1983 Kaoiki earthquake

Natural disaster in Hawaii, United States May 2025 February 2025 1983 Kaoiki earthquake 19.426 N 155.450 W inline,title USA Hawaii 1983-11-16 16:13:00 565031 https://earthquake.usgs.gov/earthquakes/eventpage/hv19832953/executive 1983 11 16 06:13:00 (UTC-10) 6.7 w y 12 km mi 0 on Right-lateral Strike-slip Hawaii IX 0.67 g yes 6 injuries Kaoiki Fault >800 aftershocks by the end of November 1983 $6-7 million (1983 rate) The 1983 Kaoiki earthquake struck southern Hawaii Island on the morning of November 16, 1983. Measuring w 6.7, it was the largest to hit the island since 1975. The epicenter was located 50 km (30 mi) southeast of Hilo with an approximated depth of 12 km (7 mi). The shallow strike-slip earthquake was assigned a maximum intensity of IX (Violent) on the Modified Mercalli scale. Six people were injured, widespread damage and landslides were reported across the island. Tectonic setting Hilina Slump The epicenter in Kaoiki lies within a valley between the western slope of Mauna Loa, and northwest of Kīlauea. Seismicity in the area is caused by the continuous movement of the Kilauea and Mauna Loa slumps generated by the continuous magmatic flow underground. This strain forms the many faults around the Kilauea block and the notable Hilina Slump. The slump is situated underwater—below the southern flanks of Kilauea. As the block continues to stretch at around 10 cm/year seaward, the crust becomes thinner, causing cracks, fissures, and a trend of aligning normal faults.Got Okubo 2003 The Kaoiki Pali is an example of a Hilina slump- induced normal fault, striking northeast and stretching 25 km (15.5 mi) across the Mauna Loa and Kilauea boundary.Jackson Endo 8776 Paul Árnadóttir 1992 The scarps that the Kaoiki Pali produces have vertical displacements of up to 100 m (300 ft). While these displacements are present in large amounts, most of these faults have not moved in over 9,500 years. However, this slump also affects the ground-level sliding on Mauna Loa. Although it rarely occurs, when it does, it causes major fractures due to its narrow connection with Kilauea. This displacement is what causes the extensive strike-slip faults and earthquakes in the area. And as these faults rupture, it produces major earthquakes above magnitude 6 that inflict extreme damage and casualties; along with deadly tsunamis and landslides as observed in 1975 and 1868.Jackson Endo 8776 Paul Árnadóttir 1992Lipman 1995 thumb|A detailed illustration of the Hilina Slump|left|262x262px Kaoiki fault One of the most active faults in the Mauna Loa trend is the Kaoiki fault. Located at the northernmost head of the volcano, but also lying within the lowest areas of the block. Earthquakes associated with the fault are known for creating multiple ground ruptures in an east-west fashion, mostly paired with left-stepping from other adjacent ruptures, and causing open ruptures of up to 0.5 m.Got Okubo 2003 This right-lateral strike-slip fault has long coexisted with the volcanic low-angle seaward normal faults within the Hilina slump for approximately 30,000 years.Jackson Endo Paul Árnadóttir 1992 8775–8777 Earthquake left|thumb|An isoseismic USGS ShakeMap of the earthquake|259x259px The earthquake was recorded by seismic stations in and around Kaoiki, recording a moment magnitude of 6.7 w, as well as recordings in other magnitude scales; magnitudes of 6.6 l,Jackson Endo 8776 Paul Árnadóttir 1992 6.6–6.7 s,Wyss 1986 785–800ISC 2022 and 6.4–6.6 tJackson Endo Paul Árnadóttir 1992 8775–8777 respectively. The Hawaiian Volcano Observatory (HVO) recorded vertical accelerations of up to 0.67 g and assigned a maximum intensity of IX (Violent) on the Modified Mercalli intensity scale.Koyanagi Endo Tanigawa Nakata 1984 According to reports, the strong oscillations lasted for almost one minute. Following the trend of the originated Kaoiki fault, as well as earthquake data from the nearby HVO Station in Hawai'i National Park, the earthquake is suggested to have a focal mechanism of right-lateral strike-slip with a northeast–trending nodal plane.Koyanagi Endo Tanigawa Nakata 1984 The sufficient inflation at the Mauna Loa and Kilauea magma reservoirs had enough parallel horizontal compressional stress to snap the strike-slip faulting regions in-between the slopes. Crustal right-lateral faulting with en echelon extensions was found on the 1,900 meter elevation at Mauna Loa road, tracing 4.5 km on both sides of the road, with extensions at lengths of about 20–30 cm (7.87 in) on the main fracture.Buchanan-Banks 1987 By the end of November, approximately 10,000 small earthquakes were reported in the vicinity of the epicenter. 