The Pacific is home to dozens of active volcanic systems including the massive Hawaiian shield volcanoes Kilauea and Mauna Loa. Most basaltic shield volcanoes in the Pacific are related to the hotspots that created the Hawaiian Islands and many of the Polynesian and Micronesian island chains.
Most residents of the Island of Hawaii live on one of four potentially active volcanoes and probably have wondered about the threat of lava flows at one time or another. Interestingly, determining future threats relies on knowledge of the past. The long-term likelihood of an area being invaded by lava in the future, is estimated in two different ways based on the history of lava flow activity.
Large quantities of volcanic gases, such as carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S), are released into the atmosphere during volcanic eruptions. But even between eruptions, smaller amounts of the same gases continue to escape and can provide important clues about the current state of the volcano and the underlying magma. But to measure them, you first must identify where gas is coming from.
We know that when a volcano erupts, molten red rock makes it to the surface, while during an intrusion it doesn’t. The difference between the two processes, if we depend on seismicity (earth shaking) or deformation (changes in ground surface) instrumentation, is not obvious. The events during the start of either are identical. But we can’t be certain that an intrusion will lead to an eruption.
Late Monday afternoon, earthquake activity picked up at Kilauea’s summit. At about 1:30 a.m. HST on Tuesday, that activity intensified, and it became clear that seismicity and increasing deformation were indicating a new intrusion of magma. The seismicity extended southward from Halema‘uma‘u crater, to an area south of the Kilauea caldera.
Scientists with the U.S. Geological Survey’s Hawaiian Volcano Observatory said Friday morning that earthquake activity and ground deformation has resumed beneath the southern part of Kilauea summit caldera within Hawaii Volcanoes National Park.
The Hawaiian Volcano Observatory reported Thursday morning the earthquake swarm that began Monday beneath the south part of Kilauea caldera, within Hawaii Volcanoes National Park, has waned.
The Hawaiian Volcano Observatory raised its alert level for Kilauea from “advisory” to “watch” Tuesday morning after an ongoing series of small earthquakes was detected beneath Hawaii Volcanoes National Park.
Kilauea volcano alternates between periods dominated by lava flows, such as the one we are currently in, and periods of explosive activity. About 1,000 years ago, effusive eruptions broke a 1,200-year period of predominantly explosive activity. During this time, lava flows accumulated on the floor of the Powers caldera — the predecessor of the present-day caldera at Kilauea summit. Eventually, lava filled and started to overflow the caldera, forming two large shields where the caldera had been.
The deaths apparently occurred along a trail crossing the northwest flank of Kilauea near Namakanipaio, when a ground-hugging surge of hot steam and rocks swept across the ground at high speed. Wet volcanic ash fell just before the lethal surge, and several hundred people left footprints in the ash beyond the limit of the surge.
Geologists at the USGS Hawaiian Volcano Observatory (HVO) had their mobile phones buzzing this past week with automated alert messages, notifying them that there was something new and hot on the Island of Hawaii. Although the internal alert system is meant to detect new volcanic activity, no eruption was occurring.
Inflation and earthquake activity ramped up prior to Mauna Loa’s 1984 eruption, so much so that in June of 1983, the USGS Hawaiian Volcano Observatory (HVO) indicated that an eruption could occur during the following year, though the exact timing was unknown.
Mauna Loa erupted 46 years ago this week, on July 5 and 6, 1975, in a 20-hour event with vents confined to the summit region (the area above 12,000 feet) and lava flows descending to just below 10,400 feet. This was the first eruption in 25 years, at the time the longest quiet stretch since 1843 (we are currently in the longest stretch at 37 years and counting).
Happy Canada Day/Bonne Fête du Canada! While some past “Volcano Watch” articles have had a July 4 theme for the USA, this year we’re taking the opportunity to ensure readers know that our neighbors to the north have volcanoes, too—including potentially active ones.
Eyewitnesses drawn to the crater rim were excited, reverent, and watchful. The eruption onset was observed near and far via technology. The USGS Hawaiian Volcano Observatory (HVO) was onsite and online, transmitting scientific information as the eruption response mounted.
Geodetic surveys measure the change in shape of our volcanoes due to changes in magma supply and storage. The USGS Hawaiian Volcano Observatory has a long history of using many different types of instruments and technologies over the decades to detect these changes.