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The documentation and understanding of variations in the Earth's magnetic field through time is fundamental for several disciplines, but current geomagnetic models rely on datasets heavily biased toward the mid‐ and high northern latitudes. The African continent and surrounding islands and oceans are particularly underrepresented. Here, we present a new record of paleo‐secular variation (PSV) of the inclinations over the last 23 ka from Lake Chala, situated at 3°S near Mt Kilimanjaro in eastern equatorial Africa. This groundwater‐fed crater lake is characterized by a high sedimentation rate (ca. 1 cm/10 years) and a particularly well‐constrained age model based on 210Pb and 14C dating. The magnetic mineralogy of the sediments is tested with rock magnetic analyses. The Lake Chala inclination record shows four highs and lows over 20 ka and compares well with that of Lake Malawi (10°S) between 20 and 16.2 ka, and from 9.8 to 2.6 ka. This record is linked to PSV records at Lakes Victoria and Malawi using a sequence slotting technique to generate a composite PSV model for east Africa. Analyzed at best‐possible resolutions up to 200 years, the Lake Chala PSV record not only represents an important contribution to improve our understanding of local and global features of the Earth's magnetic field. It also expands the utility of paleomagnetism as a key tool for dating and correlation both for archeological sites throughout East Africa and the many volcanoes, active or dormant, of the East African Rift System.

Regional tephrostratigraphic frameworks connect palaeoclimate, archaeological and volcanological records preserved in soils or lake sediments via shared volcanic ash (tephra) layers. In eastern Africa, tracing of tephra isochrons between geoarchaeological sequences is an established chronostratigraphic approach. However, to date, few long tephra records exist from sites with continuous depositional sequences, such as lake sediments, which offer the potential to connect local and discontinuous sequences at the regional scale. Long lake sediment sequences may also capture more complete eruptive histories of understudied volcanic centres. Here, we present and date the tephrostratigraphic record of a >250,000-year (>250-kyr) continuous sediment sequence extracted from Lake Chala, a crater lake on the Kenya-Tanzania border near Mt Kilimanjaro. Single-grain glass major and minor element analyses of visible and six cryptotephra layers reveal compositions ranging from mafic foidites and basanites to more evolved tephri-phonolites, phonolites, trachytes and a single rhyolite. Of these, nine are correlated to scoria cone eruptions of neighbouring Mt Kilimanjaro or the Chyulu volcanic field ∼60 km to the north; seven are correlated to phonolitic eruptions of Mt Meru, ∼100 km to the west; and four to voluminous trachytic eruptions of Central Kenyan Rift (CKR) volcanoes located ∼350 km to the north. The only rhyolitic tephra layer, a cryptotephra, correlates to the 73.7-ka BP (before present, taken as 1950 CE) Younger Toba Tuff (YTT) from Sumatra. Two of the CKR tephra layers provide direct ties with terrestrial sequences relevant to Middle Stone Age archaeology of the eastern Lake Victoria basin in Kenya. Absolute age estimates obtained by direct 40Ar/39Ar dating of 10 tephra layers are combined with six 210Pb and 162 14C dates covering the last 25-kyr and the well-constrained known age of the YTT to build a first absolute chronology for the full Lake Chala sediment sequence. T

Anthropogenic climate change is predicted to severely impact the global hydrological cycle particularly in tropical regions where agriculture-based economies depend on monsoon rainfall. In the Horn of Africa, more frequent drought conditions in recent decades contrast with climate models projecting precipitation to increase with rising temperature. Here we use organic geochemical climate-proxy data from the sediment record of Lake Chala (Kenya and Tanzania) to probe the stability of the link between hydroclimate and temperature over approximately the past 75,000 years, hence encompassing a sufficiently wide range of temperatures to test the ‘dry gets drier, wet gets wetter’ paradigm of anthropogenic climate change in the time domain. We show that the positive relationship between effective moisture and temperature in easternmost Africa during the cooler last glacial period shifted to negative around the onset of the Holocene 11,700 years ago, when the atmospheric carbon dioxide concentration exceeded 250 parts per million and mean annual temperature approached modern-day values. Thus, at that time, the budget between monsoonal precipitation and continental evaporation crossed a tipping point such that the positive influence of temperature on evaporation became greater than its positive influence on precipitation. Our results imply that under continued anthropogenic warming, the Horn of Africa will probably experience further drying, and they highlight the need for improved simulation of both dynamic and thermodynamic processes in the tropical hydrological cycle.

