Updates on volcanic activity (Smithsonian)
The Smithsonian/USGS Weekly Volcanic Activity Report provides information about global volcanism on a weekly basis. Latest Poas report has been published on 16 Apr 2025 07:56.
The Observatorio Vulcanol?gico y Sismol?gico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported ongoing inflation and frequent explosions at Po?s during 9-15 April. Sulfur dioxide emissions recorded by a mobile Differential Optical Absorption Spectroscopy (DOAS) instrument measured an average of 223 ? 210 tonnes per day (t/d) and a maximum flux of 5,524 ? 854 t/d on 9 April. Seismographs and infrasound sensors recorded volcanic tremor and acoustic signals. Gas-and-ash emissions typically rose 100-400 m above the crater.
At 2144 on 8 April a large phreatomagmatic event lasting 15-20 minutes produced an ash plume that rose 1.5 km above the crater and drifted SW. Blocks were ejected onto the crater floor. Frequent ash emissions rising less than 100 m above the crater continued following this event. The Washington VAAC reported that an ash plume rose 1.5 km above the crater and drifted S at 2350 on 8 April, based on webcam imagery. At 0738 on 9 April there was a transition to continuous ash emissions that rose 300 m above the crater and drifted W. Light ashfall and a sulfur odor was reported, along with damage to nearby vegetation and crops, on the middle and upper parts of the W flank near San Luis (11 km SW) and Trojas de Grecia. According to the Washington VAAC, at 0820 on 9 April an ash plume rose to 3 km (9,800 ft) a.s.l. and drifted W, based on webcam images.
During 1116 and 1126 on 11 April several short, intense, eruptive events were recorded. Residents of Po?s, Grecia (16 km SW), and Zarcero reported a sulfurous odor and symptoms that included headaches, nausea, sore throat, teary eyes, nasal drip, and allergies relating to the gas emissions and volcanic particles. During 12-13 April ash emissions and higher energy tremors and acoustic infrasound signals were recorded; the height of the ash emissions could not be determined due to cloudy weather conditions. On 12 April at 0710 the Washington VAAC reported a possible ash plume that rose to 3 km (9,800 ft) a.s.l. and drifted SW, though cloudy weather obscured clear views of the summit. The volcano?s Alert Level remained at 3 (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest color on a four-color scale).
Sources: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) ,Washington Volcanic Ash Advisory Center (VAAC)
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