360120

_{(was 1600-12)}
L'Observatoire Volcanologique de la Montagne Pel饼br />(Institut de Physique du Globe de Paris)
Morne des Cadets
Fond St Denis
97250 Saint Pierre
Martinique
France

Staff :

Dr Val鲩e Clouard - Geophysics
Dr Cyril Aubaud - Geochemistry
Jean-Marie Saurel - Electronics engineer
Cyril Vidal - Computer engineer
Stephen Roselia - Computer engineer
David Melezan - Electronics technician
Fr餩ric Jadelus - Electronics technician
Jean-Marc Lavenaire - Computer technician
Jean-Gilles Gabriel - Technical assistant
Marie-Am鬩e Unn-Toc - Secretary, Administration
Myrtha Jean-Baptiste - Secretary assistant
Pascale Longaygue - Administration
Edith Chenor

The Volcanological and Seismological Observatory of Martinique (OVSM) is one of the three French volcano observatories with Guadeloupe and Piton de la Fournaise (R鵮ion) observatories. The headquarters of French volcanological and seismological observatories is at the Institut de Physique du Globe de Paris (IPGP).

The Observatory of Martinique has operated since 1903, just after the Montagne Pel饠1902 eruption. Alfred Lacroix set up the first seismometers, two Bosch-Omori instruments, in 1903. In 1926, seismometers were installed in Fort-de-France. A new observatory was built in 1935 together with a 20-tons Quervain-Piccard heavy pendulum seismometer, which was operated from 1936 to 1975. In the 1970s, a modern network of seismometer with radio transmission was set up, and regularly up-graded.

Monitoring networks:

The monitoring networks set up on La Martinique island are designed to record the activity directly linked to the Montagne Pel饠volcano but also to the subduction of the Atlantic plate beneath the Caribbean one, which can give rise to major earthquakes.

a)   Seismic network
8 short-period, medium band and broadband seismic stations (respectively 6, 1 and 1) are operated around the volcano and 8 medium band to broadband seismic stations (4 of each) are spread all around the island for local to regional seismicity monitoring. This network is completed by 12 accelerometers that record ground acceleration mainly in populated area. 8 of those accelerometers are part of the R鳥au Acc鬩rom鴲ique Permanent, the French national accelerometric network. 

b)   Deformation network
A total of 4 continuous GPS stations monitor the deformations on the volcano itself, while 4 others stations all over the island can be used for tectonic studies. This network is also completed with a borehole instrumented with three inclinometers at different depths. 

c)   Geochemistry
Each month, hot spring waters and hot drill hole waters are collected for analysis. In situ measurements of pH, temperature and conductivity are made in the field. Alkalinity and major dissolved ions are measured at the observatory with by ion chromatography.

A data-logger at the bottom of the drill hole records temperature, water level, pH and conductivity.

d)   Lahar monitoring
In the Pr꣨eur River, on the , the observatory operates a tip-wire alert system and an Acoustic Flow Monitor (AFM, USGS) network to survey the occurrence of lahars in the river.

Real-time processing and database:

All the data acquired by the different instruments are sent via several technologies to the observatory:

-         VSAT communications;
-         Wifi Ethernet links;
-         serial over radio links;
-         analog radio links;
-         telephone lines;
-         GSM.

The data, together with data from neighbour networks, are processed and archived in real-time within a robust, redundant and modern computer system that hosts several virtual computers and terabytes of data storage. All the seismic data are archived using miniSEED format, GPS data uses rinex format and the other data mainly use ASCII text formats.

Seismic data are processed in real-time with Earthworm to produce detections and real-time location. The results are stored and managed in a SeisComP3 database, which allows several users to connect and revise the results. Finally, an internal website, WebObs, is used to display in a common place all the information from the networks on the island, giving a view of the activity at a glance.