Modern day volcanoes, i.e. the last few thousand years seem to be responsible for noticable cooling effects on the climate, i.e. Mount Pinatoba, Tambora etc.  This is i assume is down to dust, ash and sulphur dioxide been spewed into the air and reflecting incoming solar radiation.

 Although it seems volcanism in earths geological history appear to be responsible for notable warming events, attributed to greenhouse gas emmisions.  I know the residence time of greenhouse gasses are usualy longer than ash, dust and sulphur aerosols, however continued eruptions i would imagine would keep a constant supply of sulphur in the atmosphere thus cooling the planet.

Please explain this contradiction.

Thanks

Mark

If you look at a map, around Thera/Santorini there is a rough circle bounded by Crete & Rhodes to the South, with Thera itself near the centre, in the Cyclades. Is it possible that this area marks an enormous “supervolcano”? I know Santorini itself is proposed as the remains of a huge volcanic explosion, but I’ve only seen this applied to Santorini’s crater, not to a wider area.

Obviously magmas erupt differently.  Usually felsic based mineral magmas are explosive and mafic based mineral magmas fluidy.

 Explosive eruptions are mostly explained by the fact that the magma contains greater amounts of silica, however if the temperature was higher would that not decrease the viscosity?  Yet with higher temperatures there is a greater liklihood of an influx of more mafic minerals which typically have a higher melting point, overall making the magma less felsic.

So is magma viscosity really more influenced by temperature which effectively controls the silica content? rather than just the physical properties of silica making things viscous?

Ive recently seen an advert by Dettol which sees to trying to scare people even more than their usual methods, claiming that some bacteria can survive in lava http://bit.ly/bAJm3e. I wouldn't have thought this possiable because of the extreme temperatures and preasures the molten rock would exibit on soft object, as well as the lack of a food source that they would need to live for any amount of time. So should I worry about getting the flu if i ever fall in lava?

We assume that life possibly came to Earth through the landing of a relatively large body of mass from somewhere else in the cosmos.  Could the inverse happen?  Could a large volcano (or any other natural means such as storm pressures or atmospheric disruptions), have sufficient energy and force to eject material from our planet (no matter how small a fragment, but sufficient to contain and protect bacteria) to send life onto somewhere else (no matter how improbable)?  Could Earth be a staging post in life's spread further across the universe?