A July report from the Korea Institute of Geoscience and Mineral Resources (KIGAM) surprised volcanologists by dating Jeju’s most recent volcanic eruption to 5,000 years ago. Media outlets gleefully reported Mt. Hallasan was not dead, or dormant, but alive.
The research team, led by Jin-yeong Lee, radiocarbon dated carbonised wood (charcoal) below the basalt layer at Sangchang-ri, Seogwipo City, to 5,000 years old. This was 2,000 years more recent than the 7,000-year-old eruption at Mt. Songaksan, thought to be Jeju’s last volcanic activity.
Scientists had speculated that the basalt layer at Sangchang-ri was formed 35,000 years ago, yet the carbonised wood was below the basalt, making the rock at least as young as the ancient trees. Sangchang-ri was thus confirmed as the site of the most recent volcanic activity in South Korea. (The title of most active volcano on the peninsula goes to Mt. Baekdusan in North Korea, which last erupted in 1903.)
The findings were picked up by media outlets and headlines stated that Mt. Hallasan was “alive” and not dead, a fact already known as the earlier Songaksan activity was already within the same Smithsonian Institute’s Global Volcanism Program (GVP) 10,000 year timeframe for active volcanoes. Nevertheless, the Science Daily headline, “Jeju Island, Korea is a live volcano,” typified the reaction. [Cheju Weekly]
Here is an interesting historical account from the article:
While scientific evidence of volcanism on Jeju Island is proving difficult to confirm, one piece of historic evidence suggests that the island was active much more recently than 5,000 years ago. The “Dongguk Yeoji Seungram,” a Joseon Dynasty geography textbook (multiple volumes published between 1481 and 1530) includes this seemingly eye-witness account.
“In June 1002 CE, a mountain arose in the middle of the sea. There were four giant holes at the top of the mountain, out of which red liquid flowed and soared, and thick smoke plumed for five days. All the red liquid hardened and became stone like roof tiles.”
There has been some pretty dramatic images coming out of Japan from the eruption of Mt. Ontake in Japan in recent days and now the US military is warning servicemembers stationed at Yokota Airbase to take precautions in case the ash falls on the base:
Military officials are warning personnel at Yokota Air Base, the headquarters of U.S. Forces Japan, to be prepared for ash fallout from an erupting volcano.
Central Japan’s Mount Ontake erupted shortly before noon Saturday, stunning more than 200 hikers who were on the popular 10,062-foot peak at the time. At least seven are listed as missing and another 40 people were injured.
The eruption spewed large white plumes of ash high into the sky. Two Jetstar flights headed to Tokyo’s Narita International Airport diverted to Kansai International Airport in western Japan as a precaution, The Associated Press reported.
Yokota resdents were advised Saturday by base officials to remain indoors with pets to avoid breathing any ash that might fall.
They also were told to minimize vehicle use during periods of heavy ash fall because of reduced visibility and potential damage to air intakes. People should wear protective equipment when handling and cleaning ash fallout, officials said.
By Sunday afternoon, no ash appeared to have fallen on the base, and a number of people were outside on a warm and sunny fall day. There also was no immediate impact on Naval Air Facility Atsugi, Yokosuka Naval Base, Misawa Air Base or 7th Fleet installations, Navy officials said shortly after the eruption. (Stars & Stripes)
