Physics of the Earth and Planetary Interiors最新文献

{"title":"High-resolution U-channel paleomagnetic secular variation and magnetic field excursions from ocean drilling program site 1233 (MIS 1–4; 0–71 ka)","authors":"Steve P. Lund ,&nbsp;Joseph S. Stoner ,&nbsp;James E.T. Channell","doi":"10.1016/j.pepi.2024.107197","DOIUrl":"10.1016/j.pepi.2024.107197","url":null,"abstract":"<div><p>This paper presents new u-channel paleomagnetic secular variation (PSV) data for ODP Site 1233 (Chile margin) for the last 70 ky. This is the highest-resolution, long-term PSV record ever recovered. The u-channel study has carried out detailed af demagnetization of the natural remanence (NRM) and developed a characteristic remanence (ChRM – final PSV direction) for each sampling horizon. The u-channel rock magnetic studies have measured magnetic susceptibility and anhysteretic remanence (ARM) with af demagnetization and used them to normalize the NRM and develop a new, detailed relative paleointensity record. The paleomagnetic record contains three excursions: the Mono Lake Excursion, the Laschamp Excursion, and the Greenland/Norwegian-Sea Excursion. These excursions have nominal sampling intervals of 5–8 years. Both the Mono Lake and Greenland/Norwegian-Sea Excursions involve short duration intervals of excursional directions (&lt;300 years). The excursions are distinctly different from similar excursion records from other parts of the World. The Laschamp Excursion exhibits a full local reversal of the field with fast (&lt;200 yr) movement to/from reversed directions and ∼ 500 years of full reversed polarity directions. This pattern is distinctly different from Laschamp excursion records from other parts of the World. We have carried out a statistical analysis of the Site 1233 u-channel PSV record. Notable specific features of that analysis include documentation that the field spends &gt;1/3 of its time with anomalously large amplitude directional variability (high angular dispersion). These intervals occur at∼25–45 ka and 55–65 ka. These intervals have lower-frequency (more sluggish) directional variability and are associated with lower than average paleointensity.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107197"},"PeriodicalIF":2.3,"publicationDate":"2024-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140757657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shear-wave splitting associated with fluid processes beneath Styra, South Euboea: First results","authors":"Ioannis Spingos ,&nbsp;George Kaviris ,&nbsp;Vasilis Kapetanidis ,&nbsp;Eleftheria Papadimitriou ,&nbsp;Filippos Vallianatos","doi":"10.1016/j.pepi.2024.107196","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107196","url":null,"abstract":"<div><p>The intense and persistent seismic activity on the Island of Euboea (or Evia) was a unique opportunity to study anisotropy in a region without any notable prior seismicity. The study area is located in the central-western Aegean Sea and constitutes the endpoint where the North Aegean Trough and four parallel dextral strike-slip fault branches terminate against the Greek mainland, along with their sinistral counterparts. Even though seismicity has been recorded around the island, the affected area close to the town of Styra has no known reported earthquakes. In 2022, surprising activity was initiated by two moderate earthquakes (M_L 4.8 and M_L 5.0) that occurred on 29 November and were felt as far as Athens. The activity continued well into the second quarter of 2023, with over 1000 microearthquakes being recorded. A pre-planned nearby temporary installation of a broadband instrument (GR27), in the context of the AdriaArray project, offered recordings of the activity. Here, we investigated the occurrence and cause of shear-wave splitting beneath Styra. Based on focal mechanisms of local earthquakes we inferred the stress axes. A fully automated process was used to analyze data for shear-wave splitting and determine the polarization direction of the <em>S</em>_{<em>fast</em>} (<em>φ</em>), the time-delay (<em>t</em>_<em>d</em>) and the normalized time-delay (<em>t</em>_<em>n</em>). A total of 272 acceptable results showcased a unimodal distribution of <em>φ</em> with an average of N68°E and a mean <em>t</em>_<em>d</em> of 80 ms. We observed temporal variations of splitting parameters, associated with outbursts of seismicity, not with individual events. The determination of the shear-wave velocity anisotropy, jointly with observations of other splitting parameters, led us to hypothesize that anisotropy is the result of along-fault fluid processes. However, this would require a convincing selection of the NE-SW nodal plane as the preferred fault orientation. Further enrichment of the catalogue and an increase in splitting results is required to draw more robust conclusions.