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Active fault database for the Atacama Fault System (N-Chile) as basis for tracking forearc segmentation

The Atacama Fault System (AFS) in N-Chile is a complex fault system with a variety of fault segments showing different degrees of activity. Initiated as a trench-linked fault system during the Jurassic it is now exposed in the Coastal Cordillera in the forearc of the Nazca-South America convergent plate margin. Fault scarps and surface ruptures indicate varying degrees of reactivation of this fault system that most likely roots into the subduction zone interface at the downdip end of coupling. Therefore, the interaction of these two systems is evident though not well understood. The active fault database for the northernmost segment of the Atacama Fault System (AFS) is the result of creating a comprehensive catalogue of active faults in the forearc to investigate activity patterns of the forearc in relation with megathrust segmentation and upper plate seismicity in the Coastal Cordillera of N-Chile (19°12’S - 25°12’S). The dataset has been compiled in Arc-GIS and is available as .mpk as well as .kmz formats to be visualised in Google Earth. The activity patterns are mapped according to a well-defined set of criteria (see below). The database for activity starts out from a thorough literature review and is supplemented by new evidences combining interpretation of remote sensing data, field work and upper plate seismicity from the Integrated Plate Boundary Observatory in Chile (IPOC) (Sippl et al., 2018) and a local seismic catalogues covering the area of the Salar Grande segment (Bloch et al., 2014). It also includes the available age data of offset geological units as references to bracket the chronology of fault activity. Fault activity for this study has been defined according to the Quaternary fault and fold database of the United States (https://www.usgs.gov/natural-hazards/earthquake-hazards/faults?qt-science_support_page_related_con=4#qt-science_support_page_related_con), but is subject to significant error due to slow slip rates (< 0.2mm/yr), few chronologically constrained fault offsets and lack of historically or instrumentally observed earthquakes along the fault segments. Therefore, this database does not have the aim to serve as active fault database for seismic hazard assessment. It has been created with the clear aim to serve as database for general aspects of upper plate fault reactivation in relation with the megathrust seismic cycle and megathrust segmentation. This publication is part of an ongoing study investigating the interaction of megathrust segmentation with activity patterns in the overriding forearc.

AFG - Active Faults Greece: a comprehensive geomorphology-based 1:25,000 fault database

Greece is Europe’s most seismically active nation, as it is being deformed by an active subduction system and one of the world’s fastest-spreading rifts. Onshore active faults pose seismic hazard that cannot be reliably assessed in the absence of a comprehensive map of potential earthquake sources. Here, we use high-resolution Digital Elevation Models (DEMs), in conjunction with hillshades and slope models, to map and characterise faults in Greece at a scale of 1:25000. The Active Faults Greece (AFG) database records a total of 3815 fault-traces assigned to 892 interpreted faults. Of the AFG traces, 53% were mapped here for the first time, with their geometries and slip-sense constrained by displacement of landscape features. AFG includes >2000 active and 1632 probably active fault-traces, while 30 traces result from historic surface-rupturing earthquakes since 464 BC. About 57% of faults exhibit strong depositional control (DC) on sedimentation patterns, with active faults being characterised by approximately equal numbers of sharp (32%), moderate (29%) and rounded (29%) scarps. AFG is the first fault database in Greece generated using nationwide interpretation of geomorphology and has applications in paleoseismology, seismic-hazard assessment, mineral-resources exploration, and resilience planning. Data Access: - Download archive version via GFZ Data Services (upper left) - Web-Map Server: https://experience.arcgis.com/experience/a6c85b1edf9d4d17a3f01a70cef6d2b2 - GIS Users: https://services2.arcgis.com/T7iULq65Kp9Elquk/arcgis/rest/services/Active_Faults_Greece/FeatureServer - Layerfiles for use in ArcGIS Pro and QGIS: https://noaig.maps.arcgis.com/sharing/rest/content/items/4b93c25b931744dabc4851abf9c8ae38/data

