Semiempirical Statistics of Correlation-Detector Performance

Schaff, D. P.

doi:10.1785/0120060263

Cited by 65 publications

(71 citation statements)

References 26 publications

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“…(Schafff and Waldhauser, 2006;Schaff, 2007). One paper has been published on the semi-empirical synthetic runs (Schaff, 2008). Another paper is in review at Geophysical Journal International on the case study for Xiuyan.…”

Section: Resultsmentioning

confidence: 99%

“…Several values of the CC are quite high above 0.8. Other colors in cyan are at the 0.35 range that are at the level for a small signal buried in noise (SNR = 0.32, Schaff, 2008). The question is whether these values provide reliable detections.…”

Section: Xiuyan Case Studymentioning

confidence: 99%

“…To automatically detect the spikes above the background levels we use a scaled CC (SCC) using a threshold of 6 which quantifies the deviation of the cross correlation coefficient from an empirical distribution of background values based on a moving window throughout the correlation trace (Schaff, 2008). Each point in the cross correlation trace is scaled by the mean absolute value of the moving window before the point.…”

Section: Xiuyan Case Studymentioning

confidence: 99%

“…Each point in the cross correlation trace is scaled by the mean absolute value of the moving window before the point. Another advantage of using SCC is that it is less dependent on the frequency band and window length than CC (Schaff, 2008). A threshold of 6 corresponds to approximately one false alarm per day on continuous data or a probability of a false alarm being less than one in a million (Schaff, 2008).…”

Section: Xiuyan Case Studymentioning

confidence: 99%

“…Gibbons & Ringdal (2006) demonstrated in a case study at the NORSAR array approximately 1.1 magnitude unit reduction in detection threshold using cross correlation compared to an STA/LTA detector. Embedding a known signal in real, background, seismic noise enables an empirical estimate of the false alarms (1 per day, which is acceptably low) that corresponds to this order of magnitude improvement in detection threshold (Schaff , 2008). With so few false alarms this amount of improvement is no small feat.…”

Section: Introductionmentioning

confidence: 99%

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Improving Magnitude Detection Thresholds Using Multi-Station Multi-Event, and Multi-Phase Methods

Schaff¹,

Waldhauser²

2008

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. (31-07-2008) REPORT DATE SPONSOR/MONITOR'S ACRONYM(S)AFRL/RVBYE SPONSOR/MONITOR'S REPORT NUMBER(S) AFRL-RV-HA-TR-2008-1121 DISTRIBUTION / AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited. SUPPLEMENTARY NOTES ABSTRACTWe report on the results of both a semi-empirical analysis and a case study in Xiuyan, China, that demonstrated that a correlation detector can lower magnitude detection thresholds by over one full unit for similar events as compared to a standard STA/LTA detector. 90 out of 90 events (100%) were detected by cross correlation for the case study whereas a procedure like the pIDC employs detected only 11%. We found that less than perfect matches still provided useful detections due to location, focal mechanism, and magnitude differences. Events with magnitude differences as large as 2.3 and 3.3 were shown to produce detection spikes on the correlation traces. Further work applied the correlation techniques on a larger scale to 5,000 events at Parkfield, California, and 19,000 events in and near China. We are attempting to see how broadly applicable correlation methods can be applied to different tectonic settings and for what percentage of the seismicity. 111 million correlations were performed on Lg-waves for the events in China at 363 stations. Final results indicate two thirds of the 19,000 events can be detected by cross correlation using this relatively sparse regional network. The full magnitude unit reduction in detection threshold is confirmed on a large scale in China and Parkfield.

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Section: Resultsmentioning

confidence: 99%

Section: Xiuyan Case Studymentioning

confidence: 99%

Section: Xiuyan Case Studymentioning

confidence: 99%

Section: Xiuyan Case Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving Magnitude Detection Thresholds Using Multi-Station Multi-Event, and Multi-Phase Methods

Schaff¹,

Waldhauser²

2008

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An investigation of seismicity clustered near the Cordel Field, west central Alberta, and its relation to a nearby disposal well

Schultz¹,

Stern²,

2014

JGR Solid Earth

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Historically, seismicity documented in the Western Canada Sedimentary Basin has been relatively quiescent and earthquakes are usually restricted to the foreland belt of the Rocky Mountains. However, exceptional clusters of events, which have remained active for decades, are recognized in Alberta. In this study we investigate the seismicity in this region using data obtained from recently established regional arrays, emphasizing the relationship between a disposal well in the Cordel Field and a nearby cluster of previously reported earthquakes. We explore temporal correlations of wastewater pumping rates and local seismic activity dating back to 1960. We find that the first statistically significant increase in seismicity lags the onset of wastewater injection (October 1991) by~3.33 years. In particular, the waveform similarity of 32 events are analyzed from continuous data recorded at NOR, a nearby (~30 km) station operated by the University of Alberta starting in September of 2006. Results from this analysis suggest that many events are well correlated in the characteristics of the waveforms and thus are likely to share a similar origin and source mechanism. The most prolific of these multiplets repeats more than 10 times sporadically throughout the entire duration of recorded data from October 2006 to March 2012. Despite the limited availability of nearby stations, which adversely affects the resolution of our analysis, hypocenter depths could be relatively accurately determined from waveform synthesis and double difference methods. The results of our analysis provide first-order evidence that the seismicity is consistent with fluid injection-induced events.

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Hydraulic fracturing and the Crooked Lake Sequences: Insights gleaned from regional seismic networks

Schultz¹,

Stern²,

Novakovic

et al. 2015

Geophysical Research Letters

110

126

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Within central Alberta, Canada, a new sequence of earthquakes has been recognized as of 1 December 2013 in a region of previous seismic quiescence near Crooked Lake, ~30 km west of the town of Fox Creek. We utilize a cross‐correlation detection algorithm to detect more than 160 events to the end of 2014, which is temporally distinguished into five subsequences. This observation is corroborated by the uniqueness of waveforms clustered by subsequence. The Crooked Lake Sequences have come under scrutiny due to its strong temporal correlation (>99.99%) to the timing of hydraulic fracturing operations in the Duvernay Formation. We assert that individual subsequences are related to fracturing stimulation and, despite adverse initial station geometry, double‐difference techniques allow us to spatially relate each cluster back to a unique horizontal well. Overall, we find that seismicity in the Crooked Lake Sequences is consistent with first‐order observations of hydraulic fracturing induced seismicity.

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Semiempirical Statistics of Correlation-Detector Performance

Cited by 65 publications

References 26 publications

Improving Magnitude Detection Thresholds Using Multi-Station Multi-Event, and Multi-Phase Methods

Improving Magnitude Detection Thresholds Using Multi-Station Multi-Event, and Multi-Phase Methods

An investigation of seismicity clustered near the Cordel Field, west central Alberta, and its relation to a nearby disposal well

Hydraulic fracturing and the Crooked Lake Sequences: Insights gleaned from regional seismic networks

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