The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such ...The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such as debris flows, often impact forest stands where they cause damage to individual trees, thereby generating growth disturbances(GD) in the tree-ring records. The identification and dating of GD enables reconstruction of the age of trees colonizing bare surfaces after major events, but also allows the assessment of the frequency or spatial distribution of past geomorphic process activity. Here we used increment cores from 65 Pinus leiophylla, Abies religiosa, and Alnus jorullensis trees growing in the Axal gorge, on the southern slopes of La Malinche volcano, to unravel past debris-flow activity both temporally and spatially. Based on the combination of GD records, a weighted tree response index(Wit), field evidence and hydrometeorological records, we reconstructed 23 debris flows since 1933.Interestingly, almost two-thirds of the reconstructed years with debris-flow activity in Axal gorge match with events recorded in Axaltzintle gorge located on the NE slopes of La Malinche. These findings suggest a regional triggering mechanism, most likely related to the occurrence of hurricanes. This research could be useful for disaster risk management of the La Malinche National Park.展开更多
On 5th September 2022,a magnitude Ms-6.8 earthquake occurred nearby Mt.Gongga,western Sichuan.The stability of the glaciers in east Mt.Gongga close to the epicenter was widely concerned due to the strong shake trigger...On 5th September 2022,a magnitude Ms-6.8 earthquake occurred nearby Mt.Gongga,western Sichuan.The stability of the glaciers in east Mt.Gongga close to the epicenter was widely concerned due to the strong shake triggered by the earthquake.Using multi-source observations(including in-situ photographs,remote sensing datasets before and after the event),we carried out a preliminary assessment of the stability and hazard risks of the Hailuogou(HLG)glacier.Triggered by the earthquake,a small block of fractured ice at the lowest part of icefall collapsed.The magnitude of the coseismic ice avalanche was relatively small,which is comparable in size to most ice avalanches over the past seven years,but much less than the previous mapped largest one(03 April 2018,runout~699 m).One most recent large(runout~608 m)ice avalanche occurred between 01 and 04 September,just before the earthquake,likely unloaded large amount of ice mass and made a larger ice avalanche avoided during the earthquake shake.Nevertheless,the momentum of collapsed snow-icerock mass could be safely unloaded over a wide and gentler-slope ice tongue area,limiting its mobility and the risk of a cascading hazard.Glacier-wide surface flow dynamics monitored by Sentinel-1 satellite SAR time series(12 September 2021–19 September 2022)show that HLG glacier velocity was generally consistent before and after the earthquake.The entire HLG glacier exhibited more stable than expected,with almost no abnormal features detected in its upper accumulation part,the lower ice tongue,and its lateral paraglacial slopes.Since the glacier valley has experienced remarkable downwasting and the paraglacial environment has been strongly disturbed and destabilized,we suggested that,to efficiently evaluate glacier-related cascading hazard risks,it is also necessary to systematically combine multi-source observations(e.g.,high-resolution UAV survey,radar/Lidar scan,ground investigation,monitoring and warning systems)to continuously monitor the regional glacier anomalies in the post-earthquake seismic active areas.展开更多
In China,flash floods are one of the main natural disasters causing loss of life and damage to infrastructure.The threat of flash floods is exacerbated with climate change and increased human activities,such that the ...In China,flash floods are one of the main natural disasters causing loss of life and damage to infrastructure.The threat of flash floods is exacerbated with climate change and increased human activities,such that the number of disasters has shown a clear upward trend in recent years.However,due to the scarcity of instrumental data or overly short timeseries,we are still lacking critical data to understand spatio-temporal patterns and driving factors of extreme flash floods.This missing knowledge is however crucial for a proper management of these hazards,especially in remote mountain environments.In forested catchments,dendrogeomorphology allows the reconstruction of past process activity based on growth disturbances(GDs)in trees that have been affected by past flash floods.Therefore,in our study,for the first time,we reconstruct past flash floods in the Qilian Mountains,northeast Tibetan Plateau,over past centuries.To this end,we sampled 99 Qinghai spruce(Picea crassifolia)trees affected by flash floods,with a total of 194increment cores,and identified 302 GDs induced by past flash floods.These GDs have been caused by at least 21 flash floods that we are able to reconstruct over the last 170 years.The position of GDs within tree rings and the intra-seasonal dating of past events also allowed discussion of the likely synoptic situations that may have led to the triggering of flash floods in the past.Logistic regression analysis confirms that significant correlation exists between cumulative maximum 5-day August-September precipitation and reconstructed flash floods,which is corresponding to the majority of scars and related tangential rows of traumatic resin ducts(TRDs)found in the latewood portion of growth rings.These results support the idea that abundant precipitation occurring at the end of the summer season and early fall is the key factor driving flash floods in our study area.Our research not only fills the gaps regarding historical flash flood histories in the Qilian Mountains,but also provides a scientific basis for the region's response to climate change and flood prevention and reduction.展开更多
文摘The use of dendrochronology to study and date geomorphic processes in volcanic environments is still incipient, even more so on the volcanic slopes covered by temperate forests in central Mexico. Mass movements, such as debris flows, often impact forest stands where they cause damage to individual trees, thereby generating growth disturbances(GD) in the tree-ring records. The identification and dating of GD enables reconstruction of the age of trees colonizing bare surfaces after major events, but also allows the assessment of the frequency or spatial distribution of past geomorphic process activity. Here we used increment cores from 65 Pinus leiophylla, Abies religiosa, and Alnus jorullensis trees growing in the Axal gorge, on the southern slopes of La Malinche volcano, to unravel past debris-flow activity both temporally and spatially. Based on the combination of GD records, a weighted tree response index(Wit), field evidence and hydrometeorological records, we reconstructed 23 debris flows since 1933.Interestingly, almost two-thirds of the reconstructed years with debris-flow activity in Axal gorge match with events recorded in Axaltzintle gorge located on the NE slopes of La Malinche. These findings suggest a regional triggering mechanism, most likely related to the occurrence of hurricanes. This research could be useful for disaster risk management of the La Malinche National Park.
