Seismica最新文献

{"title":"July-December 2022 earthquake sequence in the southeastern Fars arc of Zagros mountains, Iran","authors":"Malte Metz, Behnam Maleki Asayesh, Mohammad Mohseni Aref, Mohammadreza Jamalreyhani, Pınar Büyükakpınar, Torsten Dahm","doi":"10.26443/seismica.v2i2.953","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.953","url":null,"abstract":"Within two hours on 01 July 2023, three earthquakes of Mw 5.8-6.0 hit the SE Fars arc, Iran. In the following months, the region characterized by the collision of the Iranian and the Arabian plate, thrust faulting, and salt diapirism was stroke by more than 120 aftershocks of mL 3.1-5.2, of which two of the largest events occurred within one minute on 23 July 2023 in spatial vicinity to each other. We analyzed both the large mainshocks and aftershocks using different techniques, such as the inversion of seismic and satellite deformation data in a joint process and aftershock relocation. Our results indicate the activation of thrust faults within the lower sedimentary cover of the region along with high aftershock activity in significantly larger depth, supporting the controversial model of a crustal strain decoupling during the collision in the Fars Arc. We resolved a magnitude difference of >0.2 magnitude units between seismic and joint seismic and satellite deformation inversions probably caused by afterslip, thereby allowing to bridge between results from international agencies and earlier studies. We also find evidence for an event doublet and triplet activating the same or adjacent faults within the sedimentary cover and the basement","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135618702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated shear-wave splitting analysis for single- and multi- layer anisotropic media","authors":"Thomas Samuel Hudson, Joseph Asplet, Andrew M Walker","doi":"10.26443/seismica.v2i2.1031","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.1031","url":null,"abstract":"Shear-wave velocity anisotropy is present throughout the earth. The strength and orientation of anisotropy can be observed by shear-wave splitting (birefringence) accumulated between earthquake sources and receivers. Seismic deployments are getting ever larger, increasing the number of earthquakes detected and the number of source-receiver pairs. Here, we present a new Python software package, SWSPy, that fully automates shear-wave splitting analysis, useful for large datasets. The software is written in Python, so it can be easily integrated into existing workflows. Furthermore, seismic anisotropy studies typically make a single-layer approximation, but in this work we describe a new method for measuring anisotropy for multi-layered media, which is also implemented. We demonstrate the performance of SWSPy for a range of geological settings, from glaciers to Earth's mantle. We show how the package facilitates interpretation of an extensive dataset at a volcano, and how the new multi-layer method performs on synthetic and real-world data. The automated nature of SWSPy and the discrimination of multi-layer anisotropy will improve the quantification of seismic anisotropy, especially for tomographic applications. The method is also relevant for removing anisotropic effects, important for applications including full-waveform inversion and moment magnitude analysis.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135728934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal Network Design for Microseismic Monitoring in Urban Areas - A Case Study in Munich, Germany","authors":"Sabrina Keil, Joachim Wassermann, Tobias Megies, Toni Kraft","doi":"10.26443/seismica.v2i2.1030","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.1030","url":null,"abstract":"Well-designed monitoring networks are crucial for obtaining precise locations, magnitudes and source parameters, both for natural and induced microearthqakes. The performance of a seismic network depends on many factors, including network geometry, signal-to-noise ratio (SNR) at the seismic station, instrumentation and sampling rate. Therefore, designing a high-quality monitoring network in an urban environment is challenging due to the high level of anthropogenic noise and dense building infrastructure, which can impose geometrical limitations and elevated construction costs for sensor siting. To address these challenges, we apply a numerical optimization approach to design a microseismic surveillance network for induced earthquakes in the metropolitan area of Munich (Germany), where several geothermal plants exploit a deep hydrothermal reservoir. First of all, we develop a detailed noise model for the city of Munich, to capture the heterogeneous noise conditions. Then, we calculate the expected location precision for a randomly chosen network geometry from the body-wave amplitudes and travel times of a synthetic earthquake catalog considering the modeled local noise level at each network station. In the next step, to find the optimum network configuration, we use a simulated annealing approach in order to minimize the error ellipsoid volume of the linearized earthquake location problem. The results indicate that a surface station network cannot reach the required location precision (0.5 km in epicentre and 2 km in source depth) and detection capability (magnitude of completeness Mc = 1.0) due to the city´s high seismic noise level. In order to reach this goal, borehole stations need to be added to increase the SNR of the microearthquake recordings, the accuracy of their body-wave arrival times and source parameters. The findings help to better quantify the seismic monitoring requirements for a save operation of deep geothermal projects in urban areas.