IPOC Creep

IPOC Creep is an array of 11 creepmeters installed along 4 active segments oft eh Atacama Fault Zone in Northern Chile. Installation of instruments started in 2008 within the framework of the Integrated Plate-boundary Observatory Chile (IPOC) and was completed in 2011. All installations are designed by the authors and follow a general concept, but are adapted to each site specifically. All the installed instruments use solid 12 mm thick invar rods as length standards, which are firmly attached to a concrete foundation in the hanging wall of the fault and pass through a PVC pipe to the footwall side of the fault where it is fixed to another concrete foundation. The creepmeters are buried at a depth of 30 - 70 cm, in order to increase the signal-to-noise ratio. We use a LVDT (linear variable differential transformer) with a range of 50 mm to monitor the relative displacement of the free end of the rod relative to the fixation point. Displacement is measured as voltage change and stored on a data logger with a sampling rate of 1/min (2008-2011 and 2/min (since 2011). Temperature at the rod is continuously measured with the same sampling rate to correct for thermal expansion and contraction of the length standard. The length of the instrument is dependent on the geometry at each site and ranges between 2 and 9 m. More specific information on each site can be found on http://www.ipoc-network.org/index.php/observatory/creepmeter.html . The Data is stored as time series since the initial start of operation of each creepmeter until July 2016. Data format is asci and contains 4 columns: 1st column Date[D.M.Y] 2nd column Time [HH:MM:SS] 3rd column ReferenceSensor[V]The reference signal is a steady signal of 1V and fluctuations indicate general voltage fluctuations in the setup. By normalizing to the reference signal it is possible to correct for these voltage changes. 4th column CreepSensor[V]The measured voltage of the CreepSensor is linearly proportional to the actual displacement. It can be converted to micrometers as follows: Displacement(µm) = (CreepSensor(t2)[V] - CreepSensor(t1)[V]) * 10000.

Fault database of the Northern Chile forearc between 18°50’S and 19°45’S

The knowledge about the distribution of active faults is crucial for hazard assessment (Costa et al., 2020; Santibáñez et al., 2019; Wesnousky, 1986) but also provides insights into tectonic control on hydrological processes (Binnie et al., 2020; Jeffery et al., 2013; Pan et al., 2013) or georesource distribution (Goldsworthy & Jackson, 2000; Viguier et al., 2018). Furthermore, tectonically driven topographic uplift and its impact on climate (Armijo et al., 2015; Houston & Hartley, 2003; Rech et al., 2019; Zhisheng et al., 2001) can be better understood if a systematically mapped fault database exists. Here we present an active fault database, as well as the distribution of drainages, for an area between 18.50°S and 19.45°S in Northern Chile forearc, which were systematically mapped in the framework of the project “Cluster C05-Tectonic Geomorphology: Adaptation of drainage to tectonic forcing” of the CRC1211- Earth Evolution at the Dry Limit. The Central Andes forearc at this latitude is located at a highly tectonically active convergent margin and hosts major earthquakes not only on the plate boundary itself (e.g., Métois et al., 2016), but also in the overriding crust (e.g., Comte et al., 1999). It comprises, from west to east, the Coastal Cordillera, Longitudinal Valley and the Western Flank of the Altiplano, showing an impressive amount of topographic variability of ca. 4000 m. Nevertheless, Neogene crustal tectonic structures and surface deformation are poorly documented. The overall landscape appears as a gentle west-sloping pediplain dissected by deep transversal canyons (quebradas), which reach the current Pacific Ocean (Mortimer, 1980). The Longitudinal Valley is a sedimentary basin filled with 432 to 2000 m of Tertiary to Quaternary deposits derived from the Altiplano in the east as well as the Coastal Cordillera in the west (García et al., 2017). Its surface is composed by a multiphase planation surface called the Pacific Paleosurface (PPS), which distribution is suggested to be controlled by crustal tectonics (Evenstar et al., 2017). Depending on the low ratio of tectonic displacement rate to sedimentation rate, many active faults are hidden and only a specialized approach of high-resolution fault mapping, together with a morphometric analysis of the drainage pattern provides systematic information about the distribution of active faults, folds and related structures. The present fault database is the result of creating a comprehensive catalogue of faults classified by the age of last proven/probable tectonic activity. This is accompanied by a compilation of existing age data and a map of drainage pattern. These datasets were compiled in QGIS 3.16.5 (https://www.qgis.org) and are available as. gpkg for GIS applications and as .kml formats to be visualized in Google Earth.

The Paleoseismic Database of Germany and Adjacent Regions PalSeisDB

Central Europe is an intraplate domain which is characterized by low to moderate seismicity with records of larger seismic events occurring in historical and recent times. These records of seismicity are restricted to just over one thousand years. This does not reflect the long seismic cycles in Central Europe which are expected to be in the order of tens of thousands of years. Therefore, we have developed a paleoseismic database (PalSeisDB) that documents the records of paleoseismic evidence (trenches, soft-sediment deformation, mass movements, etc.) and extends the earthquake record to at least one seismic cycle. It is intended to serve as one important basis for future seismic hazard assessments. In the compilation of PalSeisDB, paleoseismic evidence features are documented at 129 different locations in the area of Germany and adjacent regions. A brief explanation of the folder structure, file list and file contents included in the data publication of PalSeisDB is provided in the data description .A detailed explanation of the data collection, the content of the data files and the table headers is available (Hürtgen et al., 2020). A full list of source references for PalSeisDB is provided in Hürtgen (2017, Appendix 8.3, p. 128 ff) and also included in the zip folder here

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