Dome_Seicho_1 (English)

3 - 9

Growth and collapse of lava dome
(Period 1)

The lava dome

collapsed partially

in the process of

its growth, and caused

many times of

pyroclastic flows.

	The first lava dome a day after the emergence 60m in diameter. The eastern edge of the Jigokuato crater is on the right. (21 May 1991)	Ash cloud of the large-scale pyroclastic flow on 3 June Occurred at 16:08. Speed was about 130 km/hour. Hit the Kamikoba area in 2 minutes. (taken by Dr. Ono, Kyoto Univ.)

	The lava dome just after the pyroclastic flow on 3 June At the ruin of collapse of the dome has already come up new lava. Left is the east. (4 Jun. 1991)	The whole view of the Kamikoba area, the Shimabara City just after the hit by the pyroclastic flow on 3 June The pyroclastic flow itself descended for 3.5 km. Its ash-cloud surge hit 700 m further. (4 Jun. 1991)

	The fixed point just after the large-scale pyroclastic flow on 3 June Press reporters were used to take pictures at this point located inside the area from which residents were advised to evacuate. Trees and houses were completely destroyed. (4 Jun. 1991)	Cars burned by the pyroclastic flow on 4 June These were blown off by ash-cloud surge due to the pyroclastic flow. (5 Jun. 1991)

The second large-scale pyroclastic flow occurred on 8 June 1991.

	Lobe #2-A just before the collapse in large scale Half a day later, collapse of this lobe caused a large-scale pyroclastic flow. (8 Jun. 1991)	Explosive eruption Because the exit of the magma conduit was opened after the collapse of the lobe, the magma was bubbled and blew off bombs. (20:10 on 8 June 1991; taken by K. Nishikawa, the Shimabara City)

	Kamikoba, Shiratani and Tenjinmoto areas in the Shimabara City just after the pyroclastic flow on 8 June (9 Jun. 1991)	Around the front of the pyroclastic flow on 8 June It descended down along the Mizunashi River and reached 5.5km far from the crater. This is 30m before the Rout 57. (9 Jun. 1991)

	View of lava domes from the northeast side The lobe #2 grown on the eastern flank (left: about 450m in length) and the lobe #3 on the top of the summit (about 250m in diameter). (19 Aug. 1991)	View of lava domes from the south The lobe #3 (upper) grew over on the top of the lobe #2 (lower). (24 Aug. 1991)

On 15 Sep. 1991,

the third large-scale pyroclastic flow

ran down detouring

Oshigatani Valley, and

moved along the Mizunashi River.

The glowing cloud

rushed straight

from the mouth of

the Oshigatani Valley

and climbed up the southern cliff

of the Mizunashi R.

to hit the Onokoba area

in the Fukae Town.

	Lobe #3 just before the large-scale collapse The exit of the conduit for the lobe #3 moved to the northeast side. (15 Sep. 1991)	Lobe #3 just after the large-scale collapse The ruin of the big collapse at 18:54 on 15 Sep. 1991. Left is the lobe #2. (16 Sep. 1991)

	The area suffered by the large-scale pyroclastic flow on 15 Sep. The main flow ran along the Mizunashi R. but the ash cloud rushed straight to hit the Onokoba Area, Fukae Town. (22 Sep. 1991)	Around Onokoba Elementary School burned by the large pyroclastic flow (17 Sep. 1991)

	Northeast view of domes Somewhat old Dome #4 is on your side. Left is Dome #6 on growing. (10 Mar. 1992)	Northeast view of the summit of Mt. Fugen You can find old domes formed inside basin-like Myoken Caldera. New domes have grown on the east flank. On your side you can see Furuyake lava as well. (24 Aug. 1991)