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107196"},"PeriodicalIF":2.3,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140640974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 meteorology approach to assess mantle flow induced dynamic topography using object-based image processing methods","authors":"Ayodeji Taiwo ,&nbsp;H.-P. Bunge ,&nbsp;G. Craig","doi":"10.1016/j.pepi.2024.107195","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107195","url":null,"abstract":"<div><p>The construction and assessment of model trajectories that link multiple mantle states is essential to constrain poorly known mantle convection parameters. Previously, volumetric approaches have been applied to assess the quality of constructed mantle flow trajectories. However, there is a need to assess these trajectories based on their dynamic topography predictions because mantle convection cannot be directly observed and may be inferred via its surface geological expressions. Typical metrics for assessing dynamic topography suffer from the <em>double penalty problem</em> — a prediction that is correct in intensity, size, and timing, but incorrect in location, results in large root-mean-square errors when compared to an observation. Here, we introduce metrics, gleaned from meteorology, that decompose any number of dynamic topography fields into their distinct objects after which the similarity between objects is compared. We find that this object-based approach overcomes double penalty and assesses models in a robust manner by providing the ability to assess separately the quality of match between subsidence and uplift areas. Additionally, the approach allows independent quality assessment of multiple aspects of a dynamic topography field, including amplitude and location of dynamic topography.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107195"},"PeriodicalIF":2.3,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000530/pdfft?md5=ff674780b9f5a9424c1272ac8b6bc8b3&pid=1-s2.0-S0031920124000530-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140618180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The crust-mantle velocity structure beneath the Wudalianchi-Erkeshan-Keluo volcanic belt by joint inversion of receiver functions and ambient noise","authors":"Juntong Liu ,&nbsp;Yinshuang Ai ,&nbsp;Ying Chen ,&nbsp;Jianshe Lei","doi":"10.1016/j.pepi.2024.107194","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107194","url":null,"abstract":"<div><p>The Wudalianchi-Erkeshan-Keluo (WEK) volcanic belt is a significant component of intraplate volcanism in Northeast China and is composed of the Wudalianchi, Erkeshan, and Keluo volcanic clusters. Using joint inversion of receiver functions and ambient noise, we construct a high-resolution 3-D S-wave velocity model of the WEK volcanic belt and its adjacent region, taking advantage of a deployed dense seismic array around this volcanic belt. There is a prominent low-velocity anomaly at 8–15 km depth beneath the Wudalianchi volcanic cluster, suggesting the presence of a crustal magma chamber. Low-velocity anomalies are also observed at 30–35 km depth beneath the Erkeshan volcanic cluster and 30–40 km depth beneath the Keluo volcanic cluster, resulting in discontinuous velocity structures at the Moho discontinuity. We further find a distinct low-velocity anomaly in the uppermost mantle beneath the WEK volcanic belt. Combined with previous geophysical and geochemistry studies, we propose a magma system scenario for the WEK volcanic belt. The upwelling molten material from the asthenosphere accumulated in the uppermost mantle and the magma chamber was formed, which provided the same uppermost mantle magma sources for the WEK volcanic belt.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107194"},"PeriodicalIF":2.3,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140618181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magmatic underplating, plumbing system, and carbon-enhanced electrical conductivity in the Paraná Magmatic Province","authors":"Gabriel Negrucci Dragone,&nbsp;Mauricio de Souza Bologna","doi":"10.1016/j.pepi.2024.107185","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107185","url":null,"abstract":"<div><p>The origin of large igneous provinces (LIPs) is still an enigma but likely involves magma storage and pathways spread throughout the crust, requiring indirect methods for its study. Here, we present 3-D resistivity models derived from the inversion of broadband (∼0.0001–3000 s) magnetotelluric data with 