the time of day, or the day of the week. Cultural noise atthe island is very small. Quiet and noisy sites were identified to determine the best location of the T phase station to be installedjointly by the Universidad Nacional Autónoma de México and the Comprehensive Nuclear-Test-Ban Treaty Organization. Duringthe survey six earthquakes were recorded at epicentral distances between 42 km and 2202 km, with magnitudes between 2.8 and7.0. Two small earthquakes (Mc = 2.8 and 3.3) occurred on the Clarión Fracture Zone. The four largest and more distant earthquakesproduced T waves. One T wave from an epicenter near the coast of Guatemala had a duration of about 100 s and afrequency content between 2 and 8 Hz, with maximum amplitude at about 4.75 Hz. The Tehuacán earthquake of June 15, 1999 (Mw= 7.0) produced arrivals of P→ T and S → T waves, with energy between 2 Hz and 3.75 Hz. The earthquake occurred inland withinthe subducted Cocos plate at a depth of 60 km; a significant portion of the path was continental. Seismic P and S waves probablypropagated upward in the subducted slab, and were converted to acoustic energy at the continental slope. Total duration of the Tphase is close to 500 s and reaches its maximum amplitude about 200 s after the P → T arrival. The T wave contains energy atfrequencies between 2 and 10 Hz and reaches its maximum amplitude at about 2.5 Hz. T phases were also recorded from twoearthquakes in Guerrero, Mexico and in the Rivera Fracture Zone. 2005 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56844103 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.1 Vol.44 |
| format | Artículo científico |
| id | redalyc_56844103 |
| institution | Redalyc |
| language | en |
| publishDate | 2005 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases Marta Galindo Ciencias de la Tierra Test T phases Pacific ocean Socorro Island Ban Treaty (CTBT) Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases Marta Galindo Arturo Iglesias Luis F. Terán José L. Barreda Carlos Coba Raúl W. Valenzuela Javier F. Pacheco Ciencias de la Tierra Test T phases Pacific ocean Socorro Island Ban Treaty (CTBT) We carried out a seismic survey and installed five portable, broadband seismometers in the southeastern corner of SocorroIsland during June 1999. Power spectral densities for all five sites were relatively noisy when compared to reference curvesaround the world. Power spectral densities remain constant regardless of the time of day, or the day of the week. Cultural noise atthe island is very small. Quiet and noisy sites were identified to determine the best location of the T phase station to be installedjointly by the Universidad Nacional Autónoma de México and the Comprehensive Nuclear-Test-Ban Treaty Organization. Duringthe survey six earthquakes were recorded at epicentral distances between 42 km and 2202 km, with magnitudes between 2.8 and7.0. Two small earthquakes (Mc = 2.8 and 3.3) occurred on the Clarión Fracture Zone. The four largest and more distant earthquakesproduced T waves. One T wave from an epicenter near the coast of Guatemala had a duration of about 100 s and afrequency content between 2 and 8 Hz, with maximum amplitude at about 4.75 Hz. The Tehuacán earthquake of June 15, 1999 (Mw= 7.0) produced arrivals of P→ T and S → T waves, with energy between 2 Hz and 3.75 Hz. The earthquake occurred inland withinthe subducted Cocos plate at a depth of 60 km; a significant portion of the path was continental. Seismic P and S waves probablypropagated upward in the subducted slab, and were converted to acoustic energy at the continental slope. Total duration of the Tphase is close to 500 s and reaches its maximum amplitude about 200 s after the P → T arrival. The T wave contains energy atfrequencies between 2 and 10 Hz and reaches its maximum amplitude at about 2.5 Hz. T phases were also recorded from twoearthquakes in Guerrero, Mexico and in the Rivera Fracture Zone. 2005 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56844103 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.1 Vol.44 |
| title | Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases |
| topic | Ciencias de la Tierra Test T phases Pacific ocean Socorro Island Ban Treaty (CTBT) |
| url | https://www.redalyc.org/articulo.oa?id=56844103 |