Spatial variations of b-values in the subduction zone of Central America
Frequency-magnitude distribution along the Mid-American Trench (MAT) has been studied by means of 2345 earthquakes during the period 1964-1994. We used the regional MIDAS catalogue with a magnitude of completeness of 4.2. To resolve the b-value as a function of depth (one dimensional approach), we a...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Universidad Nacional Autónoma de México, Instituto de Geofísica
2003-04-01
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| Series: | Geofísica Internacional |
| Subjects: | |
| Online Access: | http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/2003/04/monterroso.pdf |
| _version_ | 1797727178592354304 |
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| author | Ota Kulhánek David A. Monterroso |
| author_facet | Ota Kulhánek David A. Monterroso |
| author_sort | Ota Kulhánek |
| collection | DOAJ |
| description | Frequency-magnitude distribution along the Mid-American Trench (MAT) has been studied by means of 2345 earthquakes during the period 1964-1994. We used the regional MIDAS catalogue with a magnitude of completeness of 4.2. To resolve the b-value as a function of depth (one dimensional approach), we applied vertically sliding windows containing a constant number of events. To obtain more details in the b distribution, we projected catalogue hypocenters in three selected regions (approximately Guatemala and El Salvador, Nicaragua, Costa Rica), onto planes perpendicular to the trench. The b-values were calculated in sliding cylindrical volumes (two-dimensional approach) containing a constant number of earthquakes and centered at nodes of a 5 km x 5 km grid. The b-value varies significantly along a large part of MAT. High b-values were identified in the upper part of the slab at depths of 80-110 km beneath Guatemala-El Salvador and at depths 130-170 km beneath Nicaragua. Anomalous (high) b-values in the lower part of the slab were located at depths of 50-90 km and 50-160 km beneath Guatemala-El Salvador and Nicaragua, respectively. Anomalies observed at the upper part of the slab may be related to dehydration and successive increase in pore pressure in the down-going lithosphere, which may generate volcanism above the anomalies in the upper part of the slab. Anomalies on the lower surface of the Wadati-Benioff zone are likely to be associated with high thermal gradients between the slab and mantle. |
| first_indexed | 2024-03-12T10:56:06Z |
| format | Article |
| id | doaj.art-0ed7e0a40d2d474ab3601df0863f371e |
| institution | Directory Open Access Journal |
| issn | 0016-7169 |
| language | English |
| last_indexed | 2024-03-12T10:56:06Z |
| publishDate | 2003-04-01 |
| publisher | Universidad Nacional Autónoma de México, Instituto de Geofísica |
| record_format | Article |
| series | Geofísica Internacional |
| spelling | doaj.art-0ed7e0a40d2d474ab3601df0863f371e2023-09-02T06:15:43ZengUniversidad Nacional Autónoma de México, Instituto de GeofísicaGeofísica Internacional0016-71692003-04-01424575587Spatial variations of b-values in the subduction zone of Central AmericaOta KulhánekDavid A. MonterrosoFrequency-magnitude distribution along the Mid-American Trench (MAT) has been studied by means of 2345 earthquakes during the period 1964-1994. We used the regional MIDAS catalogue with a magnitude of completeness of 4.2. To resolve the b-value as a function of depth (one dimensional approach), we applied vertically sliding windows containing a constant number of events. To obtain more details in the b distribution, we projected catalogue hypocenters in three selected regions (approximately Guatemala and El Salvador, Nicaragua, Costa Rica), onto planes perpendicular to the trench. The b-values were calculated in sliding cylindrical volumes (two-dimensional approach) containing a constant number of earthquakes and centered at nodes of a 5 km x 5 km grid. The b-value varies significantly along a large part of MAT. High b-values were identified in the upper part of the slab at depths of 80-110 km beneath Guatemala-El Salvador and at depths 130-170 km beneath Nicaragua. Anomalous (high) b-values in the lower part of the slab were located at depths of 50-90 km and 50-160 km beneath Guatemala-El Salvador and Nicaragua, respectively. Anomalies observed at the upper part of the slab may be related to dehydration and successive increase in pore pressure in the down-going lithosphere, which may generate volcanism above the anomalies in the upper part of the slab. Anomalies on the lower surface of the Wadati-Benioff zone are likely to be associated with high thermal gradients between the slab and mantle.http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/2003/04/monterroso.pdfb-valuesubduction zoneCentral Americavolcanic chainstress |
| spellingShingle | Ota Kulhánek David A. Monterroso Spatial variations of b-values in the subduction zone of Central America Geofísica Internacional b-value subduction zone Central America volcanic chain stress |
| title | Spatial variations of b-values in the subduction zone of Central America |
| title_full | Spatial variations of b-values in the subduction zone of Central America |
| title_fullStr | Spatial variations of b-values in the subduction zone of Central America |
| title_full_unstemmed | Spatial variations of b-values in the subduction zone of Central America |
| title_short | Spatial variations of b-values in the subduction zone of Central America |
| title_sort | spatial variations of b values in the subduction zone of central america |
| topic | b-value subduction zone Central America volcanic chain stress |
| url | http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/2003/04/monterroso.pdf |
| work_keys_str_mv | AT otakulhanek spatialvariationsofbvaluesinthesubductionzoneofcentralamerica AT davidamonterroso spatialvariationsofbvaluesinthesubductionzoneofcentralamerica |