6 research outputs found
Novel Autonomous and Cabled OBS Solutions for Offshore Seismic Research
No full text<p>Seismologists have historically focused on land-based seismic research, due to the logistical and financial challenges presented by offshore installations. Guralp has developed technology which allows the seismology community monitor offshore seismicity with greater ease, improving global seismic data resolution. This is due to systems such as the Aquarius autonomous ocean bottom seismometer (OBS) and world-leading engineering advancements in Science Monitoring and Reliable Telecommunications (SMART) cables.</p>
<p>Autonomous free-fall OBS units allow users flexibility in deployment and ability to redeploy a number of times in different locations. The Guralp Aquarius functions at any angle without using a gimbal system, and can wirelessly transmit SOH and seismic data to the surface via an integrated acoustic modem. These features allow researchers to monitor and transmit data without offshore cabling, thereby reducing logistical challenges whilst maintaining some degree of real-time data transmission. Optional surface communications can be permanent (buoy-mounted), semi-permanent (wave-glider) or on demand (ship-of-opportunity or dedicated voyage).</p>
<p>Alternatively, cabled solutions give users access to high-resolution data in real-time via a physical link to an onshore data centre. As an example, the Guralp Orcus provides a complete underwater seismic station with observatory grade seismometer and strong-motion accelerometer in a single package. The slimline Guralp Maris also provides a more versatile solution, making use of the same omnidirectional sensor as the Aquarius and can be installed either on the seabed or in a narrow-diameter subsea borehole.</p>
&lt;p&gt;SMART cables show great potential for increasing the number of cabled ocean observatory deployments in the future with substantially reduced deployment costs to the research institute. Combining several applications into a single system, including seismic monitoring and telecommunications, large scale monitoring networks can be created cost effectively by combining efforts from several industries. Guralp is deploying a demonstration SMART Cable system to monitor volcanic and seismic activity offshore in the Ionian Sea in collaboration with Instituto Nazionale Di Geofisica e Vulcanologia (INGV). This will be the first practical demonstration of this technology and there are plans for additional projects in the future.&lt;/p&gt;</jats:p
The Minimus digitizer platform: a user-friendly ecosystem for efficient network management and seismic station configuration
No full text&lt;p&gt;The Guralp Minimus broadband digitizer has led the way with introducing a number of innovative features to broadband digitizers including easy network configuration, compact form-factor, extensive State of Health (SOH) monitoring and low latency digitization. Since its introduction, there have been major technological advances in processing chips resulting in the power consumption of seismic digitizers decreasing drastically in the last few years. The next iteration of Minimus, Minimus2, takes advantage of modern chip power consumption to reduce overall nominal power consumption by over 50% whilst maintaining high functionality. This significant decrease in power consumption will facilitate far more simplified field deployments for offline deployments.&lt;/p&gt;
&lt;p&gt;The Minimus platform also provides a high level of functionality for online stations, including the industry unique option of sending State of Health (SOH) data via the SEEDlink protocol. This makes SOH monitoring far simpler for larger networks as SOH data be managed using similar methods as waveform data. This also allows for time-series analysis of SOH data to be able to proactively maintain stations and advance diagnose any issues before they result in any loss of data. The Minimus platform seamlessly interfaces the Discovery software to seamlessly integrate new stations into existing networks. The management of large numbers of real-time seismic stations is further enhanced with Guralp Data Centre (&amp;#8220;GDC&amp;#8221;) a cloud-based software package to build on the Discovery tool set.&lt;/p&gt;
&lt;p&gt;The Minimus platform was built from the ground up to provide one of the lowest latency digitizers available with digitization latencies down to 40ms, making it well suited to Earthquake Early Warning applications. This is achieved with the use of causal decimation filters, high sample rates and Guralp&amp;#8217;s proprietary GDI protocol. The Minimus platform is built as a modular digitizer platform that is available within a number of different packages to suit a range of applications, including as a standalone digitizer or built within Broadband seismometer and Force Balance Accelerometer systems.&amp;#160;&lt;/p&gt;</jats:p
A Rugged, Portable and Intelligent Analogue Seismometer for Future and Pre-Existing Arrays &#8211; G&#252;ralp Certis
No full text&lt;p&gt;Seismic networks often face logistical and financial challenges that require portability, longevity and interoperability with existing equipment.&lt;/p&gt;
