# Volcano Watch — Kīlauea Volcano divided into lava-risk zones

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Kīlauea is the world's most active volcano. About 70% of Kīlauea's surface is covered by lava less than 500 years old and over 90% is covered by lava less than 1,100 years old. Much of the surface of Kīlauea Volcano lies within Hawaii Volcanoes National Park, where eruptions are generally welcome tourist attractions.

Kīlauea Volcano divided into lava-risk zones

(Public domain.)

Kīlauea is the world's most active volcano. About 70% of Kīlauea's surface is covered by lava less than 500 years old and over 90% is covered by lava less than 1,100 years old. Much of the surface of Kīlauea Volcano lies within Hawaii Volcanoes National Park, where eruptions are generally welcome tourist attractions. However, the rest of the volcano is in the district of Puna which has a large and rapidly growing population and is particularly vulnerable to inundation by lava flows.

Kīlauea Volcano can be subdivided into four lava-flow hazard zones (1, 2, 3, and 5) which are based on the location of active vents in historic time, the past lava-flow coverage, and the topography of the volcano. As the population of the Puna District grows, it becomes increasingly important for residents to understand what the hazards zones mean. Nearly thirty-five percent of the land in hazard zones 1 and 2 has been covered by lava flows since 1955.

Zone 1, the most hazardous zone, includes the summit and rift zones of Kīlauea where vents have been repeatedly active in historic time. Zone 1 includes the relatively narrow zone along the rift zones characterized by faults, fissures, ground cracks, vents, and collapse pits. It is bounded by the outermost faults or fissures of the rift zone. Thirty-nine percent of the surface of zone 1 is covered by lava younger than 190 years old. Kapoho, Leilani Estates, Lanipuna Gardens, and the southern part of Kaohe Homesteads are in zone 1. Vacationland Hawaii and Kapoho Beach Lots straddle the boundary between zones 1 and 2.

Zone 2 includes areas adjacent to and downslope from the active rift zones. On the north side of the East Rift Zone between the summit and a few miles west of Pahoa, there is no zone 2 between zones 1 and 3 because the faults along the north edge of the rift zone block the flow of lava to the northeast. Pahoa, Nanawale Estates, Hawaiian Beaches, Hawaiian Parks, Hawaiian Shores, Pahoa Agricultural Park, Nanawale Homesteads, Alohalani Meadows, the north part of Kaohe Homesteads, Waa Waa, Kaueleau Farm Lots, Opihikao Homesteads, Opihikao, Kalapana Sea View Estates, Puna Beach Palisades, Kehena Beach Estates, Black Sand Beach Subdivision, Kaimu-Makena Homesteads, and what is left of Royal Gardens are in zone 2. Kalapana, Kalapana Gardens, and Kapaahu, destroyed by the flows from the current eruption, were also located in zone 2. About 33 percent of zone 2 is covered by lava younger than 190 years old.

Zone 3 includes areas gradationally less hazardous than zone 2 because of greater distance from recently active vents or because the topography makes it less likely that flows will cover these areas. Developed areas between Keaau and Pahoa and on the south side of Highway 11 between Keaau and Volcano are in zone 3. Only seven percent of zone 3 is covered by lava younger than 190 years old. An area to the south of the summit of Kīlauea, and entirely within the National Park is ranked as zone 5 because it is shielded from lava flows by the Koae fault zone and no lava flows have entered the area in historic times.

Historic flows erupted from vents on the East Rift Zone include a large flow in 1840 that underlies nearly all of Nanawale Estates and forms the southern edge of Hawaiian Shores. The 1955 eruption issued from a series of fissures along the southern edge of the rift zone. Most of Kalapana Sea View Estates and all of Puna Beach Palisades are on 1955 flows. The 1960 eruption destroyed Kapoho village and flowed to the sea at Cape Kumukahi. There were brief East Rift eruptions in 1961, 1962, 1963, 2 each in 1965 and 1968, and one in 1969. The next eruption also began in 1969, but lasted until 1974, and built the lava shield at Mauna Ulu. This was the longest historic East Rift eruption before the current eruption. Before Mauna Ulu was done erupting, two separate fissure eruptions occurred in the upper East Rift near Pauahi Crater in 1973 and another fissure erupted near Keanakako`i Crater in 1974. The next East Rift Zone eruption occurred just downrift of the currently active Kupaianaha vent in 1977 and sent a flow to the edge of Kalapana. The East Rift Zone was then quiet until early 1983, when the ongoing eruption began.

### Volcano Activity Update

The eruption on the East Rift Zone of Kīlauea Volcano continues with low-volume, steady effusion of lava from the breakout at about the 1,900-foot level of the tube downslope from the Kupaianaha vent. This is the same area that has had active flows for the last month. The volume of lava has continued to slowly decline, as it has since last summer.

From Thursday at about 4:00 p.m. until Friday at about 7 a.m., increased tremor near the Kupaianaha vent, coupled with slow deflation at the summit and low-amplitude seismic activity in the upper East Rift Zone suggested that the volume may have increased. However, visual observation of the area on Friday afternoon did not detect any change in activity.

Several earthquakes with magnitudes greater than 3 occurred this week; they are located on the inset to the figure. On Sunday January 26 at 6:23 a.m., there was a magnitude 3.4 earthquake about five miles beneath the Hamakua coast. On the same day at 9:14 a.m., a 3.3-magnitude earthquake occurred about two miles beneath Puhimau Crater on the upper East Rift of Kīlauea Volcano. On Tuesday January 28, two additional earthquakes occurred beneath Puhimau Crater. The first, at 7:48 p.m., had a magnitude of 3.7 and was followed four minutes later by a magnitude 3.3. The Puhimau area was also the location of numerous other small (less than magnitude 3.0) earthquakes during the week.