USGS Preliminary Analysis_LERZ_7-15-18_v1.1

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Appendix: Comparisons to other eruptions along the LERZ The ongoing LERZ eruption is occurring in a similar location to the 1840, 1955, and 1960 LERZ eruptions, as well as the location of intrusive activity in 1924. Discharge or effusion rates during the peak phases of the 1955 and 1960 eruptions are very similar to that occurring now. The onset of the current activity, with fissures opening both uprift and downrift from the initial outbreak, shifting back and forth amongst these fissures, and starting and stopping erratically, was similar to the 1955 and the 1960 eruptions, although the 1960 fissure system was considerably shorter so the effects of the eruption were more focused. The start of the current eruption prior to the continuous eruption of fissure 8 that started on May 27, resembles the opening of the 1955 eruption, but ramped up more slowly and was more chaotic. The current eruption has not produced high (>50 m?) fountains of 1955 and 1960 eruption, and instead has evolved into a relatively steady eruption at fissure 8 characterized by low fountaining and Strombolian activity that feeds a large -volume channelized flow. 1840 LERZ eruption: May 30 -June 24 (See Coan, 1841) The 1840 eruption started in the upper East Rift zone and quickly migrated to a fissure just west of present day Pahoa. "On Monday, June V, the stream began to flow off in a northeasterly direction and on the following Wednesday, June 3d, at evening, the burning river reached the sea having averaged about half a mile an hour in its progress... Sometimes it is supposed to have moved five miles an hour, and at other times, ... make no apparent progress... For three weeks this terrific river disgorged itself into the sea with little abatement." The fissure sources extended about 6.1 km (3.8 mi) along a NE -SW trend parallel to, and 2.6 km (1.6 mi) northwest of, the 2018 fissure system. The volume of the 1840 flow was more recently estimated to be 210 x 106 m3 at an average rate of 94 m3/s over 26 days of the eruption. The distance from fissure vent to coast is about 11 km (7 mi) for an average initial advance rate of 150-230 m/hr (170-250 yds/hr). Also of interest were the changes at Kilauea summit just before this eruption started. "For several years past the great crater of Kilauea [sic] has been rapidly filling up, by the rising of the superincumbent crust, and by the frequent gushing forth of the molten sea below. In this manner the great basin below the black ledge, which has been computed from three to five hundred feet deep, was long since filled up by the ejection and cooling of successive masses of the fiery fluid. These silent eruptions continued to occur at intervals, until the black ledge was repeatedly overflowed, each cooling, and forming a new layer from two feet thick and upwards, until the whole area of the crater was filled up, at least fifty feet above the original black ledge, and thus reducing the whole depth of the crater to less than nine hundred feet. This process of filling up continued till the latter part of May, 1840, when ... the whole area of the crater became one entire sea of ignifluous matter, raging like old ocean when lashed into fury by a tempest. For several days the fires raged with fearful intensity, exhibiting a scene awfully terrific. For several days .. The infuriated waves sent up infernal sounds, and dashed with such 12