By close cooperation with the U.S. Coast and Geodetic Survey we placed a tide gauge at Hilo, both for a sea level base and to record tidal waves. Wilson also, in 1921, ran a level line from Hilo to the Volcano House benchmark, where the Geological Survey had run levels in 1911. The county roadway was marked with bronze plates inscribed with leveling heights, and Wilson’s results showed the edge of Kilauea Crater to be three feet higher in 1921 than it had been in 1911.
Wilson’s determination of heights above sea level certified that the whole mountain swelled up during the ten years prior to 1921. About 1918, lava and seismographs had proved rising overflow at the center, while the edge of Kilauea Crater was being tilted away from the center. This went on during the massive rising of the interior lava of Halemaumau into a dome where the pit had been, and it proved that Kilauea Mountain was being injected along cracks, not only under the pit, but along the rifts, as indicated by outflow on the southwest and east in the years 1920 and 1924.
But this was not all of Wilson’s work. He revisited all surveying stations after the big collapse of Halemaumau that accompanied the explosive eruption of May 1924, and found that the Volcano House benchmark lowered a little more than three feet during May 1924 and that places close to Halemaumau dropped nearly fifteen feet. This lowering of the mountain was graduated outward twenty miles from the center at trig stations, or concrete posts, in the Kau Desert and at stations along the road to Hilo. These stations changed altitude to show that the big mountain tumefied or swelled up to that distance of twenty miles during the big intrusion of cracks at the overflowing time, as though the mountain dome were a tumor forty miles in diameter with Halemaumau at the center. Of course there is no certainty that the shore line in Puna, or even the Hilo tide gauge itself, did not go down with the slumping of the mountain, for the thing called sea level is nothing but an average of tide gauge readings at a fixed wharf. Remember that the east point of Hawaii sank eight feet on the Kilauea rift during the April crisis.
Wilson also surveyed by horizontal triangulation in 1921, determining that stations around Halemaumau had moved inward toward the center, by a specified number of feet, different at each station, and that other stations outside of Kilauea Crater had changed position horizontally on the map, as though the mountain were shrinking. This entire series of measurements of change between 1911 and 1926 jibed with the seismograph’s measurements of the tilting of the ground. The seismograph picked out 1918, when Halemaumau overflowed, as the swelling year. In 1924 the tilt reversed itself, turning inward toward Halemaumau, and became tremendous when the pit collapsed and exploded.
It is impossible to accent sufficiently the importance of the discovery of a measured swelling and slumping of a volcano throughout a lava crisis occupying fifteen years. It was so tremendous that critical engineers in Washington refused to believe Wilson’s results. However, his findings were verified by the contemporaneous lava measurement results, earthquake enumerations, and tilt meter results. These showed that earthquake frequency increased when Kilauea slumped and that a lava mountain had swelled until it was three feet higher at the summit in ten years and had contracted by a larger amount during the years of an explosive eruption period immediately thereafter. This all agrees with the excellent results in Omori’s volcanic and seismic events, obtained by Japanese army and navy engineers at several volcanoes and earthquakes. It also agrees with the positive facts of Vesuvius and the Canary Islands, starting with the controversy about “elevation craters” started by Leopold von Buch in the first half of the nineteenth century and carried forward by Mercalli on Vesuvius in 1894 when a lava hill was seen to swell up. There, too, others would not believe. The opposition always insisted that a volcano was built by heaped material, that it could not possibly swell.
Wilson’s results are far-reaching, for the whole of geology depends on uplift of continents and downsinking of sedimentary basins. Most geologists account for these things by the theory of weighting and underflow at a thin crust (isostasy), refusing to grant that volcanic heat and tumefaction yield intrusive power everywhere through cracks in the deeper crust.
I wish that I could describe adequately the high adventure of this fruitful time. We built a vehicle from a model T Ford with a Ruckstell axle, stripped of mudguards and equipped with balloon tires doubled at the rear, so as to travel and carry loads over the smooth pahoehoe of the Kilauea floor. We found that a powerful light rig of this type, with excessively low gear, could climb up on lava lobes one to two feet high. But this called for experienced driving and special methods. Sending a man on foot ahead to pick a way and to drag a crowbar which scratched a track, we could drive anywhere on the lava. And we used this rig to haul drums of water and drill apparatus. I once drove artillery officers out over the rough floor of the crater, and afterwards saw similar cars used by the army in the first World War as cross-country transportation for the doctors and wounded in No Man’s Land.
Before a roadway encircled Kilauea Crater, Mr. Finch and I, carrying two-inch planks for bridging cracks, made the complete circuit of the crater by way of the rifted Kau Desert in our special vehicle, which has now been succeeded by the jeep, the most universal vehicle of World War II. Volcanology prospected the field of war in more ways than one, so I named my popular book “Volcanoes declare war.”
Inventions led to expeditions both in Hawaii and in distant lands during the decade of the twenties, some by invitation, some to offer assistance at disasters, and some for the natural extension of my own work. On September 1, 1923, came the big earthquake at Tokyo. With Mrs. Jaggar, I was permitted to land in Japan and make a study of the effects of the disaster. The destruction of Tokyo and Yokohama was a final, sad tragedy for Omori, who for years had worked to protect the Emperor and Japan by studying earthquake forecasts for Tokyo and by conducting research in earthquake-proof engineering. It was a cruel commentary that the disaster came while he was attending a science congress in Australia, particularly as the great destruction of life was occasioned by fire and typhoon winds. But Omori’s organization handled the seismic event admirably. Omori returned at once, but almost immediately died.
We steamed into Yokohama harbor, were welcomed by Captain Gatesford Lincoln U. S. N. and his destroyer flotilla. We went on board his flagship, and were sent in his launch to the broken jetties of Yokohama, where we found no custom house or police. We walked up to the camp of United States marines, amid the wreckage of the United States Consulate, where the Consul had been killed.