Report on the final activity in the NATO-funded project SPS G5690 – “Earthquake Hazard and Environmental Security in Kazakhstan and Kyrgyzstan”: 2024 USA meeting and field trip
Participants:
- Prof. Ramón Arrowsmith, ASU Tempe, USA
- Prof. Magali Rizza, UQAM, Canada
- Dr. Cholponbek Ormukov, American University of Central Asia, Kyrgyzstan
- Dr. Christoph Grützner, FSU Jena, Germany
- Aidyn Mukambayev, KNDC, Kazakhstan
- Gulkaiyr Tilekova, Institute of Seismology, Bishkek, Kyrgyzstan
- Erkin Rakhmedinov, Institute of Seismology, Bishkek, Kyrgyzstan
- Sultan Baikulov, Institute of Seismology, Bishkek, Kyrgyzstan
The final activity in the NATO-funded project SPS G5690 – “Earthquake Hazard and Environmental Security in Kazakhstan and Kyrgyzstan” took place from 5 – 19 September in the western United States. The activity was organized by PI Ramón Arrowsmith of Arizona State University, Tempe (ASU). Project leaders Magali Rizza and Christoph Grützner participated on site; Richard Walker joined the meetings online. From the Central Asian partner institutions, we welcomed Cholponbek Ormukov, Aidyn Mukambayev, Gulkaiyr Tilekova, Erkin Rakhmedinov, and Sultan Baikulov.
The goals of the two week visit included 1) Exchange knowledge on active faulting and seismic hazard, 2) Strengthen and broaden our collaboration, and 3) Discuss current and future projects. See the overview map for the path of our travels.
The first days of the activity were devoted to discussions on project progress and the evaluation of project aims. Ramón Arrowsmith organised a tour to the School of Earth and Space Exploration at ASU and kindly hosted us at his institution (Figure 1). During a short field trip, we visited the South Mountains (south of Phoenix, Arizona), where a brittle-ductile shear zone is exposed (Figure 2). Due to the frictional heat that is created by two blocks of rock sliding past each other in strong earthquakes, frictional melt can form locally. These so-called pseudotachylytes are preserved in the rock record here (Figure 3). The fact that these rocks are deformed indicates that ductile, aseismic fault creep occurred after pseudotachylyte formation. This shear zone is part of an exhumed low-angle detachment that helped to accommodate the ~east-west extension of the western United States since the Oligocene.
Our group then moved from Tempe to Palm Springs to participate in the annual meeting of the Statewide California Earthquake Center (SCEC) (Figure 4). Excellent talks were held as keynote lectures not only on the state-of-the-art of earthquake science in California, but also on the organisational structure of SCEC and science communication. These aspects are highly relevant for our work in the Tian Shan, where such large-scale research collaborations of hundreds of scientists are yet to be established. More than one hundred scientific posters informed about the latest progress in earthquake studies from the fields of seismology, geodesy, modelling, earthquake geology, and geomorphology.
After the SCEC Meeting we headed north to Battle Mountain in northern Nevada. On our way we visited the San Andreas Fault zone, the Garlock Fault, and several other active faults with a clear surface expression of tectonic activity (Figure 5). In contrast to the Tian Shan, the extensional deformation of the western US led to young volcanism—a feature unknown from the contracting mountains of Central Asia. Thus, studying these processes on our way led us to gain new knowledge on the different tectonic deformation styles. The western US exhibits distributed deformation which is a feature of Central Asian tectonics and an issue for seismic hazard assessment.
Near Battle Mountain we joined the Friends of the Pleistocene (FOP) field trip to the Basin and Range tectonic province (Figures 6-9). This field trip was led by international experts on earthquake geology and had ca. 80 participants. One highlight was the visit to the historical earthquake rupture of 1915 in Pleasant Valley. The up to 6 m-high fault scarp reminded us of the large fault scarps formed by historical earthquakes in the Tian Shan in 1889 and 1911. However, those events happened on thrust and reverse faults, while the Pleasant Valley Earthquake was an extensional event. Remarkably, the scarp had undergone very little degradation in the desert environment of Northern Nevada.
Another interesting topic of the excursion was the Buffallo Valley Fault with its impressive cumulative scarps—that is, scarps which formed in several earthquakes. We know similar features, although in a different tectonic setting, from our joint studies in Central Asia.
Apart from the tectonics, the FOP field trip also taught about late Quaternary climate variations and their impact on a former lake system in the Basin and Range. The change of environmental conditions and their geological footprint is a scientific field of growing importance worldwide due to the rapid changes we are seeing in the currently developing climate change. Central Asia will have to deal with the consequences of these changes as do other regions, and we need to better understand what lies in front of us.
In summary, both the FOP field trip and the SCEC meeting were a great success, not only because of the interesting science but also because of the networking possibilities.
Leaving the Battle Mountain area we headed south towards the Las Vegas shear zone and continued all the way to Flagstaff in Arizona. A visit to the Grand Canyon (Figure 10) was certainly one highlight of the entire trip and we walked the recently installed Trail of Time that teaches the 2 billion year-long history of the rocks exposed in the canyon. This is a great idea for science outreach and certainly inspired ideas on similar projects to be realised in Central Asia, where geotourism is quickly growing.
Ramón Arrowsmith led our group to a couple of smaller extension structures on our way from the Grand Canyon back to Tempe. The Arrowhead Graben offsets Quaternary lava flows, which are great markers, and testifies to the very much distributed deformation in the Western US (Figure 11). Actually, the plate boundary here is extraordinarily wide and diffuse, bearing some similarity to the tectonics of the Alpine-Himalayan zone. There, we also observe deformation spanning hundreds and thousands of kilometres wide areas. The Lake Mary Fault zone south of Flagstaff was the last stop on our field trip.
We are grateful to Ramon Arrowsmith who not only organised the entire trip for us, but who also provided cars and other infrastructure for our project activity. We would furthermore like to thank his colleagues at ASU for hosting us, the attendees of the SCEC meeting for interesting and stimulating discussions, and the leaders of the FOP for a fabulous field experience.