Journal of Geophysical Research: Solid Earth最新文献

{"title":"The Role of Earth Tides in Reactivating Shallow Faults and Triggering Seafloor Methane Emissions","authors":"N. Sultan, V. Riboulot, S. Dupré, S. Garziglia, S. Ker","doi":"10.1029/2024jb030253","DOIUrl":"https://doi.org/10.1029/2024jb030253","url":null,"abstract":"The role of solid Earth tide in fault reactivation has significant implications for understanding earthquake triggering, carbon sequestration, and the global carbon budget. Despite extensive research on this topic, the relationship between Earth tide and fault reactivation remains unclear. In this study, we investigate the influence of solid Earth tide on the reactivation of sub-seabed faults, which may lead to the release of methane. We monitored the sub-seabed temperature and pore-fluid pressure at two sites on a fault system located in the Black Sea. Two sets of data obtained from distinct periods revealed inconsistent results. For the first set of data and despite the distance between the two sites (∼790 m), the responses in terms of temperature and pore pressure changes were synchronous (September 2021). We showed from these data that the presence of over-pressured fluid promotes fault reactivation under Earth tide cycles, resulting in synchronized degassing events. For the second set of data recorded from the same two sites (September 2021–May 2023), we did not identify any concomitance between Earth tides and the monitored parameters. Our analyses show that discrepancies in observations could be related to the fluid discharge/recharge process. The fluid discharge observed during the first period resulted in a decrease in excess pore-pressure, making the fault insensitive to Earth tides during the subsequent recharge period. Our data also sheds light on conflicting literature results, suggesting that the interaction between faults and Earth tides primarily depends on fluid pore pressure, a parameter rarely measured.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"252 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679063","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}

{"title":"The Influence of Using a Seismically Inferred Magma Reservoir Geometry in a Volcano Deformation Model for Soufrière Hills Volcano, Montserrat","authors":"J. Dibben, J. Hickey, K. Pascal, M. Paulatto","doi":"10.1029/2024jb030102","DOIUrl":"https://doi.org/10.1029/2024jb030102","url":null,"abstract":"Volcano deformation models contribute to hazard assessment by simulating magma system dynamics. Traditional magma reservoir pressure source shape assumptions often fail to replicate irregular, geophysically identified geometries. Uncertainties regarding the influence of reservoir geometry can limit the effectiveness of using deformation models to decipher unrest signals. Here, we aim to determine the feasibility of using a magma reservoir geometry directly derived from a seismic tomography survey in a volcano deformation model for Soufrière Hills Volcano, Montserrat. Three-dimensional deformation models are created to simulate displacement using a pressure source geometry constrained from a low seismic velocity anomaly, inferred to be a region of partial melt, and contrasted against a traditional ellipsoid reservoir geometry. We also test a “hybrid” model combining a seismically inferred reservoir upper geometry and ellipsoidal base. Results of each model are evaluated against ground displacement observed on Montserrat from 2010 to 2022. Our results show that different reservoir geometries change the horizontal and vertical displacement fields across the island: the ellipsoid reservoir best reproduces vertical displacement magnitude, while the hybrid reservoirs best simulate horizontal displacement vectors and the region of maximum uplift. Overall, the ellipsoid-shaped reservoir provides our best-fit to the observed data, but we note this result could be biased due to prior years of optimization helping constrain the ellipsoid shape, size, and location. Our results show the potential for further use of geophysically constrained reservoir geometries in deformation modeling, and our methods could be applied to other deforming volcanoes worldwide.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"16 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679122","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}

{"title":"A Novel 3-D Seismic Scattering and Intrinsic Attenuation Tomography and Its Application to Northern Sumatra","authors":"Jia Wei, Qiancheng Liu, Ling Chen, Shengji Wei, Liang Zhao","doi":"10.1029/2024jb029116","DOIUrl":"https://doi.org/10.1029/2024jb029116","url":null,"abstract":"Studying the subsurface structure of volcanoes is crucial for understanding volcanic mechanisms, current status, and potential risks. However, the intricate physical and chemical processes occurring over geological timescales make it challenging to characterize subsurface features such as volcanic structures and hydrothermal systems. Given the highly attenuating nature of magma, 3-D scattering and intrinsic attenuation tomography are critical methods for advancing our understanding of tectonic, magmatic, and hydrothermal processes and their interactions. Previous imaging techniques, however, required substantial memory usage and long computational times, limiting their application to only 1-D velocity models. This paper proposes a novel sensitivity-kernel calculation method for imaging shear wave seismic scattering and intrinsic attenuation. This method has the advantages of dramatically reducing memory and computational costs, as well as incorporating a 3-D seismic velocity model. We apply this approach to illustrate the 3-D scattering and intrinsic attenuation structures beneath the Toba volcano region in Northern Sumatra down to 20 km depth. Our results show high-intrinsic attenuation anomalies around the Toba caldera, revealing the magma chambers feeding the volcanoes. A conspicuous high-scattering attenuation anomaly is identified along the Great Sumatran Fault, possibly caused by the fault zone structure. Magmatism also likely contributes to the seismic activity south of the Toba caldera, as evidenced by the overlap of scattering and intrinsic attenuation anomalies.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"57 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679068","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}

