REYKJAVIK, Aug. 24 (Xinhua) -- Iceland announced Sunday it moved the aviation color-code from red back to orange as the reported small sub-glacial eruption did not occur yesterday, according to the Icelandic Meteorological Office (IMO).
Observations showed that a sub-glacial eruption under Dyngjujokull glacier did not occur yesterday. The intense low-frequency seismic signal observed yesterday had other explanations, said the IMO, adding it has degraded the aviation color-code to orange.
The IMO said, the activity under Dyngjujokull has propagated northwards and was now mostly under the edge of the glacier, where an earthquake of 4.2 magnitude was recorded on Sunday morning.
The dyke under Dyngjujokull was now estimated to be approximately 30 km long. There were no indications that the activity was slowing down, and therefore an eruption could not be excluded.
Earthquake activity in northwestern Vatnajokull glacier was still very strong, about 700 earthquakes have been observed since midnight. Some of them were larger than previous days, including a 5.3 magnitude earthquake occurred at Bardarbunga volcano caldera at 0009 GMT on Sunday.
Another large earthquake of magnitude 5.1, originated at the southern rim of the Bardarbunga caldera, occurred at 0533 GMT.
The IMO said earthquakes near the Bardarbunga caldera were a consequence of adjustment to changes in pressure because of the flow of magma from under the caldera into the dyke which stretched to Dyngjujokull, more than 25 km away. But no signs of tremor or indicative of eruption were detected during the night.
The IMO on Saturday raised the aviation color code from orange to red as a small sub-glacial lava-eruption has been detected beneath the Dyngjujokull near Bardarbunga volcano, and ordered a no-fly zone over the site.