Enhancing earthquake location in deep ocean environments with DAS
- 1Institute of Marine Sciences - CSIC, Barcelona, Spain (hlatorre@icm.csic.es, sventosa@icm.csic.es, melania@icm.csic.es, antonio.villasenor@csic.es, rafael@icm.csic.es, a.ugalde@icm.csic.es)
- 2University of Milano-Bicocca, Milan, Italy (e.bozzi3@campus.unimib.it)
- 3University of Alcalá, Alcalá de Henares, Spain (pedro.vidal@uah.es)
Earthquake location schemes for regional oceanic earthquakes within archipelago regions
are limited by the azimuthal resolution that land stations provide for each specific event. Although
ocean bottom seismometers (OBS) can help, they are not suited for real time monitoring and thus
can only provide a posteriori improvements. An alternative approach to improve coverage, not
strictly limited to a temporal increase of onshore stations, is to use Distributed Acoustic Sensing
(DAS) on oceanic fiber-optic cables. With DAS, real time monitoring in areas up to 100 km
offshore is possible, which can potentially improve azimuthal resolution by reaching previously
inaccessible locations within the archipelago. A great example of such a region are the Canary
Islands, where land-based coverage is already phenomenal yet volcanic activity monitoring from
underwater sources still has poor coverage in some cases.
Recently, the deployment of additional land stations at the islands of Gran Canaria and
Fuerteventura has revealed existing seismicity between the two islands. When locating the source of
this seismicity, there is a considerable east-west bias on the azimuthal distribution of those stations.
An existing fiber-optic cable that connects the islands of Tenerife and Gran Canaria has been
interrogated with DAS before, on both sides. The most recent experiment, which was set up on the
Gran Canaria side, recorded such seismicity from late 2022 to early 2023.
This work attempts to use the DAS-recorded onsets of some events for location purposes.
First, we test DAS by itself, and subsequently, DAS in combination with land stations. Automatic picking methods are tested for this purpose, since manual picking of onsets is not feasible for DAS. The possibility of catalog revisions using just a few hand-picked onsets at
previously selected DAS channels is also considered, since there is a lot of redundancy in DAS data
and visual inspection is not unreasonable if limited to a number of channels.
How to cite: Latorre, H., Bozzi, E., Ventosa, S., Cubas Armas, M., Vidal-Moreno, P., Villaseñor, A., Bartolomé, R., and Ugalde, A.: Enhancing earthquake location in deep ocean environments with DAS, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-7, https://doi.org/10.5194/egusphere-gc12-fibreoptic-7, 2024.
