Performance_Work_Statement_for_Open_Comp_Feb2022_V2_AB.pdf

Performance Work Statement February – May 2022.

1.0 Introduction and Background.

The USGS operates the ShakeAlert Earthquake Early Warning system in CA, OR, and WA.

Offshore earthquakes in these states pose significant seismic hazard and are challenging to provide timely warnings for due to the lack of seismic and geodetic instrumentation offshore. A potential solution to this problem results from the fiber-optic cables installed on the seafloor offshore of a growing number of west coast cities. The Distributed Acoustic Sensing technology uses lasers to interrogate a fiber at a high-rate and is able to detect the passing of seismic waves through the cable. There are numerous basic research questions to be investigated to determine if this is a viable technology for ShakeAlert and this project will collect an initial test dataset in the highly seismically area surrounding Eureka and Arcata California.

This is an initial pilot experiment. One key aspect is to familiarize both the Cal Poly Humboldt University staff and the cable owners in the vicinity with this technology and its requirements in hopes of building up a large long-term effort there. A number of universities will collaborate on the project including the data analysis and possibly side projects.

2.0 Scope

The contractor will collect a Distributed Acoustic Sensing (DAS) dataset on a fiber optic cable being rented by Cal Poly Humboldt University in Arcata California. The 15 km cable will be interrogated with an DAS interrogator, and the instrument configuration will be set to maximize dynamic range. The strain data will be saved at between 100 and 150 samples per second.

While the cable is only 15 km long, the experiment should be done with an interrogator capable of achieving high quality data on submarine cables out to 100km distance as we would like to familiarize our scientist team with these types of interrogators.

The contractor’s seismic monitoring triggering algorithms will be run on the acquisition machine and the timing of trigger logging will be archived with GPS quality timing for comparison to network seismometers. Multiple copies of the raw continuous data, and the processed data (e.g., earthquake records) will be provided at the end of the experiment on appropriate storage devices. The contractor will provide an online portal to perform general data inspection and state-of-health monitoring during the deployment

The project will collect eight weeks of data between February and May 2022, and the contractor may break this experiment up into two time segments to accommodate other contracts that require the hardware.

3.0 Applicable Documents. None

4.0 Technical Requirements

Experiment will collect 8 weeks of data between February and May 2022.

The contractor will be responsible for all equipment mobilization and demobilization.

USGS will request an Optical Time Domain Reflectometer (OTDR) test from cable owner. If one has not previously been done, the contractor will conduct one prior to choosing a fiber to connect with.

The interrogator will be configured to maximize dynamic range while recording the full 15km length of the cable. Additionally, the interrogator will be configured to give the highest signal-to-noise ratios in the seismic frequency band, with noise levels comparable to standard reference curves for seismic data, such as Peterson’s New Low Noise Model.

The data will be processed in real time for triggers on seismic waves from local earthquakes and the timing of when those triggers are derived from the software will be logged with GPS timing accuracy.

The contractor will provide the ability to download data snippets at times of earthquakes or other notable events.

5.0 Deliverables.

The contractor will provide two copies of the continuous raw data and the triggered datasets at the end of the experiment. The dataset is expected to be approximately 2 Terabytes in size.

During the experiment, the contractor will monitor state of health information to ensure a high-quality dataset. Small amounts of data during significant earthquakes will be downloaded in real time.