effusion rates for July 31 were 300 to 500 m^3 s−^1
beforethesummitcollapseevent,withvalues
peaking at ~1400 m^3 s−^1 ~3 hours after the
event (Fig. 7F). Three other events in late July
to early August illustrate this pattern of in-
creased effusion rate after summit collapse
events (Fig. 8). In these examples, precollapse
bulk effusion rates were 300 to 700 m^3 s−^1 ,
increasing to peaks of 1400 to 1700 m^3 s−^1 over
~4 hours. The precise onset times of lava-level
rise in these three additional examples were
obscured by natural variations, but we can con-
strain the onsets as occurring no later than
20 min after the summit collapses (fig. S13) ( 30 ).
We chose these four surge events for analysis
because of their good observational condi-
tions; observation was limited in part by the
period that the time-lapse camera was opera-
ting ( 30 ). Infrasound suggests that collapse-
triggered surges in effusion rate were present
as early as mid-June, if not earlier. However,
infrasound also suggests that surging was
absent or subdued for several weeks in early
to mid-July despite continued summit collap-
ses ( 30 ).
The four surge examples from late July and
early August indicated that the effusion rates
we estimated showed similar trends as the
RSAM, with both having a broad peak after
the summit collapse events with a prolonged
(hours long) decline toward background values.
The RSAM and bulk effusion rate (Fig. 5C)showed a linear correlation (R= 0.80). We
disregard the July 26 surge because of the
presence of intense pulsations around the time
of the surge event. A linear correlation (R=
0.78) also existed between the bulk effusion
rate and infrasound energy during the surges
(Fig. 5D).
Time-lapse imagery in the distal channel
7.5 km from the vent recorded the down-
stream effects of thesesurges (movie S6). For
example, on August 2, a summit collapse event
at 11:55 Hawai‘i Standard Time (HST) was fol-
lowed ~20 min later by rising effusion rates
at the fissure 8 vent. By 14:21 HST, a flood of
lava was visible coming down the channel,
triggering overflows (shown by white smokePatricket al.,Science 366 , eaay9070 (2019) 6 December 2019 4of10
07/18 07/19 07/20 07/21050100150200250RSAM10:00 11:00 13:00 14:00
0102030Relative spillway lava level, m
RSAM/5pulsing regime non-pulsing regimeAB07/13 07/14 07/15 07/16 07/1712:00non-pulsing regime pulsing regime14 July 2018 19 July 2018Plume temperature over channel,°C
Plume temperature over vent,°C /2DE0102030405060Temperature °C07:45 08:00 08:15 08:30 08:45050100150200250300KLUD RSAM12:20 12:30 12:40 12:50 13:00 13:10 13:20010203040
Relative spillway lava level, m
RSAM/8
Infrasound energy x7 Pa^2 sCFig. 3. Short-term cycles in eruption rates (pulses).(A) Ten days of RSAM
showing nonpulsing behavior (white background) and pulsing behavior (pink
background). Pulsing is evident by the higher variance. (B) Lava level and
RSAM on 14 July 2018. Nonpulsing behavior is shown by a stable trend
in these parameters, whereas pulsing behavior is distinctive with higher
shared variance. (C) Lava level, RSAM, and infrasound energy on 14 July 2018,
showing the inverse relationship between RSAM (and infrasound) and lava
level. (D) Thermal image data of the pulses on 19 July 2018. Average
temperatures are shown in small measurement windows in the plume above
the lava channel spillway (orange line) and the vent where fountaining
was occurring (blue line). (E) RSAM showing peaks that correlate with high
vent temperatures (increased fountaining vigor).RESEARCH | RESEARCH ARTICLE
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