We turn from the dying flutter of California’s last remaining active volcano to the excessive violence of a volcano in the extremely active Alaskan coast range. The Mount Katmai National Monument will have few visitors because it is inaccessible by anything less than an exploring-party. We know it principally from the reports of four expeditions by the National Geographic Society. Informed by these reports, President Wilson created it a national monument in 1918.
A remarkable volcanic belt begins in southern Alaska at the head of Cook Inlet, and follows the coast in a broad southwesterly curve fifteen hundred miles long through the Alaskan Peninsula to the end of the Aleutian Islands, nearly enclosing Bering Sea. It is very ancient. Its mainland segment contains a dozen peaks, which are classed as active or latent, and its island segment many other volcanoes. St. Augustine’s eruption in 1883 was one of extreme violence. Kugak was active in 1889. Veniaminof’s eruption in 1892 ranked with St. Augustine’s. Redoubt erupted in 1902, and Katmai, with excessive violence, in June, 1912. The entire belt is alive with volcanic excitement. Pavlof, at the peninsula’s end, has been steaming for years, and several others are under expectant scientific observation. Katmai may be outdone at any time.
Katmai is a peak of 6,970 feet altitude, on treacherous Shelikof Strait, opposite Kodiak Island. It rises from an inhospitable shore far from steamer routes or other recognized lines of travel. Until it announced itself with a roar which was heard at Juneau, seven hundred and fifty miles away, its very existence was probably unknown except to a few prospectors, fisher-men, geographers, and geologists. Earthquakes followed the blast, then followed night of smoke and dust. Darkness lasted sixty hours at Kodiak, a hundred miles away. Dust fell as far as Ketchikan, nine hundred miles away. Fumes were borne on the wind as far as Vancouver Island, fifteen hundred miles away. Weather Bureau reports noted haziness as far away as Virginia during succeeding weeks, and the extraordinary haziness in Europe during the following summer is noted by Doctor C. S. Abbott, Director of the Astrophysical TObservatory of the Smithsonian Institution, in connection with this eruption.
Nevertheless, Katmai’s is by no means the greatest volcanic eruption. Katmai’s output of ash was about five cubic miles. Several eruptions have greatly exceeded that in bulk, notably that of Tomboro, in the island of Sumbawa, near Java, in 1815, when more than twenty-eight cubic miles of ash were flung to the winds. Comparison with many great eruptions whose output was principally lava is of course impossible.
The scene of this explosion is the national monument of today. The hollowed shell of Katmai’s summit is a spectacle of wonderment and grandeur. Robert F. Griggs, who headed the expeditions which explored it, states that the area of the crater is 8.4 square miles, measured along the highest point of the rim. The abyss is 2.6 miles long, 7.6 miles in circumference, and 4.2 square miles in area. A lake has formed within it which is 1.4 miles long and nine-tenths of a mile wide. Its depth is unknown. The precipice from the lake to the highest point of the rim measures thirty-seven hundred feet.
The most interesting exhibit of the Katmai National Monument, however, is a group of neighboring valleys just across the western divide, the principal one of which Mr. Griggs, with picturesque inaccuracy, named the “Valley of Ten Thousand Smokes”; for, from its floor and sides and the floors and sides of smaller tributary valleys, superheated steam issues in thousands of hissing columns. It is an appalling spectacle. The temperatures of this steam are extremely high; Griggs reports one instance of 432 degrees Centigrade, which would equal 948 degrees Fahrenheit; in some vents he found a higher temperature at the surface than a few feet down its throat. The very ground is hot.
This phenomenal valley is not to be fully explained offhand; as Griggs says, there are many problems to work out. The steam vents appear to be very recent. They did not exist when Spurr crossed the valley in 1898, and Martin heard nothing of them when he was in the near neighborhood in 1903 and 1904. The same volcanic impulse which found its main relief in the ex-plosive eruption of near-by Katmai in 1912 no doubt cracked the deep-lying rocks beneath this group of valleys, exposing super-heated rocks to subterranean waters which forthwith turned to steam and forced these vents for escape. Griggs reports that volcanic gases mingle freely with the steam.
The waters may have one or more of several sources; perhaps they come from deep springs originating in surface snows and rains; perhaps they seep in from the sea. Whatever their origin the region especially interests us as a probably early stage of phenomena whose later stages find conspicuous examples in several of our national parks. Some day, with the cooling of the region, this may become the valley of ten thousand hot springs.
But it is useful and within scientific probability to carry this conception much further. The comparison between Katmai’s steaming valleys and the geyser basin of Yellowstone is especially instructive because Yellowstone’s basins doubtless once were what Katmai’s steaming valleys are now. The “Valley of Ten Thousand Smokes” may well be a coming geyser-field of enormous size. The explanation is simple. Bunsen’s geyser theory, now generally accepted, presupposes a column of water filling the geyser vent above a deep rocky superheated chamber, in which entering water is being rapidly turned into steam. When this steam becomes plentiful enough and sufficiently compressed to overcome the weight of the water in the vent, it suddenly expands and hurls the water out. That is what makes the geyser play.
Now one difference between the Yellowstone geyser-fields and Katmai’s steaming valleys is just a difference in temperature. The entire depth of earth under these valleys is heated far above boiling-point, so that it is not possible for water to remain in the vents; it turns to steam as fast as it collects and rushes out at the top in continuous flow. But when enough thousands of centuries elapse for the rocks between the surface and the deep internal pockets to cool, the water will remain in many vents as water until, at regular intervals, enough steam gathers be-low to hurl it out. Then these valleys will become basins of geysers and hot springs like Yellowstone’s.