STUDYING VOLCANOES

Dominion, Volume 14, Issue 61, 6 December 1920, Page 5

STUDYING VOLCANOES

IMPORTANT WORK IN HAWAII

DR. ALLAN THOMSON'S REPORT

Dr. J. Allan Thomson, Director of the dominion Museum, has returned from Honolulu, where he and Dr. Chilton (thnstchureh) represented New Zealand at tho Pan-Pacific Science Congress. He was able to,give much attention while •life lt V hestud y of volcanblogy. He m™iV l f. Jne ßar. and spent about a month studying- the methods employed SSL-r" «f S « Hth 6 d i ff « oat Manra N«' 7«i tl f 8 -'° u ? before Kerning to Aew Zealand via Samoa. Dr. Jaggar while on a visit to Now Zealand in May' upphed to the Government a report on the question of establishing an obsenatory and a Department of Volcanic Rh-

The crater of Kilauea, says Dr. Thomw!' i S a Srcat pit about three miles long by two miles wide, with walls jWMy 500 ft. high. The bottom is filled with recent lava flows, which have issued' tram « smaller pit, Halemaumhu ,' within the greater. This pit is of variable, uopth, and its bottom is occupied- bv. wags and lava lakes. Both crags and lakes rise and fall, generally very slowly, so that sometimes the pit is 600 ft. doep and sometimes has no depth at all, and the. lava then flows over the brim Jflto Kilauea. At the time of his visit the pit was about 250 ft. deep, and was sinking a few foot each week. There were then three lava lukes, and the lava was in constant motion. ' The largest lake was three-armed, and the lava flowed from a point on one side of tho three arms. A dark skin covered tho surface of the lava, but this continually cracked over the flow, and a constant succession of fiery hieroglyphic figures appeared.' Again, when the flow impigned on points on the pit-sides or on small islands, the lava rose in fountains six to ten feet high. It was nlways nec.essnry.ito. move to the windward sido of the nit, as the Btcnm and sulphur on the leeward sido were very irritating, besides obscuring the view. The scene was more- impresr sivo in its weirdness at night, when tho orange-red of tho cracks and fountains, was intensified and the steam and. sulphur clouds glowed violet red from tho reflection from tho lava flow. .

The rise and fall of the lava column have, been measured twico ( weekly • for lime years by Dr. Jaggar aiid liis assistants, and during that time records have been kept of the minor earthquakes, the "tilts," and micro-tremors, and it has been found'that the movements of, the lava column can bo corrected with tho very complex earth movements'duo. to the "solid tide'' upon the earth caused by the sun and moon and that the rises are always precededby a "tilting" at the, observatory about 18 days earlier. As the earth tides can be predicted, it has now become possible to predict the rise and fall of the lava column, and sudden rises can bo. predicted' 18 days ahead by tho "tilting." The eruption of Mauna-loa, s, neighbouring but much larger volcano, whose lava column is obviously in close connection with that of Kilauea, and a simultaneous eruption of Kilauea during last: year wero successfully predicted by Dr. Jaggar.

The areas covered by tho Hawaiian lara'flow are fortunately not at all closoly populated. • being- mostly given up to cattle ranching, but it can be won, 6nul Dr. Thomson, how important such predictions would be in a closely-populated area. The most successful case of prediction was that of the eruption of the volcano of Sakura-jivna, on an island of tho same name off the south-wfstern coast of Japan, in 1914, by Professor Omori, the chief earthquake authority- of Japan. Only two weeks' notice of "this eruption was given, but such was the confidence of the Japanese Government in Professor Omori's work'that all people were taken off the island and the. population of tho neighbouring coask voluntarily eniigrated. A' fortnight later the island blew practically to pieces,'but not a, single life was lost. New Zealand's volcano district extends from Ruapehu to Whito Island, and on that line tho disastrous Tnrawera eruption, tho eruptions of 'Waimangu and White .-.lsland and lesser disturbances, especially thoso of Ngauruhoe, all oecurrod. ' "Groat volcanic disturbances must toe anticipated in that bolt at long intervals," said Dr. Thomson, "and surely it is worth the serious consideration of the people of New Zealand whether a form of insurance should not be prepared in tho shape of a volcanic observatory, which, after a few years' study of conditions, could issue successful predictions both of the place and time of eruptions." •