ALBERT

Description: The Makran subduction zone has produced M 8+ earthquakes and subsequent tsunamis in historic times, hence indicating high risk for the coastal regions of southern Iran, Pakistan, and neighboring countries. Besides this, the Makran subduction zone is an end-member subduction zone featuring extreme properties, with one of the largest sediment inputs and the widest accretionary wedge on Earth. While surface geology and shallow structure of the offshore wedge have been relatively well studied, primary information on the deeper structure of the onshore part is largely absent. We present three crustal-scale, trench-perpendicular, deep seismic sounding profiles crossing the subaerial part of the accretionary wedge of the western Makran subduction zone in Iran. P-wave travel-time tomography based on a Monte Carlo Markov chain algorithm as well as the migration of automatic line drawings of wide-angle reflections reveal the crustal structure of the wedge and geometry of the subducting oceanic plate at high resolution. The images shed light on the accretionary processes, in particular the generation of continental crust by basal accretion, and provide vital basic information for hazard assessment and tsunami modeling

Description: We present an interactive graphical tool for extraction of group‐velocity dispersion curves of seismic traces for rapid manual picking of large amounts of data: a task commonly encountered in ambient‐noise tomography. The program can be used for group‐velocity analysis of surface waves from earthquakes and controlled source data as well as of Green’s functions from cross‐correlated ambient‐noise data. The presented tool is especially suited to datasets in which automatic picking algorithms fail and so dispersion analysis is only possible by visual inspection. Such situations can occur in highly heterogeneous regions with complex surface‐wave dispersion or where surface‐wave arrivals are poorly emerged (as can often be the case with ambient‐noise‐derived Green’s functions from temporary seismic deployments). In these datasets, the poor signal‐to‐noise ratio, spectral holes, or limited bandwidth may therefore mean that manual analysis is the only choice. However, without an efficient workflow the feasibility of this can be seriously constrained by the analysis time for the potentially vast number of traces to be analyzed. We tackled this problem by implementing well‐known techniques of dispersion curve analysis (traditional frequency–time analysis) in a fast and interactive graphical environment. It is specifically developed for high user processing speed, prioritizing fast computation, and high display responsiveness. This solution retains the benefits of manual dispersion picking for complex datasets, while maintaining good user processing efficiency. An experienced analyst can measure upward of 200 traces per hour. xdcpick stands for an X‐window‐based picking of dispersion curves.

Description: During the 2018 “Mackenzie Delta Permafrost Field Campaign” (mCan2018), a test campaign within the “Modular Observation solutions for Earth Systems” (MOSES) program, ambient seismic noise recordings at the sea bottom were acquired along two 300 m long transects from the shoreline to shallow marine area close to Tuktoyaktuk Island (Canada). In total, 21 measurements were taken. Raw data is provided in proprietary “Cube” format and standard mseed format.

Description: In September 2017 three crustal-scale seismic profiles were acquired in southern Iran covering the subaerial accretionary wedge of the western part of the Makran Subduction zone. Each of the roughly north-south trending profiles was approximately 200 km long, and on each profile 9 to 10 artificial shots with charges between 400 and 800 kg of explosives were fired. The seismic signals were observed by 300 autonomous digital recorders with geophones on each profile. This dataset consists of the raw (continuous) data of the recorders (in proprietary cube format and MSEED-format) and the shot records in SEGY-format (standard exchange formats).

Description: A network of 400 continuously running, digital, short-period seismic stations was deployed for a time period of approximately 2 weeks in an area of ~1 x 1.7 km in the Geyer region (Saxony, Germany). The network is part of a feasibility study to check whether and to which extent passive seismic methods, i.e. ambient noise techniques with a large number of stations (LARGE-N) can be used in a mineral exploration context. The project is attached to the INFACT project („Innovative, Non-invasive and Fully Acceptable Exploration Technologies“) funded by the European Union’s Horizon 2020 programme. At the same time it serves as a first field test for newly acquired LARGE-N instrumentation of the GIPP instrument pool.

Description: The dataset contains waveform data of shallow seismic profiles at two locations in the western part of the Alai valley, Kyrgyzstan. At each location a “long” profile (~5 km and ~2.5 km length, respectively) and one or two short profiles (~120 m and ~250 m) were acquired, centered on known or presumed tectonic faults. As sources, a trailer-mounted weight drop and a hammer were used. The measurements were part of the CaTeNA project. Within the sub-project "The recent deformation in the Pamir based on seismic and geodetic data, dynamic landslide-susceptibility and risk analysis, and seismic imaging of the North Pamir Thrust", which forms part of the international and interdisciplinary CaTeNA project (Climatic and Tectonic Natural Hazards in Central Asia), shallow seismic profiling at two locations has been carried out in the Alai Valley, southern Kyrgyzstan, to investigate the spatio-temporal evolution of the Pamir Frontal Thrust (PFT). Eight seismic profiles were acquired in September 2019 at two locations in the western part of the Alai valley, (1) in the village of Achyk Suu and b) at the Koman fault (SSW of the village of Kashka Suu). At each location a long profile (5 and 2.5km, respectively) and one or two short profiles (~250m) across interesting (presumed) fault structures were acquired.