Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array
The seismicity of the South Atlantic Ocean has been recorded by the MARCHE network of 4 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed south of the Azores Plateau between 32° and 39°N from July 2005...
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ftsouthampton:oai:eprints.soton.ac.uk:382723 2023-08-27T04:11:59+02:00 Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array Perrot, Julie Cevatoglu, Melis Cannat, Mathilde Escartin, Javier Maia, Marcia Tisseau, Chantal Dziak, Robert Goslin, Jean 2013-04 https://eprints.soton.ac.uk/382723/ English eng Perrot, Julie, Cevatoglu, Melis, Cannat, Mathilde, Escartin, Javier, Maia, Marcia, Tisseau, Chantal, Dziak, Robert and Goslin, Jean (2013) Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array. EGU General Assembly 2013, Vienna, Austria. 07 Apr 2013 - 12 Apr 2017 . Conference or Workshop Item NonPeerReviewed 2013 ftsouthampton 2023-08-03T22:21:15Z The seismicity of the South Atlantic Ocean has been recorded by the MARCHE network of 4 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed south of the Azores Plateau between 32° and 39°N from July 2005 to August 2008. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction from a magnitude completeness level (Mc) of ~4.3 for MAR events recorded by the land-based seismic networks to Mc=2.1 using this hydrophone array. A spatio-temporal analysis has been performed among the 5600 events recorded inside the MARCHE array. Most events are distributed along the ridge between lat. 39°N on the Azores Platform and the Rainbow (36°N) segment. In the hydrophone catalogue, acoustic magnitude (Source Level, SL) is used as a measure of earthquake size. The source level above which the data set is complete is SLc=205 dB. We look for seismic swarms using the cluster software of the SEISAN package. The criterion used are a minimum SL of 210 to detect a possible mainshock, and a radius of 30 km and a time window of 40 days after this mainshock (Cevatoglu, 2010, Goslin et al., 2012). 7 swarms with more than 15 events are identified using this approach between 32°et 39°N of latitude. The maximum number of earthquake in a swarm is 57 events. This result differs from the study of Simao et al. (2010) as we processed a further year of data and selected sequences with fewer events. Looking at the distribution of the SL as a function of time after the mainshock, we discuss the possible mechanism of these earthquakes : tectonic events with a "mainshock-aftershock" distribution fitting a modified Omori law or volcanic events showing more constant SL values. We also present the geophysical setting of these 7 swarms, using gravity, bathymetry, and available local geological data. This study illustrates the potential of hydrophone data to monitor segment-scale ridges ... Conference Object South Atlantic Ocean University of Southampton: e-Prints Soton Mid-Atlantic Ridge |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
The seismicity of the South Atlantic Ocean has been recorded by the MARCHE network of 4 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed south of the Azores Plateau between 32° and 39°N from July 2005 to August 2008. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction from a magnitude completeness level (Mc) of ~4.3 for MAR events recorded by the land-based seismic networks to Mc=2.1 using this hydrophone array. A spatio-temporal analysis has been performed among the 5600 events recorded inside the MARCHE array. Most events are distributed along the ridge between lat. 39°N on the Azores Platform and the Rainbow (36°N) segment. In the hydrophone catalogue, acoustic magnitude (Source Level, SL) is used as a measure of earthquake size. The source level above which the data set is complete is SLc=205 dB. We look for seismic swarms using the cluster software of the SEISAN package. The criterion used are a minimum SL of 210 to detect a possible mainshock, and a radius of 30 km and a time window of 40 days after this mainshock (Cevatoglu, 2010, Goslin et al., 2012). 7 swarms with more than 15 events are identified using this approach between 32°et 39°N of latitude. The maximum number of earthquake in a swarm is 57 events. This result differs from the study of Simao et al. (2010) as we processed a further year of data and selected sequences with fewer events. Looking at the distribution of the SL as a function of time after the mainshock, we discuss the possible mechanism of these earthquakes : tectonic events with a "mainshock-aftershock" distribution fitting a modified Omori law or volcanic events showing more constant SL values. We also present the geophysical setting of these 7 swarms, using gravity, bathymetry, and available local geological data. This study illustrates the potential of hydrophone data to monitor segment-scale ridges ... |
format |
Conference Object |
author |
Perrot, Julie Cevatoglu, Melis Cannat, Mathilde Escartin, Javier Maia, Marcia Tisseau, Chantal Dziak, Robert Goslin, Jean |
spellingShingle |
Perrot, Julie Cevatoglu, Melis Cannat, Mathilde Escartin, Javier Maia, Marcia Tisseau, Chantal Dziak, Robert Goslin, Jean Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array |
author_facet |
Perrot, Julie Cevatoglu, Melis Cannat, Mathilde Escartin, Javier Maia, Marcia Tisseau, Chantal Dziak, Robert Goslin, Jean |
author_sort |
Perrot, Julie |
title |
Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array |
title_short |
Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array |
title_full |
Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array |
title_fullStr |
Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array |
title_full_unstemmed |
Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array |
title_sort |
seismicity and accretion processes along the mid-atlantic ridge south of the azores using data from the marche autonomous hydrophone array |
publishDate |
2013 |
url |
https://eprints.soton.ac.uk/382723/ |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_relation |
Perrot, Julie, Cevatoglu, Melis, Cannat, Mathilde, Escartin, Javier, Maia, Marcia, Tisseau, Chantal, Dziak, Robert and Goslin, Jean (2013) Seismicity and accretion processes along the Mid-Atlantic Ridge south of the Azores using data from the MARCHE autonomous hydrophone array. EGU General Assembly 2013, Vienna, Austria. 07 Apr 2013 - 12 Apr 2017 . |
_version_ |
1775355723272683520 |