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135888306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Red-light thresholds for induced seismicity in the UK","authors":"Ryan Schultz, Brian Baptie, Benjamin Edwards, Stefan Wiemer","doi":"10.26443/seismica.v2i2.1086","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.1086","url":null,"abstract":"Induced earthquakes pose a serious hurdle to subsurface energy development. Concerns about induced seismicity led to terminal public opposition of hydraulic fracturing in the UK. Traffic light protocols (TLPs) are typically used to manage these risks, with the red-light designed as the last-possible stopping-point before exceeding a risk tolerance. We simulate trailing earthquake scenarios for the UK, focusing on three risk metrics: nuisance, damage, and local personal risk (LPR) – the likelihood of building collapse fatality for an individual. The severity of these risks can spatially vary (by orders-of-magnitude), depending on exposure. Estimated risks from the Preston New Road earthquakes are used to calibrate our UK earthquake risk tolerances, which we find to be comparable to Albertan (Canadian) tolerances. We find that nuisance and damage concerns supersede those from fatality and that the safest regions for Bowland Shale development would be along the east coast. A retrospective comparison of our TLP result with the Preston New Road case highlights the importance of red-light thresholds that adapt to new information. Overall, our findings provide recommendations for red-light thresholds (ML 2-2.5) and proactive management of induced seismicity – regardless of anthropogenic source.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136114114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observation of a Synchronicity between Shallow and Deep Seismic Activities during the Foreshock Crisis Preceding the Iquique Megathrust Earthquake","authors":"Michel Bouchon, Stéphane Guillot, David Marsan, Anne Socquet, Jorge Jara, François Renard","doi":"10.26443/seismica.v2i2.849","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.849","url":null,"abstract":"We analyze at a broad spatial scale the slab seismicity during one of the longest and best recorded foreshock sequence of a subduction earthquake to date: the M8.1 2014 Iquique earthquake in Chile. We observe the synchronisation of this sequence with seismic events occurring in the deep slab (depth ~100km). This synchronisation supports the existence of long-range seismic bursts already observed in the Japan Trench subduction. It suggests that, like for the 2011 Tohoku earthquake, the deep slab was involved in the nucleation process of the Iquique earthquake. We interpret these observations by the presence of pressure pulses propagating in transient fluid channels linking the deep slab where dehydration occurs to the shallow seismogenic zone before the earthquake. These observations may seem surprising but they are in line with the short-lived pulse-like channelized water escape from the dehydration zone predicted by recent studies in slab mineralogy and geochemistry.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136295520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Continuous isolated noise sources induce repeating waves in the coda of ambient noise correlations","authors":"Sven Schippkus, Céline Hadziioannou, Mahsa Safarkhani","doi":"10.26443/seismica.v2i2.499","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.499","url":null,"abstract":"
 Continuous excitation of isolated noise sources leads to repeating wave arrivals in cross correlations of ambient seismic noise, including throughout their coda. These waves propagate from the isolated sources. We observe this effect on correlation wavefields computed from two years of field data recorded at the Gräfenberg array in Germany and two master stations in Europe. Beamforming the correlation functions in the secondary microseism frequency band reveals repeating waves incoming from distinct directions to the West, which correspond to well-known dominant microseism source locations in the Northeastern Atlantic Ocean. These emerge in addition to the expected acausal and causal correlation wavefield contributions by boundary sources, which are converging onto and diverging from the master station, respectively. Numerical simulations reproduce this observation. We first model a source repeatedly exciting a wavelet, which helps illustrate the fundamental mechanism behind repeated wave generation. Second, we model continuously acting secondary microseism sources and find good agreement with our observations. Our observations and modelling have potentially significant implications for the understanding of correlation wavefields and monitoring of relative velocity changes in particular. Velocity monitoring commonly assumes that only multiply scattered waves, originating from the master station, are present in the coda of the correlation wavefield. We show that repeating waves propagating from isolated noise sources may dominate instead, including the very late coda. Our results imply that in the presence of continously acting noise sources, which we show is the case for ordinary recordings of ocean microseisms, velocity monitoring assuming scattered waves may be adversely affected with regard to measurement technique, spatial resolution, as well as temporal resolution. We further demonstrate that the very late coda of correlation functions contains useful signal, contrary to the common sentiment that it is dominated by instrument noise.
