The glacial geology of two massifs, Muztag Ata and Kongur Shan, in western Tibet was examined to help define the timing and style of glaciation in the semiarid regions of western Tibet. Remote sensing, geomorphic mapping, and ¹⁰Be terrestrial cosmogenic nuclide (TCN) surface-exposure dating of boulders on the moraines and sediment in depth profiles show that glaciers advanced at least 12 times during at least the last two glacial cycles. Over this time, the style of glaciation changed progressively from one that produced ice caps to one that produced less extensive and more deeply entrenched valley glaciers. The timing of the two earliest glaciations is poorly defined, but they likely occurred prior to the penultimate glacial cycle (the Karasu glacial stage) and the early part of the last glacial cycle or during the penultimate glacial cycle (the Subaxh glacial stage). In contrast, the timing of later glacial advances (the Olimde glacial stage) is relatively well defined showing quasiperiodical oscillations on millennial time scales (17.1 ± 0.3 ka, 13.7 ± 0.5 ka, 11.2 ± 0.1 ka, 10.2 ± 0.3 ka, 8.4 ± 0.4 ka, 6.7 ± 0.2 ka, 4.2 ± 0.3 ka, 3.3 ± 0.6 ka, 1.4 ± 0.1 ka, and a few hundred years before the present). These data suggest that since the global Last Glacial Maximum (LGM), the glaciers in western Tibet likely responded to Northern Hemisphere climate oscillations (rapid climate changes), with minor influences from the south Asian monsoon. This study provides the first well-defined glacial geologic evidence to suggest that glaciers in western Tibet respond to rapid climate changes on millennial time scales throughout the Late Glacial and Holocene.

Korea has been recognized as an earthquake-safe zone, but over recent decades, several earthquakes, at a medium scale or higher, have occurred in succession in and around the major fault zones, hence there is a need for studying active faults to mitigate earthquake risks. In Korea, research on active faults has been challenging owing to urbanization, high precipitation, and erosion rates, and relatively low earthquake activity compared to the countries on plate boundaries. To overcome these difficulties, the use of aerial light detection and ranging (LiDAR) techniques providing high-resolution images and digital elevation models (DEM) that filter vegetation cover has been introduced. Multiple active fault outcrops have been reported along the Yangsan Fault, which is in the southeastern area of the Korean Peninsula. This study aimed to detect active faults by performing a detailed topographic analysis of aerial LiDAR images in the central segment of the Yangsan Fault. The aerial LiDAR image covered an area of 4.5 km by 15 km and had an average ground point density of 3.5 points per m², which produced high-resolution images and DEMs at greater than 20 cm. Using LiDAR images and DEMs, we identified a 2–4 m high fault scarp and 50–150 m deflected streams with dextral offset. Based on the image analysis, we further conducted a trench field investigation and successfully located the active fault that cut the Quaternary deposits. The N–S to NNE-striking fault surfaces cut unconsolidated deposits comprising nine units, and the observed slickenlines indicated dextral reverse strike-slip. The optically stimulated luminescence (OSL) age dating results of the unconsolidated deposits indicate that the last earthquake occurred 3200 years ago, which is one of the most recent along the Yangsan Fault.

Quantitative satellite observations only provide an assessment of ice sheet mass loss over the last four decades. To assess long-term drivers of ice sheet change, geological records are needed. Here we present the first millennial-scale reconstruction of David Glacier, the largest East Antarctic outlet glacier in Victoria Land. To reconstruct changes in ice thickness, we use surface exposure ages of glacial erratics deposited on nunataks adjacent to fast-flowing sections of David Glacier. We then use numerical modelling experiments to determine the drivers of glacial thinning. Thinning profiles derived from 45 ¹⁰Be and ³He surface exposure ages show David Glacier experienced rapid thinning of up to 2 m/yr during the mid-Holocene (∼ 6.5 ka). Thinning slowed at 6 ka, suggesting the initial formation of the Drygalski Ice Tongue at this time. Our work, along with ice thinning records from adjacent glaciers, shows simultaneous glacier thinning in this sector of the Transantarctic Mountains occurred 4–7 kyr after the peak period of ice thinning indicated in a suite of published ice sheet models. The timing and rapidity of the reconstructed thinning at David Glacier is similar to reconstructions in the Amundsen and Weddell embayments. To identify the drivers of glacier thinning along the David Glacier, we use a glacier flowline model designed for calving glaciers and compare modelled results against our geological data. We show that glacier thinning and marine-based grounding-line retreat are controlled by either enhanced sub-ice-shelf melting, reduced lateral buttressing or a combination of the two, leading to marine ice sheet instability. Such rapid glacier thinning events during the mid-Holocene are not fully captured in continental- or catchment-scale numerical modelling reconstructions. Together, our chronology and modelling identify and constrain the drivers of a ∼ 2000-year period of dynamic glacier thinning in the recent geological past.