Dynamics of CO2-driven lake eruptions

ON 21 August 1986, a massive release of carbon dioxide from Lake Nyos in Cameroon killed about 1,700 people. A similar event occurred on 15 August 1984 at Lake Monoun, also in Cameroon. It was suggested(1-5) that the CO2 released was initially dissolved in the hypolimnion (dense lower layer) of the lake, and was released by eruptive outgassing. Because of its violence, the Nyos outburst was at first thought(6) to have been volcanic, but undisturbed sediments and other evidence indicate that no large volcanic eruption occurred(7-9). Recent experiments(10,11) have shown that decompression of CO2-saturated water is able to power explosive eruptions. Here I analyse the dynamics of CO2-driven lake-water eruptions by deriving an equation of state for gas-liquid mixtures and using it to integrate the Bernoulli equation, which describes the dynamics of the bubbly flow. I find that under certain conditions these eruptions can be violent: the lake-surface exit velocity of an initially gas-saturated water parcel may reach 89 m s(-1) for Lake Nyos and 51 m s(-1) for Lake Monoun. The dynamics are similar to those of water-driven volcanic eruptions, which are also powered by gas exsolution from a liquid.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62537/1/379057a0.pd

Basic social cognition without mindreading: minding minds without attributing contents

This paper argues that mind-reading hypotheses (MRHs), of any kind, are not needed to best describe or best explain basic acts of social cognition. It considers the two most popular MRHs: one-ToM and two-ToM theories. These MRHs face competition in the form of complementary behaviour reading hypotheses (CBRHs). Following Buckner (Mind Lang 29:566–589, 2014), it is argued that the best strategy for putting CBRHs out of play is to appeal to theoretical considerations about the psychosemantics of basic acts of social cognition. In particular, need-based accounts that satisfy a teleological criterion have the ability to put CBRHs out of play. Yet, against this backdrop, a new competitor for MRHs is revealed: mind minding hypothesis (MMHs). MMHs are capable of explaining all the known facts about basic forms of social cognition and they also satisfy the teleological criterion. In conclusion, some objections concerning the theoretical tenability of MMHs are addressed and prospects for further research are canvassed