9 documents found in 170ms
# 1
Kufner, Sofia-Katerina • Kakar, Najibullah • Murodkulov, Shokhruhk • Schurr, Bernd • Yuan, Xiaohui • (et. al.)
Abstract: The Pamir-Hindu Kush region of Tajikistan and NE Afghanistan stands out due to its worldwide unique zone of intense intermediate depth seismicity, accommodating frequent Mw 7+ earthquakes with hypocenters reaching down to 250 km depth. With this network we aim to collect data allowing to characterize the active deformation within the Hindu Kush mountains and the Tajik-Afghan basin at the northwestern tip of the India-Asia collision zone. The network consists 15 sites (14 stations in Afghanistan, 1 station in Tajikistan), situated on top of the nest of intermediate depth seismicity and further west in the Afghan platform. The stations are equipped with short period Mark seismometers and Cube data recorders. Waveform data are available from the GEOFON data centre, under network code 4C, and are embargoed until 2023. After the end of embargo, data will be openly available under CC-BY 4.0 license according to GIPP-rules.
# 2
Schurr, Bernd • Yuan, Xiaohui • Haberland, Christian • Mechie, James • Kufner, Sofia-Katerina
Abstract: The TIPTIMON seismic deployment in Afghanistan aimed to study the seismotectonics of the Hindu Kush and the Tajik-Afghan basin. Within this network 8 seismic stations were deployed between 2013 to 2014 to study shallow and intermediate depth seismicity. TIPTIMON (Tien Shan-Pamir Monitoring) is a research programme funded by the German Federal Ministry of Education and Research (BMBF) within the CAME Programme (Central Asia - Monsoon dynamics and Geo-ecosystems). All stations were equipped with MARK L-4C-3D geophones and DSS CUBE recorders, continuously recording with 100 samples per second. Waveform data is available from the GEOFON data centre, under network code 6C, and is embargoed until Oct 2018.
# 3
Schurr, Bernd • Yuan, Xiaohui • Haberland, Christian • Mechie, James • Kufner, Sofia-Katerina
Abstract: The TIPTIMON seismic deployment in Tajikistan aimed to study the seismotectonics of the western Pamir and Tajik-Afghan basin. Within this network 25 seismic stations were deployed between 2012 to 2014 to study shallow and intermediate depth seismicity. TIPTIMON (Tien Shan-Pamir Monitoring) is a research programme funded by the German Federal Ministry of Education and Research (BMBF) within the CAME Programme (Central Asia - Monsoon dynamics and Geo-ecosystems). All stations recorded continuously with 100 samples per second and were equipped with EDL (EarthData PR6-24) recorders and broadband seismometers. Waveform data is available from the GEOFON data centre, under network code 5C, and is embargoed until April 2018.
# 4
Tilmann, Frederik • Yuan, Xiaohui • Rümpker, Georg • Rindraharisaona, Elisa
Abstract: The island of Madagascar occupies a key region in both the assembly and the multi-stage breakup of Gondwanaland, itself part of the super-continent Pangaea. Madagascar consists of an amalgamation of continental material, with the oldest rocks being of Archaean age. Its ancient fabric is characterised by several shear zones, some of them running oblique to the N-S trend, in particular in the south of the island. More recently during the Neogene, moderate volcanism has occurred in the Central and Northern part of the island, and there are indications of uplift throughout Eastern Madagascar over the last 10 Ma. Although Madagascar is now located within the interior of the African plate and far away from major plate boundaries (>1000 km from the East African rift system and even further from the Central and South-West Indian Ridges), its seismic activity indicates that some deformation is taking place, and present-day kinematic models based on geodetic data and earthquake moment tensors in the global catalogues identify a diffuse N-S-oriented minor boundary separating two microplates, which appears to pass through Madagascar. In spite of the presence of Archaean and Proterozoic rocks continent-wide scale studies indicate a thin lithosphere (<120 km) throughout Madagascar, but are based on sparse data and cannot resolve the difference between eastern and western Madagascar. We have operated an ENE-WSW oriented linear array of 25 broadband stations in southern Madagascar, extending from coast to coast and sampling the sedimentary basins in the west as well as the metamorphic rocks in the East, cutting geological boundaries seen at the surface at high angle. The array crosses the prominent Bongolava-Ranotsara shear zone which is thought to have been formed during Gondwanaland assembly. The array recorded the magnitude 5.3 earthquake of January 25, 2013 which occurred just off its western edge. In addition, in May 2013 we have deployed 25 short period sensors in the eastern part of the study area, where there is some so-far poorly characterised seismicity. Waveform data is available from the GEOFON data centre, under network code ZE, and is embargoed until DEC 2018.
