Implementation of Filter Picker Algorithm For Aftershock Identification of Lombok Earthquake 2018
KeywordsAftershock Identification, Lombok 2018 Event, Automatic Arrival Time Pick, Filter Picker
The ability to identify earthquake events that are consistent, efficient and accurate is increasingly needed along with the increase in the amount of data analyzed. In this paper a filter picker algorithm is implemented to identify aftershock events and determination of arrival time automatically, especially for the P wave phase. Here modifications are made in determining the uncertainty of arrival time and there are additional criteria in determining the time of arrival used. The additional criteria are that in a certain time span, there are at least 5 stations determined by the time the filter picker arrives. This is done to minimize identification errors due to local noise and other practical reasons, namely the minimum number of stations to determine the location and other seismological analysis. To test the filter picker algorithm, aftershock data from the Lombok earthquake occurred on July 29 (M 6.4), August 5 (M 7), and August 19 (M 6.3 and M 6.9) 2018. The aftershock data were used for 30 days, from August 4, 2018 to September 4, 2018 using local seismic station in Lombok Island. The results of the filter picker algorithm were evaluated by comparing the number of earthquake events detected and the accuracy of determining the P wave arrival time automatically to the results of manually arriving time. In addition, a comparison of the results obtained from a broadband type seismometer with a short period is used to find out how much influence the type of tool has on its performance results. The results of the comparison with the manual arrival time show that more than 85 percent of the results of the automatic arrival time have a difference below 0.2 seconds. Therefore, it can be said that the filter picker algorithm is quite effective for identifying events and determining the arrival time of P waves. In this paper it is also shown that this algorithm can be used for broad band and short period seismometer sensor, even without the prior correction of instruments.
Baer, M. dan Kradolfer, U. (1987): An automatic phase picker for local and teleseismic events, Bulletin of the Seismological Society of America, 77, 1437 – 1445.
Baillard, C., Crawford, W. C., Ballu, V., Hibert, C. dan Mangeney, A. (2014): An automatic kurtosis-based P- and S-phase picker designed for local seismic networks, Bulletin of the Seismological Society of America, 104, no.1, 1-16.
De Meersman, K., Kendall, M., dan Vand der Baan, M. (2009): The 1988 Valhall microseismic data set: An integrated study of relocated source, seismic multiplets, and S-wave splitting, Geophysics, 74, no.5, B183-B195.
Earle, P. S., dan Shearer, P. M. (1994): Characterization of global seismograms using an automated picking algorithm, Bulletin of the Seismological Society of America, 84, 366-376.
Han, L., Wong, J., dan Bancroft, J. (2009): Time picking and random noise reduction on microseismic data: CREWES Research Report, 21, 1-13.
Kurzon, I., Vernon, F. L., Rosenberger, A., dan Ben-Zion, Y. (2014): Real-time automatic detectors of P and S waves using singular value decomposition, Bulletin of the Seismological Society of America, 104, 1696 – 1708.
Leonard, M., dan Kennett, B. L. N. (1999): Multi-component autoregressive techniques for the analysis of seismograms, Physics of The Earth and Planetary Interiors, 113, 247 – 263.
Lomax, A., Satriano, C., dan Vassallo, M. (2012): Automatic picker developments and optimization: filterpicker – a robust, broadband picker for real-time seismic monitoring and earthquake early warning, Seismological Research Letters, 83, 531-540.
Ross, Z. E., dan Ben-Zion, Y. (2014): Automatic picking of direct P, S seismic phase and fault zone head waves, Geophysical Journal International, 199, 368-381.
Vassallo, M., Satriano, C., dan Lomax, A. (2012): Automatic picker developments and optimization: a strategy for improving the performance of automatic phase picker, Seismological Research Letters, 83, 541-554.
This work is licensed under a Creative Commons Attribution 4.0 International License.
The copyright of all articles belongs to the authors. All other copyrights is held by the Journal