Frequently Asked Questions and Answers – Hawaiian Volcanoes and Hazards

Scientists at the USGS Hawaiian Volcano Observatory are often asked questions about various volcanic processes, hazards, and conditions associated with Hawaiian volcanoes. Based upon these questions, we have compiled a list of those most frequently asked with answers provided by geologists and geophysicists who monitor activity and conduct research at the USGS Hawaiian Volcano Observatory. Answers often include links to resources where you can find additional information. Below is a list of subjects and specific questions. Please click the subject to access the answers.

Frequently Asked Questions about Kīlauea Volcano's Summit Earthquakes

• Why are there so many earthquakes occurring around the summit?
• Explain the cycle of earthquakes surrounding the summit collapse/explosion events.
• Why is there a collapse/explosion event nearly every day at such a regular interval?
• Why do so many of the collapse/explosion events have the same energy equivalent as a magnitude around 5.3?
• Why does the collapse/explosion event feel smaller/larger than the magnitude shown?
• Why are the plumes produced during a collapse/explosion so much smaller now? Could there be another tall 30,000 ft plume during this eruption?
• Why are earthquakes occurring further outboard of Halema‘uma‘u with time?
• Why does it take so long for the collapse/explosion events to appear in the earthquake catalog on the website?
• Why do earthquakes posted online sometimes get removed?
• Why are the larger earthquakes at the Kīlauea summit not a tsunami threat?
• Is the summit seismic activity influenced by tides?

Vog, or volcanic smog

• What is "vog"? How is it related to SO₂ emissions?
• What controls vog on the Island of Hawai‘i?
• What health effects are associated with vog?
• Where can I find results from scientific research or technical data about the effects of vog on human health?
• Does vog impact plants and animals?
• Who monitors air quality and vog in Hawai‘i, and where can I find current information?
• Why are some roads and trails in Hawai‘i Volcanoes National Park closed?
• What can I do to protect myself from vog?
• Should I cancel my plans to visit Hawai‘i because of SO₂ and vog?
• How do other communities near active volcanoes deal with SO₂ emissions?

Volcanic gas

• What gases are emitted by Kīlauea and other active volcanoes?
• Who monitors volcanic gases emitted by Kīlauea?
• How do HVO scientists measure volcanic gas emissions at Kīlauea?
• How much sulfur dioxide (SO₂) gas comes from Kīlauea?
• How long will the Halema‘uma‘u Overlook vent emit high levels of SO₂?

Lava-flow hazards

• Who prepared the Lava-Flow Hazard Zone Map for Hawai‘i Island?
• What does the Lava-Flow Hazard Zone Map show?
• Are the boundaries between lava-flow hazard zones distinct lines?
• Why did the USGS prepare the Lava-Flow Hazard Zone Map?
• If the map was made for general planning purposes, why were so many building permits issued and so much construction allowed in Zones 1 and 2?
• How were the lava-flow hazard zones determined?
• The Lava-Flow Hazard Zone Map is 20 years old. Is it still accurate?
• Will the Lava-Flow Hazard Zone Map be revised?
• How can Hawai‘i Island residents determine the lava-flow hazard zones in which their properties are located?
• How and why is the Lava-Flow Hazard Zone Map used by home insurance or mortgage companies?
• What can a homeowner do if a company uses the map to set elevated insurance or mortgage rates?
• What can a homeowner do if a lava-flow hazard zone is used as a reason for non-renewal of a home owner's insurance policy?
• How does location near a rift zone affect lava-flow hazards?
• Why is an area freshly covered by lava designated as Zone 2, while another area not recently threatened by lava is designated as Zone 1?
• As a specific example, why is Kalapana in Zone 2, while Leilani Estates in Zone 1?
• Have lava-flow hazard zone maps been prepared for other Hawaiian Islands?
• Where can Maui residents find lava-flow hazard zone information?
• How do Maui lava-flow hazard zone numbers compare to those on Hawai‘i Island?
• Where can I read more about lava-flow hazard zones in Hawai‘i?

Volcanic ash and tephra

• What is volcanic ash?
• Is this the first time Kīlauea has erupted volcanic ash?
• Who monitors ashfall from Kīlauea?
• How much as is Kīlauea currently erupting?
• Does volcanic ash pose hazards to human health?
• What other hazards are associated with volcanic ash?
• What can I do to minimize the impacts of volcanic ash?

Mauna Loa

• What does the name "Mauna Loa" mean?
• How big is Mauna Loa?
• Is Mauna Loa an active volcano? Will it erupt again?
• How often has Mauna Loa erupted?
• Where on Mauna Loa is an eruption likely to occur?
• When was the most recent eruption of Mauna Loa?
• Can HVO scientists forecast a Mauna Loa eruption?
• What kinds of instruments are used to monitor Mauna Loa and other Hawaiian volcanoes?
• How can I stay informed about the status of Mauna Loa?
• Is Mauna Loa expected to erupt soon?
• What do the USGS Volcano Alert Levels and Aviation Color Codes mean?
• Under what circumstances will the Volcano Alert Level for Mauna Loa be upgraded from NORMAL to ADVISORY?
• How will HVO scientists respond to a change in the Volcano Alert Level for Mauna Loa?
• Does and ADVISORY Alert level mean that Mauna Loa is about to erupt?
• Why do HVO scientists think that a Mauna Loa eruption is NOT imminent at this time?
• Are Mauna Loa eruptions similar to Kīlauea eruptions?
• What kinds of volcanic hazards will a Mauna Loa eruption pose?
• What are the possible impacts of a Mauna Loa eruption?
• How much time will I have to respond to a Mauna Loa eruption?
• How will I find out about a Mauna Loa eruption?
• What can I do to prepare for a Mauna Loa eruption?