The AlpArray Research Seismicity-Catalogue

Abstract

Summary We take advantage of the new large AlpArray Seismic Network (AASN) as part of the AlpArray research initiative (www.alparray.ethz.ch), to establish a consistent seismicity catalogue for the greater Alpine region (GAR) for the time-period January 1st, 2016–December 31st, 2019. We use data from 1103 stations including the AASN backbone composed of 352 permanent and 276 (including 30 OBS) temporary broadband stations (network code Z3). Although characterized by a moderate seismic hazard, the European Alps and surrounding regions have a higher seismic risk due to the higher concentration of values and people. For these reasons, the GAR seismicity is monitored and routinely reported in catalogues by a 11 national and 2 regional seismic observatories. The heterogeneity of these dataset limits the possibility of extracting consistent information by simply merging to investigate the GAR's seismicity as a whole. The uniformly spaced and dense AASN provides, for the first time, a unique opportunity to calculate high-precision hypocentre locations and consistent magnitude estimation with uniformity and equal uncertainty across the GAR. We present a new, multi-step, semi-automatic method to process ∼50 TB of seismic signals, combining three different software. We used the SeisComP3 for the initial earthquake detection, a newly developed Python library ADAPT for high-quality repicking, and the well-established VELEST algorithm both for filtering and final location purposes. Moreover, we computed new local magnitudes based on the final high-precision hypocentre locations and re-evaluation of the amplitude observations. The final catalogue contains 3293 seismic events and is complete down to local magnitude 2.4 and regionally consistent with the magnitude 3 + of national catalogues for the same time period. Despite covering only 4 years of seismicity, our catalogue evidences the main fault systems and orogens’ front in the region, that are documented as seismically active by the EPOS-EMSC manually-revised regional bulletin for the same time period. Additionally, we jointly inverted for a new regional minimum 1D P-wave velocity model for the GAR and station delays for both permanent station networks and temporary arrays. These results provide the base for a future re-evaluation of the past decades of seismicity, and for the future seismicity, eventually improving seismic-hazard studies in the region. Moreover, we provide a unique, consistent seismic dataset fundamental to further investigate this complex and seismically active area. The catalogue, the minimum 1D P-wave velocity model, and station delays associated are openly shared and distributed with a permanent DOI listed in the Data Availability section.

Revealing Subtle Active Tectonic Deformation: Integrating Lidar, Photogrammetry, Field Mapping, and Geophysical Surveys to Assess the Late Quaternary Activity of the Sava Fault (Southern Alps, Slovenia)

“…Archeological evidence for damage that could be associated with an older severe earthquake occurred before 350 CE was found in the town of Celje (Roman name is Celeia) near the easternmost part of the Sava Fault, for which this fault is considered to be one of the possible sources [52]. However, up to now, no moderate to strong earthquakes could be reliably tied to this fault (Figure 1), and instrumental seismicity is not increased in its proximity [53,54].…”

Present‐Day Upper‐Mantle Architecture of the Alps: Insights From Data‐Driven Dynamic Modeling

“…Kästle et al (2020) compared all available regional high-resolution body-wave tomography models and concluded that slabs below the Alps differ significantly in their shapes and lengths. Such differences in the tomography interpretation arise from the choice of the reference model adopted, and the (Bagagli et al, 2022) in the Alps and surrounding regions. Vertical velocities from Global Navigation Satellite Systems measurements (Sternai et al, 2019) are interpolated and contoured at a 0.5 mm/yr interval; white contours represent uplift, and red represents subsidence.…”

“…Figure1. Topography map showing surface uplift (solid lines) and seismicity (circles), scaled by magnitude (M Lv : 0.4-4.9) and color-coded by depth, taken from the AlpArray Research Seismiciy-Catalog(Bagagli et al, 2022) in the Alps and surrounding regions. Vertical velocities from Global Navigation Satellite Systems measurements(Sternai et al, 2019) are interpolated and contoured at a 0.5 mm/yr interval; white contours represent uplift, and red represents subsidence.…”