Repeated precise leveling in the earthquake swarm area of Ontake, central Japan has revealed uplift of 3-6 mm in proximity to the epicentral region of the most active earthquake cluster in 2002-2004. Although the uplift is small, the vertical displacement is significant even considering leveling error. This uplift is associated with increases in 3 He/ 4 He ratios and CO 2 δ 13 C values at a mineral spring in the region, indicating an upper mantle contribution. A region of low resistivity at a depth of 2 km beneath the uplift area has also been inferred, suggesting that the observed uplift is related to changes in a shallow seismogenic layer due to increased hydrothermal input from the earthquake swarm area.

We use a Global Positioning System (GPS) to unravel the complex geodynamics of the Azores Triple Junction where tectonic and volcanic activities coexist. The temporal analysis of densely distributed continuous GPS data on São Miguel for the period 2008-13 provides an improved understanding of interactions between present-day plate boundary kinematics and volcanic deformation. We find a high-strain-rate (0.28 ppm a -1 ) zone between Congro and Furnas, which accommodates about 50% of the Eurasian-Nubian plate spreading as predicted by the MORVEL plate angular velocity model. The seismic unrest of Fogo-Congro (2011-12) shows a strong similarity with the Matsushiro (Japan) earthquake swarm (1965-66) and the Campi Flegrei (Italy) volcanic unrest (1969-72 and 1982-85), in that an edifice-scale inflation associated with intense high-frequency earthquakes and inflation-deflation reversals coincided with a sharp drop in seismicity. We propose the following hypothesis for the Fogo unrest: (1) the primary inflation source beneath Fogo promotes lateral diffusion of fluids that is selectively guided by existing cracks/fissures formed from regional extension;(2) an influx of fluids increases pressure in cracks/fissures and generates lower-frequency earthquakes; and (3) discharge of fluids causes pressure decrease and dilatancy recovery (i.e. seismic quiescence).

Lake Tazawa, the deepest lake (423.4 m depth at maximum) in Japan underwent drastically changed water quality in 1940, because volcanic water from two active volcanos was then drawn into the lake for power generation and irrigation. Thereby, the pH of lake water decreased from 6.7 to 4.2, which exterminated a land-locked type of sockeye salmon, Oncorhynchus nerkakawamurae (locally called Kunimasu trout). Additionally, the mean residence time of lake water changed from 195 years to 8.9 years by rapidly increasing the outflow for power generation and irrigation. In this study, long-term chemical fluxes controlling lake water chemistry were obtained, and a groundwater water cycle system between the lake and the volcano was explored by estimating hydrological and chemical budgets of the lake. In the chemical budget estimate, two ionic species, SO42− and Cl−, in volcanic fluids were chosen and each mass conservation equation was yielded. The hydrological budget estimate gave us the net groundwater inflow at −1.36 m3/s on average over three periods in 2020–2021, and then the simultaneous equation coupled with the chemical budget equation allowed us to separate into groundwater inflow and outflow at 6.01 m3/s and 7.37 m3/s, averaged over the three periods, respectively. The evaluated groundwater inflow and outflow were compared with those of the other crater or caldera lakes. The linear relationship between the lake volume and the magnitude of groundwater inflow or outflow suggests that the groundwater cycle scale in such a lake increases with the magnitude of the volcanic eruption to have formed the lake.

fact enolization, we can estimate a hydronium-ion catalytic coefficient of ka, = 4 x M -' s-' for the enohation reaction at 25 "C. Combination of this with the hydroniumion catalytic coefficient for ketonization measured at 25 "C, k,!& = 9.3 x lo3 M -' s -' , [ '~] then leads to the keto-enol equilibrium constant pKE = 15.4.This keto-enol equilibrium [Eq. (f)] and the acid ionization of the enol, [Eq. (d)] form two branches of a thermodynamic cycle whose third member is the deprotonation of mandelic acid 5 as a carbon acid [Eq. (g)]. The equilibrium constant for this reaction may therefore be calculated from the other two: pKf = pK, i pKB = 22.0.These three equilibrium constants, pKE, pKF, and pKF, are the first ever measured for a simple carboxylic acid ketoenol system in aqueous They show the enol content to be very low-orders of magnitude less than of simple aldehydes and ketones-as expected from stabilization of the keto tautomer of the carboxylic acid system through conjugative interaction of its carbonyl and hydroxyl groups. The carboxylic acid enol, on the other hand, is more acidic than those of simple aldehydes and ketones, and that makes the carbon acidity of this carboxylic acid greater than it would otherwise be. Received: March 27, 1990 [Z 3881 IE] German version: Angew. Chem. 102 (1990) 810 CAS Registry numbers: 2, 127645-81-2; 5, 90-64-2.4 3 R)SiCI, P Scheme 1. Synthesis of la-c (Ar = aryl).excess dichlorosilane (Sa-c) to provide l a in 31 %, l b in 12 Yo, and lc in 15 % yield, respectively. The spectral data of these compounds (Table 1) are consistent with the proposed structures. Particularly revealing are the 29Si-NMR spectra,

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