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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.

Kīlauea's Recent Summit Eruptions

  • What is happening at the summit of Kīlauea?
  • How long will an eruption last?
  • Will the crater and/or caldera fill up and overflow with all this lava?

  • How deep is the crater? How deep is the caldera?

  • Are there any official names for features in the caldera from USGS or how does USGS refer to them?

  • In the dark is the livestream camera using some kind of filter to see the lava (red filter, infrared, etc.), or is this just natural light from the lava?

  • How can I view an eruption?

  • Why are some areas within Hawai‘i Volcanoes National Park closed to the public?
  • What steps do HVO and NPS staff take to be safe in hazardous areas?
  • Why is it necessary for USGS HVO staff to enter hazardous areas?
  • Why is there so much gas coming from the crater?  
  • Is it safe to breathe volcanic gas or vog?

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?
  • Why do I still smell sulfur when SO2 emissions are low?
  • Will Kīlauea emit high levels of SO2 again?

Lava-flow hazards

  • Why did the U.S. Geological Survey prepare the Lava-Flow Hazard Zone Map for the Island of Hawai‘i?
  • What is a hazard and how does it differ from risk? 
  • What are the hazards related to an individual lava flow? 
  • What does the Lava-Flow Hazard Zone Map represent? 

  • Are the boundaries between lava-flow hazard zones distinct lines? 

  • The Lava-Flow Hazard Zone Map is 30 years old. Is it still accurate?
  • How can Hawai‘i Island residents determine the lava-flow hazard zones in which their properties are located?
  • 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 the other Hawaiian Islands?
  • Who prepared the Lava-Flow Hazard Zone Map for the Island of Hawai‘i
  • Where can I read more about lava-flow hazards?

Volcanic ash and other tephra

  • What is volcanic ash?
  • When has Kīlauea erupted volcanic ash?
  • Who monitors ashfall from Kīlauea?
  • How much ash 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?

Kīlauea's summit water

  • What was the source of the water in Kīlauea's summit water lake?
  • What did the level, temperature, color, and chemistry of the water in the lake tell us? 
  • What eruption styles are possible at Kīlauea’s summit? 
  • What did the water lake atop Kīlauea mean for future eruptions and hazards at the summit of Kīlauea? 
  • What did HVO doing to monitor the water lake and greater Kīlauea summit area? 

Mauna Loa

  • Is Mauna Loa an active volcano? Will it erupt again?
  • Where on Mauna Loa is an eruption likely to occur?
  • How often does Mauna Loa erupt?
  • When was the most recent eruption of Mauna Loa?
  • How does a typical Mauna Loa eruption progress? 
  • What kinds of volcanic hazards will a Mauna Loa eruption pose?
  • What are the possible impacts of a Mauna Loa eruption?
  • How can I stay informed about the status of Mauna Loa?
  • What do the USGS Volcano Alert Levels and Aviation Color Codes mean?
  • What can I do to prepare for a potential Mauna Loa eruption?
  • Has Mauna Loa's Northeast Rift Zone erupted in the past? 
  • What does the name "Mauna Loa" mean?
  • How big is Mauna Loa?
  • Can HVO scientists forecast a Mauna Loa eruption?
  • What kinds of instruments are used to monitor Mauna Loa and other Hawaiian volcanoes?
  • Are Mauna Loa eruptions similar to Kīlauea eruptions?
  • Is Mauna Loa expected to erupt soon?

Earthquakes and volcanoes in American Samoa

  • What happened in American Samoa in 2022? 

  • Why were earthquakes felt in American Samoa in 2022?  

  • Where were the earthquakes located in the American Samoa 2022 earthquake swarm? 

  • Why was it difficult to locate earthquakes in American Samoa? 

  • Why are there volcanoes in American Samoa, and how often do they erupt? 

  • What is the USGS doing to better understand volcanoes in American Samoa? 

  • How long do earthquake swarms last? 

  • What caused the earthquakes in American Samoa in 2022 and what volcanic hazards could impact American Samoa Islands? 

  • What should I do to protect myself and my family now and if there is an eruption in American Samoa? 

  • How can I stay informed about volcanoes in American Samoa?  

  • How can I report observations about volcanoes in American Samoa?