Long Minh Ho

and 4 more

As seismic data collection continues to grow, advanced automated processing techniques for robust phase identification and event detection are becoming increasingly important. However, the performance, benefits, and limitations of different automated detection approaches have not been fully evaluated. Our study examines how the performance of conventional techniques, including the Short-Term Average/Long-Term Average (STA/LTA) method and cross-correlation approaches, compares to that of various deep learning models. We also evaluate the added benefits that transfer learning may provide to machine learning applications. Each detection approach has been applied to three years of seismic data recorded by stations in East Antarctica. Our results emphasize that the most appropriate detection approach depends on the data attributes and the study objectives. STA/LTA is well-suited for applications that require rapid results even if there is a greater likelihood for false positive detections, and correlation-based techniques work well for identifying events with a high degree of waveform similarity. Deep learning models offer the most adaptability if dealing with a range of seismic sources and noise, and their performance can be enhanced with transfer learning, if the detection parameters are fine-tuned to ensure the accuracy and reliability of the generated catalog. Our results in East Antarctic provide new insight into polar seismicity, highlighting both cryospheric and tectonic events, and demonstrate how automated event detection approaches can be optimized to investigate seismic activity in challenging environments.
The Carrascoy and Palomares faults are two major active faults of the Eastern Betic Shear Zone (SE Iberia), both controlling conspicuous mountain fronts. However, the area in between both faults, corresponding to the Mazarron Graben (MG), is a nearly flat plain bounded by a relief of smooth hills whose tectonic origin and evolution remains uncertain. By means of a morphotectonic analysis, geophysical survey and paleoseismological trenching we point out that this is area of distributed deformation controlled by folds of variable amplitude nucleated in high angle reverse faults with sinistral component without a well-defined deformation front. The MG developed a marine basin during the Upper Miocene evolving into an alluvial environment with calcrete pedogenic development through the Pleistocene, which formed a tableland landscape that favors the identification of tectonic structures. In this study we demonstrate how some of the ancient normal faults controlling the graben were reactivated as reverse during the late Middle Pleistocene within a regional frame of positive tectonic inversion. Such inversion is evidenced by several emblematic structures: (i) presence of harpoon folding, and (ii) newly formed high angle reverse faults, which dips increase and ruptures become younger backwards on the hanging wall. Based on the timing of the observed deformation, we also suggest that the onset of the regional tectonic inversion might be related to the tectonic evolution of the neighboring Carrascoy and Palomares faults, producing a local stress tensor varying dramatically from extension to compression within the neotectonic period in a regional convergence tectonic frame.
The Carrascoy and Palomares faults are two major active faults of the Eastern Betic Shear Zone (SE Iberia), both controlling conspicuous mountain fronts. However, the area in between both faults, corresponding to the Mazarron Graben (MG), is a nearly flat plain bounded by a relief of smooth hills whose tectonic origin and evolution remains uncertain. By means of a morphotectonic analysis, geophysical survey and paleoseismological trenching we point out that this is area of distributed deformation controlled by folds of variable amplitude nucleated in high angle reverse faults with sinistral component without a well-defined deformation front. The MG developed a marine basin during the Upper Miocene evolving into an alluvial environment with calcrete pedogenic development through the Pleistocene, which formed a tableland landscape that favors the identification of tectonic structures. In this study we demonstrate how some of the ancient normal faults controlling the graben were reactivated as reverse during the late Middle Pleistocene within a regional frame of positive tectonic inversion. Such inversion is evidenced by several emblematic structures: (i) presence of harpoon folding, and (ii) newly formed high angle reverse faults, which dips increase and ruptures become younger backwards on the hanging wall. Based on the timing of the observed deformation, we also suggest that the onset of the regional tectonic inversion might be related to the tectonic evolution of the neighboring Carrascoy and Palomares faults, producing a local stress tensor varying dramatically from extension to compression within the neotectonic period in a regional convergence tectonic frame.