Volcano news: Poás volcano, Costa Rica
Poas volcano (Costa Rica): phreatic eruption on 23 Jan 10
Our correspondant in Costa Rica reports a beautiful phreatic eruption at Poas volcano today at noon time. This is the second eruption (after the one on 25 Dec 09) in a short time span.
On 1 April, scientists visited Poás volcano and confirmed that Laguna Caliente at the volcano's summit had widened, and that sediments and blocks fromthe lake's bottom and surrounding walls were ejected during the explosions on 24-26 March 2006. The lava dome's (or pyroclastic cone's) N wall was greatly fractured and a 40 x 7 x8 m segment of the wall was gone. In addition, a 40 x 4 x 6 m chunk of the SE wall of the lake was missing and must have been destroyed during the explosions. They also found that the lake was light gray due to large quantities of suspended sediments, had a temperature of 54 degrees Celsius, had a pH of 0.63, and the lake level had decreased in comparison to the level before the explosions.[more]
Seismicity decreased at Poás volcano by 27 March, 2006. Harmonic tremor that was recorded during the recent heightened activity ceased. As of the 27th, no significant deformation was recorded at the volcano and abundant evaporation continued at Caliente Lake.
Small phreatic eruptions began at Poás on 24 March 2006. The eruptions originated from the bottom of the volcano's Caliente Lake. Witnesses described a sudden emission of water and sediments S of the lake. Roaring was heard in a nearby tourist area and weak earthquakes were felt.
OVSICORI-UNA visited the E side of the volcano on 25 March and confirmed that water, blocks, and sediments from the bottom of the lake had been ejected.Several dozens of impact craters were seen with diameters between 15 and 60 cm, extending E as far as 700 m. Blocks were found that ranged in diameter from a few to 50 cm wide. During 22-27 March, harmonic tremor was recorded. On the 27th, there was a reduction in seismicity and it returned to normal levels. No deformation was measured at the volcano. A news article reported that the area around the volcano was closed to visitors.
Poás volcano erupted after 12 years of dormancy with two small steam and ash eruptions on 25th of March 2006 from the crater lake known as Laguna Calients. Authorities consider closing the easy-to-access crater rim to the public.[more]