Detecting tectonic tremor through frequency scanning at a single station: Application to the Cascadia margin

Sit, S. M.; Brudzinski, M. R.; Kao, Honn

doi:10.1016/j.epsl.2012.08.002

Cited by 16 publications

(25 citation statements)

References 31 publications

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“…We used the frequency passbands recorded by short‐period OBSs. The fundamental utility of this analysis has been confirmed by detecting TTs in Cascadia (Sit et al, ). Therefore, this is useful to avoid missing detections owing to ocean conditions, microseisms, and regular earthquakes that could influence the tremor band.…”

Section: Observation and Methodsmentioning

confidence: 90%

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Tidal Response in Shallow Tectonic Tremors

Katakami

Yamashita

Yakihara

et al. 2017

Geophysical Research Letters

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Various types of slow earthquakes (e.g., tectonic tremors and slow slip events) have been reported in tectonic zones, especially in the subduction zone. The tidal response of a tremor is considered to be strongly related to the weak friction state of the plate interface, and many studies have reported observational evidence of such correlation between tides and deep tremor activity. Here we used the modified frequency scanning method at a single station to detect micro tectonic tremors that have not been previously reported in southern Kyushu. In the early stage of the tremor activity, tremors are mostly modulated by slow slip events. In contrast, we found a seismic response to ocean tides during the later stage in the shallower part of the subduction zone. This might indicate that the tremors are triggered by tidal changes caused by fault weakening due to slow slip events as same as deeper condition.

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Section: Observation and Methodsmentioning

confidence: 90%

“…Shallow low‐frequency tremor distribution (Yamashita et al, ) and R 2m values calculated using frequency scanning method (Sit et al, ) at OBS08, OBS09, and OBS10 from 28 May to 2 July 2013. Distribution of shallow tremors is shown by colored circles; time zone is Japan Standard Time (JST) or universal time coordinated +09:00.…”

Section: Introductionmentioning

confidence: 99%

Tidal Response in Shallow Tectonic Tremors

Katakami

Yamashita

Yakihara

et al. 2017

Geophysical Research Letters

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“…Because tremor is often episodic elsewhere and the frequency content of tremor distinguishes it from other seismic sources, time periods of increased tremor activity may be able to be identified by increased amplitudes in the tremor frequency band relative to other passbands. For example, Sit et al (2012) used a frequency ratio scanning algorithm to identify tectonic tremor in Cascadia. We apply this method to the NAFPSE data set.…”

Section: Methodsmentioning

confidence: 99%

“…Sit et al (2012) tested different duration windows and ratio calculations to find the most appropriate parameters for identifying isolated tremor bursts and excluding local earthquakes with energy that bleeds into the tremor passband. In Cascadia, tremor detections were defined as time periods when R was greater than two sigma above the mean for the entire time period, which we use as a guide for our study.…”

Section: Methodsmentioning

confidence: 99%

Search for Tectonic Tremor on the Central North Anatolian Fault, Turkey

Pfohl

Warren

Sit

et al. 2015

Bulletin of the Seismological Society of America

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Tectonic tremor has previously been observed along two major transform faults: the San Andreas fault (SAF) and the Alpine fault (AF); and we extend the search for tectonic tremor to another transform fault, the North Anatolian fault (NAF). We investigate a two-year-long temporary broadband seismic deployment on an ∼400 km long NAF segment in central Turkey. The central NAF network has stations within a few kilometers of the fault. Although the station spacing is larger than for the SAF and AF networks, we still expect to be able to observe coherent tremor at several stations, if it occurs in similar amounts as elsewhere. We search for tremor triggered by the surface waves of regional and teleseismic earthquakes but do not observe any tremor associated with the passage of surface waves. Next, we search for ambient tremor and observe occasional tremor-like signals, but the signals are not coherent between stations. Thus, we cannot identify any unambiguous tremor episodes and suggest that if tremor occurs along the central NAF, it occurs at a lower amplitude and/or rate than along the SAF or AF.

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“…In this detection method, it is implicitly assumed that all tectonic tremor events have an almost constant duration length in average. Although Sit et al (2012) calculated the mean and SD using several years of data, the OBS deployments featured in this study were short term (Table A1), which limited the duration of the available data. It was also necessary to exclude periods with significant increases in seismic amplitudes of various types, as explained in section 2.…”

Section: Tectonic Tremor Detection Via the Modified Frequency Scanninmentioning

confidence: 99%

Spatiotemporal Variation of Tectonic Tremor Activity Before the Tohoku‐Oki Earthquake

et al. 2018

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A slow slip event (SSE) and tectonic tremors occurred approximately 1.5 month prior to the occurrence of the 2011 Tohoku‐Oki earthquake near the Japan Trench. Although we cannot completely rule out other sources of noise near the observation site, slow earthquakes would demonstrate the nucleation of a fast slip event from prior slow earthquake activity. Here we report on tectonic tremor activity detected from short‐period ocean‐bottom seismometer (OBS) data with a modified frequency scanning method that allows robust tectonic tremor detection by incorporating information from multiple frequency passbands in order to suppress false detections. We have identified at least five tectonic tremor sequences on the OBS records from the end of January 2011 to just before the occurrence of the Tohoku‐Oki earthquake in March 2011. To reveal the spatial distributions of tectonic tremors before the Tohoku‐Oki earthquake, we then calculated tremor energy, with corrected site amplification, from the identified tectonic tremor time window at each OBS that detected tremors. Possible sources of tremors were distributed in trenchward side of the SSE fault prior to the main shock. These tremors could be modulated by SSE to take into account consistent timing between tremor and SSE term, and consistency of spatial locations between estimated tremor sources and SSE faults. This spatiotemporal pattern in tectonic tremor activity demonstrates a significant separation of occurrence sources between tectonic tremors and regular earthquakes.

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Detecting tectonic tremor through frequency scanning at a single station: Application to the Cascadia margin

Cited by 16 publications

References 31 publications

Tidal Response in Shallow Tectonic Tremors

Tidal Response in Shallow Tectonic Tremors

Search for Tectonic Tremor on the Central North Anatolian Fault, Turkey

Spatiotemporal Variation of Tectonic Tremor Activity Before the Tohoku‐Oki Earthquake

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