NEAREST 1st Annual Meeting 25-26 October, 2007 - Marralech

NEAREST NEAREST

WP4WP4

Leader: INGV Leader: INGV INGV Team:INGV Team: Laura BeranzoliLaura Beranzoli, Davide Embriaco, Paolo Favali, , Davide Embriaco, Paolo Favali,

Francesco Frugoni, Marco Lagalante, Nadia Lo Bue, Giuditta Francesco Frugoni, Marco Lagalante, Nadia Lo Bue, Giuditta Marinaro, Stephen Monna, Claudio ViezzoliMarinaro, Stephen Monna, Claudio Viezzoli

Summary

• General on WP4 and WP Tasks

• Status of the activity

• Mission details

• Present status of the experiment

ObjectivesObjectives

The WP is aimed at carrying out geophysical and The WP is aimed at carrying out geophysical and oceanographic measurements on the seafloor and in the oceanographic measurements on the seafloor and in the water column in the nearby of near-shore tsunamigenic water column in the nearby of near-shore tsunamigenic sources for the sources for the identifications of tsunami signalsidentifications of tsunami signals. .

The seafloor and water column measurements will be The seafloor and water column measurements will be performed performed by means of a deep seafloor multiparameter by means of a deep seafloor multiparameter observatoryobservatory of GEOSTAR type, developed in previous of GEOSTAR type, developed in previous EC projects and will be transmitted to shore in EC projects and will be transmitted to shore in real-real-timetime (some essential parameters). (some essential parameters).

WP4 - Tsunami signal detection General

Task 4.1 Definition of sensor requirements and sensor selection; Task 4.1 Definition of sensor requirements and sensor selection; requirements of the detection software (e.g., detection requirements of the detection software (e.g., detection algorithm, triggering threshold, messages).algorithm, triggering threshold, messages).

Task 4.2 Design and development of modifications (e.g., sensor Task 4.2 Design and development of modifications (e.g., sensor supports of the frame); design and development of the supports of the frame); design and development of the software.software.

Task 4.3 Integration of new sensors/devices and new software in Task 4.3 Integration of new sensors/devices and new software in the seafloor observatory, tests of the functionality in the seafloor observatory, tests of the functionality in

laboratory.laboratory.

Task 4.4 Preparation planning and implementation of a long-term Task 4.4 Preparation planning and implementation of a long-term (about 1 year) mission; cruises for deployment and (about 1 year) mission; cruises for deployment and

recovery. recovery.

Task 4.5 Data back-up, quality checks, preparation of the data Task 4.5 Data back-up, quality checks, preparation of the data base to be integrated with other data; pre-analysis of base to be integrated with other data; pre-analysis of ‘parent’ ‘parent’ tsunami signals.tsunami signals.

General

ISMAR-BO.ISMAR-BO. FFCUL, CSIC FFCUL, CSIC marine site selection and marine site selection and characterisation for the pilot experimentcharacterisation for the pilot experimenton the basis of the on the basis of the knowledge of the areaknowledge of the area

ISMAR-BOISMAR-BO cruises responsiblecruises responsible

AWI, UGR, IM AWI, UGR, IM requirements of sensor sampling rates requirements of sensor sampling rates

TFH TFH MODUS for the pilot experiment MODUS for the pilot experiment (deployment/recovery) (deployment/recovery)

INGVINGV Seafloor observatory (GEOSTAR) Seafloor observatory (GEOSTAR)

ISMARBO

FFCUL CSIC AWI UBO INGV TFH UGR IM CNRST XISTOS

H H M M Leader H H M

Partners involved WP4 Partners involved WP4 General

D10D10 definition of sensors’, software definition of sensors’, software requirements for the deep-sea platformrequirements for the deep-sea platform

D11D11 detailed design for the integration of detailed design for the integration of new sensors and device in the deep-sea new sensors and device in the deep-sea platformplatform

D12D12 integration of new sensors, test of integration of new sensors, test of functionality of the deep-sea platformfunctionality of the deep-sea platform

D13D13 deployment procedure for the deep-sea deployment procedure for the deep-sea platformplatform

D14D14 deployment cruise of the deep-sea deployment cruise of the deep-sea platform and cruise reportplatform and cruise report

D15a recovery cruise of the deep-sea platform D15a recovery cruise of the deep-sea platform and data quality checksand data quality checks

D15bD15b cruise reportcruise report

WP4 DeliverablesWP4 Deliverables

m 4m 4

m 8m 8

m 11m 11

m 11m 11

m 12m 12

m 24m 24

m 24m 24

General

Experiment overview

Acoustictransmission

Satellite Link

GEOSTAR

MODUS

Task 4.1

Buoy

GEOSTAR Task 4.1

Tasks: • Scientific multiparametric data acquisition on relevant seismic source site

• Nearly real time warning event (seismic and sea level) identification and notification

The GEOSTAR seafloor observatory will be equipped with•sensor packages •acquisition, control units •data processing unit•local memory storage•acoustic communication system (towards sea surface buoy)

Sensor requirementsSensorSensor rate Acquisition

Triaxial broad band seismometer

100Hz - 3 comp. Continuous + (decimated) triggered events

Triaxial accelerometer 100Hz - 3 comp. Continuous + (decimated) triggered events

Hydrophone 100Hz Continuous

Pressure sensor 15sec Continuous

Structure accelerometer+Gyros

100Hz - 6 comp. Only on triggered events

Gravity meter 1Hz Continuous

CTD + Transmissometer

1smp/hour Continuous

ADCP 1profile/hour (40 layers/3 comp.)

