SSA 2021 Annual Meeting - Virtual

Date
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We will miss seeing all of you in person this year's SSA Annual Meeting but hope we can still connect virtually, to book a time with a member of our team please contact us or drop by our booth.

TECHNICAL PRESENTATIONS:

Fully Integrated OBS Platform for Multi-Use Case Deployments and Future OBS Components for Long-Term Deployments

Presenting Author: Michael Perlin
Time: 4/19/2021 at 11:30 AM - 12:30 PM Pacific

View the abstract

 

Scientific Strong Motion Nodes for Diverse Use Cases

Presenting Author: Nick Pelyk
Time: 4/19/2021 at 3:45 PM - 4:45 PM Pacific

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Evolution of EEW Instrumentation

Presenting Author: Tim Parker
Time: 4/20/2021 at 11:30 AM - 12:30 PM Pacific

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Insights on the Criticality of Faults From Dense Monitoring of Induced Seismicity from Moment Tensor Based Stress Inversion

Presenting Author: Adam Baig
Time: 4/20/2021 at 2:30 PM - 3:45 PM Pacific

View the abstract

 

INNOVATION SHOWCASE

Expanding the Boundaries of Seismic Research

Presenter: Andrew O. Moores

Time: 3:30 PM - 4:30 PM EDT on Wednesday, April 21

 

 


ABSTRACTS
Fully Integrated OBS Platform for Multi-Use Case Deployments and Future OBS Components for Long-Term Deployments

Broadband seismic sciences in the oceans has been supported by many academic institutions, who have each developed a unique OBS platform which has made it complex and expensive to integrate new or updated equipment. Nanometrics has partnered with Scripps Institute of Oceanography to use their well proven Abalone OBS platform and create a fully integrated and updated OBS system, forward compatible with the newest and fully integrated Nanometrics digitizers and sensors. The OBS developments include a new low-power and low-noise PegasusOBS digitizer as well as gimbaled broadband OBS instruments based on the Horizon120 and 360 long period sensors. Like the innovative Trillium Compact OBS, these new low noise broadband systems are smaller, lower power and have wider bandwidth and will be able to test new emplacement techniques for reduced noise resulting in higher quality seismic data. This updated Abalones platform will be able to support a diverse set of sensors and larger payloads for extended deployments along with important new development such as transferring data to autonomous robotic data harvesters and resyncing timing of the system. Along with these hardware developments a complete software ecosystem for station management, deployment and data harvesting including automated metadata creation has been completed. While these systems are fairly far along in development, we are seeking partners for prioritizing new developments such as for longer term autonomous GSN data quality OBS observatories and new cabled hazard monitoring multi-disciplinary broadband OBS systems based on these new components.


Scientific Strong Motion Nodes for Diverse Use Cases

Nanometrics makes turnkey Class-A accelerometer systems for vibration monitoring with low latency telemetry needed for EEW and critical infrastructure. We also support quick deploy systems with Titan Accelerometers coupled with a Pegasus digitizer for rapid response after earthquakes. This technology was designed for very low SWaP (size, weight and power) enabling high density collection of critical strong motion data used as a key input into structural analysis of buildings, structures, and dams both before and after events. These kits can be used for research studies that define regional attenuation properties and site amplification maps. Ground motions studies before events also provide data used in models that are used in early prediction of ground shaking distribution as an input for emergency response. These new instruments packages are supported by a complete ecosystem of software to easily plan, deploy and manage a project including data and metadata automatically generated on site making it simpler to conduct these types of emergency responses and projects. There is also turnkey deploying, monitoring, analysis, engineering and data products available through services that use this same equipment.

 

Evolution of EEW Instrumentation

Nanometrics has responded to EEW program requirements with innovative instrument developments, specifically a wide dynamic range instrument, the Cascadia, combining strong and weak motion sensors in a single case. This instrument has a very large dynamic range, 200dB, wide bandwidth and low noise floor with a configurable clip level. The sensors are packaged in a robust case that can be deployed in shallow direct burial deployments used in aftershock studies or in state-of-the-art boreholes used for combined EEW monitoring sites/regional arrays and scientific studies. We have released a new version of the Cascadia, the Cascadia Slim with a lower noise floor at the long period frequencies based on the Trillium T120 Slim broadband sensor. The Cascadia Slim has a wide dynamic range, 215dB, in a similar environmental package and will improve the magnitude of completeness (Mc) of a seismic network where it was limited by broadband sensor performance and in most EEW networks will only be limited by the site noise and emplacement techniques. Using this new instrument the economy and confidence of station performance in a network can be measurably improved and enables new station installs to be lower cost and with better emplacement technologies through use of properly built and deeper cased holes.

 

Insights on the Criticality of Faults From Dense Monitoring of Induced Seismicity from Moment Tensor Based Stress Inversion

Seismic monitoring of waste-water injection, hydraulic fracturing, and other processes has increased across North America. With the increased injection concerns about induced seismicity have risen, and traffic-light systems (TLS) have become a model for managing the risk of shutting down operations. While locations and magnitudes are necessary input for these TLS, seismic monitoring can yield more products providing a detailed level of understanding of the geological and geomechanical setting of the array, allowing for proactive versus reactive reservoir management.

In this paper, I detail how the advanced products of a monitoring system -- high-precision locations, moment tensors, and stress inversions derived therefrom -- can be used to answer questions on the criticality of the faults, that gives insight into the triggering mechanisms. I look at an example in North America where sequences of large events have been detected over a number of hydraulic fracture completions. Large events, characterized by magnitude above ML2, are selected for moment tensor inversion. By selecting the moment tensors for events within 20km of a grid point, I obtain a relatively high-resolution stress map using a stochastic stress inversion (if at least 10 mechanisms are within that radius). Simultaneously, cross-correlation-based repicking and double difference relocation is used to define lineations associated with faults. By clustering the high-precision locations, these faults can be identified and imaged. Frequently, especially in strike-slip stress regimes in sedimentary basins, this workflow results in the first discovery of such faults as other geophysical means are not amenable. Finally,I assess how critically stressed these faults are in the moment-tensor determined stress regime by calculating the shear and normal stresses on these faults.

 

If you missed one of these presentations but are interested in hearing more about the topic don’t hesitate to reach out to a member of our team.