{"title":"Ambient Noise Array Tomography Using Regionalized Phase Velocities From Array-Based Methods","authors":"Kaifeng Zhao, Yingjie Yang, Yinhe Luo, Hao Jin, Chengxin Jiang","doi":"10.1029/2024JB030280","DOIUrl":"https://doi.org/10.1029/2024JB030280","url":null,"abstract":"<p>With the advancement of dense seismic arrays, array-processing methods for ambient noise data have become highly effective in extracting high-quality broadband surface wave dispersion curves from ambient noise. Recent advancements in array data processing methods have enabled the extraction of multimode dispersion curves, offering improved constraints on deep Earth structures. However, these array-based methods often produce regionalized dispersion curves, and conventional phase velocity maps constructed by interpolating these dispersion curves typically have limited resolution, and display smooth images of phase velocities. In this study, we develop an array tomography method aimed at improving the resolution of ambient noise tomography by utilizing dispersion curves extracted through array-based data processing. To demonstrate the effectiveness of our method in enhancing tomography resolution, we construct fundamental-mode 2-D Rayleigh wave phase velocity maps by applying our approach to regionalized dispersion curves obtained from array-based methods in the western United States. By comparing our tomographic results with those from conventional array-based methods, we show that our method can produce more accurate and higher-resolution phase velocity maps. Additionally, our approach is versatile and can be applied to construct high-resolution 1-D and 2-D velocity structures using regionalized phase velocities obtained from various other array-based data processing methods.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 3","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143690274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HyeJeong Kim, Fan-Chi Lin, James C. Pechmann, Christian L. Hardwick, Adam P. McKean
{"title":"Seismic Imaging of the Salt Lake Basin Using Joint Inversion of Receiver Functions and Rayleigh Wave Data","authors":"HyeJeong Kim, Fan-Chi Lin, James C. Pechmann, Christian L. Hardwick, Adam P. McKean","doi":"10.1029/2024JB030927","DOIUrl":"https://doi.org/10.1029/2024JB030927","url":null,"abstract":"<p>This study presents a new velocity model for the Salt Lake basin (SLB) in Utah, determined using data from permanent and temporary seismic stations located on top of the basin in the Salt Lake Valley (SLV) and nearby. A three-dimensional (3D) velocity model for the SLB is needed for accurate predictions of future damaging earthquake ground shaking in the heavily urbanized SLV, including Salt Lake City. The SLB part of the Wasatch Front community velocity model (WFCVM) currently serves this purpose. However, the current WFCVM is based primarily on gravity and borehole data with relatively few seismic constraints below depths of 100 m. In this study we use the first peak of SLV receiver functions (RFs), which is sensitive to a strong impedance contrast at the base of a semi-consolidated sediment layer. We jointly invert the RF waveform with Rayleigh wave ellipticity (H/V) and phase velocity measurements using the Markov chain Monte Carlo approach. Our new velocity model shows a greater combined thickness of unconsolidated and semi-consolidated sediments, compared to the WFCVM, in the northeastern SLB between the west-dipping East Bench fault section of the Wasatch fault and the antithetic West Valley fault zone to the west. We show that the new seismic velocity model explains the gravity patterns in the valley. The new velocity model from this study provides a basis for revising the SLB model in the WFCVM.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 3","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030927","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143690276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Systematic Differences in Energy Radiation Processes Between Regular and Intraplate Low-Frequency Earthquakes Around the Focal Area of the 2008 \u0000 \u0000 \u0000 \u0000 M\u0000 w\u0000 \u0000 \u0000 ${boldsymbol{M}}_{boldsymbol{w}}$\u0000 6.9 Iwate-Miyagi, Japan, Earthquake","authors":"Masaki Orimo, Keisuke Yoshida, Toru Matsuzawa, Taka'aki Taira, Kentaro Emoto, Akira Hasegawa","doi":"10.1029/2024JB030750","DOIUrl":"10.1029/2024JB030750","url":null,"abstract":"<p>Many unknowns exist regarding the energy radiation processes of intraplate low-frequency earthquakes (LFEs), which are frequently observed beneath volcanoes. To evaluate their energy radiation characteristics, we estimated scaled energy (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>e</mi>\u0000 <mi>R</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${e}_{R}$</annotation>\u0000 </semantics></math>) for LFEs and regular earthquakes around the focal area of the 2008 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>w</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${M}_{w}$</annotation>\u0000 </semantics></math> 6.9 Iwate-Miyagi, Japan, earthquake. Their source spectra were first obtained by correcting for the site and path effects from direct S-waves. We then estimated the radiated energy and seismic moment and obtained the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>e</mi>\u0000 <mi>R</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${e}_{R}$</annotation>\u0000 </semantics></math> for the 1,421 regular earthquakes, 62 deep LFEs, and 46 shallow LFEs. The <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>e</mi>\u0000 <mi>R</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${e}_{R}$</annotation>\u0000 </semantics></math> for the regular earthquakes is in the order of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>5</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${10}^{-5}$</annotation>\u0000 </semantics></math> to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>4</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${10}^{-4}$</annotation>\u0000 </semantics></math>, typical for crustal earthquakes and tends to be smaller near volcanoes and the shallow LFEs. In contrast, the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>e</mi>\u0000 ","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 3","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030750","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}