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Waveform cross-correlation for differential time measurement: Bias and limitations
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SYSNO ASEP 0509540 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Waveform cross-correlation for differential time measurement: Bias and limitations Tvůrce(i) Bachura, Martin (GFU-E) ORCID
Fischer, T. (CZ)Zdroj.dok. Seismological Research Letters. - : Seismological Society of America - ISSN 0895-0695
Roč. 90, č. 5 (2019), s. 2005-2014Poč.str. 10 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova waveform cross-correlation ; differential time ; relative earthquake location Vědní obor RIV DC - Seismologie, vulkanologie a struktura Země Obor OECD Volcanology CEP EF16_013/0001792 GA MŠMT - Ministerstvo školství, mládeže a tělovýchovy GA18-05053S GA ČR - Grantová agentura ČR Způsob publikování Omezený přístup Institucionální podpora GFU-E - RVO:67985530 UT WOS 000484569600028 EID SCOPUS 85072770825 DOI 10.1785/0220190096 Anotace The waveform cross-correlation technique is a popular tool for estimating the differential times of seismic phases in a fast and reliable manner. Differential times are used for a variety of methods, with the double-difference relocation method HypoDD being the most popular. In this work, we analyzed the precision and possible error of cross-correlated differential times by conducting a simple comparison with reference manual datasets. Our study was carried out on two well-studied mainshock-aftershock datasets from the seismically active West Bohemia region (Czechia). We observed that the magnitude difference delta M-L between two cross-correlated earthquakes presents a significant bias, resulting in the over- or underestimation of the final differential time of both P and S waves. The earthquakes of differing magnitudes exhibit unequal first pulse durations in otherwise similar waveforms. As a result, the cross-correlated differential time, which shifts seismograms to the position of maximum cross-correlation, is different from the differential time between phase arrivals. Our test cases revealed that the resulting deviation from the true differential time depends on the actual delta M-L and can reach values higher than 0.025 s when delta M-L > 2. Hence, in standard differential time datasets, the error has a greater impact on the data related to strong events-mainshocks. In HypoDD applications, the error leads to mislocations of mainshocks, and at the same time, the locations of the weak events are improved. We demonstrate the mislocation potential of the error on relocated hypocenters of mainshock-aftershock sequences and earthquake swarms from West Bohemia, as well as on synthetic tests. The error cannot be avoided by changing the cross-correlated window length or filtration. We propose a few suggestions to suppress the consequences of the magnitude difference data bias. Pracoviště Geofyzikální ústav Kontakt Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Rok sběru 2020 Elektronická adresa https://pubs.geoscienceworld.org/ssa/srl/article-abstract/90/5/2005/573148/Waveform-Cross-Correlation-for-Differential-Time?redirectedFrom=fulltext
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