Continuous

Currentmeter 5Hz Continuous

Task 4.1

SensorsSensor rate MODEL

Triaxial broad band seismometer

100Hz Guralp CMG-40

Triaxial accelerometer 100Hz Guralp CMG5-T

Hydrophone 100Hz OAS E-2PD

Pressure sensor 15secParoscientific 8CB4000-1

Accelerometer+Gyros (IMU) 100Hz Gladiator Technologies Landmark 10

Gravity meter 1Hz IFSI (INAF) Prototype #2

CTD + Transmissometer 1smp/hour SeaBird SBE 16 plus Wet Labs ECO-BBRTD 6000m

ADCP 1profile/hour RDI Workhorse 300 Khz

Currentmeter 5Hz Nobska MAVS-3

Task 4.2

Tsunami Detection Procedure

Trigger on Pressure and Seismic events

• Seismometer: trigger on local strong seismic event

• Pressure: detection of sea level anomalies (Tsunamis wave) details in the PART 2 of presentation (ISMAR)

Task 4.1

Buoy

The buoy is equipped with:• acoustic communication system (to the seafloor station)• satellite communication systems:

– to shore stations for data transmission (Globalstar) – buoy position tracking (ARGOS )

• meteo station

Task 4.1

Tasks:

• allows communication between GEOSTAR and shore stations (notification of possible tsunamis events)

• detects meteo data

Hydrophone

3D-ACM correntometro- da aggiornare

•Unique time reference for easy comparison of the signals

Paroscientific 8CB4000-1

Task 4.2

IMU

CMG-40T

Buoy layoutTask 4.2

Towards GEOSTAR

SatelIite

Real time Communication schemeTask 4.2

Acoustic link

Main station (INGV-Roma)

Service station

(backUp)

Secondary station

(ISMAR-BO)

Buoy

Satellite link

LAN - Internet link

Auxiliary stations

(mailboxes)

Messages/data availablesTipe of Tipe of messagesmessages

Available Available informationinformation

Direct Direct RecipientsRecipients

Periodic Sea level/meteo data/mission status

INGV-ISMAR

Event (seismic - pressure)

Time of event, pressure data (samples @15 sec)

All partners (nearly real time via e-mail)

End of mission

All sensor data NEAREST partners

Task 4.2

Mission scheduling 10 Aug -5 Sept.

r/v Urania (CNR-ISMAR)

GEOSTAR deployment in the selected site (B)

Buoy deadweight coordinates: GEOSTAR observatory coordinates: Lat. 36° 22.058’ N Lat. 36° 21,875’ N Lon. 09° 28.812’ W Lon 09° 28’.885 W Estimated depth: -3200 m Depth: -3207 m

Date: 25/08/2007Time: 21:14 GMT

Gulf of Cadiz Mission

The trigger algorithm used for the seismometer is run by the GURALP digitizer DM24. In this standard algorithm two data windows of different length are used to calculate a STA/LTA (Short Time Average over Long Term Average), where the signal amplitude averages are taken over two running windows:

The length in seconds of STW and LTW can be set by the operator.

An event is detected when

STA/LTA > RATIO

where RATIO is a number indicating a threshold value set by the operator.The smaller RATIO is, the more sensitive is the algorithm, i.e. it will trigger for smaller magnitude events.

STW- Short Term Window

LTW- Long Time Window

Another important parameter the operator can set is the

bandpass FILTER

In our case we want the algorithm to trigger only for events that have

M > Mx

where Mx, the lower bound magnitude, is defined by the following constrains:

•It should be big enough so that the algorithm doesn’t trigger too often, using up the observatory’s batteries too quickly

•It should be small enough too detect a “sufficient” number of events during the experiment so the triggering system can be tested

…….but this depends on the seismicity of the area….(and the background seismic noise level)……

So, to define the trigger parameters we consider……

NEARESTobservatory

Significant seismicity in the area of the Gulf of Cadiz (1960-present)Red circles are epicentres within 150 km of the 2007.02.12 ML5.9

From F. Carriho et al., Orfeus Newsletter, May 2007, vol. 7 No. 2

Distribution of recorded earthquakes over time

Magenta line shows the chosen lower bound magnitude (Mx) for triggering

From F. Carriho et al., Orfeus Newsletter, May 2007, vol. 7 No. 2

Then…

We decided that Magnitude=3 is the lower bound magnitude

We then decided to set the trigger parameters.