9–13 km lateral spacing in the central Paraná Magmatic Province, an expressive Early Cretaceous LIP in South America. Our results map in greater detail the previously interpreted LIP magma conduit and support, in contrast with seismological models, significant magmatic underplating to explain the observed conductivity near the LIP central axis. The potential axial lava feeder appears as a pair of crustal conductors (5–15 km; &gt;0.1 S/m) parallel to the region of maximum thickness of both pre-volcanic sedimentary rocks and erupted tholeiitic basalts along an extension of at least 800 km. We propose the high conductivity is due to graphite films of precipitated carbon during the ascension of carbon-bearing fluids released by crystallizing magmas underplated at the base of the crust. The association of high conductivity with underplating is supported by high Vp/Vs ratios close to the conductive lineament, by a lower-crustal zone of high P-wave velocities at the basin axis attributed to mafic intrusions, and by a residual gravity high interpreted as gabbros underplated/intruded in the lower crust. Moreover, the conductive lineament is spatially associated with intracrustal high densities inferred from geoid inversion and upper-crustal high P-wave velocities. Early CO₂ release during crystallization of underplated magma before eruption could explain the time gap between the Weissert ocean anoxic event and the volcanism. Our study advances in the controversial topic of magmatic intrusive components in the Paraná LIP with implications for LIP generation and paleo-climate studies.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107185"},"PeriodicalIF":2.3,"publicationDate":"2024-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140350196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large variations in the lithospheric thickness of northwestern India: Imprints of collisional and thermal reworking","authors":"Niraj Kumar,&nbsp;Om Prakash,&nbsp;V.M. Tiwari,&nbsp;A.P. Singh","doi":"10.1016/j.pepi.2024.107186","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107186","url":null,"abstract":"<div><p>The fold belts, which border the cratons, are the building blocks for understanding the origin and modification of older continents. The Aravalli-Delhi Fold Belt (ADFB) in northwestern India provides evidence of crustal block accretion due to continental collision, whereas Malani Igneous Suite (MIS) modified with widespread magmatism. Imaging of upper mantle structure and lithospheric modifications, if any, of such regions has been intricate owing to reworking by subsequent superimposed tectono-magmatic processes. We applied a 2D modelling approach to model the lithospheric architecture along a 1000-km long WNW-SSE geotransect across northwestern India, which has been deformed in the past. Our modelling technique combines terrestrial gravity anomaly, heat flow data, satellite-based geoid, and topographic datasets using the basic premise of thermal steady-state and local isostasy. The overall 38 to 40 km thick crustal geometry underneath the Marwar Block had the maximum lithological heterogeneity. The region surrounding the MIS is characterised by 8–10 km thick high-density (2.78 g/cm³) sills deposited in the upper crust down to 9 km depth and another 10–15 km thick high-density (3.05 g/cm³) mafic mantle material near the Moho. About 42 km thick crust, including an 8 to 10-km thick high-density (3.05 g/cm³) underplated layer at its bottom, characterises the high-relief ADFB. The Vindhyan region of Bundelkhand craton is defined by a ∼ 1 km thick trap, having Moho extending at a depth of ∼40 km. The lithospheric thickness varies substantially from ∼143–168 km underneath the Marwar block, which thins to ∼135 km under the ADFB and thickens gradually to ∼150–165 km beneath the Vindhyan region. Substantial crustal density differences in distinct crustal domains, when integrated with the thin lithosphere, reinforce the concept that tectono-magmatic processes might have modified the lithosphere in NW India.