Reconstructions of the timing and frequency of past eruptions are important to assess the propensity for future volcanic activity, yet in volcanic areas such as the East African Rift only piecemeal eruption histories exist. Understanding the volcanic history of scoria-cone fields, where eruptions are often infrequent and deposits strongly weathered, is particularly challenging. Here we reconstruct a history of volcanism from scoria cones situated along the eastern shoulders of the Kenya-Tanzania Rift, using a sequence of tephra (volcanic ash) layers preserved in the similar to 250-ka sediment record of Lake Chala near Mount Kilimanjaro. Seven visible and two non-visible (crypto-) tephra layers in the Lake Chala sequence are attributed to activity from the Mt Kilimanjaro (northern Tanzania) and the Chyulu Hills (southern Kenya) volcanic fields, on the basis of their glass chemistry, textural characteristics and known eruption chronology. The Lake Chala record of eruptions from scoria cones in the Chyulu Hills volcanic field confirms geological and historical evidence of its recent activity, and provides first-order age estimates for seven previously unknown eruptions. Long and well-resolved sedimentary records such as that of Lake Chala have significant potential for resolving regional eruption chronologies spanning hundreds of thousands of years.

On 21 April 2007, an Mw 6.2 earthquake produced an unforeseen chain of events in the Aysén fjord (Chilean Patagonia, 45.5°S). The earthquake triggered hundreds of subaerial landslides along the fjord flanks. Some of the landslides eventually involved a subaqueous component that, in turn, generated a series of displacement waves tsunami- like waves produced by the fast entry of a ubaerial landmass into a water body within the fjord [Naranjo et al., 2009; Sepúlveda and Serey, 2009; Hermanns et al., 2013]. These waves, with run-ups several meters high along the shoreline, caused 10 fatalities. In addition, they severely damaged salmon farms, which constitute the main economic activity in the region, setting free millions of cultivated salmon with still unknown ecological consequences.

Lake sediments contain valuable information about past volcanic and seismic events that have affected the lake catchment, and they provide unique records of the recurrence interval and magnitude of such events. This study uses a multilake and multiproxy analytical approach to obtain reliable and high-resolution records of past natural catastrophes from similar to 600-yr-old annually laminated (varved) lake sediment sequences extracted from two lakes, Villarrica and Calafquen, in the volcanically and seismically active Chilean Lake District. Using a combination of micro-X-ray fluorescence (mu XRF) scanning, microfacies analysis, grain-size analysis, color analysis, and magnetic-susceptibility measurements, we detect and characterize four different types of event deposits (lacustrine turbidites, tephra-fall layers, runoff cryptotephras, and lahar deposits) and produce a revised eruption record for Villarrica Volcano, which is unprecedented in its continuity and temporal resolution. Glass geochemistry and mineralogy also reveal deposits of eruptions from the more remote Carran-Los Venados volcanic complex, Quetrupillan Volcano, and the Huanquihue Group in the studied lake sediments. Time-series analysis shows 112 eruptions with a volcanic explosivity index (VEI) >= 2 from Villarrica Volcano in the last similar to 600 yr, of which at least 22 also produced lahars. This significantly expands our knowledge of the eruptive frequency of the volcano in this time window, compared to the previously known eruptive history from historical records. The last VEI >= 2 eruption of Villarrica Volcano occurred in 1991. Based on the last similar to 500 yr, for which we have a complete record from both lakes, we estimate the probability of the occurrence of future eruptions from Villarrica Volcano and statistically demonstrate that the probability of a 22 yr repose period (anno 2013) without VEI >= 2 eruptions is <= 1.7%. This new perspective on the recurrence interval of eruptions and

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Primary or idiopathic erythermalgia is characterized by recurrent, red, warm, and painful lower extremities. It arises at young age and persists throughout life because no treatment is available. We report the cutaneous pathology of affected skin lesions of three patients with primary erythermalgia. Biopsy specimens showed a mild perivascular mononuclear infiltrate, thickened blood vessel basement membranes, abundant perivascular edema, and moderate endothelial swelling. The thickened basal membrane of the blood vessels showed a laminar structure, and abundant perivascular edema and moderate endothelial cell swelling were evident. These histopathologic findings in primary erythermalgia appear to be nonspecific but allow diagnostic differentiation from erythromelalgia in which fibromuscular intimal proliferation and occlusive thrombi in the endarteriolar capillaries are apparent and from erythermalgia secondary to vasculitis. Histopathologic examination of affected skin lesions in patients with red, congested, warm, and painful burning extremities is a valuable tool in the diagnostic process.