I remember hearing some time ago about a huge volcanic event in 18th century Iceland whose aftereffects included the agricultural crisis and famine that served as the last straw for the French peasants whose uprising began the French Revolution*.
Any truth to this? What was the volcanic event? Who witnessed it? Who has written about it?
*How’s THAT for a sentence?
The 1783 Laki eruption.
this was mentioned on the show, lava hunters. it was recently on tlc. you could try their website for more info.
You are talking about a category of volcanic event known as a basaltic flow eruption.
These are differant to most other eruptions in that is is the earhts mantl fowing up out of the earth on internal convection flows.
Most other eruptions are due to the massive focres generated in areas where on tectonic plate is subdusted under another.
Hawaii is the best known example.
It is only very recently that the scale of these events has emerged with lava fields being discovered that cover much of South America, Brazil and surruondings, in Siberia - this is the largest of all and is greater in area than all Europe, Australia has one. I am not sure about North America.
The most recent and possibly the mosr obviously interesting is the one that covers over a third of India on the north-west side. It is known that this was active over a period of at least a few hundred years with breaks of decades between. It is speculated that this had a lot to do with the extinction of the dinosaurs as it took place at the right time and that the asteriod that hit Chixcelub in Northern Mexico merely finished them off.
It is further thought that such massive events correspond with other mass extinctions.
This is all very recent as it was only in the 90’s that the satellite mapping technology became available enough to discover the lava fields.
casdave:
I’m pretty sure that Craters of the Moon National Monument in Idaho is one such basaltic lava field.
Was anyone else here considering coming in and making an Arne Saknussemm joke?
I thought about it, Uke, but the last time I used a literary reference to subterranean explorers (Abner Perry and David Innes), someone asked what their research had shown.
The Columbia basin in eastern Washington, and parts of Oregon and Idaho is the result of a basaltic lava flow. This was about 15 million years ago or so. I don’t know of any extinctions that accompanied it.
I believe the Craters of the Moon and some other areas in southern Idaho are the result of the Yellowstone hotspot as it “moved” across country. Of course, it doesn’t move. The hotspot stays in one place and the continent moves over it.
“Laki” is one of the vents of the larger Grimsvoton volcano, just like Pu’u o’o is the currently active vent of the Kilauea volcano in Hawai’i. The significance of its 1783-1785 eruption is that in terms of eruptive volume, it represents the largest eruption (>10^10 cubic meters of lava and >10^8 cubic meters of tephra) in historic times. Eruptions are fundamentally of one of two different types, explosive (which generates tephra, and pyroclastic rock) or effusive (which generates lava). Within a single eruption event, though, both can–and frequently do–occur. Laki, although primarily an effusive event, was also quite explosive and ranks a 4 on the Volcano Explosivity Index (VEI; St. Helens by comparison, ranks a 5, but erupted much less).
To mop up a few other points:
It’s not the Earth’s mantle that flows up, but a melt generated from the mantle (they are very different things) that may include a significant crustal component. Magma absolutely does NOT equal mantle!
Craters of the Moon National Monument is a relatively pip-squeek event compared to Laki and other Flood Basalts. Also, it dates from ca. 5890 to 126 B.C., long after the Yellowstone hot spot “passed through” (it’s been about where it is now for the past 2 million years).
The Columbia River Basalt mentioned, in addition to several other large Mafic provinces (Deccan in India, Prana in South America, and others) are a unique sort of event that involves eruptions of thousands of cubic kilomters of basalt, usually over about 1 million years. Laki, although large, still doesn’t quite quailify.
For those interested in the type of topic raised in the OP, you might also be interested in Catastrophe: an investigation into the origins of the modern world by David Keys.
Keys traces all sort of consequences- social, economic, political, etc.- arising from the climate changes caused by a massive eruption of Krakatoa in 535 AD. IMHO he goes way overboard with his hypothesis, but it is an interesting read.
Oops. My bad on that. Somewhere I’d read that the Yellowstone hotspot was responsible for southern Idaho being the way it is and just assumed that all volcanic activity there was its fault.
Don’t lose any sleep over it; it was a good guess. The entire Snake River Plain (including the Snake River Plain basalts, a sort-of Idaho equivalent to the Columbia River basalts in Washington and Oregon) is the hot spot track, after all. Craters of the Moon Nat’l Mon is just a little too far north and a little too young.
But it does have the best Pahoehoe this side of Hawai’i!
Anyone know if a book along the lines of Catastrophe specifically about the Laki event?
Ummm…don’t go swimming with the mahars?