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Prepare: Mauna Loa Resources

Mauna Loa is Earth's largest active volcano and covers just over half of the Island of Hawaiʻi. It erupted most recently in 2022 and it will erupt again. This page provides resources to help you understand Mauna Loa eruption hazards and develop an emergency plan. 

Hawaiʻi Volcanoes National Park Information:

County of Hawaiʻi Civil Defense Agency:


What can you do before a future Mauna Loa eruption? 

Learn the Hazards

eruptive fissures along the Northeast Rift Zone of Mauna Loa
As the sun rose above Mauna Kea (background) on July 6, 1975, eruptive fissures along the Northeast Rift Zone of Mauna Loa fed voluminous ‘a‘ā lava flows that quickly moved down the north flank of the volcano.

Hazards associated with Mauna Loa eruptions include: 

  • Large and fast-moving lava flows
  • Volcanic air pollution (VOG)
  • Fine rock particles downwind
  • Damaging earthquakes
  • Ground cracks and fissures
  • Local tsunami in coastal areas

Learn more on the HVO volcanic hazards webpage:

See the geonarrative: Mauna Loa: Preparing for the next eruption of Earth's largest active volcano.


Stay Informed

Official sources of information:

What can you do during a future Mauna Loa eruption? 

  • Get information from official sources
  • Implement the emergency plan that you and your family have developed
  • Heed County of Hawaiʻi guidance and evacuate if necessary



Mauna Loa reference maps

Color map of lava flow response times
This map shows the response time people can expect based on Mauna Loa eruptions over the past 200 years.  Different sectors around Mauna Loa are colored according to how quickly lava flows can reach populated areas.  The warmer the color, the more quickly the flows travel.  Mauna Loa lava flows over the past 200 years are shown in gray, and the numbers along the coastline indicate lava travel times to the ocean after the vent(s) opened.  Large, bold numbers record the average effusion rates for the different parts of the volcano in millions of cubic meters per day (Mm3/d).
image related to volcanoes. See description
Map showing the subaerial extents of historical lava flows from Mauna Loa. Lava flow hazard zones and districts of the County of Hawai‘i are also depicted.
Map of post-1823 lava flows erupted from Mauna Loa (gray) and numbe...
Slope map of Mauna Loa, including lava flows erupted since 1823 (gray), showing the approximate number of hours or days it took for a flow to advance from the vent location to the ocean or maximum reach of a flow. One flow that moved down the steep slopes on west flank of Mauna Loa reached the ocean in as little as 3 hours after the vent started erupting in 1950. The bold numbers (for example, 12Mm3/d) are the average rates of lava effusion (outpouring of lava) in millions of cubic meters per day. Note the west flank has the steepest slopes (red-orange areas), shortest distance from vent to the ocean, and the highest average rate of effusion during eruptions, resulting in precious little time for warning residents during an eruption from the Southwest Rift Zone of Mauna Loa.