{"title":"Electrical Conductivity and Sound Velocities of Talc Under High Pressure and High Temperature Conditions and Application to the Subducting Cocos Plate","authors":"Ming Hao, Anne Pommier, Emmanuel A. Codillo, Michael J. Walter, Andrew J. Cross, Rostislav Hrubiak, Lara Wagner, Andrew R. Thomson, Jing Yang, Nicholas Backhouse","doi":"10.1029/2024jb029824","DOIUrl":"https://doi.org/10.1029/2024jb029824","url":null,"abstract":"Talc is expected to be an important water carrier in Earth's upper mantle, and understanding its electrical and seismic properties under high pressure and temperature conditions is required to detect possible talc-rich regions in subduction zones imaged using geophysical observations. We conducted acoustic and electrical experiments on natural talc aggregates at relevant pressure-temperature conditions. Compressional wave velocity (<i>Vp</i>) was measured using ultrasonic interferometry in a Paris-Edinburgh press at pressures up to 3.4 GPa and temperatures up to 873 K. Similar <i>Vp</i> values are obtained regardless of the initial crystallographic preferred orientation of the samples, which can be explained by talc grain reorientation during the experiment, with the (001) plane becoming perpendicular to the uniaxial compression axis. Electrical conductivity of the same starting material was determined using impedance spectroscopy in a multi-anvil press up to 6 GPa and 1263 K. Two conductivity jumps are observed, at ∼860–1025 K and ∼940–1080 K, depending on pressure, and interpreted as talc dehydroxylation and decomposition, respectively. Electrical anisotropy is observed at low temperature and decreases with increasing pressure (∼10 at 1.5 GPa and ∼2 at 3.5 GPa). Comparison of acoustic and electrical results with geophysical observations in central Mexico supports the presence of a talc-bearing layer atop the subducted Cocos plate.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"18 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142672930","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}

{"title":"Fault Interaction and Strain Partitioning Deduced From Deformed Fluvial Terraces of the Eastern North Qilian Foreland, NE Tibetan Plateau","authors":"Xiu Hu,&nbsp;Yiran Wang,&nbsp;Weitao Wang,&nbsp;Michael E. Oskin,&nbsp;Zhigang Li,&nbsp;Jinghao Lei,&nbsp;Youli Li,&nbsp;Peizhen Zhang,&nbsp;Wenjun Zheng,&nbsp;Kairong Lin,&nbsp;Shanfeng Xiao,&nbsp;Honghua Lu,&nbsp;Junxiang Zhao,&nbsp;Yipeng Zhang,&nbsp;Ruizhi Jin,&nbsp;Yuezhi Zhong","doi":"10.1029/2024JB028924","DOIUrl":"https://doi.org/10.1029/2024JB028924","url":null,"abstract":"<p>Faulting and folding of basement rocks together accommodate convergence within continental orogens, forming complex zones of intraplate deformation shaped by the fault interaction. Here we use the river terraces along the Dongda river to examine the tectonic deformation patterns of the hinterland and the foreland of the eastern North Qilian Shan, a zone of crustal shortening located at the northeast margin of the Tibetan Plateau. Five Late Pleistocene–Holocene terraces of Dongda river are displaced by three major reverse faults: Minle-Damaying fault, Huangcheng-Ta'erzhuang fault, and Fengle fault, from south to north. Based on displaced terrace treads, we estimated vertical slip rates along the Minle-Damaying fault as 0.7–0.8 mm/a, and along the Fengle fault as 0.5–0.7 mm/a. Deformed terraces suggest an additional uplift of ∼0.2 mm/a through the folding of the Dahuang Shan anticline. Inhomogeneous uplift of the intermontane basins between the Minle-Damaying fault and the Dahuang Shan anticline indicates a 0.9 ± 0.2 mm/a uplift rate along the Huangcheng-Ta'erzhuang fault. Kinematic modeling of this thrust system shows that deformation propagated northward toward the foreland along a south-dipping 10° décollement rooted into the Haiyuan fault at the depth of ∼20 km. This system accommodates 2.7–3.4 mm/a total crustal shortening rate. We suggest this broad thrust belt and the relatively high rate of shortening within this part of the eastern Qilian Shan is a result of the oblique convergence along a restraining bend of Haiyuan fault system. The elevated shortening rate within this area indicates high potential seismic hazard.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB028924","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142666053","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":"Limited Preservation of Strike-Slip Surface Displacement in the Geomorphic Record","authors":"Nadine G. Reitman,&nbsp;Yann Klinger,&nbsp;Richard W. Briggs,&nbsp;Ryan D. Gold","doi":"10.1029/2024JB028692","DOIUrl":"https://doi.org/10.1029/2024JB028692","url":null,"abstract":"<p>Offset geomorphic markers are commonly used to interpret slip history of strike-slip faults and have played an important role in forming earthquake recurrence models. These data sets are typically analyzed using cumulative probability methods to interpret average amounts of slip in past earthquakes. However, interpretation of the geomorphic record to infer surface slip history is complicated by slip variability, measurement uncertainty, and modification of offset features in the landscape. To investigate how well geomorphic data record surface slip, we use offset measurements from recent strike-slip surface ruptures (<i>n</i> = 39), faults with geomorphic evidence of multiple strike-slip earthquakes (<i>n</i> = 29), and synthetic slip distributions with added noise (<i>n</i><span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math>10,000) to examine the constraints of the geomorphic record and the underlying assumptions of the cumulative offset probability distribution analysis method. We find that the geomorphic record is unlikely to resolve more than two paleo-slip distributions, except in specific cases with low slip variability, high slip-per-event, and semiarid climate. In cases where site-specific conditions allow for interpretation of more than two earthquakes, lateral extrapolation along a fault is not straightforward because on-fault displacement and distributed deformation may be spatially variable in each earthquake. We also find that average slip in modern earthquakes is adequately recovered by probability methods, but the reported prevalence of strike-slip faults with characteristic slip history is not supported by geomorphic data. We also propose updated methods to interpret slip history and construct uncertainty bounds for paleo-slip distributions.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142666081","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}

