An Automatic Kurtosis‐Based P ‐ and S ‐Phase Picker Designed for Local Seismic Networks

Abstract We present an automatic P ‐ and S ‐wave onset‐picking algorithm, using kurtosis‐derived characteristic functions (CF) and eigenvalue decompositions on three‐component seismic data. We modified the kurtosis CF (Saragiotis et al. , 2002) to improve pick precision by computing the CF over several frequency bandwidths, window sizes, and smoothing parameters. Once phases are picked, our algorithm determines the onset type ( P or S ) using polarization parameters, removes bad picks using a clustering procedure and the signal‐to‐noise ratio (SNR) and assigns a pick quality index based on the SNR. We tested our algorithm on data from two different networks: (1) a 30‐station, 100×100  km array of mostly onland wideband seismometers in a subduction context and (2) a four‐station, 7×4  km array of ocean‐bottom seismometers over a midocean ridge volcano. We compared picks from the automatic algorithm with manual and short‐term average/long‐term average (STA/LTA)‐based automatic picks on subsets of each dataset. For the larger array, the automatic algorithm resulted in more locations than manual picking (133 versus 93 locations out of 163 total events detected), picking as many P onsets and twice as many S onsets as with manual picking or the STA/LTA algorithm. The difference between manual and automatic pick times for P ‐wave onsets was 0.01±0.08  s overall, compared with −0.18±0.19  s using the STA/LTA picker. For S ‐wave onsets, the difference was −0.09±0.23  s, which is comparable to the STA/LTA picker, but our picker provided nearly twice as many picks. The pick accuracy was constant over the range of event magnitudes (0.7–3.7 M l ). For the smaller array, the time difference between our algorithm and manual picks is 0.04±0.17  s for P waves and 0.07±0.08  s for S waves. Misfit between the automatic and manual picks is significantly lower using our procedure than using the STA/LTA algorithm.

[1]  Andres Heinloo,et al.  Networked Seismographs : GEOFON Real-Time Data Distribution , 2000 .

[2]  Reinoud Sleeman,et al.  Robust automatic P-phase picking: an on-line implementation in the analysis of broadband seismogram recordings , 1999 .

[3]  The “little variable factor” a statistical discussion of the reading of seismograms , 1966 .

[4]  John E. Vidale,et al.  Complex polarization analysis of particle motion , 1986 .

[5]  Stavros M. Panas,et al.  PAI-S/K: A robust automatic seismic P phase arrival identification scheme , 2002, IEEE Trans. Geosci. Remote. Sens..

[6]  Christoph Waldmann,et al.  MoMAR-D: a technological challenge to monitor the dynamics of the Lucky Strike vent ecosystem , 2011 .

[7]  D. Giardini,et al.  Automatic seismic phase picking and consistent observation error assessment: application to the Italian seismicity , 2006 .

[8]  POLARIZATION ANALYSIS OF THREE-COMPONENT ARRAY DATA BY ANDY JURKEVICS , 2005 .

[9]  Aaron A. Velasco,et al.  Seismogram Picking Error from Analyst Review (SPEAR): Single-Analyst and Institution Analysis , 2009 .

[10]  Manfred Baer,et al.  An automatic phase picker for local and teleseismic events , 1987 .

[11]  J. Escartín,et al.  Hydrothermal seismicity beneath the summit of Lucky Strike volcano, Mid-Atlantic Ridge , 2013 .

[12]  Thomas Meier,et al.  Automated determination of P-phase arrival times at regional and local distances using higher order statistics , 2010 .

[13]  L. T. DeCarlo.  On the meaning and use of kurtosis. , 1997 .

[14]  M. Leonard,et al.  Multi-component autoregressive techniques for the analysis of seismograms , 1999 .

[15]  H. Akaike.  Markovian Representation of Stochastic Processes and Its Application to the Analysis of Autoregressive Moving Average Processes , 1974 .

[16]  B. Pelletier,et al.  Current tectonics of the Tonga–New Hebrides region , 1998 .

[17]  Andreas Rietbrock,et al.  Event Detection and Phase Picking Using a Time-Domain Estimate of Predominate Period Tpd , 2008 .

[18]  Jens Havskov,et al.  A Computer Program for Locating Earthquakes Both Locally and Globally , 1995 .

[19]  Andreas Rietbrock,et al.  Optimized automatic pickers: application to the ANCORP data set , 2010 .

[20]  Genshiro Kitagawa,et al.  Multivariate time-series model to estimate the arrival times of S-waves , 1993 .

[21]  Joan S. Gomberg,et al.  The effect of S-wave arrival times on the accuracy of hypocenter estimation , 1990, Bulletin of the Seismological Society of America.

[22]  R. V. Allen,et al.  Automatic phase pickers: Their present use and future prospects , 1982 .

[23]  Jens Havskov,et al.  Routine Data Processing in Earthquake Seismology: With Sample Data, Exercises and Software , 2010 .

[24]  A. Jurkevics.  Polarization analysis of three-component array data , 1988 .

[25]  B. Lienert,et al.  HYPOCENTER: An earthquake location method using centered, scaled, and adaptively damped least squares , 1986 .