AGU 2014 - Nanometrics Event Schedule - Booth # 2223

 
  • „  Oral and Poster Paper abstracts
  • „  Daily on-booth paper presentations
  • „  New product announcements 
  • „  Annual customer appreciation event

Not going to the AGU this year?  Please click here to request a post-meeting summary.

 

Daily On-Booth Presentations

Time: 10:15 am & 2:15 pm (10 mins. + Q&A)
Location: Booth 2223
 
1. "An Analysis of Tradeoffs Between Seismometer Performance and Convenience" 
 
2. “Comparison of a Waveform Cross Correlation Detection Method to a Traditional STA/LTA Picker: Application to the Crooked Lake Sequence Near Fox Creek, Alberta” 
 
3. “Seismic Network Performance Estimation: Comparing Predictions of Magnitude of Completeness and Location Accuracy to Observations from an Earthquake Catalogue”
 
 

Annual Customer Appreciation Event

Please join us for a glass of wine as our gesture of appreciation.
Wednesday • 4:00 pm • Booth # 2223
 
 

Paper Presentations - Oral & Posters

 

S12B-04 "An Analysis of Tradeoffs Between Seismometer Performance and Convenience"

Monday, December 15, 2014, 11:05 AM - 11:20 AM, Marriott Marquis-Golden Gate B1

In recent years, a multitude of different broadband seismometers of varying periods and performance specifications have been developed. Scientists often have the unenviable task of selecting the best equipment to suit a broad range of applications. We provide a high level view of some of the tradeoffs available to the sensor design team that directly impact the utility and cost of the final product. Additionally we review costs related to network installation, maintenance and operation and investigate how these can be influenced by instrument choice. We compare the low noise model, the high noise model, and the site noise of a typical installation to the expected signal strength for a variety of case studies ranging from teleseismic to microseismic settings. For each case study we determine the effective passband, the frequency range in which the expected signal exceeds both the site and instrument noise. We compare the effective passband of a number of different instruments and investigate the effects of changes to both instrument and site noise on the size of the passband. We find that for typical installations, the site noise has the largest influence on the effective passband of an instrument. We demonstrate that in some circumstances tradeoffs in certain performance specifications can pay dividends in ease and cost of deployment without compromising overall network performance.

 

 

S51A-4386 “Comparison of a Waveform Cross Correlation Detection Method to a Traditional STA/LTA Picker: Application to the Crooked Lake Sequence Near Fox Creek, Alberta”

Friday, December 19, 2014, 08:00 AM - 12:20 PM, Moscone South-Poster Hall

Waveform cross correlation, or template matching as it is sometimes called, has long been known to be an effective method for finding occurrences of a known repeating signal within a waveform. Because seismic signals are rarely known a priori, waveform cross correlation is not often used as a detection method for seismic networks. However, past studies (e.g. Gibbons and Ringdal, 2006) have shown that cross correlation can be effective in identifying events with similar locations and focal mechanisms (and thus waveforms) to a pre-existing template. Because induced seismicity often satisfies these requirements the method is well-suited to induced seismicity monitoring. We apply the method of waveform cross correlation to a sequence of events between Nov. 29, 2013 and Dec. 13, 2013 occurring at Crooked Lake near Fox Creek, Alberta. These events are believed to be attributable to injection activities in the area. A total of 24 events were detected using traditional STA/LTA triggering methods. The largest event, measured at local magnitude 3.9, is used as a template to identify other events. We compare the effectiveness of the traditional STA/LTA detection method to the cross correlation technique. With a modest correlation threshold we identify all 24 of the original events and an additional 89 new events for a total of 113 events identified by waveform cross correlation. We estimate the magnitude of completeness using the maximum curvature method (Wiemer and Wyss, 2000) and compare the result for the STA/LTA catalogue and the cross correlation catalogue. We find that the magnitude of completeness is about 0.8 magnitude units lower for the cross correlation catalogue. We explore the possibility of determining a probability density function to describe the values of observed correlation between a template and a seismic signal and reconcile theoretical expectations with empirical data. We further suggest a trigger threshold for cross correlation detection algorithms based on the probability density function. Finally, we discuss the practicality of implementing waveform cross correlation detection methods to monitor induced seismicity.

 

 

S51A-4410 “Seismic Network Performance Estimation: Comparing Predictions of Magnitude of Completeness and Location Accuracy to Observations from an Earthquake Catalogue”

Friday, December 19, 2014, 08:00 AM - 12:20 PM, Moscone South-Poster Hall

The design of seismic networks for the monitoring of induced seismicity is of critical importance. The recent introduction of regulations in various locations around the world (with more upcoming) has created a need for a priori confirmation that certain performance standards are met. We develop a tool to assess two key measures of network performance without an earthquake catalogue: magnitude of completeness and location accuracy. Site noise measurements are taken at existing seismic stations or as part of a noise survey. We then interpolate between measured values to determine a noise map for the entire region. The site noise is then summed with the instrument noise to determine the effective station noise at each of the proposed station locations. Location accuracy is evaluated by generating a covariance matrix that represents the error ellipsoid from the travel time derivatives (Peters and Crosson, 1972). To determine the magnitude of completeness we assume isotropic radiation and mandate a minimum signal to noise ratio for detection. For every gridpoint, we compute the Brune spectra for synthetic events and iterate to determine the smallest magnitude event that can be detected by at least four stations. We apply this methodology to an example network. We predict the magnitude of completeness and the location accuracy and compare the predicted values to observed values generated from the existing earthquake catalogue for the network. We discuss the effects of hypothetical station additions and removals on network performance to simulate network expansions and station failures. The ability to predict hypothetical station performance allows for the optimization of seismic network design and enables prediction of network performance even for a purely hypothetical seismic network. This allows the operators of networks for induced seismicity monitoring to be confident that performance criteria are met from day one of operations.

 

Dec 9, 2014