Batu Tara (Sunda Islands, Indonesia): Explosions that produce ash plumes large enough to be spotted on satellite images occur almost daily now.
This could be merely an effect of better visibility due to currently better weather with less cloud cover, or indicate an increase of activity.
This morning, an ash plume was seen extending 25 nautical miles to the NE, at an estimated altitude of 7,000 ft (2.1 km).
Dukono (Halmahera): An explosion yesterday produced an ash plume rising to about 10,000 ft (3 km) altitude and drifting 25 nautical miles to the NE. (VAAC Darwin)
Mauna Loa (Big Island, Hawai’i): A small earthquake swarm occurred last week under the volcano. During 5-7 September, HVO detected about 350 small earthquakes up to magnitude 2.4 in a tightly clustered area at about 7 km depth west of the summit caldera. Only about 25 were strong enough to be located (map).
The swarm was in the same region where earthquakes began to occur a year or more before Mauna Loa’s 1975 and 1984 eruptions. A likely interpretation is that the most recent swarm is a sign that some magma has intruded at the base of the volcano.
It is certainly no sign of an impending eruption in the very near future, but suggests that Mauna Loa, which still is the world’s largest ACTIVE volcano, on the medium term, continues to prepare itself for its next eruption.
Arenal (Costa Rica): OVSICORI mentioned that rockfalls with rumbling noises have increased at the volcano over the past weeks. This could suggest that the volcano has started to wake up from its 3 years of slumber. – Volcano Discovery