{"title":"Rapid Gas Bubble Growth in Basaltic Magma as a Source of Deep Long Period Volcanic Earthquakes","authors":"Oleg Melnik,&nbsp;Vladimir Lyakhovsky,&nbsp;Nikolai M. Shapiro","doi":"10.1029/2024JB029602","DOIUrl":"10.1029/2024JB029602","url":null,"abstract":"<p>In this paper, we present numerical modeling aimed to explain Deep Long Period (DLP) events occurring in middle-to-lower crust beneath volcanoes and often observed in association with volcanic eruptions or their precursors. We consider a DLP generating mechanism caused by the rapid growth of gas bubbles in response to the slow decompression of H₂O–CO₂ over-saturated basaltic magma. The nucleation and rapid growth of gas bubbles lead to rapid pressure change in the magma and elastic rebound of the host rocks, radiating seismic waves recorded as DLP events. The magma and host rocks are modeled as Maxwell bodies with different relaxation times and elastic moduli. Simulations of a single sill-shaped intrusion with different parameters demonstrate that realistic amplitudes and frequencies of P and S seismic waves can be obtained when considering intrusions with linear sizes of the order of 100 m. We then consider a case of two closely located sills and model their interaction. We speculate on conditions that can result in consecutive triggering of the bubble growth in multiple closely located batches of magma, leading to the generation of earthquake swarms or seismic tremors.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029602","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665332","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":"Seismic Response of Hectometer-Scale Fracture Systems to Hydraulic Stimulation in the Bedretto Underground Laboratory, Switzerland","authors":"Anne Obermann,&nbsp;Martina Rosskopf,&nbsp;Virginie Durand,&nbsp;Katrin Plenkers,&nbsp;Kai Bröker,&nbsp;Antonio Pio Rinaldi,&nbsp;Nima Gholizadeh Doonechaly,&nbsp;Valentin Gischig,&nbsp;Alba Zappone,&nbsp;Florian Amann,&nbsp;Massimo Cocco,&nbsp;Marian Hertrich,&nbsp;Mohammadreza Jalali,&nbsp;Jonas Simon Junker,&nbsp;Philipp Kästli,&nbsp;Xiaodong Ma,&nbsp;Hansruedi Maurer,&nbsp;Men-Andrin Meier,&nbsp;Miriam Schwarz,&nbsp;Paul Selvadurai,&nbsp;Linus Villiger,&nbsp;Stefan Wiemer,&nbsp;Luca Dal Zilio,&nbsp;Domenico Giardini","doi":"10.1029/2024JB029836","DOIUrl":"10.1029/2024JB029836","url":null,"abstract":"<p>We performed a series of hydraulic stimulations at 1.1 km depth in the Bedretto underground laboratory, Switzerland, as part of an overall research strategy attempting to understand induced seismicity on different scales. Using an ultra-high frequency seismic network we detect seismic events as small as <i>M</i>_<i>w</i> &lt; −4, revealing intricate details of a complex fracture network extending over 100 m from the injection sites. Here, we outline the experimental approach and present seismic catalogs as well as a comparative analysis of event number per injection, magnitudes, <i>b</i>-values, seismogenic index and reactivation pressures. In our first-order seismicity analysis, we could make the following observations: The rock volume impacted by the stimulations in different intervals differs significantly with a lateral extent from a few meters to more than 150 m. In most intervals multiple fractures were reactivated. The seismicity typically propagates upwards toward shallower depth on parallel oriented planes that are consistent with the stress field and seem to a large extent associated with preexisting open fractures. This experiment confirms the diversity in seismic behavior independent from the injection protocol. The overall seismicity patterns demonstrate that multi-stage stimulations using zonal isolation allow developing an extended fracture network in a 3D rock volume, which is necessary for enhanced geothermal systems. Our stimulations covering two orders of magnitude in terms of injected volume will give insights into upscaling of induced seismicity from underground laboratory scale to field scale.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029836","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637825","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":"Rapid Coalescence of Bubbles Driven by Buoyancy Force: Implication for Slug Formation in Basaltic Eruptions","authors":"Takafumi Maruishi,&nbsp;Atsushi Toramaru","doi":"10.1029/2024JB029130","DOIUrl":"10.1029/2024JB029130","url":null,"abstract":"<p>In basaltic eruptions, bubbles move freely and collide within a volcanic conduit, leading to frequent bubble coalescence. Understanding the dynamics of buoyancy-driven coalescence of bubbles is crucial for predicting the explosivity of basaltic eruptions. We examine the evolution of the bubble volume distribution while considering buoyancy-driven coalescence and expansion due to decompression. We find that, at lower decompression rates, the bubble volume distribution <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>n</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>v</mi>\u0000 <mo>,</mo>\u0000 <mi>t</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $n(v,t)$</annotation>\u0000 </semantics></math> rapidly evolves into a power-law distribution with an exponent of approximately <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> ${-}2$</annotation>\u0000 </semantics></math> as <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>n</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>v</mi>\u0000 <mo>,</mo>\u0000 <mi>t</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <mo>∝</mo>\u0000 <msup>\u0000 <mi>v</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $n(v,t)propto {v}^{-2}$</annotation>\u0000 </semantics></math>. This suggests that, in basaltic magma, the repeated coalescence of bubbles rapidly forms large bubbles within 45 min to 3 days. We then examine the occurrence of eruption styles, specifically Strombolian or Hawaiian, under the assumption that the bursts of slugs, produced from bubble coalescence within the conduit, trigger Strombolian eruptions. Consequently, we identify a critical condition for the transition between eruption styles in terms of the ascent velocity of magma. This critical ascent velocity is consistent with the observed transitions between Strombolian and Hawaiian eruptions at Izu-Oshima and Kilauea.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637558","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}

