From a detailed survey and sampling study of corrugated massifs north of the Fifteen-Twenty Fracture Zone on the Mid-Atlantic Ridge, we demonstrate that their surfaces are low-angle detachment fault planes, as proposed but not previously verified. Spreadingdirection-parallel striations on the massifs occur at wavelengths from kilometers to centimeters. Oriented drill-core samples from the striated surfaces are dominated by fault rocks with low-angle shear planes and highly deformed greenschist facies assemblages that include talc, chlorite, tremolite, and serpentine. Deformation was very localized and occurred in the brittle regime; no evidence is seen for ductile deformation of the footwall. Synkinematic emplacement of diabase dikes into the fault zone from an immediately subjacent gabbro pluton implies that the detachment must have been active as a low-angle fault surface at very shallow levels directly beneath the ridge axis. Strain localization occurred in response to the weakening of a range of hydrous secondary minerals at a very early stage and was highly efficient.

Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity of observations has obscured the mechanisms underpinning such behaviour. Here we combine a unique multiparametric dataset to show how the 2018 eruption of Sierra Negra contributed to caldera resurgence. Magma supply to a shallow reservoir drove 6.5 m of pre-eruptive uplift and seismicity over thirteen years, including an Mw5.4 earthquake that triggered the eruption. Although co-eruptive magma withdrawal resulted in 8.5 m of subsidence, net uplift of the inner-caldera on a trapdoor fault resulted in 1.5 m of permanent resurgence. These observations reveal the importance of intra-caldera faulting in affecting resurgence, and the mechanisms of eruption in the absence of well-developed rift systems.

SUMMARY A 44-year-old woman is described with an endocrine tumour arising in the kidney. There were associated abnormalities of small intestinal morphology, motility, and absorptive function. These abnormalities reversed on removal of the tumour. Detailed studies showed that the tumour contained, and was secreting, glucagon. It is postulated that the intestinal abnormalities may have resulted from glucagon itself or another, as yet unidentified, hormone.Glucagon-secreting tumours are rare and the few cases described have, with one exception, arisen in the pancreas

The Main Ethiopian Rift hosts a number of peralkaline volcanic centres, with many showing signs of recent unrest. Due, in part, to the low number of historical eruptions recorded in the region, volcanism in the Main Ethiopian Rift remains understudied relative to other volcanic settings and conditions of magma storage remain almost entirely unknown. Aluto is one of these restless caldera systems and identifying magma storage conditions is vital for evaluating the risks posed by recent periods of unrest. In this study, we ran ~150 fractional crystallisation models, using the Rhyolite-MELTS thermodynamic software, within the range P = 50-300 MPa, starting H 2 O = 0.5-3 wt% and fO 2 = QFM-2-QFM+1. This represents a realistic range of potential magma storage conditions at Aluto. We assessed the fractionation trends produced using two different starting compositions, which represent different estimates of the parental melt feeding the system. The predicted liquid lines of descent produced by these models are compared with Aluto whole-rock data from the literature, and are presented along with new observations of the natural phase assemblage and erupted mineral compositions to provide information on the magma storage conditions.