12/06/2002

GEOSCOPE in 2002

Geneviève Roult

FDSN meetingHawaii, June 2002

12/06/2002

Meeting in Paris on March 25th, 2002‘ GEOSCOPE: its future’

Participants:P. Vidal, J. Ludden, directors of INSU National Institute of Sciences of Universe (part of CNRS National Center of Scientific Research,A. Galdeano, representative of INSU,C. Jaupart, director of IPGP Institute of Physics of the Earth of Paris, P. Bernard, M. Cara, S. Chevrot, P. Dayre, A. Deschamps, M. Granet, A. Hirn, J.C Lépine, J.J. Lévêque, R. Louat, A. Mocquet, G. Poupinet, L. Riveira, G. Roult, A. Souriau, E. Stutzmann, J.P. Vilotte, J. Virieux, seismologists of the different french institutes (Paris, Strasbourg, Grenoble, Nice, Toulouse, Nantes),S. Barrientos, representative of CTBTO,F. Schindele, B. Feignier, representatives of CEA/DASE,T. Van Eck, representative of the european Data Center ORFEUS, T. Ahern, representative of the FDSN and the IRIS Consortium.

Some points discussed at this meeting are presented on the following pages.

G.Roult

G.Roult

12/06/2002

DATA DISTRIBUTION

1 - CD-ROMs 

36 CD-ROMs spanning the period from March 1982 to July 1992, have been created. These CD-ROMs have been distributed worldwide.

2 - Anonymous ftp site (ftp://geoscope.ipgp.jussieu.fr)

Events with Ms>6.3 or of particular interest are uploaded from 17 stations by phone line. The data are available within one or two days. 

DATA DISTRIBUTION3 - WWW server (http://geoscope.ipgp.jussieu.fr)

Products : Station book Instrument responsesNoise level plots Plots and data files of recent eventsReal-time data from SSB station (in France) Archived data files

 

4 - NetDC (Networked Data Centers) procedure at netdc@ipgp.jussieu.fr 

The best way to get information from all Networked Data Centers, Iris, UC Berkeley, Geoscope, Orfeus and Geofon.

You can retrieve: the INVentory the instrumental RESPonses the DATA directly to your disk

Number of data requests in 2001 (NetDC procedure)

Data volume through NetDC procedure (last quarter)

Archive traffic / monthGeoscope data requests

Remark: data are distributed in SEED format. For the equivalence in SAC format multiply the volume by 4.

Geoscope DC

Web site

110

2 000

1.6 Gbytes

Geoscope DC NetDC

procedure

655

110 000

12 Gbytes

through thWebat Geoscopt

requests

seismograms

volume

IRIS_DMC NetDC

procedure

150

6570

0.33 Gbytes

The Geoscope stations are very important thanks to their original geographical situation. Example:

azimuthal distribution of the 1995 Jan 15th Kobe event

Message to the FDSN: Rayleigh wave train clipping at some far stations,

example Kobe event, OBN station

INU 202 km

MDJ 1207 km

SSE 1350 km

ENH 2441 km

OBN 7429 km

G.Patau/G.Roult

12/06/2002

What does GEOSCOPE provide?

I - A unique station distribution that permits :

1.Better azimuthal coverage seismic source studies

 2.Ray paths not provided by other FDSN stations tomographic studies

 3. Detection and location of events that would otherwise be overlooked in bulletins of global seismicity, thanks to our Southern Hemisphere stations

  

12/06/2002

The near future

1) Transfer the maintenance of some stations from IPGP to local authorities.

Why? There are now many stations in the Northern Hemisphere, and sometimes at the same location.

The black crosses on the next figure correspond to stations for which we’ll reconsider that problem.

12/06/2002 G.Roult/S.Barbier

12/06/2002

The near future

1) Transfer the maintenance of some stations from IPGP to local authorities

2) Install new sites that improve the global network (SEY and VOR in Russia)

Why? SEY and VOR are located on the same meridians than frequent large events. The PKP waves provided by such polar paths will help our knowledge on anisotropy. See next figure.

G.Roult

12/06/2002

The near future

1) Transfer the maintenance of some stations from IPGP to local authorities.

2) Install new sites that improve the global network (SEY and VOR in Russia).

3) Standardize the acquisition chain (sensors, digitizers)

We’ll keep our STS1 seismometers as long as possible

We started to replace our old Streckeisen digitizers by Quanterra ones (Q4120 and Q330).

12/06/2002

The near future

1) Transfer the maintenance of some stations from IPGP to local authorities.

2) Install new sites (SEY and VOR in Russia).

3) Standardize the acquisition chain (sensors and digitizers).

4) Install microbarometers and thermometers in all stations.

Why? To improve the signal to noise ratio by subtracting the atmospheric pressure effect. 7 Geoscope stations are now equipped with microbarometers. See next figure.

G.Roult/S.Barbier

Why microbarometers?

Litterature: Zürn & Widmer (1995), Beauduin (1996)

New Guinea event of 1996 Feb 17th (Ms=8.1). Thin and thick lines correspond respectively to spectra before and after atmospheric pressure correction (Roult and Crawford, 2000 )

12/06/2002

The near future

1) Transfer the maintenance of some stations from IPGP to local authorities...

2) Install new sites at high latitudes (VOR and SEY) ..

3) Standardize the acquisition chain..

4) Install microbarometers and thermometers...

5) Cooperate with the french military agency CEA/DASE to get real-time data at some stations (we disagree with the CTBTO solution).

Five stations are involved by CTBTO. On the next figure the 3 red dots correspond to the near future.

G.Roult

12/06/2002

Comparison ofCTBTO and DASE solutions

CTBTO

. Segmented data

. High gain, frequent clipped records

. Availability ???

DASE

. Continuous data at 20sps. Low gain in order to get no clipped records in case of large near events

12/06/2002

The near future

1) Transfer the maintenance of some stations …

2) Install new sites at high latitudes..

3) Standardize the acquisition chain ..

4) Install microbarometers and thermometers...  5) Cooperate with CEA/DASE/CTBTO to get real-time data..

6) Adopt the best adapted solution for every station to get real-time data.

12/06/2002

WHY REAL TIME ?

Real time is necessary for quality control, in order to:

- know rapidly if the instruments are working - check time corrections… - follow the instrument responses - react in case of problems - distribute rapidly correct data…… - help every Data Center to determine more precise CMTs - satisfy impatient scientists

We are developping an automatic data process filling some regulations, acquisition, control, documentation, format data archiving

12/06/2002

The near future

1) Transfer the maintenance of some stations .....2) Install new sites at high latitudes..3) Standardize the acquisition chain..4) Install microbarometers in all stations..5) Cooperate with DASE/CTBT to get real-time data.. 6) Adopt the best adapted real-time solution ...

7) Obtain a better path coverage of the Earth by cooperating with all ocean bottom projects.

12/06/2002

GEOSCOPE and the ocean bottom conquest

At the present time, different concepts are being analysed

in Japan, in Europ (France,…)

We’ll cooperate with any operational project in order to install a few stations on the ocean bottom floor, to provide a better instrumental coverage of the Earth.