HA05 hydroacoustic station
(French West Indies) of the CTBTO (Comprehensive Test-Ban Treaty Organization)

The International Monitoring System for the Comprehensive Test-Ban Treaty (IMS/CTBT) comprises, among others, 11 hydroacoustic stations providing continuous recordings, including the HA05 T-phase station in the French West Indies and the HA04 station on Crozet Island.

The HA05 station comprises two facilities:


H05N1, located on Desirade Island just east of Guadeloupe, detects T-waves from the middle and north of the Atlantic Ocean.


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Desirade Island.


H05S1, located to the south of Martinique, detects T-waves from the middle and south of the Atlantic Ocean.

The HA05 station also monitors seismicity along the Antilles subduction zone.

Earthquakes in oceanic plates and underwater or underground explosions occurring in the vicinity of a sea or ocean generate hydroacoustic waves. These waves, propagating through the ocean, sometimes over thousands of kilometers, are recorded by underwater sensors (hydrophones) or coastal seismic stations (T-wave stations).


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Section of the HA05 seismic vault


The station site location was chosen following a survey conducted in May 1999. The station was set up in October 1999 and certified by the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization) in March 2002.


Seismic vault and GPS antenna mast.


The HA05 station is equipped with 3 high-sensitivity short-period seismometers:

One ZM 500 short-period seismometer.


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Inside the vault.



Two HM 500 short-period seismometers.



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HA05 station layout.
 
Acquisition
 
Signals from short-period seismometers are recorded at a sampling frequency of 100 points per second. Samples are dated by a GPS-synchronized clock.

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VSAT antenna and solar panels.
 
Transmission
 
Signals are transmitted continuously by VSAT (Very Small Aperture Terminal) satellite link to the French National Data Center of the DASE, then to the CTBTO (Comprehensive Test-Ban Treaty Organization) International Data Center in Vienna.