Three‐dimensional compressional wave attenuation tomography for the crust and uppermost mantle of Northern and central California

Abstract

I present a frequency-independent three-dimensional (3-D) compressional wave attenuation model (indicated by quality factor Q p ) for the crust and uppermost mantle of Northern and central California. The tomographic inversion used t * values measured from amplitude spectra of 80,988 P wave arrivals of 3247 events recorded by 463 network stations through a 3-D seismic velocity model. The model has a uniform horizontal grid spacing of 15 km, and the vertical node intervals range between 2 and 10 km down to 45 km depth. In general, the resulting Q p values increase with depth and agree with the surface geology at shallow depth layers. The most significant features observed in the Q p model are the high Q p values in the Sierra Nevada mountains and low Q p anomalies in the western fault zones. Low Q p values are also imaged in Owens Valley and Long Valley at shallow depths and the Cape Mendocino region in the lower crust (∼25 km depth). An overall contrast of Q p values across the fault is observed in the creeping, Parkfield and Cholame-Carrizo sections of the San Andreas Fault. The new 3-D Q p model provides an important complement to the existing regional-scale velocity models for interpreting structural heterogeneity and fluid saturation of rocks in the study area.

Seismic tomography of compressional wave attenuation structure for Kı̄lauea Volcano, Hawai‘i

“…The RMS of the t * residuals drops from 0.015 to 0.010 s after the inversion (Figure 7). This amount of reduction is comparable with other local-/regional-scale attenuation studies [e.g., Eberhart-Phillips and Chadwick, 2002;Hauksson and Shearer, 2006;Bennington et al, 2008;Nakajima et al, 2013;Lin, 2014aLin, , 2014b.…”

“…As shown in Figure a, the constant Q p value that gives the minimum RMS of the t * residuals is 200 based on an f −2 source model [ Brune , ], which is significantly smaller than the values for tectonically active regions such as California. For comparison, the minimum constant Q p value is 400 for Northern California [ Lin , ] and 450 for the Salton Trough in Southern California [ Lin , ], when an f −2 source model is assumed. The low‐constant Q p value in this study indicates the generally high attenuation in Kı̄lauea, which is expected for magmatic systems [ Lees , ].…”

Upper Crustal Weak Zone in Central Tibet: An Implication From Three‐Dimensional Seismic Velocity and Attenuation Tomography Results

“…Furthermore, resolvable shallow attenuation structure might be included in station parameters, which is not our preference. We performed an iterative fitting approach described in Lin () to determine the three unresolved parameters: Ω oij , f ci , and values. The corner frequency f ci of each event was searched for, over the frequency range, by minimizing the average difference between the calculated and observed velocity amplitude spectra: where N is the number of observations and A ij ( f ) and D ij ( f ) are calculated and observed velocity amplitude spectra, respectively.…”

“…We performed ray tracing through the obtained Vp model. The initial Qp model was determined according to the procedure in Lin (). We searched the initial uniform Qp through a sequence of values from 100 to 2,000 with an interval of 50.…”

A three‐dimensional QP imaging of the shallowest subsurface of Campi Flegrei offshore caldera, southern Italy

“…As a starting model during these inversions, different homogeneous Q P structures are used [Martinez-Arevalo et al, 2005;Chiarabba et al, 2009;Bisrat et al, 2013]. Values of Q P ranging from 30 to 150, with a step of 10, are tested [Hansen et al, 2004;Lin, 2014]. The one producing the greatest reduction of Δt * residuals at the first iteration is selected for further iterations: the initial uniform value Q P is found to be 70 ( Figure S8).…”