Geologic Background:
Yasur (or Yasour), the best-known and most
frequently visited of the Vanuatu volcanoes, has been in
more-or-less continuous strombolian and vulcanian
activity since Captain Cook observed ash eruptions in
1774. This style of activity may have continued for the
past 800 years. Yasur is a mostly unvegetated pyroclastic
cone with a nearly circular, 400-m-wide summit crater.
Yasur is largely contained within the small Yenkahe
caldera in SE Tanna Island. It is the youngest of a group
of Holocene volcanic centers constructed over the
down-dropped NE flank of the Pleistocene Tukosmeru
volcano. Active tectonism along the Yenkahe horst
accompanying eruptions of Yasur has raised Port
Resolution harbor more than 20 m during the past century.
Historic Activity:
- Continuous Strombolian and Vulcanian activity from
Yasur has been reported since before 1774, when ash
eruptions were observed by Captain Cook.
- Numerous small explosions hurl lava 20 to 200 meters
in the air.
Recent Activity:
- Volcanic activity, consists of block and ash
emissions, and bubbling lava lakes, was continuing in
August 1991.
- Volcanic activity continued at Yasur through 1992
with substantial gas emission and heavily ash-ladened
explosions.
- The very intense activity recorded throughout 1994
decreased in 1995, but returned to normal in November and
was continuing in July 1996.
- Continuing activity thru early 1998 then very low
level activity until May 1999 when activie
increased.
- Activity was continuing in Feb. 2000.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 11, No. 3 and V. 13,
No. 12)
- Global Volcanism Network (V. 15, No. 11 to V. 25, No.
4).
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