Indonesia Volcano Semeru Erupts Eight Times With 700-Meter Ash Column

Mount Semeru, an Indonesia volcano in East Java, erupted eight times on Tuesday morning and sent a white-to-gray ash column as high as 700 meters above the summit while remaining at Alert Level III. [1]

Semeru Eruption Sequence

The eruptions occurred at 4:39 a.m., 4:56 a.m., 5:16 a.m., 5:54 a.m., 6:30 a.m., 6:56 a.m., 7:37 a.m. and 8:23 a.m. local time. [1] The largest took place at 8:23 a.m. and produced a 700-meter ash plume that drifted southeast. [1] Seismic recordings showed a maximum amplitude of 19 mm and duration of 132 seconds for the first eruption. [1] The 8:23 a.m. event registered 13 mm amplitude and lasted 55 seconds. [1] Each plume was described as white-to-gray with moderate intensity. [1]

Seismic Data from Eruptions

The first eruption at 4:39 a.m. was recorded on a seismograph with a maximum amplitude of 19 mm and a duration of 132 seconds. [1] The 8:23 a.m. eruption produced a maximum seismic amplitude of 13 mm and lasted 55 seconds. [1] These measurements were reported by officer Dany Erlangga Yosa Putra at the Mount Semeru Observation Post. [1] The sequence demonstrated repeated explosive activity throughout the morning hours. [1]

Current Alert Status and Hazard Zones

Authorities maintain an Alert Level III status for the Indonesia volcano. [1] They prohibit activity within 13 km along the southeast sector of Besuk Kobokan River. [1] People must stay within 5 km of the crater due to falling rocks. [1] Residents are advised to remain at least 500 meters from riverbanks due to possible hot ash clouds and lava flows extending up to 17 km. [1] Residents must remain alert for hot clouds and lava flows along Besuk Kobokan, Besuk Bang, Besuk Kembar and Besuk Sat rivers. [1]

Mount Semeru in East Java erupts sending a 700-meter ash column southeast. — Source: gdelt

Merapi Activity Observations

Mount Merapi emitted one hot ash cloud avalanche traveling up to 2,000 meters toward Kali Sat/Putih. [2] Visual observation showed the volcano covered by fog rated 0-III with thick white crater smoke reaching about 300 meters from the peak. [2] Weather conditions included cloudy to overcast skies, calm winds toward the east, temperatures of 21.1-24.9°C, humidity of 77.8-85 percent and air pressure of 874.3-919.4 mmHg. [2] Seismic counts included 32 lava avalanches with amplitudes of 1-120 mm and durations of 32.93-164.37 seconds. [2] One hot ash cloud avalanche earthquake registered 66 mm amplitude and lasted 134.77 seconds. [2] Nine hybrid or multiphase earthquakes were recorded with amplitudes of 2-31 mm and durations of 11.88-35.78 seconds. [2] Three shallow volcanic earthquakes showed amplitudes of 2-7 mm and durations of 13.01-25.8 seconds. [2] Mount Merapi remains at Level III. [2]

Merapi Hazard Recommendations

Defined danger zones for lava avalanches and hot clouds exist on the southern and southwestern flanks along Sungai Boyong up to 5 km, and along Sungai Bedog, Krasak and Bebeng up to 7 km. [2] On the southeastern flank the zones cover Sungai Woro up to 3 km and Sungai Gendol up to 5 km. [2] Ballistic ejecta from any explosive eruption could reach a 3 km radius from the summit. [2] The public is urged not to conduct any activities inside these hazard zones. [2]

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Ongoing Monitoring and Advice

Data monitoring shows that magma supply continues at Mount Merapi and could trigger further hot ash cloud avalanches inside the hazard areas. [2] Residents are advised to stay vigilant for lahar and hot ash cloud dangers especially during rain around the volcano. [2] Activity levels will be reviewed again if significant changes occur. [2] For Mount Semeru the same Level III status continues with the listed river and crater restrictions remaining in force. [1] The combined observations from both volcanoes underscore the need for continued public caution in the affected river valleys. [1][2]

Public Vigilance Requirements

Communities near both the Indonesia volcano sites are reminded to avoid all prohibited zones and to monitor updates from official observation posts. [1][2] The restrictions on the southeast sector of Besuk Kobokan and the multiple rivers around Merapi remain the primary safety measures. [1][2] Authorities continue to stress that no activities should take place inside the defined danger radii. [2]

What to watch next: Continued magma supply at Mount Merapi may trigger additional hot ash cloud avalanches, while Mount Semeru stays at Alert Level III with the same river and crater restrictions in place.

Further Reading

• Live Earthquake Tracker
• Live Volcano Activity