{"title":"Subsurface Imaging in Urban Areas With Ambient Noise Using DAS and Seismometer Data Sets: Granada, Spain","authors":"B. Benjumea,&nbsp;B. Gaite,&nbsp;M. Schimmel,&nbsp;F. Bohoyo,&nbsp;Z. J. Spica,&nbsp;F. D. L. Mancilla,&nbsp;Y. Li,&nbsp;J. Almendros,&nbsp;J. Morales","doi":"10.1029/2024JB029820","DOIUrl":"10.1029/2024JB029820","url":null,"abstract":"<p>Distributed acoustic sensing (DAS) is an innovative technology with great potential for acquiring seismic data sets in urban areas. In this work, we check the suitability of a DAS data set acquired in Granada (Spain) for retrieving subsurface reflectivity from ambient noise. The fiber-optic is a pre-existing underground telecommunication cable that crosses the city from Northwest to Southeast. We use a 10 hr recording of strain rate from a 2020 experiment to obtain seismic reflections using the autocorrelation method. We compare the DAS results with reflections obtained from seismic ambient noise recorded in nine seismometers deployed close to the fiber-cable for 7 days in November 2022. The novel approach proposed in this study for the identification of the reflections is to use autocorrelations after bandpass filtering for specific central frequencies and to check the stability of the signals over a broad frequency band. Microtremor Horizontal to Vertical Spectral Ratio (MHVSR) measurements at a total of 14 stations, five of them outside the city, help to constrain the reflection interpretation. These include one station at the borehole that reaches the basement in the Granada Basin crossing all the Cenozoic units. We use the legacy sonic log to obtain a relationship between frequencies of MHVSR peaks and depth. Autocorrelation and MHVSR methods give consistent results delineating bedrock depth deeper than 1,000 m in Granada. These results confirm that DAS can provide valuable subsurface information in urban areas.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029820","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142610377","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}