基金funded by the Natural Science Foundation of China(Grants Nos.41871069 and 42071084)Outstanding Youth Scholars Foundation of Sichuan Province(Grants No.2021JDJQ0009)。
文摘On 5th September 2022,a magnitude Ms-6.8 earthquake occurred nearby Mt.Gongga,western Sichuan.The stability of the glaciers in east Mt.Gongga close to the epicenter was widely concerned due to the strong shake triggered by the earthquake.Using multi-source observations(including in-situ photographs,remote sensing datasets before and after the event),we carried out a preliminary assessment of the stability and hazard risks of the Hailuogou(HLG)glacier.Triggered by the earthquake,a small block of fractured ice at the lowest part of icefall collapsed.The magnitude of the coseismic ice avalanche was relatively small,which is comparable in size to most ice avalanches over the past seven years,but much less than the previous mapped largest one(03 April 2018,runout~699 m).One most recent large(runout~608 m)ice avalanche occurred between 01 and 04 September,just before the earthquake,likely unloaded large amount of ice mass and made a larger ice avalanche avoided during the earthquake shake.Nevertheless,the momentum of collapsed snow-icerock mass could be safely unloaded over a wide and gentler-slope ice tongue area,limiting its mobility and the risk of a cascading hazard.Glacier-wide surface flow dynamics monitored by Sentinel-1 satellite SAR time series(12 September 2021–19 September 2022)show that HLG glacier velocity was generally consistent before and after the earthquake.The entire HLG glacier exhibited more stable than expected,with almost no abnormal features detected in its upper accumulation part,the lower ice tongue,and its lateral paraglacial slopes.Since the glacier valley has experienced remarkable downwasting and the paraglacial environment has been strongly disturbed and destabilized,we suggested that,to efficiently evaluate glacier-related cascading hazard risks,it is also necessary to systematically combine multi-source observations(e.g.,high-resolution UAV survey,radar/Lidar scan,ground investigation,monitoring and warning systems)to continuously monitor the regional glacier anomalies in the post-earthquake seismic active areas.
基金supported by the National Natural Science Foundation of China[Grant No.41977392]the National Key R&D Program of China[Grant No.2019YFA0606602]+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20090000)Qilian Mountain National Park Qinghai Province management bureaufinanced by the China Scholarship Council。
文摘In China,flash floods are one of the main natural disasters causing loss of life and damage to infrastructure.The threat of flash floods is exacerbated with climate change and increased human activities,such that the number of disasters has shown a clear upward trend in recent years.However,due to the scarcity of instrumental data or overly short timeseries,we are still lacking critical data to understand spatio-temporal patterns and driving factors of extreme flash floods.This missing knowledge is however crucial for a proper management of these hazards,especially in remote mountain environments.In forested catchments,dendrogeomorphology allows the reconstruction of past process activity based on growth disturbances(GDs)in trees that have been affected by past flash floods.Therefore,in our study,for the first time,we reconstruct past flash floods in the Qilian Mountains,northeast Tibetan Plateau,over past centuries.To this end,we sampled 99 Qinghai spruce(Picea crassifolia)trees affected by flash floods,with a total of 194increment cores,and identified 302 GDs induced by past flash floods.These GDs have been caused by at least 21 flash floods that we are able to reconstruct over the last 170 years.The position of GDs within tree rings and the intra-seasonal dating of past events also allowed discussion of the likely synoptic situations that may have led to the triggering of flash floods in the past.Logistic regression analysis confirms that significant correlation exists between cumulative maximum 5-day August-September precipitation and reconstructed flash floods,which is corresponding to the majority of scars and related tangential rows of traumatic resin ducts(TRDs)found in the latewood portion of growth rings.These results support the idea that abundant precipitation occurring at the end of the summer season and early fall is the key factor driving flash floods in our study area.Our research not only fills the gaps regarding historical flash flood histories in the Qilian Mountains,but also provides a scientific basis for the region's response to climate change and flood prevention and reduction.
基金funding from the ERC Advanced Project MONOSTAR (Ad G 882727)funding from Sust ES: adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_0 19/0000797)+11 种基金funding from the Fritz & Elisabeth Schweingruber Foundation. Duncan A. Christie and Carlos Le Quesne received funding from the ANID (FONDECYT 1201411, 1221307, FONDAP 15110009, BASAL FB210018)funding from the Russian Science Foundation grant (RSF 21-17-00006)funding from NSF Arctic Social Science 2112314NSF Arctic Natural Science 2124885the NSF P2C2 (Paleo Perspectives on Climatic Change) program (various grants)funding from the Russian Science Foundation grant (RSF 21-1400330)funding from the Russian Science Foundation grant (RSF 18-14-00072P)supported by the Swedish Research Council (201801272)funding from the Swiss National Science Foundation through the SNSF Sinergia CALDERA project (CRSII5 183571)funding from the National Science Foundation’s P2C2 Program (1902625 and 1203749)the Malcolm H.Wiener Foundationfunded through NSF P2C2 Program (2002454)