(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)
The West Hawaii Today issue for September 11, 2009, contained a letter to the editor titled “Hualalai is a real and present threat.” The writer’s main point was that “Hualalai is the ‘secret in the closet’ that nobody wants to talk about,” that Hualalai is under-monitored, and that, should Hualalai erupt, there is no evacuation plan.
The letter writer’s concerns about Hualalai were valid, but he was not aware of HVO’s current efforts and plans to improve the monitoring of Hualalai. We hope to shed some light on recent and future activities planned for Hualalai.
Hualalai is the third most active volcano on Hawaii Island behind Kilauea and Mauna Loa, according to the Hawaiian Volcano Observatory’s (HVO) Web site (hvo.wr.usgs.gov/), and attained national ranking of “High Threat” for active volcanoes in the U.S.
In the ranking, there were 37 volcanoes nationwide that were highest-priority targets for improved monitoring; Kilauea and Mauna Loa were included in this group.
Furthermore, 21 additional volcanoes were found to be under-monitored and were regarded high priority for improved monitoring; Hualalai is in this group.
Hualalai has erupted three times in the last 1,000 years, the most recent eruption occurring in 1801. An intense and damaging seismic swarm in 1929 marked a failed eruption.
In the same interval, Mauna Loa and Kilauea have each erupted more than 150 times, and Haleakala has erupted at least 10 times.
Hualalai was rated a higher threat than Haleakala, due to the extent of development (airport, power station, etc.) and the larger population living on the volcano’s flanks.
In 2005, HVO and the Pacific Tsunami Warning Center (PTWC) each had one seismometer on the volcano, and bi-annual deformation surveys were conducted by our staff.
With the permission of Kamehameha Schools, a continuous GPS receiver was installed near the summit in late 2006. In 2009, HVO still has one seismometer and uses two instruments operated by PTWC for eruption monitoring, and we continue the bi-annual surveys.
Plans for the next two years include upgrading our seismic site and adding a new one.
We routinely scrutinize all available satellite imagery daily, including visual and thermal images to indicate any significant visual and temperature changes, or increased gas emissions.
Moreover, radar scans several times each year can pinpoint any ground deformation that may be a precursor to volcanic activity. The radar scans are so sensitive that several small areas of subsidence were detected after the Oct. 15, 2006 Kiholo earthquakes.
The conclusion from evaluating all of these data is that there have been no signs of swelling, major subsidence, temperature changes, gas emissions, or unusual seismic activity on Hualalai that would indicate volcanic activity in the near future. Nevertheless, we continue to look for any changes.
If the rankings were done today, Hualalai would be nearly fully monitored.
We agree with the letter writer that “the more people know about Hualalai, the more will be prepared.”
In 2004, University of Hawaii at Manoa scientists published two studies on Kona community’s perception of volcanic risk and preparedness for lava flows from Hualalai and Mauna Loa.
They concluded that “current community understanding and preparedness… falls short of that required for a volcanic crisis, particularly for those eruptions with short onset and high effusion rates on steep slopes that would impact Kona in just a few hours…”
There are several reasons for the lack of understanding, but foremost may be the constant influx of new residents who haven’t educated themselves about volcanic hazards.
The primary mission of the U.S. Geological Survey’s Hawaiian Volcano Observatory is to monitor the active volcanoes in the state. Through our Web site, public forums, and newspaper articles, we strive to disseminate information on the volcanoes and their hazards.
The people of Kona should know that we are keeping an eye on Hualalai and that if there are any changes (in its eruption status), we will let the public know!