Using Automated, High-precision Repicking to Improve Delineation of Microseismic Structures at the Soultz Geothermal Reservoir

Rowe, C. A.; Aster, R. C.; Phillips, W. S.; Jones, R. H.; Borchers, Brian; Fehler, Michael

doi:10.1007/pl00001265

Cited by 79 publications

(33 citation statements)

References 48 publications

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“…This makes the method robust in the presence of electronic noise by only saving time lags when the two signals are sufficiently similar to warrant doing so. This is similar to the coherency‐based filtering technique described by Rowe et al [2002].…”

Section: Interstation Arrival Times: Vertical Componentsmentioning

confidence: 83%

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Location and mechanism of very long period tremor during the 2008 eruption of Okmok Volcano from interstation arrival times

Haney¹

2010

J. Geophys. Res.

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[1] We describe continuous, very long period (VLP) tremor that occurred during the 2008 eruption of Okmok Volcano, Alaska. Due to its low frequency content in band from the 0.2-0.4 Hz, the wave field of the VLP tremor is relatively free of path effects. From continuous recordings of the VLP tremor on 2 three-component broadband and 3 singlecomponent short-period instruments, we devise a method to locate the epicenter of the tremor based on interstation arrival times computed with cross correlation. We find the epicenter since the vertical and radial components of the VLP tremor wave field are dominated by Rayleigh waves and the time shifts are related to lateral propagation. Over the 4 h period studied, this procedure yields a location NNW of Cone D, close to the new cone built over the course of the eruption. Similar analysis using the transverse horizontal components from the 2 three-component broadband instruments yields strong constraints on the source mechanism of the VLP tremor. We observe an anomalous interstation arrival time due to the existence of a nodal plane in the Love wave radiation pattern. The orientation of a compensated linear vector dipole (CLVD) source estimated from the transverse components closely aligns with the regional maximum horizontal stress direction. The depth of the CLVD source is constrained by matching the vertical components to the Rayleigh wave radiation pattern at all five stations. We find the VLP tremor source depth to be 2 km BSL, positioned between the magma chamber at Okmok (>3 km BSL) and the surface.

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Section: Interstation Arrival Times: Vertical Componentsmentioning

confidence: 83%

“…In the cross‐spectral technique [ Poupinet et al , 1984], a time delay between a signal pair is found from the linearity of the difference in their phase spectra. This approach can be improved considerably with the use of coherency‐based filtering [ Rowe et al , 2002]. …”

Section: Interstation Arrival Times: Vertical Componentsmentioning

confidence: 99%

Location and mechanism of very long period tremor during the 2008 eruption of Okmok Volcano from interstation arrival times

Haney¹

2010

J. Geophys. Res.

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“…Recent retrospective analyses of seismic data have taken advantage of waveform alignment and joint location methods to obtain remarkable improvements in the spatial clarity of event locations. Examples of such studies include Shearer [1997, 1998], Rubin et al [1999], Waldhauser et al [1999], Aster and Rowe [2000], Rowe et al [2002a, 2002b], Waldhauser and Ellsworth [2002], and Schaff et al [2002] for fault zones and Got et al [1994], Rubin et al [1998], Battaglia et al [2004], and Rowe et al [2004] for volcanoes. Waveform alignment reduces relative picking errors between earthquakes with similar waveforms, leading to higher‐precision differential times or absolute arrival time adjustments.…”

Section: Introductionmentioning

confidence: 99%

High‐precision earthquake location and three‐dimensional P wave velocity determination at Redoubt Volcano, Alaska

DeShon¹,

Thurber²,

Rowe³

2007

J. Geophys. Res.

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[1] Redoubt Volcano, Alaska poses significant volcanic hazard to the Cook Inlet region and overlying flight paths. During and following the most recent eruption in [1989][1990] the Alaska Volcano Observatory deployed up to 10 seismometers to improve real-time monitoring capabilities at Redoubt and continues to produce an annual earthquake catalog with associated arrival times for this volcano. We compute a three-dimensional P wave velocity model using double-difference tomography combined with waveform cross-correlation techniques to identify families of similar earthquakes and increase earthquake location precision at Redoubt. Absolute and differential times for well-constrained events are used to simultaneously invert for hypocenter location and P wave velocity structure. Shot and earthquake arrival times recorded by temporary stations deployed on Redoubt in July 1991 supplement the catalog picks. Double-difference tomography reduces uncertainties associated with absolute and relative earthquake locations and provides a clearer picture of three-dimensional velocity heterogeneity. All Redoubt data available through November 2005 are relocated through the three-dimensional model, and we investigate seismicity associated with the 1989-1990 eruption and compare cross-correlation coefficients to identify similar earthquakes within the catalog. Waveform similarity is high at Redoubt, especially during the eruptive phases, and event families include long-period shallow summit, hybrid, and both shallow summit and midcrust level volcano-tectonic earthquakes. We do not resolve a low-velocity feature in the three-dimensional P wave model that can be interpreted as a source magma chamber and prefer the idea of an interconnected body of dikes and sills as the source of magma erupted in 1989-1990. Citation: DeShon, H. R., C. H. Thurber, and C. Rowe (2007), High-precision earthquake location and three-dimensional P wave velocity determination at Redoubt Volcano, Alaska,

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“…Recently, accurate differential traveltimes obtained from seismic waveforms have been used to improve dramatically the relocation results for shallow crustal earthquakes (Got et al 1994; Dodge et al 1995; Shearer 1997; Rubin et al 1999; Waldhauser & Ellsworth 2000; Rowe et al 2002; Schaff et al 2002). Such studies often use a cross‐correlation (CC) technique to calculate the relative time delay between the waveforms of two events recorded at the same station to obtain sample‐level (sometimes even subsample‐level) relative pick accuracy.…”

Section: Introductionmentioning

confidence: 99%

New constraints on seismicity in the Wellington region of New Zealand from relocated earthquake hypocentres

Du¹,

Thurber²,

Reyners

et al. 2004

Geophysical Journal International

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SUMMARY The Wellington region of New Zealand overlies a strongly coupled portion of the shallow subduction interface between the Pacific and Australian plates. To better understand the active deformation in the area, we perform a double‐difference (DD) relocation of 6825 local earthquakes that occurred between 1990 and 2001. Using both cross‐correlation (CC) and bispectrum (BS) methods, we calculate high‐quality waveform‐based differential times (WBDTs) for event pairs. We manage to more than triple the S‐wave differential time measurements after reasonably estimating many of the unpicked S arrivals. After relocation, the image of the double seismic zone beneath this region is greatly sharpened. We find several northeast‐striking linear seismic features near Lake Wairarapa on the North Island, which may result from slip along normal faults within the subducting Pacific Plate. We further search for repeating events that might define creeping patches along the interplate thrust. Using a 20‐s data window for CC, we find 287 event clusters with very high waveform similarities. Most of these clusters contain just a doublet that occurred within a short time period. The failure to find repeating earthquakes along the plate boundary in this 12‐yr time period is consistent with the hypothesized strong coupling between the Pacific and Australian plates under the Wellington region.

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Using Automated, High-precision Repicking to Improve Delineation of Microseismic Structures at the Soultz Geothermal Reservoir

Cited by 79 publications

References 48 publications

Location and mechanism of very long period tremor during the 2008 eruption of Okmok Volcano from interstation arrival times

Location and mechanism of very long period tremor during the 2008 eruption of Okmok Volcano from interstation arrival times

High‐precision earthquake location and three‐dimensional P wave velocity determination at Redoubt Volcano, Alaska

New constraints on seismicity in the Wellington region of New Zealand from relocated earthquake hypocentres

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