Watch Sicily's Mount Etna Erupt in This Timelapse Video
BY Kirstin Fawcett
December 9, 2015
Last week, Sicily’s Mount Etna violently erupted after two years of dormancy. For nearly an hour, Europe’s tallest active volcano shot flames, lava, and ash into the sky as it experienced its strongest eruption in nearly two decades. The geological phenomenon also triggered a spectacular show of rare volcanic lightning, which, as Slate’s Eric Holthaus explains, was caused by ash particles rubbing together to create electrical charges. No one was harmed by the spectacle—and now, you can safely witness the stunning natural show in full via this timelapse video released by Barcroft TV.
UK engineers have discovered evidence of a prehistoric coastline just outside London while preparing for a new high-speed railway, The Guardian reports.
The UK government has been analyzing the ground at the proposed locations for the railway, HS2, since 2015. Engineers are using radar, taking core samples, and digging pits before Phase 1 of construction. While evaluating the site of a future tunnel, geologists found signs that the site in the West London area of Ruislip was once a coastal marsh. Almost 110 feet under the ground, they discovered black clay they believe was formed from wooded swampland on the coast of a subtropical sea.
The unusually well-preserved layer of clay, which features traces of vegetation, dates back to around 56 million years ago, when Great Britain was partially covered by a warm sea. Less than 200 feet away from where the black clay was discovered, the layer of earth at the same depth is made of sand and gravel, likely deposited by the sea.
"Although ground investigations regularly take place across the country, it's really exciting and very unusual to come across a material that no one has ever seen before," geological expert Jacqueline Skipper said in a press release from HS2. "The 'Ruislip Bed' discovery is particularly fascinating, as it is a window into our geological history." While researchers knew that much of England was underwater during this period, this evidence helps them pinpoint exactly where that sea began.
Researchers at the Alaska Volcano Observatory in Anchorage have managed to record the sound of volcanic thunder for the first time, Smithsonian magazine and The Guardian report. It's extremely difficult to differentiate the sound of thunder from the sounds of the eruption itself, which has made conclusively identifying the sonic phenomenon on tape impossible until now.
"It's something that people who've been at eruptions have certainly seen and heard before, but this is the first time we've definitively caught it and identified it in scientific data," Alaska Volcano Observatory seismologist Matt Haney explained in a press release. He and his colleagues published their observations in the journal Geophysical Research Letters.
Using a microphone array almost 40 miles away, Haney's team picked up the sounds of volcanic thunder in March and June 2017 in the midst of two explosive eruptions of the Bogoslof volcano, a mostly submarine volcano in Alaska's Aleutian Islands. (Only about 300 feet of the approximately 6000-foot-tall volcano is above sea level.) The eruptions resulted in huge plumes of ash, a prime environment for volcanic lightning to occur. The volcano continued to generate ash plumes long after the eruptions ended, so the researchers could compare the post-eruption lightning with the timing and volume of the sounds they picked up on the microphones, and positively identified the volcanic thunder. They found that the intensity of the lightning was about the same as the intensity of the thunder's noise.
The technique could allow scientists to study volcanic lightning more easily by using the sound of thunder as an approximation, which may indicate how big the ash plume could grow. That information could reveal dangers for nearby aircraft.
You can hear the thunder for yourself in the audio tracks below. The recordings are sped up, and the thunder sounds clicks and pops. The whirring sounds in the first recording are the eruptions themselves.