# 5
Asch, Günter • Heit, Benjamin • Yuan, Xiaohui
Abstract: A set of 60 seismological stations (45 short period and 15 broadband) was installed at 21°S between the coast in Chile (70°W) and the Eastern Cordillera in Bolivia (64°W) along a 600 km long profile and operated during two years in the Central Andes region. The stations operating at a rate of 50 samples per second (sps) recorded large and local events as well as quarry blasts from the copper mines in the vicinity of the profile. The results will be used to improve the crust velocity model and to identify the Andean shear zones and their extension to the west. In addition, a shorter profile consisting of 20 stations (10 short period and 10 broadband) was installed in Argentina along a 200 km profile at 26°S with the aim to investigate lithospheric delamination across the Cerro Galan caldera, one of the most prominent intra-plate volcanoes in the world. The instruments recorded local and teleseismic events during two years and were used to map the Moho and LAB, as well as to investigate the Galan Caldera by teleseismic tomography.
# 6
Heit, Benjamin • Yuan, Xiaohui • Mancilla, Flor de Lis
Abstract: We operated a densely spaced broadband seismic field experiment to study the structure of the crust and mantle lithosphere across the Sierra Nevada mountain range, southern Spain. The Sierra Nevada is one of the key areas within the complicated Betic-Alboran-Rif system. It contains the highest mountain of the Iberian Peninsula and is located in the close vicinity of a very deep seismic zone (>600 km depth). This region plays a decisive role in answering the question if subduction or delamination is the dominant geological process in the western Mediterranean. The seismic array, consisting of 40 broadband stations spaced 2 km apart (compared to earlier station spacing of ~50 km), has been deployed in September 2010 by a joint effort of GFZ Potsdam and University of Granada, and has been operated until the end of 2011. The proposed scientific work is the analysis of the data collected with the present experiment which includes mainly P and S receiver function analysis and surface wave tomography with ambient noise data. We will image the seismic structure and thickness variation of the crust and mantle lithosphere at high resolution and hence infer tectonic and geodynamic processes related to the Africa-Eurasia collision. The resulting structural details especially of the mantle lithosphere will contribute essentially to the recognition of the geodynamic deformations in the western part of the African-Eurasian plate collision. Data are available from the GFZ seismological data archive.
# 7
Yuan, Xiaohui • Mechie, James • Schurr, Bernd
Abstract: We study deep structures and geodynamic processes in the Tien Shan and Pamir collision zones, central Asia, with passive source seismic experiments in Kyrgyzstan and Tajikistan. In 2008, a total of 40 seismic stations were deployed predominantly along a 350 km long N-S profile and partly as a sparse 2D seismic network covering an area of 300x300 km of the central Pamir plateau. In 2009, the array was rearranged into a 2D network with higher station density. The proposed scientific tasks to study the crust and upper mantle with seismic methods include (i) teleseismic P and S receiver functions, (ii) shear wave splitting, (iii) location of local earthquakes and waveform inversion for source mechanism, (iv) seismic tomography using local and teleseismic earthquakes, and (v) tomography of surface waves and ambient noise.
# 8
Heit, Benjamin • Yuan, Xiaohui • Kind, Rainer • Asch, Günter
Abstract: The seismic array is part of a collaborative international passive-source seismic experiment in the southern Puna (25°S to 28°S) that aims to address fundamental questions on the processes that form, modify and destroy continental lithosphere and control lithospheric dynamics along Andean-type continental margins. The southern Puna is anomalous with respect to the rest of the Andean plateau in having a distinct magmatic and structural history, a large deficit in crustal shortening compared to its elevation and an underlying slab with a transitional dip between a steeper segment to the north and the Chilean flat-slab to the south. With the international project we proposed to test the hypothesis of the lithospheric delamination beneath the southern Puna. The total network consists of 75 seismic stations and has been operated in Argentina and chile for 2 years. The GFZ has contributed 30 stations with EarthData logger (EDL). Sensors include broadband Güralp 3ESP (60 s) and 3T (100 s) and short-period Mark L4 (1 s). Continuous data are freely available on the GEOFON. The US data can be requested from the IRIS.
# 9
Heit, Ben • Yuan, Xiaohui • Jokat, Wilfried • Weber, Michael • Geissler, Wolfram
Abstract: The Etendeka continental flood-basalt province in northern Namibia, linked by the Walvis Ridge to the Tristan da Cunha hotspot, has great importance in global plate tectonic concepts, and is an ideal place to understand the role of the plume-lithosphere interaction during the break-up of the Southern Atlantic Ocean. Within this frame we operated an amphibian passive-source seismic network (WALPASS for Walvis Ridge Passive Source Experiment) in the region where the Walvis Ridge intersects with the continental margin of northern Namibia. The land network operated for over two years while the OBS stations were in operation for one year. The broadband seismic network is composed of 28 three-component land stations and 12 ocean-bottom stations. This configuration of stations will allow us to map the lithospheric and upper mantle structure in the ocean-continent transition beneath the passive continental margin of northern Namibia and to examine possible seismic anomalies related to the postulated hotspot track from the continent to the ocean along the Walvis Ridge. The acquired data should help clarify the velocity anomaly in the lowermost mantle caused by the Africa super plume and to improve the distribution of seismicity in this geophysically little studied region.
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