GEOFON

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Cite as

Geissler, Wolfram; Schmidt-Aursch, Mechita; Matias, Luis; Embriaco, Davide; Corela, Carlos; Favali, Paolo; Zitellini, Nevio; Jokat, Wilfried (2025): Integrated observations from NEAR shore sourcES of Tsunamis: towards an early warning system (NEAREST). GFZ Data Services. Dataset/Seismic Network. doi:10.14470/4U972300.

Identifier

10.14470/4U972300

DataCite metadata

HTML | JSON | XML | INSPIRE | Local XML source file

Terms/rights

Creative Commons Attribution 4.0 International Available since 2025-07-08

Creator(s)

Geissler, Wolfram ^a; Schmidt-Aursch, Mechita ^a; Matias, Luis ^b; Embriaco, Davide ^c; Corela, Carlos ^b; Favali, Paolo ^c; Zitellini, Nevio ^d; Jokat, Wilfried ^a
a Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
^b University of Lisbon, Lisbon, Portugal
^c National Institute of Geophysics and Volcanology, Rome, Italy
^d Institute of Marine Science, Bologna, Italy

Description

• (Abstract) The NEARESTproject (Integrated observations from NEAR shore sourcES of Tsunamis:  towards an early warning system) aimed at the identification and characterization of potential near-shore sources of tsunamis in the Gulf of Cadiz. This area is well known from the catastrophic earthquake and tsunami that destroyed Lisbon and several other places mainly along the EastAtlantic coast on November 1st, 1755. One of the project's work packages dealed with monitoring of recent seismic activity in the Gulf of Cadiz area. For this purpose 24 broadband ocean-bottom seismometers (OBS) from the German DEPAS instrument pool were deployed for 11 months in addition to the GEOSTAR multi-parameter deep-sea observatory and two temporary land stations in Portugal. The GEOSTAR observatory and the 24 OBS were deployed and recovered during two expeditions with RV Urania in 2007 and 2008. The OBSs consist of  three‐component Guralp CMG‐40T‐OBS seismometers and HighTech HTI‐04‐PCA/ULF hydrophones. A wide range of signals was recorded, ncluding teleseismic, regional and local earthquakes, and low‐frequency (∼20 Hz) vocalization of fin whales.  The GEOSTAR  observatory was again deployed between 2009 and 2011. The Portuguese temporary land station PDRG was additionally recording during the NEAREST project. Originally, the position of recovery on deck was taken to calculate the mean coordinate of the OBS at depth from deployment and recovery coordinates. In most cases the difference in coordinates between deployment and recovery is very small (table 3 and 4 in Carrara et al., 2008). For two stations, the location at the seafloor could be measured by triangulation (Carrara et al., 2008). Due to experience of other experiments over the years, we finally suggest to use the deployment coordinates as the station coordinates for all stations that could not be tri-angulated. The clocks were synchronized with GPS time before the deployment and if possible again after the recovery. Unfortunately, most of the batteries were empty at the end of the recording period. That either made it impossible to realize the second synchronisation (skew time measurement) or in some case also caused erroneous synchronisations. Therefore, the internal clock drift was estimated by ambient noise analysis (Corela, 2014). The internal clock drifts were corrected using a linear interpolation method. Generally, the data quality is very good, especially for the intended study of local and regional earthquakes. Studies relying on wideband seismological recordings can also be carried out. The sensor package and noise conditions hamper the use for broadband and very broadband applications. Unfortunately, also not all channels operated properly, therefore hampering the use of multi-component methods for the relevant stations. We thank the captain E. Gentile, crew, G. Carrara, and all participants of the R/V URANIA expeditions in 2007 and 2008. We are grateful to all people and institutions involved in the NEAREST project. Waveform data is available from the GEOFON data centre, under network code 9H.

Title

Integrated observations from NEAR shore sourcES of Tsunamis: towards an early warning system (NEAREST)

Publisher

GFZ Data Services

Publication year

2025

Resource type

Dataset / Seismic Network

Dates

1. Collected 2007-09-01(start of data collection)
2. Accepted 2025-05-06(accepted for archiving)
3. Submitted 2025-06-12(data and metadata completely submitted)
4. Issued 2025-07-08(actually published/made available on server)
5. Created 2025-07-08(creation of DOI)
6. Available 2025-07-08(end of embargo period)

Place(s)

1. Gulf of Cadiz

Contributor(s)

• Hosting institution: GFZ Helmholtz-Zentrum für Geoforschung
• Data manager: GEOFON Data Centre
• Project members: Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; University of Lisbon, Lisbon, Portugal; National Institute of Geophysics and Volcanology, Rome, Italy
• Project leader: Institute of Marine Science, Bologna, Italy

Subjects

• SeisData terms: DEPAS Pool Geophysics Hydrophones MiniSEED OBS Passive seismic Seismometers Temporary Velocity
• GCMD keywords: Marine geophysics Earthquakes Geophysical stations/networks Seismometers Hydrophones
• Other terms: Tsunami

Funding reference(s)

1. European Commission (037110)

Language

en

Sizes

1. 457GB

Reference(s)

FDSN network code

9H

Network dates

2007–2011

Data time range

2007–2008

Station count

26

Seismic metadata

fdsnws-station FDSN StationXML SC3 XML

To retrieve waveform data and metadata (including instrument responses) for this and other seismic networks, see here. Network (data set) values are taken from DataCite XML with Metadata Properties version 4.4. Contact us if you are the PI and wish to make changes. Old-style network page for this network here.

Station List for Network Code 9H