* Tremors shake Iceland as volcano spews more ash into sky
* Ash column above volcano now lower at a height of 4-5 km
* Farmers, livestock moved indoors as ash falls
* Icelandic airlines now running flights to Norway
(Adds quotes from President, AccuWeather, more detail)
By Omar Valdimarsson
REYKJAVIK, April 18 (Reuters) - Powerful tremors from an Icelandic volcano that has been a menace for travellers across Europe shook the countryside on Sunday as eruptions hurled a steady stream of ash into the sky.
Ash from the volcano drifted southeast towards the European continent, sparing the capital Reykjavik and other more populated centres but forcing farmers and their livestock indoors as a blanket of ash fell on the surrounding areas.
"We are all doing our utmost to make sure that the farming community in this area survives this disaster," Icelandic President Olafur Grimsson told Reuters Television.
He said it was difficult to assess the impact on tourism in the country, which is only just emerging from a deep recession, but that recent events had put Iceland in the spotlight and that the country might even lure in more visitors.
"What we are experiencing here in Iceland is forces of nature on display... And that is a spectacle -- the combination of volcanic eruption and glaciers you cannot see anywhere else in the world," he said.
Iceland's Meterological Office said tremors from the volcano had grown more intense but that the column of ash rising from the volcano had eased back to 4-5 km (2.5-3 miles) from as high as 11 km when it started erupting earlier this week....MORE
From The Christian Science Monitor:
Every time in recorded history that Eyjafjallajökull volcano has erupted, the much larger Katla volcano has also erupted. Scientists are watching Katla carefully.
This history of Iceland will not make for comforting reading for thousands of would-be air travelers stranded across northern Europe and beyond.
The last time Eyjafjallajökull erupted, it continued belching the Earth's unsettled insides for 14 months, from December 1821 to January 1823.
Scientists do not expect Eyjafjallajökull to keep northern Europe's airports closed for 14 months, but they suggest that Eyjafjallajökull's impact on world travel might not end with the end of this current eruption.
Moreover, Iceland's "Angry Sister" hasn't even awoken yet. The three times in recorded history when Eyjafjallajökull has erupted, its neighbor, the much larger Katla, has followed suit.
Data do not yet suggest that a Katla eruption is imminent. Yet, in some respects, it is the far greater concern, both in Iceland and beyond.
Katla: the sleeping sister
Katla has erupted 16 times since 930, in 1755 exploding so violently that its ash settled on parts of Scotland. In 1918, Katla tore chunks of ice the size of houses from the Myrdalsjökull glacier atop it, sending them careening down its slopes and into the Atlantic on floods of melted glacier water.
While Eyjafjallavökull is virtually anonymous in Icelandic lore, Katla is one of the "Angry Sisters" along its even-more active twin, Hekla.
The 1918 eruption was the last major eruption of Katla – a volcano that has erupted twice a century, on average – which is why scientists have paid particularly close attention to it in recent days.
But while earth beneath Eyjafjallajökull trembled with thousands of small earthquakes in the months before the eruption – signaling that magma was welling up beneath the volcano – scientists have not seen the same activity at Katla yet....MORE
Spectacular: Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul (More via the Daily Mail)