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107186"},"PeriodicalIF":2.3,"publicationDate":"2024-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140350195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Remagnetization of magnetite-bearing rocks in the Eastern Qiangtang Terrane, Tibetan Plateau (China): Mechanism and diagnosis","authors":"Qiang Fu ,&nbsp;Maodu Yan ,&nbsp;Mark J. Dekkers ,&nbsp;Chong Guan ,&nbsp;Liang Yu ,&nbsp;Wanlong Xu ,&nbsp;Zunbo Xu ,&nbsp;Miaomiao Shen ,&nbsp;Bingshuai Li","doi":"10.1016/j.pepi.2024.107184","DOIUrl":"10.1016/j.pepi.2024.107184","url":null,"abstract":"<div><p>Remagnetization is a common yet notorious phenomenon that interferes with paleogeographic reconstruction. Classical paleomagnetic field tests are helpful in detecting remagnetization but their diagnostic power is limited: remagnetization may occur before folding, the tilting age may be ambiguous, or protracted remagnetization may yield dual polarities. Rock magnetic information can provide other constraints on our understanding of the origin of natural remanent magnetization (NRM). Here we focus on the rock magnetic properties of acknowledged remagnetized limestones and unremagnetized rocks of the Zaduo area in the Eastern Qiangtang Terrane, Tibetan Plateau (China). Chemical remanent magnetization is suggested as a more frequent mechanism than the thermoviscous resetting of the NRM. The secondary NRM resides in authigenic magnetite of stable single domain and superparamagnetic (SP) size which grew during post-depositional burial processes. Both high-field and low-field thermomagnetic runs reveal the alteration of existing iron sulfides to magnetite in the remagnetized limestones. NRM decay curves show that the maximum unblocking temperature of the remagnetized samples is significantly lower than that of the unremagnetized samples. Component analysis of acquisition curves of the isothermal remanent magnetization (IRM) reveals a hard component that represents SP magnetite in remagnetized limestones. This component is absent in unremagnetized rocks. End-member modelling reveals a convex curve in the coefficient of determination versus the number of end-members plot for the unremagnetized limestones, whereas the remagnetized rocks exhibit both near-linear and convex shapes. In addition, quantitative analysis of the hysteresis loop shape for different lithologies indicates its validity in detecting remagnetization. Furthermore, we show the differences in the hysteresis data distributions of the two rock types on the Day plot, the Néel diagram, the Borradaile diagram, and the Fabian diagram. Our research emphasizes that rock magnetic properties can serve as tools to diagnose remagnetization in magnetite-dominated rocks. We recommend a comprehensive rock magnetic study to discriminate remagnetization, involving the Day plot, Fabian diagram, thermal demagnetization curves, IRM component analysis and end member modelling.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107184"},"PeriodicalIF":2.3,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140403961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraining seismic anisotropy on the mantle transition zone boundaries beneath the subducting Nazca slab","authors":"Zhu Zhang ,&nbsp;Wen-Che Yu ,&nbsp;Hsin-Hua Huang","doi":"10.1016/j.pepi.2024.107179","DOIUrl":"10.1016/j.pepi.2024.107179","url":null,"abstract":"<div><p>Some seismic evidence suggests that the mantle transition zone (MTZ) may become highly hydrous and anisotropic, particularly in the vicinity of subduction zones. The two-dimensional path-integrated anisotropy from the upper mantle to the MTZ has been well established beneath the northwestern region of South America. However, explicit details of azimuthal anisotropy on the MTZ boundaries remains ambiguous. Therefore, we attempted to constrain the azimuthal anisotropy on the MTZ boundaries by implementing the P-to-S anisotropic receiver function analysis. We detected significant seismic evidence of azimuthal anisotropy on the 410-km discontinuity, but weak anisotropy on the 660-km discontinuity. The synthetic waveform modeling indicated the fast symmetry axis of anisotropy trends 50° from the north and plunges 40° downwards from horizontal with an anisotropy strength of 4.0% near 410 km depth. The direction of anisotropy suggests the mantle material moves downwards and towards the subducting Nazca slab near the depth of 410 km. The increased anisotropy strength around the 410 km suggests the hydrous wadsleyite may attribute to anisotropy in the upper MTZ. The lack of detectable seismic anisotropy near the depth of 660 km could be caused by the insufficient amount of aligned anisotropic minerals, even though the mantle material continues moving downwards.