Hawaii‐2 observatory pioneers opportunities for remote instrumentation in ocean studies

Abstract

Beneath 5000 m of water midway between Hawaii and California, the Hawaii‐2 Observatory (H20) rests on the seafloor (Figure 1). Telemetry and power come to this pioneer, deep‐ocean scientific observatory via a retired telephone cable, Hawaii‐2, donated by AT&T to the Incorporated Research Institutions for Seismology (IRIS) Consortium for the benefit of the scientific community. H20 is the first Global Seismographic Network (GSN) station on the seafloor.With a suite of wet‐mateable connectors on a junction box (j‐box), H20 offers marine scientists a new opportunity to deploy and operate remote instrumentation in the middle of the ocean.

Coupled seismoacoustic modes on the seafloor

“…Figure 1 shows a typical seismogram recorded at the Hawaii‐2 Observatory (H2O), a new facility located on the seafloor between Hawaii and California at 4979 m depth [ Butler et al , 2000]. Rayleigh waves from the earthquake are observed on seismic and hydrophone channels.…”

Low‐frequency seismic signals recorded by OBS at Stromboli volcano (Southern Tyrrhenian Sea)

“…[4] In the last few years, Ocean Bottom Seismometers (OBSs) and seafloor observatories have frequently been used around the world to monitor the off-shore microseismicity and seismic signals also of volcanic origin [e.g., Butler et al, 2000;Caplan-Auerbach et al, 2001;Goslin et al, 2005;Sgroi et al, 2006]. Recently, OBSs, deployed on the East Pacific Rise, have recorded the micro-earthquake character of a mid-ocean ridge eruption, including precursory activity [Tolstoy et al, 2006].…”

High quality seismological recordings from the SN‐1 deep seafloor observatory in the Mt. Etna region

“…Furthermore, the installation should result in good ground coupling of the sensor to obtain reliable short‐period recordings. The main installation procedures used for ocean bottom seismometers are: 1) complete or shallow burial on the ocean floor [ Romanowicz et al , 1998; Butler et al , 2000], 2) borehole re‐entry [ Araki et al , 2004]‐ both by using ROVs‐, 3) free‐fall and pop‐up procedures. The best results are obtained with sensors cemented into a borehole [ Araki et al , 2004] when certain precautions are taken to avoid water circulation in the borehole [ Beauduin and Montagner , 1996] or else by burying the sensor in the sediments at shallow depths [e.g., Collins et al , 2001].…”