&lt;p&gt;G&amp;#252;ralp have combined proven ocean bottom, borehole and digitiser technology to produce an analogue seismometer with intelligence that benefits networks of all sizes. The G&amp;#252;ralp Certis is a broadband analogue instrument that incorporates specific aspects of its sister digital instrument (Certimus) while still remaining compatible with third-party digitisers.&lt;/p&gt;
&lt;p&gt;Each Certis stores its own serial number, calibration and response parameters internally and will automatically communicate these to a connected Minimus digitiser. This allows seismometer-digitiser pairings to be changed without manual entry of new parameters. If using GDI-link streaming protocol with the Minimus, these metadata parameters are transmitted within (and therefore inseparable from) the datastream itself. Therefore, this small piece of intelligence in the analogue sensor removes the need for any manual re-entry of response parameters anywhere along the sensor-digitiser-client chain.&lt;/p&gt;
&lt;p&gt;Certis enables users to install in locations with poor horizontal stability (e.g., glaciers, dynamic landslide scarps, water-saturated soils), without the need for cement bases or precise levelling, as the sensor can be deployed at any angle regardless of which model digitiser is connected. Due to its small size, low weight and ultra-low power consumption, Certis significantly reduces logistical efforts and makes short term temporary deployments far easier.&lt;/p&gt;
&lt;p&gt;Certis addresses many challenges of traditional seismometer deployments, including cost, but provides a flexible and simple solution for seismic monitoring applications across all disciplines.&lt;/p&gt;</jats:p
Utilising ocean bottom seismometer platforms for tsunami early warning and hazard assessment
No full text&lt;p&gt;Seismic instrumentation is critical for instantaneous tsunami early warning systems as well as assessing long-term risk of tsunami activity in areas with high seismic hazard. Ocean Bottom Seismometer (OBS) systems provide real-time data in areas with appropriate infrastructure or batch data from offline temporary autonomous stations.&lt;/p&gt;&lt;p&gt;OBS systems detect ground motion from seismic waves significantly before detecting any pressure change in the water column from an associated tsunami due to the order of magnitude difference in wave velocity. G&amp;#252;ralp&amp;#8217;s OBS systems combine seismic and pressure detection in both permanent cabled networks and temporary non-cabled systems utilising near-real-time acoustic transmission. All seismic sensors used in G&amp;#252;ralp systems are sensitive to both earthquakes as well as other tsunami-triggering events such as landslides (e.g. Anak Krakatau, 2018) or volcanic eruptions (e.g. Hunga Tonga&amp;#8211;Hunga Ha&amp;#699;apai, 2022).&lt;/p&gt;&lt;p&gt;Cabled systems provide obvious benefits of real-time data, confidence of installation and flexibility to add additional instrumentation without power consideration. For example, G&amp;#252;ralp Orcus and Maris cabled OBS systems are both deployed off the western coast of North America monitoring volcanic and tectonically induced earthquakes that have potential to cause tsunamis. Seismometers at these stations coupled with pressure gauges allow for immediate notification of a threat and subsequent refinement of hazard estimates using surrounding assets such as dedicated DART buoys.&lt;/p&gt;&lt;p&gt;Both Orcus and Maris allow for multiple auxiliary systems to be incorporated into the system while maintaining as well as providing additional installation flexibility for operators. Orcus has facility for both strong &amp; weak motion seismometers in addition to auxiliary sensors while Maris has the unique feature of operating at any angle without the need for a gimbal mechanism, simplifying installation and network design considerations.&lt;/p&gt;&lt;p&gt;The G&amp;#252;ralp Aquarius is the latest generation autonomous OBS for short-to-medium term or rapid response campaigns to monitor areas with increased seismic and tsunami hazard. Aquarius also uses omnidirectional capabilities as well as acoustic communication of seismic data to the surface to improve operator confidence of installation. Acoustic communication also allows for near-real-time communication with land-based warning systems after a significant seismic event in anticipation of a tsunami. This can be verified and communicated after the initial seismic wave using onboard pressure gauges. In areas where surface communication is not required, intelligent battery systems optimise deployment lengths beyond 18 months for maximum data/cost benefit.&lt;/p&gt;&lt;p&gt;G&amp;#252;ralp is also pioneering the use of seismic sensors and auxiliary equipment within Science Monitoring And Reliable Telecommunications (&amp;#8220;SMART&amp;#8221;) cables which have already been shown to be useful in incorporating pressure gauges to detect tsunami events. These cables utilise regular telecommunication cables making uses of their natural communication and power source qualities to improve sensor network coverage. G&amp;#252;ralp is currently manufacturing a demonstration system to be deployed in the Ionian Sea, monitoring seismic and volcanic activity with the aim of indicating practicality and data quality using this installation method.&lt;/p&gt;</jats:p
