Volcano Watch: Lessons for the future from Mauna Loa’s 1916 eruption – Hawaii Tribune-Herald

The yr 1916 not solely marked the start of Hawaii Volcanoes Nationwide Park, but additionally is remembered for the eruption of the Honamalino circulate from the Southwest Rift Zone (SWRZ) of Mauna Loa 106 years in the past.

The eruption started on Might nineteenth, 1916, and was transient, lasting lower than two weeks, nevertheless it gives classes for future Mauna Loa eruptions.

Dr. Thomas Jaggar, who had based the Hawaiian Volcano Observatory a mere 4 years earlier in 1912, tried to forecast the subsequent Mauna Loa eruption primarily based on the sample of rift zone eruptions on the volcano since 1868. The earlier rift eruptions alternated areas between the Northeast Rift Zone (NERZ) and the SWRZ although these have been often separated in time by eruptions confined to Mauna Loa’s summit caldera (Moku‘aweoweo).

Mauna Loa had erupted in 1907 from the SWRZ and in 1914–15 from the summit. Due to this fact, Dr. Jaggar hypothesized that the subsequent Mauna Loa flank eruption would happen from the NERZ, assuming the prior sample meant there was an underlying motive for the alternation of rift eruption websites.

The Might 19, 1916, SWRZ outbreak deviated from the sample of eruptions Dr. Jaggar had noticed at Mauna Loa, suggesting that the eruption likelihood could be extra like a “coin flip” mannequin. Whereas the long-term odds for flipping heads and tails are equal, it doesn’t imply you may’t flip 4 tails in a row.

Like many eruptions on the Island of Hawaii, the Might 19, 1916, eruption was preceded by earthquake exercise. Residents of Ka‘u felt quite a few earthquakes early within the morning earlier than a formidable steam plume, seen from Kilauea’s summit, rose excessive up on Mauna Loa’s SWRZ at about 7:15 a.m., marking the beginning of the eruption. Exercise on this high-elevation space, technically thought-about the summit area, lasted lower than 24 hours.

Later, one other swarm of earthquakes shook Ka‘u residents as lava intruded the SWRZ leading to a line of fissures opening on the decrease SWRZ on the night of Might 21. Lava from the vents unfold over the crest of the rift zone feeding lava flows on both aspect — the Honomalino circulate transferring down the steep southwest aspect and the bigger Kahuku circulate spreading extra extensively to the southeast.

The branched nature of the 1916 eruption — with the eruption supplying lava flows on both aspect of the rift zone — coupled with the comparatively small whole erupted quantity ensured that the lava flows didn’t journey very far. Just one homestead (the Bertlemann’s) was destroyed throughout the 1916 eruption, which ended on Might 31.

The 1916 eruption was adopted in comparatively speedy succession by Mauna Loa’s 1919 and 1926 SWRZ eruptions with no intervening eruptions. Throughout each eruptions, lava flows reached the ocean and destroyed Hawaiian coastal villages (Alika and Ho‘opuloa). The 1919 and 1926 lava flows would have lower Freeway 11 and induced extreme disruptions for present residents. The village of Miloli‘i and its boat entry have been narrowly missed by the 1926 circulate.

A number of different lava flows from Mauna Loa’s SWRZ, together with in 1868, 1887, and 1950, have additionally traveled shortly by means of this area, crossing roads and getting into the ocean, generally inside a matter of hours of the vent opening.

The 1950 eruption on the SWRZ was the most important recorded Mauna Loa eruption and fed flows on both aspect of the rift zone crest just like the 1916 eruption. In a distinction to the 1916 eruption, three lava flows erupted in 1950 entered the ocean inside lower than 24 hours of that eruption beginning. A repeat of the 1950 eruption is of nice concern in the present day because of the elevated inhabitants of the realm.

What can we be taught from Mauna Loa’s 1916 eruption? Although eruptions and volcanoes exhibit patterns, they don’t at all times observe them. Whereas repeats of most recorded SWRZ eruptions would at a minimal lower off Freeway 11, the smaller 1916 eruption demonstrates this isn’t at all times the case.

Over the previous 200 years, Mauna Loa rift zone eruptions are evenly divided between the SWRZ and the NERZ. Nevertheless, the outstanding run of 4 SWRZ eruptions in a row (1907, 1916, 1919, 1926) reveals the weak point of long-term regular likelihood fashions in forecasting eruptions within the brief time period. It’s a continuing reminder that none of us ought to develop complacent dwelling on our volcanic island.

Volcano
exercise updates

Kilauea volcano is erupting. Its USGS Volcano Alert degree is at WATCH (https://www.usgs.gov/natural-hazards/volcano-hazards/about-alert-levels). Kilauea updates are issued day by day.

Over the previous week, lava has continued to erupt from the western vent inside Halema‘uma‘u crater. All lava is confined inside Halema‘uma‘u crater in Hawaii Volcanoes Nationwide Park. Sulfur dioxide emission charges stay elevated and have been final measured at roughly 2,800 tonnes per day (t/d) on Might 12. Seismicity is elevated however steady, with few earthquakes and ongoing volcanic tremor. Summit tiltmeters present comparatively little floor deformation over the previous week. For extra info on the present eruption of Kilauea, see https://www.usgs.gov/volcanoes/Kilauea/recent-eruption.

Mauna Loa is just not erupting and stays at Volcano Alert Stage ADVISORY. This alert degree doesn’t imply that an eruption is imminent or that development to an eruption from the present degree of unrest is for certain. Mauna Loa updates are issued weekly.

This previous week, about 50 small-magnitude earthquakes have been recorded under the summit and higher elevation flanks of Mauna Loa — nearly all of these occurred at shallow depths lower than 15 kilometers (9 miles) under sea degree. World Positioning System measurements present low charges of floor deformation over the previous week. Gasoline concentrations and fumarole temperatures at each the summit and at Sulphur Cone on the Southwest Rift Zone have remained steady over the previous week. Webcams present no modifications to the panorama.

For extra info on present monitoring of Mauna Loa, see: https://www.usgs.gov/volcanoes/mauna-loa/monitoring.

4 earthquakes have been reported felt within the Hawaiian Islands throughout the previous week: a M3.2 earthquake 21 km (13 mi) SSE of Naalehu at 13 km (8 mi) depth on Might 19 at 2:03 a.m. HST, a M3.1 earthquake 3 km (1 mi) SSE of Pahala at 32 km (20 mi) depth on Might 18 at 12:14 a.m. HST, a M2.6 earthquake 21 km (13 mi) SSE of Waimea at 22 km (13 mi) depth on Might 15 at 10:48 p.m. HST, and a M3.2 earthquake 2 km (1 mi) WSW of Pahala at 35 km (22 mi) depth on Might 13 at 5:46 a.m. HST.

HVO continues to carefully monitor Kilauea’s ongoing eruption and Mauna Loa for any indicators of elevated exercise.

E-mail inquiries to askHVO@usgs.gov. Volcano Watch is a weekly article and exercise replace written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and associates.