About this Research Topic
Since the beginning of the XXI Century, our society has witnessed a number of catastrophic earthquakes with devastating consequences (e.g., Sumatra 2004, Haiti 2010, Japan 2010, Nepal 2015, Italy 2009 and 2016). Localizing the active faults and understanding their earthquake history is key to improve modern probabilistic seismic hazard assessment (PSHA) and, thus, to be able to mitigate the consequences of future events. Seismicity models have been traditionally based on archaeological, historical and instrumental seismicity records. However, in the last decades the rapid advance of active tectonics and paleoseismological studies has significantly improved those models, since they allow characterizing the active faults, reconstructing their 3D geometry at depth, and determining their past earthquakes and seismic potential based on the interpretation of the geological record.
Although most active tectonics and paleoseismological research had been mainly conducted to study onshore active faults, the occurrence of the offshore Sumatra (2004) and Japan (2010) earthquakes and consequent tsunamis, which caused tens of thousands of casualties and extensive and severe damage, have brought into sharp focus the need to understand better the geohazards related to submarine active faults.
In the last few years, the availability of offshore geological and geophysical data at various scales (deep and shallow borehole, wide angle seismic profiles, tomography, 3D and 2D seismic reflection surveys, high resolution bathymetry and profiling) allow for a better definition of offshore fault systems both at the seafloor and at seismogenic depth. In addition, paleoseismological concepts have been increasingly exported to underwater areas taking advantage of: 1) expression and preservation of fault morphology and segmentation due to usually low erosional rates; 2) local and/or regional stratigraphic and chronostratigraphic correlations due to generally continuous sedimentation in time and space; 3) multiscale seafloor mapping and sub-seafloor seismic imaging; and 4) the almost lack of human modification in underwater regions.
Generally, submarine paleoearthquake studies have focused on off-fault turbidite paleoseismology, which is based on the identification and dating of earthquake-triggered landslides and turbidite deposits to obtain the recurrence of large magnitude (Mw > 6) earthquakes. However, the use of leading-edge high-resolution geophysical systems (i.e., seismic reflection, swath-bathymetry and underwater vehicles) is making it possible to acquire offshore data on active fault systems with unprecedented detail and resolution (i.e., cm-microbathymetry, mm-scale imaging, or sub-metric seismic imaging). With these different levels of resolution, it is possible to constrain accurately the kinematic, architecture and linkage of submarine active faults and, in some cases, identify recent earthquake ruptures or recognize and date individual events on specific faults. This information can then be used to derive their upper Quaternary or Holocene earthquake history of the faults and to estimate the slip per event and short-term slip-rate.
This Research Topic aims to gather present studies and/or new perspectives and ideas in marine active tectonics, turbidite paleoseismology, on-fault paleoseismology or tectonic geomorphology, and seismotectonics, from local to regional scale analysis. We welcome original research papers focused on identifying and characterizing the seismic cycle of active faults using multidisciplinary approaches and/or innovative methodologies. We also encourage the submission of studies that explore the application of new ideas to estimate coseismic seafloor deformation, to constrain earthquake timing, as well as the application of fault geometrical and kinematic reconstruction to seismic and tsunami hazard analysis. The main goal of this collection is to influence the future advance in marine active tectonics and paleoseismology in order to improve our understanding about the seismic and tsunami hazard related to submarine faults.
This Research Topic has been realized in collaboration with Dr. Laura Gómez de la Peña, at the GEOMAR - Helmholtz Centre for Ocean Research Kiel, Germany.
Keywords: Active faulting, seismic cycle, earthquake geology, seismic hazard, marine geosciences, active seismic methods, offshore paleoseismology methods
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