Source: Volcano Discovery
Niigata-Yake-yama (Honshu): An increase in small earthquakes has been detected under the volcano located on the border between Niigata and Nagano Prefecture recently.
In addition, a slight increase in fumarolic activity on the eastern side of the summit crater was noted and some inflation of the volcanic edifice recorded.
According to the Niigata Meteorological Observatory monitoring the volcano, the number of volcanic earthquakes has been up to 4 times that of normal background levels, with up to 23 quakes recorded on a single day. Seismic activity has been dominated by low-frequency earthquakes, which are thought to reflect internal fluid movements (gasses, hot watery solutions, as well as magma).
While the observed unrest is far from at alarming levels, they might reflect a change in the internal hydrothermal and /or magma storage system and could (but not necessarily must) be precursors to new activity at the surface.
Cleveland (Aleutian Islands, Alaska): The Alaska Volcano Observatory (AVO) raised the alert level of the volcano from yellow to orange after a new explosion was detected that had occurred this morning (18:44 AKDT local time).
The size of the new eruption is unknown, but probably small; there are no direct observations of the remote volcano, but the explosion could be seen on both infrasound (air pressure) and seismic data.
“There are no recent satellite views since the detected explosion, but previous Cleveland explosions have typically produced ash emissions”, AVO wrote in its bulletin this morning.
Turrialba (Costa Rica): The volcano remains at elevated unrest and had a new small eruption yesterday noon (at 12:05 local time), producing ash emissions similar to those during the past weekend.
Alaid (Northern Kuriles): intense thermal signal from summit crater, strong degassing (updated 31 Mar 2016)
Ambrym (Vanuatu): active lava lakes in several craters (updated 18 Feb 2016)
Aso (central Kyushu, Japan): degassing, sporadic steam / ash explosions (updated 8 Mar 2016)
Batu Tara (Sunda Islands, Indonesia): strombolian explosions, ash plumes up to 500 m, extrusion of a small lava dome with rockfalls (updated 28 Nov 2015)
Chikurachki (Paramushir Island): new eruption since end of March 2016 (updated 31 Mar 2016)
Colima (Western Mexico): sporadic small explosions (updated 31 Mar 2016)
Copahue (Chile/Argentina): seismic unrest, occasional ash venting (updated 22 Mar 2016)
Dukono (Halmahera): mild strombolian activity, continuous intense ash emissions (updated 21 Mar 2016)
Erebus (Antarctica): active lava lake in summit crater (updated 8 Dec 2014)
Erta Ale (Danakil depression, Ethiopia): overflowing lava lake (updated 2 Mar 2016)
Fuego (Guatemala): lava flows on S and W flanks, lava fountaining from summit vent (updated 11 Apr 2016)
Ibu (Halmahera, Indonesia): stromolian and phreatomagmatic explosions (updated 29 Oct 2015)
Karymsky (Kamchatka): occasional small explosions, thermal anomaly (updated 1 Mar 2016)
Kilauea (Hawai’i): new lava flow from vents on NE flank of Pu’u ‘O’o (updated 28 Apr 2015)
Kliuchevskoi (Kamchatka): mild strombolian activity in summit crater (updated 7 Apr 2016)
Masaya (Nicaragua): active lava lake in summit crater since mid Dec 2015 (updated 3 Apr 2016)
Momotombo (Nicaragua): intermittent vulcanian explosions (updated 29 Mar 2016)
Nevado del Ruiz (Colombia): intermittent explosions, steaming, ash venting (updated 31 Mar 2016)
Nyiragongo (DRCongo): new vent on crater floor (updated 8 Mar 2016)
Ol Doinyo Lengai (Tanzania): effusion of natrocarbonatite lava inside the crater (updated 8 Jul 2013)
Pacaya (Guatemala): intense spattering from intra-crater cone (updated 29 Mar 2016)
Popocatépetl (Central Mexico): degassing, sporadic explosions, slowly growing lava dome (updated 4 Apr 2016)
Rabaul (Tavurvur) (New Britain, Papua New Guinea): lava fountains, ash emissions from Tavurvur cone (updated 12 Sep 2014)
Reventador (Ecuador): lava flow on SW flank (updated 24 Feb 2016)
Sakurajima (Kyushu, Japan): sporadic vulcanian explosions from Minamidake and Showa crater (updated 8 Apr 2016)
Sangay (Ecuador): small strombolian activity in summit crater (updated 4 Apr 2016)
Santiaguito (Guatemala): intermittent explosions from Caliente dome, strong degassing (updated 13 Apr 2016)
Semeru (East Java, Indonesia): growing lava dome, lava flow, strombolian activity (updated 14 Feb 2016)
Shiveluch (Kamchatka): growing lava dome (updated 31 Mar 2016)
Sinabung (Sumatra, Indonesia): continuing pyroclastic flows (updated 31 Mar 2016)
Stromboli (Eolian Islands, Italy): weak, intermittent strombolian explosions (updated 31 Mar 2016)
Suwanose-jima (Ryukyu Islands): strombolian explosions in Ontake crater (updated 11 Apr 2016)
Tungurahua (Ecuador): large and frequent explosions, ash columns rising several km (updated 9 Mar 2016)
Ubinas (Peru): sporadic vulcanian explosions (updated 16 Jan 2016)
Villarrica (Central Chile): lava lake in summit crater, spattering, strombolian explosions (updated 4 Apr 2016)
Yasur (Tanna Island, Vanuatu): ash emissions, weak strombolian explosions (updated 13 Nov 2015)
Zhupanovsky (Kamchatka, Russia): steaming / degassing (updated 31 Mar 2016)
More continued coverage and updates at Volcano Discovery: Volcanic Activity Worldwide 6 May 2016