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Dagelet to the Europeans,Ulleungdo is about
120 km (75 mi) east of the
Korean
Peninsula. Volcanic in origin, the rocky steep-sided island is the top of a
large
strato volcano
which rises from the seafloor,
reaching a maximum elevation of 984 meters (3,228 ft) at Seonginbong Peak.
The island consists primarily of
trachyande site
rock. A major explosive eruption about
9,350 years ago reached a
Volcanic Explosive Index
of
6 and deposited
tephra
as far as central
Honshū
over 800 km (500 mi) away,
while producing
pyroclastic flows
on the island and decapitating its top
to form a
caldera. The island is
11.3 kilometres (7.0 mi) in length and 12.4 kilometres (7.7 mi) in
width; it has an area of 73.15 km(28.24 sq mi) with about 10,000
inhabitants.
The island makes up the main part of Ulleung County, North Gyeongsang
