Posts in the category »  Field work «  ( 116 Posts )

  • New papers on paleoseismology in the Tien Shan

    Between 1885 and 1938, the northern Tien Shan at the border between present Kyrgyzstan and Kazakhstan experienced a remarkable series of five major earthquakes, exceeding M6.9 and reaching up to M ~ 8 (1885 Belovodskoe M6.9, 1887 Verny M7.3, 1889 Chilik M~8, 1911 Chon Kemin M8, and 1938 Kemino Chu M6.9). Combined, the seismic moments add up to almost moment magnitude 9, which is a significant amount of strain released in roughly 50 years and across an E-W stretch of less than 500 kilometers. Even more intriguing is the fact that the ruptured region is located more than thousand km north of the nearest plate boundary and associated India-Eurasia collision zone. The macroseismic areas of these earthquakes include the present-day capital of Kyrgyzstan, Bishkek (Frunze) and the former capital and still largest city of Kazakhstan, Almaty (earlier names Alma Ata and Verny).
    more

  • Guest blog by Sascha Schneiderwind (RWTH Aachen University): Multiparametric trenching investigations

    [Update 15 February 2017: Since Sascha is an author here now, the post was attributed to him.]
    Greece is one of the main targets of RWTH Aachen’s Neotectonics & Geohazards group. They worked on paleo-tsunamis, active faults on the Peloponnese, in Attica, and on Crete, and on the application of terrestrial LiDAR and shallow geophysics for active tectonics research. In their latest paper, Sascha Schneiderwind et al. developed a methodology to aid paleoseismic trenching studies. They use t-LiDAR and georadar to better and more objectively characterise lithological units. His paper includes nice examples from Crete and from the famous Kaparelli Fault. Here is his guest blog: more

  • Guest blog by Bastian Schneider (RWTH Aachen University): Tsunami hazard in Muscat, Oman

    Tsunamis are a very real threat in the Indian Ocean. Most people will immediately think of the 2004 tsunami and the Sumatra subduction zone, but the Arabian Sea has seen strong tsunamis in the past, too. In 1945, a major earthquake at the Makran Subduction Zone caused a large tsunami (Hoffmann et al., 2013a). In 2013, the on-shore Balochistan earthquake caused a submarine slide which in turn triggered a tsunami that reached the coast of Oman (Heidarzadeh & Satake, 2014; Hoffmann et al., 2014a). There is also evidence for paleotsunamis along Oman’s coast (Hoffmann et al., 2013b; Hoffmann et al., 2014b). Now a team of scientists from RWTH Aachen University (Germany) and GUtech (Muscat, Oman) have published a tsunami inundation scenario for Muscat (Schneider et al., 2016). This is lead author Bastian Schneider’s guest blog on this research: more

  • Guest blog: “Photogrammetry for Paleoseismic Trenching” by Nadine Reitman (USGS)

    A few weeks ago, Nadine Reitman (USGS) published an interesting paper about the use of Photogrammetry for Paleoseismic Trenching in BSSA. In this guest blog she shares her key findings and explains how to minimise errors without spending too much time measuring control points. Thanks Nadine!

    Structure-from-motion (SfM) is now routinely used to construct orthophotos and high-resolution, 3D topographic models of geologic field sites. Here, we turn SfM on its side and use it to construct photomosaics and 3D models of paleoseismic trench exposures. Our results include a workflow for the semi-automated creation of seamless, high resolution photomosaics designed for rapid implementation in a field setting and a new error analysis of SfM models. more

  • EGU deadline tomorrow

    Just a friendly reminder that the deadline for abstract submission for the EGU general assembly 2016 in Vienna is tomorrow, January 13th at 13:00 CET/12:00 GMT. If you are still looking for a session to submit your abstract to, please have a look at our session about Active Faults and the Earthquake Cycle (TS4.2/NH4.16/SM3.8)

    By the way, the Vienna Basin is the perfect place to discuss active faults, as you see on our newest gravel pit outcrop. If you interested in having a closer look at this fault during the EGU – let me know…

    Hopefully see you soon in Vienna,

    Esther, Kris, Matthieu, Angela

    more

  • This was my field work on active faults in Kazakhstan 2015 (pt. II)