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107179"},"PeriodicalIF":2.3,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140277834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adjoint inversion of antipodal PKPab waveforms for P wave velocity anomaly at the base of the lower mantle","authors":"Seiji Tsuboi ,&nbsp;Rhett Butler","doi":"10.1016/j.pepi.2024.107181","DOIUrl":"10.1016/j.pepi.2024.107181","url":null,"abstract":"<div><p>We perform an adjoint inversion by using antipodal <em>PKPab</em> phases to estimate the heterogeneous <em>Vp</em> structure at the base of the lowermost mantle. We have carefully examined antipodal stations with high S/N ratios during the past 30 years and selected 20 source-receiver pairs with the epicentral distances &gt;179.0 degree and the Mw &lt;7.0. We have used the spectral-element method on the Earth Simulator of JAMSTEC to calculate the synthetic seismograms for a heterogeneous mantle <em>Vp</em> model with the accuracy of period about 8 s (110 km wavelength at the CMB). We have set up the time window to retrieve the <em>PKPab</em> phase from the vertical component of both observed and computed seismograms to calculate the adjoint source to obtain the sensitivity kernels of <em>Vp</em> in the mantle. The computed <em>Vp</em> sensitivity kernel for each event shows the characteristic annulus pattern in the lowermost mantle, which covers a large area of the CMB. The twenty <em>PKPab</em> earthquake-station pairs in this antipodal study contribute the equivalent of about 3140 measurements at the CMB—compared with 1871 previously studied—and provide new data. Therefore, although the number of individual source-receiver pairs is not large, the summed sensitivity kernels of the <em>PKPab</em> phase for <em>Vp</em> structure at the base of the mantle may be sufficient to model heterogeneity of the <em>Vp</em> structure at the CMB. We summed each event kernel to set up a sensitivity kernel of <em>Vp</em> in the lowermost mantle and iterated the inversion to estimate a heterogeneous structure in D″. Although we have iterations that dominantly affect both South America and the South Pacific, the summary final model shows features within South of Africa, South Pacific, SE Australia, and Central &amp; South America. Keeping the Vs model fixed, we map the CMB <em>Vp</em> heterogeneity measured by the parameter <em>R</em>_<em>s,p</em> = <em>dlnVs/dlnV</em>p and find qualitative, proximal correspondence with the degree-2 pattern of Large Low Velocity Shear Provinces observed in shear tomographic models: in the Pacific and Africa <em>R</em>_<em>s,p</em> &gt; 2.0, whereas the surrounding edges of the edges of the Pacific show <em>R</em>_<em>s,p</em> &lt; 2.0.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107181"},"PeriodicalIF":2.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000396/pdfft?md5=6364b7763d0a4d7b6f2c96d7852286ff&pid=1-s2.0-S0031920124000396-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140182069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Data-driven identification of earthquake clusters: Clusters before the 2010 El mayor-Cucapah earthquake MW 7.1, Baja California, Mexico","authors":"F. Alejandro Nava ,&nbsp;Lenin Ávila-Barrientos","doi":"10.1016/j.pepi.2024.107182","DOIUrl":"10.1016/j.pepi.2024.107182","url":null,"abstract":"<div><p>Seismic clusters in background seismicity have been associated with high stress levels and can be an important precursor to large earthquakes, but there is not a unanimous concept of cluster and most cluster identification methods are cumbersome and involve a priori assumptions. We propose a simple definition of seismic cluster and a straightforward method of identification involving a minimum of parameters that can be objectively determined in a data-driven way according to a principle of low random occurrence. As an illustration, definition and method were applied to the identification of cluster activity from October 1979 to March 2010 in northern Baja California, Mexico, between 118°W to 113°W and 30°N to 33°N, a tectonically complex seismic region with several fault systems. Twenty-one clusters were identified, of which 17 located around the places at the northeastern corner of the study area that would be ruptured on April 4, 2010 by the El Mayor-Cucapah <em>M</em>_<em>w</em> 7.1 earthquake, the largest recorded earthquake in Baja California, Mexico, and the four others occurred within 9 km from its epicenter. Clustering also became slightly more frequent as the time of the earthquake approached, so that if the clustering survey had been carried out before the whole northern Baja California area, the clustering might have identified the future epicentral region as a region of interest to be closely monitored (this earthquake featured foreshock activity starting some 15 days before the main event). Although the reliability of clusters as precursors to large earthquakes is still to be studied, it is certainly useful to have a reliable and simple method to identify and characterize them.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107182"},"PeriodicalIF":2.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140182033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}