My experiments with volcanoes

by Thomas Augustus Jaggar

I returned to my Hawaii headquarters in the fall of 1928. The year 1929 was marked by an earthquake crisis which began in mid-September with an unusual number of shocks in the vicinity of Hualalai Volcano, a place hitherto notably free from earthquakes. This was of interest because events on Mauna Loa had shown higher and higher lava sources and quake centers for the south rift. The 1926 outflow had begun by splitting northward across the summit crater, and there making a considerable flow eastward toward Wood Valley while Wingate and his topographic party were in camp close to the summit. Therefore, when the 1929 quakes began near Puuwaawaa, it looked as though Mauna Loa eruptions might begin again at the northwest.

A very strong quake of September 25 was felt all over the island, and in our seismograph cellar was a peculiar swaying movement that set all the instruments jiggling, dismantled recording pens, and produced a queer feeling that the building was floating like a boat in a whirlpool. Immediately came word that North Kona had suffered heavily, particularly at Puuwaawaa Ranch near the cone of that name, where the 1859 Mauna Loa flow had swept past.

I motored at once with Mrs. Jaggar to Puuwaawaa, where we were hospitably entertained by the family of Mrs. Robert Hind. The damage all about was fantastic, with houses pulled apart, stone walls flung down in a seaward direction, redwood water tanks wrecked, and shops on the lower side of the highway moved toward the sea leaving a chasm between them and the road. Resting in our bedroom, we could hear the window frames ticking like clocks for long periods of time, then coming to a sudden wrench which felt as though a lifting wave had passed through the mountain under us.

I returned to the Observatory to get a shock recorder for use at the ranch porch to count these strong motion shocks. Meanwhile residents in Kona jotted down times of the shocks, which were coming by hundreds. On October 5 at about 6 P.M., as I was returning through North Kona in my car, I noticed a little unexplained excitement among people by the roadside. I stopped at the residence of Frank Greenwell, whose wife was a faithful counter of quakes, to find Mrs. Greenwell and her daughter on the veranda in tears. They had just been through fearful earthquakes, which in a moving car I had not felt. Flower vases were overturned, furniture was disarranged, dishes were flung off the dining room table, and kitchen utensils and milk were in a jumble. It was hard to believe that anything so terrific could have happened without my feeling it.

I found even more dire catastrophe at Puuwaawaa. The stone chimney was overturned, breakage of china and of glass in the preserve closet in the basement was severe, a stone bench was flung down and broken on the lawn, and one side of the cellar was caved in. We took to living in automobiles, for there had been land slips on the mountain. This earthquake had been worse than that of September 25. Even hillside cottages were split apart.

I set up the shock recorder, which registered about 3,000 earthquakes during the next three months, until mid-December. The intensity and frequency of these quakes declined, as is usual with aftershocks of a big earthquake, recalling 1868 and the south end of the island. At that time both Mauna Loa and Kilauea had had rift outflows, and as the seismographic center of the new earthquakes was close to the 1800 and 1859 flows from Hualalai and Mauna Loa, everybody expected a lava flow; but none came. Armine von Tempski who was a visitor during this period was inspired to write “Lava.” She added a Hualalai lava flow using material that I gave her to describe it. Her description is magnificent although she, herself, had never seen a lava flow.

The October 5 shock was bad on the west flank of Mauna Kea, where water tanks were overturned and the high wireless station was damaged, and at Kamuela, where plumbing pipes were fractured. Parker Ranch was damaged, and the constant racking along the entire length of the Kona settlements caused land slips and broken masonry in many places, always damaging north-south stone fences more than those at right angles to the seashore.

This three months of northwest earthquakes, a condition unknown since 1801, the year when Hualalai lava flowed into the sea, indicated that lava was coming north of Mauna Loa. This had not happened since 1899, for the flows on the southwest rift, always beginning near the summit crater, had been during 1903, 1907, 1914, 1916, 1919, and 1926.

Belief was that the southwestern rift of the mountain was filling progressively higher with solidified redhot cement, not brittle enough to fracture open easily, whereas the northern rifts—such as the sources of 1859, 1881, and 1899—were now hard and brittle and ready for fracture. The fracturing took the form of northwest cracking and this was lava wedging, confirmed by the summit and northern outflows which were to come in 1933 and 1935.

July of 1929 produced a new influx of lava into Halemaumau, nineteen degrees north of the equator. And a curiously simultaneous event occurred on nearly the same date 2,000 miles away at Tin Can Island (Niuafoou) in Tonga where the influx broke into basaltic eruption fifteen degrees south of the equator. Apparently a stress lagging behind the solstice time had acted on the equatorial protuberance to release the wedging open of lava fractures on both sides of the equator.