    The first part of my report on the field work that I did in Kazakhstan this year focussed on the stuff we had done in the South. Here is part II which is all about the Dzhungarian Fault. You’ve never heard about this fault? That’s easily possible. There are only very few papers that deal with this fault. In the 1960s Soviet geologist V.S. Voytovich published results from extensive field work on this fault (Voytovich, 1965; 1969). 40-50 years later a few studies on geodesy and geodynamics covered the broader study area and Shen et al. (2003) did some work in the Chinese part of the fault, but it took until 2013 before Campbell et al. revisited the Kazakh side and came up with new field data. They focussed on the tectonic geomorphology of this structure and determined a slip rate. Given this little amount of research done one would assume that the fault is not very large and of minor importance, but the opposite is true. The fault is around 300 km long in its Kazakh section and probably twice as long in total! more

  • This was my field work on active faults in Kazakhstan 2015 (pt. I)

    I’ve spent several weeks in Eastern Kazakhstan this summer for paleoseismological field work. During the first part of this trip we looked at some thrust and strike-slip faults in the Ili Basin and the Saty area. The second part was almost entirely devoted to study the Dzhungarian Fault. I’ll blog about this second part later. Eleanor, David, Austin and me were the UK representatives in our team. We were so lucky to have Kanatbek from Kyrgyzstan and Aydin from Kazakhstan with us. They did not only lead us to all the interesting places and helped us to understand the geology and the tectonics, but they also did a fanatastic job organizing the field trip and dealing with the local surprises, which as you know happen in basically every field trip.

    Our first study site was located at the northern boundary of the Ili Basin, where we did some work last year already. more

  • New paper: Evolution of dilatant faults in the Canyonlands NP, Utah

    The Canyonlands National Park, Utah, is famous for its beautiful landscape and spectacular landforms. For many geoscientists it is also well-known as a sandstone reservoir analogue and as a tourist you’ll often run into groups of geologists on field trips. It’s a matter of debate how and how fast the beautiful grabens in the Needles Fault zone formed – these are large arcuate canyons several tens of kilometres in length, paralleling the Colorado River. In a new paper we present results from remote sensing, mapping, and georadar (GPR). Our aim was to better understand the coupling between deformation, erosion and deposition in such an active system. Based on our findings we developed a model of graben formation and describe the geometry of the dilatant faults at depth. We argue that either the grabens are older than previously assumed or that sedimentation rates were much higher in the Pleistocene.

    more

  • Paleoseismological field work in Kyrgyzstan

    A few weeks ago I spent ten days of field work in the Suusamyr Valley in Kyrgyzstan. In the framework of the EwF Project and COMET a team from Oxford (Eleanor Ainscoe, Austin Elliott, Richard Walker) and Kyrgyzstan (Kanatbek Abdrakhmatov, Azat Moldobaev) re-visited the epicentral area of the 1992 MS7.3 Suusamyr earthquake. This thrust earthquake is quite special for it produced intense and widespread secondary earthquake environmental effects (landslides, rockfalls, secondary ruptures, mud eruptions, etc.), but remarkably short primary surface ruptures only. Actually, surface ruptures of several metres height were found near the Suusamyr river, but limited to few hundreds of metres in length. Some 25 km to the west, another set of surface ruptures appeared, which were only about 1 m in height and less than 3 km long. Here are some impressions from our field work. more

  • Paleoseismology Through Sedimentology

    The Megablock Complex: An example from the East African Rift

    Recognizing and interpreting seismite horizons (soft-sediment deformation generated by earthquakes) preserved in the sedimentary record is an underappreciated approach for paleoseismic analysis. The addition of sedimentological studies to a toolkit that includes other well-established methods, such as instrumental seismic monitoring and fault trenching, can provide a less expensive and more practical option for earthquake hazard prediction and preparation in certain areas. For example, this may be a good option in less developed regions and in areas where fault trenching may not be possible. Moreover, there is a lot that we can learn rheologically from the study of seismites that could be invaluable for modeling the behavior of the surface/near-surface during seismic activity. Similarly, investigating Quaternary strata in areas that may be prone to seismicity, which may or may not have a recorded history of major earthquakes, can illuminate important information about earthquake recurrence patterns and intervals, in much the same way as fault trenching. more

Newsletter

Just click the "Unsubscribe" link which you find in every newsletter you get and your email adress will be removed from the subscribers list in seconds.

Facebook

} ?>

Sharing Options

Digg this
Delicious
Stumbleupon
Reddit
Like us on Facebook
Follow us on Twitter
Follow us on Google +
The paleosesismicity.org group on LinkedIn
Subscribe to the paleoseismicity Newsletter