I like to keep a weather eye on Hekla . A long time ago it really blew up and the ash cloud ended agriculture across Northern Europe for a solid generation. The year was 1159 BC, twenty years after the
Trojan War. Both dates are good as
gold. 1159 BC is by Irish bog tree rings
and the Trojan date by astronomical information in the texts.
There is more to the story that
just that of course and followers of my blog know that. Moreover, knowing the scale of the historical event and its damage warns us to never under estimate Hekla .
It is survivable in the modern
world simply because we can move food instead of the starving millions. Yet its sheer scale must be respected. And history is the only tool we have that
lets us understand the potential risk.
In any event anything happening
in Iceland
can be annoying as we discovered a couple of years ago.
by Staff Writers
The Icelandic Met Office said it had raised its aviation warning level
a notch Tuesday for the first time in two years following "elevated unrest
above a known background level during the last weeks."
The office told AFP there was no smoke rising from the mountain, but
dark clouds seen from the ground could lead people to think there had been an
eruption.
The alert level for the aviation industry was raised from
"green" to "yellow", which it described as a precautionary
measure due to the volcano's "increased earthquake activity."
Emergency services said in a separate statement that they had declared
"an uncertainty phase", the lowest level of warning issued for events
"that may threaten public health and safety, or that an environment or
inhabited area may be threatened."
The eruption of Iceland 's
Eyjafjoell volcano in April 2010 stranded more than eight million travellers as
volcanic ash spread across Europe .
Eruption History
1104: After a least 250 years of sleep, Hekla erupted violently with an explosive eruption that sent tephra northward, covering more than half the country.
1158: This eruption is believed to be responsible for the formation of the Efrahvolshraun lava flow on the west side of Hekla .
1206: Small scale eruption where tephra was sent in a northeasterly direction.
1222: Another small eruption similar to the one in 1206.
1300: Large eruption lasting the whole year; the second largest tephra eruption in Iceland
1341: Medium size eruption that ejected tephra that was carried to the west and southwest of Hekla , poisoning a large number of livestock most likely by fluorine.
1389: This eruption was responsible for the Nordurhraun or northern
Selsundshraun lava flow.
1440: Uncertian eruption might have occurred southeast of Hekla at Raudoldur.
1510: Starting out very violently sending stones flying up to 25 miles (40 km) away; one such rocks hit and killed a man in Landsveit, Iceland.Considerable tephra damage to the southwest.
1554: Poorly documented eruption occurred southwest of Hekla at Raudubjallar.
1597: Similar to the 1947 eruption and lasting over six months.
1636: Small scale eruption that lasted over a year causing extensive
mortality to local livestock.
1693: Starting out very violently Hekla produced nearly 60,000 cu. meters of tephra per second. This eruption event lasted for at least 7 months causing great numbers of wildlife and livestock to die off from fluorine poisoning or starvation. A considerable lava flow was associated with this event, which also ejected fine ash high enough for it to be carried all the way to Norway
1725: A poorly documented eruption occurred to the south, southwest and east of Helka.
1766: The largest Hekla eruption in historical times occurred 3:30 in the morning April 5th and continued until May of 1768. This was Iceland
1845: This eruption lasted over seven months. In the first four hours tephra was ejected at a rate of about 20,000 cu. meters per second; fine ash was found as far as the Shetland Islands and Scotland
1878: An explosive eruption occurred to the east of Helka at Krakagigar that produced lava.
1913: Explosive eruptions occurred to the east and northeast of Hekla at Mundafit and Lambafit. Those eruption events also produced lava flows.
1947: A hundred years went by without a rumbling from Hekla¹s depths, then on Saturday, March 29th at about 6:41 in the morning an eruption cloud consisting mainly of water vapor rose to a height of 19 miles (98,000 ft. or 30,000 m) into the sky within ten minutes. Within the first half hour lava began to well up in the fissure and poured over and down Hekla¹s south-eastern slopes at a rate of about 3,500 cu. meters of lava per second. By the end of the day, lava was rushing out of both ends of the fissure. Great clouds of steam bellowed from Hekla¹s western slope where floods had originated from what had been ice and snow fields. Eight separate eruption columns were visible by the second day and at the lower end of the fissure a crater had opened up and from it streamed an enormous river of lava. This crater was given the name Hraungigur (Lava Crater). Another two large craters had also formed, an explosion crater on the southwest slope named Axlargigur (Shoulder Crater) and a summit crater named Toppgigur. This eruption continued until mid-April of the next year and over this time grew 184 ft. (56 meters) to a elevation of 4,930 ft. (1,503 m).
1970: After a 22 year interval of inactivity Hekla came back to life, first shooting a huge ash-laden cloud to a height of 15,000 meters, and then covering a 40,000 sq. km. area with ash. This ash had high fluorine content (800-2,000 ppm) which poisoned over 7,000 sheep in the local area. This eruption's breakthrough points occurred along the Hekla 's south-south-west and north-east slopes.
1980: On the 17th of August Helka started erupting explosively first from the summit area and then spead along the whole 4.3 mile (7 km) fissure. The eruption column of steam and then dark tephra reached an altitude of over 49,000 ft.(15 km). The maximum tephra thinkness for this eruption was reported ~6 miles (10 km) north of the summit with a depth of 8 inches (20 cm). The fluorine content in the tephra was high enough to cause heath problems with livestock. Lava started to flowing from the summit of Helka and continued along the length of the fissure, all together forming four seperate flows. The largest amount of lava was erupted within the first twelve hours and and by August 20th the only activity left was eruptions of steam.
1981:The event that occurred on April 9th started out with explosive eruptions of ash, some columns extended as high as 21,648 ft. (6.6 km) above sea level. Shortly after the explosive events lava began flowing from a new crater that had been formed at Helka's summit. Three main flows originated here, the largest two flowed down Helka's northern slope and the smaller down its southern face. This eruption is thought to be a continuation of Helka's 1980 eruption.
1991: On January 17th Helka violently erupted with a cloud of ash and tephra that reached an altitude of 39,360 ft. (12 km). During this eruption a summit fissure and a main crater were created and from these lava flows extended down the southeastern and northwestern slopes. Lava fountains in these craters reached a height of 984 ft. (300m). This eruption continued until March 11th when activity once again died down.
Sources of Information:
Bahn,Paul G. 1993,Volcanoes: Fire from the Earth, Harry N.Abrams, Inc.,
New York
Bullard, F. M. 1976, Volcanoes of the Earth, Univ. of Texas
Gronvold,K. 1994, Bullitin of Volcanic Eruptions No.31: Annual report of the world volcanic eruptions in 1991, Volc. Society of Japan , Tokyo
Jakobsson, Sveinn P. 1979, Acta Naturalia Islandica #26: Petrology of Recent basalts of the Eastern Volcanic Zone, Iceland, Icelandic Museum of Natural History, Reykjavik p.18
McClelland, L.;T.Simkin, M. Summers, E. Nielsen, T.C. Stein; eds. 1989 Global Volcanism 1975-1985, Prentice-Hall, Inc. New Jersey
Thorarinsson, Sigurdur 1970, Hekla: A Notorious Volcano, Almenna Bokafelagid, Reykjavik
1 comment:
...probably the volcano explode about 18 April ...
Regards merti
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