","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135142229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing High Rate GNSS Velocity Noise for Synthesizing a GNSS Strong Motion Learning Catalog","authors":"Timothy Dittmann, Y. Jade Morton, Brendan Crowell, Diego Melgar, Jensen DeGrande, David Mencin","doi":"10.26443/seismica.v2i2.978","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.978","url":null,"abstract":"Data-driven approaches to identify geophysical signals have proven beneficial in high dimensional environments where model-driven methods fall short. GNSS offers a source of unsaturated ground motion observations that are the data currency of ground motion forecasting and rapid seismic hazard assessment and alerting. However, these GNSS-sourced signals are superposed onto hardware-, location- and time-dependent noise signatures influenced by the Earth’s atmosphere, low-cost or spaceborne oscillators, and complex radio frequency environments. Eschewing heuristic or physics based models for a data-driven approach in this context is a step forward in autonomous signal discrimination. However, the performance of a data-driven approach depends upon substantial representative samples with accurate classifications, and more complex algorithm architectures for deeper scientific insights compound this need. The existing catalogs of high-rate (≥1Hz) GNSS ground motions are relatively limited. In this work, we model and evaluate the probabilistic noise of GNSS velocity measurements over a hemispheric network. We generate stochastic noise time series to augment transferred low-noise strong motion signals from within 70 kilometers of strong events (≥ MW 5.0) from an existing inertial catalog. We leverage known signal and noise information to assess feature extraction strategies and quantify augmentation benefits. We find a classifier model trained on this expanded pseudo-synthetic catalog improves generalization compared to a model trained solely on a real-GNSS velocity catalog, and offers a framework for future enhanced data driven approaches.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial workflow of a community-led, all-volunteer scientific journal: lessons from the launch of Seismica","authors":"Hannah Mark, Théa Ragon, Gareth Funning, Stephen P. Hicks, Christie Rowe, Samantha Teplitzky, Jaime Convers, Ezgi Karasözen, R. Daniel Corona-Fernandez, Åke Fagereng","doi":"10.26443/seismica.v2i2.1091","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.1091","url":null,"abstract":"Seismica is a community-led, volunteer-run, diamond open-access journal for seismology and earthquake science, and Seismica's mission and core values align with the principles of Open Science. This article describes the editorial workflow that Seismica uses to go from a submitted manuscript to a published article. In keeping with Open Science principles, the main goals of sharing this workflow description are to increase transparency around academic publishing, and to enable others to use elements of Seismica's workflow for journals of a similar size and ethos. We highlight aspects of Seismica's workflow that differ from practices at journals with paid staff members, and also discuss some of the challenges encountered, solutions developed, and lessons learned while this workflow was developed and deployed over Seismica's first year of operations.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135591463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A call from early‑career Turkish scientists: seismic resilience is only feasible with “earthquake culture”","authors":"Ezgi Karasözen, Pınar Büyükakpınar, Deniz Ertuncay, Emre Havazlı, Elif Oral","doi":"10.26443/seismica.v2i3.1012","DOIUrl":"https://doi.org/10.26443/seismica.v2i3.1012","url":null,"abstract":"Despite significant scientific advances in earthquake research and building codes, Türkiye remains vulnerable to earthquakes, as demonstrated by the tragic Kahramanmaraş earthquake in February 2023. In contrast, countries such as Chile and Japan have successfully reduced earthquake damage through strict enforcement of building codes and effective public awareness campaigns. This paper highlights the need for seismic resilience in Türkiye and proposes actionable guidelines to bridge the gap between science and society. These guidelines include comprehensive geoscience education, the establishment of local earthquake centers, effective science communication, preparation for future earthquakes through scenario modeling, and development of an earthquake culture. Geoscience education should be integrated into the education system, and opportunities for geoscientists should be increased. Local earthquake centers can improve seismic monitoring, research, and public outreach. Geoscientists should prioritize science communication training to engage the public and combat misinformation. Scenario modeling and annual preparedness exercises can improve earthquake preparedness across the country, and promoting earthquake memory and awareness initiatives will build a collective consciousness about earthquakes. By implementing these guidelines, Türkiye can build earthquake resilience and mitigate the impact of future earthquakes; however, the active engagement of scientists, institutions, and the public is essential to achieve earthquake resilience.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135385670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the Evolution of an Unusually Active Earthquake Sequence Near Sheldon, Nevada","authors":"Daniel Trugman, William Savran, Christine Ruhl, Kenneth Smith","doi":"10.26443/seismica.v2i2.1051","DOIUrl":"https://doi.org/10.26443/seismica.v2i2.1051","url":null,"abstract":"One of most universal statistical properties of earthquakes is the tendency to cluster in space and time. Yet while clustering is pervasive, individual earthquake sequences can vary markedly in duration, spatial extent, and time evolution. In July 2014, a prolific earthquake sequence initiated within the Sheldon Wildlife Refuge in northwest Nevada, USA. The sequence produced 26 M4 earthquakes and several hundred M3s, with no clear mainshock or obvious driving force. Here we combine a suite of seismological analysis techniques to better characterize this unusual earthquake sequence. High-precision relocations reveal a clear, east dipping normal fault as the dominant structure that intersects with a secondary, subvertical cross fault. Seismicity occurs in burst of activity along these two structures before eventually transitioning to shallower structures to the east. Inversion of hundreds of moment tensors constrain the overall normal faulting stress regime. Source spectral analysis suggests that the stress drops and rupture properties of these events are typical for tectonic earthquakes in the western US. While regional station coverage is sparse in this remote study region, the timely installation of a temporary seismometer allows us to detect nearly 70,000 earthquakes over a 40-month time period when the seismic activity is highest. Such immense productivity is difficult to reconcile with current understanding of crustal deformation in the region and may be facilitated by local hydrothermal processes and earthquake triggering at the transitional intersection of subparallel fault systems.","PeriodicalId":498743,"journal":{"name":"Seismica","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134961042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}