To avoid triggering for small magnitude local earthquakes (i.e. Ml2.5) the FILTER parameters are set to perform a

bandpass filter from 0.5 to 4.5 Hz

The RATIO parameter is set to 11 (STW to 1s, LTW to 50 s) based on the following:

•Trigger algorithm was run on deep sea broadband (Guralp 360 s) recordings from the Ionian Sea (SN-1 site) from events of varying amplitude. This dataset was chosen given the similar recording instruments and conditions.

•Trigger algorithm was run on on-land recordings from the Portuguese seismic network (IMP). Recordings show efficient propagation of seismic waves- good S/N ratio.

•General considerations on earthquake energy scaling with magnitude.

Following the observatory’s deposition unexpected triggering of the seismometer took place RATIO increased to 20 to make the algorithm less sensitive (and STW to 5 s).

Furthermore an OBS (obs07) was deployed close to the observatory’s site, for almost 2 days (from about 10:30 of 29/08 to about 9:30 of 31/08), to have a quick look at the seismic signal and infer something about signal recorded by the observatory’s sensor.After the deposition we found out that at the same time there was an active seismic experiment (shot energy is recorded above 5 Hz- shot frequency about every 20 s) and initially the frequent seismometer triggering was thought to be caused by the shots.

time (s)

velo

city

(m

/s)

Time scheduling

General

  1 2 3 4 5 6 7 8 91

01

11

2

WP4                        

Task 4.1 Provisional          

Actual x x x x x x x          

Task 4.2 Provisional              

Actual     x x x x x x x      

Task 4.3 Provisional        

Actual                 x x    

Task 4.4 Provisional    

Actual                   x x x

Task 4.5 Provisional  

Actual                        

Present status of the activities (m 12)

Evidence that the buoy answered interrogation from VEGA –

17 October 2007 15:58

Call to underwater modem attempted from VEGA

….connection with underwater modem from VEGA failed

Direct buoy link- Call on the buoy from Lisbon, positive response- 16 October 2007

Acoustic surface communication on-ship by the buoy site- configuration file correctly received by GEOSTAR-17 October 2007

Acoustic surface communication: Response to dacs status request command-

-17 October 2007

Acoustic communication with the observatory is attempted…….

17 October 2007

ATS-V-USS

(underwater) modem. Sending request (upload) of all values

in particular:

request of modem emission time parameter

Management of

……failure in the acoustic communication with the underwater modem- Time out signal received indicates no answer from GEOSTAR acoustic modem

An analysis with the trigger algorithm on obs07 signal, deployed during the active experiment:

there is no triggering with RATIO set to 20 (not even with RATIO set to 3).

So it seems unlikely (also given the filtering in the algorithm 0.5-4.5 Hz) that the shots started the initial triggering of the observatory sensor.

This was confirmed by a recent visit to the buoy where the operator did not find any trigger messages from the seismometer during the active experiment:

The only trigger found was of ‘pressure-type’, during an hour when a M=3.6 event at epicentral distance about 180 km fropm the observatory was recorded on land.

The absence of seismometer triggers prompted us to revert to the original RATIO=12 value.

The cause of the initial triggering is still unknown.

Deviations

• Anticipation of the cruise. Remedial action anticipation of Tasks (4.2, 4.3)

• Interference with the R/V Atalante seismic reflection experiment in the area: Remedial action: observatory software was properly reconfigured.

Atalante shot oceanographic cruise(info received from CNR-ISMAR)

Start End Shot occurrence

(s)

SignalFreq. (Hz)

Annotation

Date Time (GMT)

Date Time (GMT)

25 Aug. ‘07

01:45 28 Aug. ‘07

9:46 19.4 s (50 m)

10-50

29 Aug. ‘07

03:00 09/Sept. ‘07

06:00 29.2 s (75 m)

10-40 LON=6º 41.64468 ' W

LAT=36º 22.71906 ' N

(shot 1686-líne

MF22)

Deviations

• Acoustic communications malfunctioning: Immediately after the GEOSTAR deployment, a final check on the communication systems (acoustics and satellite) was performed both from the ship board and from the land station in Italy. A malfunctioning in the communication system, namely the acoustic modem, was discovered

Remedial action: the acoustic modem and the electronics of the buoy was removed and shipped to laboratory in order to set up again the communication chain. The system was restored and re-configured. On 17 October a new cruise has been planned in order to rebuild the communication on the buoy.

Deviations

• Inefficiency of the Globalstar satellite system coverage: by the early October, the Globalstar service provider (Elsacom) communicated that 4 satellites of the constellation failed.

Remedail Actions: the service provider was contacted in order to solicit the restoration of the constellation. The provider has then communicated that 2 satellites will be again operating from late October while other 2 satellites will be restored by the second half of November.

Last week….

• Buoy drift and ARGOS alarms emission to INGV (18 October)

• Extraordinary cruise for the buoy recovery

(18-22 October)

• Buoy mooring cut and mooring cable at sea

• Recovery of the buoy mooringRecovery of the buoy mooring

• Restoration of the buoy and deploymentRestoration of the buoy and deployment

• Integration of seismic data in the marine Integration of seismic data in the marine data-base of the OBS data (WP3 – data-base of the OBS data (WP3 – seismological monitoring) (task 4.5)seismological monitoring) (task 4.5)

Work for the next period