800 of these had magnitudes ranging from 1.0–4.3 w. The zone of aftershocks highlighted an area of Kaoiki from the summit of Mauna Loa to the southeast slope of Kilauea. These aftershocks reportedly had depths ranging from 2–12 km below and radiated from the epicenter. Most aftershocks within a few hours after the mainshock occurred 5–6 km from the epicenter.Jackson Endo Paul Árnadóttir 1992 8775–8777 Theories suggest that after the mainshock rupture, another low angle slip had released compression, reversing the pattern of the aftershocks from the mainshock.Jackson Endo 8778 Paul Árnadóttir 1992 Seismic quiescence About 2.5 years prior to the earthquake, a range of 65–90% drop in seismicity was observed within a 10 km radius of the epicenter. Seismic rate samples from the mid-1970s to the 1980s were compared to the window of time, and the region lacked more than 300 earthquakes with M ≥1.8. The drop in seismicity is said to be one of the most prevalent examples proving the theory of seismic quiescence. The seismic quiescence theory focuses on the phenomenon of abnormal decreases in seismic activity within a particular area. This theory has yet to be fully recognized due to its lack of evidence and research dedicated to the topic. While other examples of seismic quiescence have occurred in the past, it has been disregarded or overlapped by other theories as to why that is. One of the main characteristics of seismic quiesences is the lack of 50% or more seismic volume compared to its usual rate, which was the case of the Kaoiki quake. While the real reason on how this occurs is still unknown, people who support the theory say its due to the ranging tectonic differences along plates and plate boundaries.Wyss 1986 785–800 Another reason as to why that is may have been caused by the shear pause on the magmatic plain and strain release.Wyss 1986 785–800Jackson Endo 8776 Paul Árnadóttir 1992 Damage The earthquake threw houses off their foundations, toppled water tanks, cracked bridges, collapsed chimneys, damaged multiple government facilities, and toppled electric cables, generating multiple power interruptions in the area. About 35 commercial buildings sustained damage, 317 houses sustained minor damage, and around 39 other houses were seriously damaged. These reports were recorded as far as Hilo. The damage suggested intensities of VIII (Severe). In total, financial losses were estimated at around $6–7 million (1983 rate). Landslides had also occurred, blocking multiple roads and suspending travel across the island. There were only a few casualties; 6 individuals received light injuries, which may have been due to the fact that it occurred early in the morning, when most people were in bed.Buchanan-Banks 1987 Ground ruptures were prominent in the areas surrounding the epicenter, observed 4 km northeast following the nodal trend. This trail continues for 7 km in the same direction and trend. It stops beyond the expected aftershock zone, which suggests that the elastic release of the last ruptures may have been a result of aseismic deformations of the fault. These ruptures extend up to heights of 20 m (65.6 ft) with jagged walls hanging with suggested pre-existing joints that were hidden beneath the sediment.Jackson Endo 8778 Paul Árnadóttir 1992 The expected left-stepping was observed in the rupture zone, which was less deformed compared to other ruptures and showed less subdued zig-zag patterns.Buchanan-Banks 1987Jackson Endo 8778 Paul Árnadóttir 1992 See also Lists of 20th-century earthquakes List of earthquakes in 1983 List of earthquakes in Hawaii 1975 Hawaii earthquake Hilina Slump References Sources Jackson Marie Endo Elliott Paul Delaney Árnadóttir Thóra Rubin Allan 1992-06-10 Ground Ruptures of the 1974 and 1983 Kaoiki Earthquakes, Mauna Loa Volcano, Hawaii https://www.researchgate.net/publication/248794026 Journal of Geophysical Research 97 B6 8775–8796 1992JGR....97.8775J 10.1029/92JB00649 ResearchGate Got Jean-Luc Okubo Paul 2003-07-15 New insights into Kilauea's volcano dynamics brought by large-scale relative relocation of microearthquakes: EARTHQUAKE RELOCATION AT KILAUEA VOLCANO Journal of Geophysical Research: Solid Earth en 108 B7 10.1029/2002JB002060 free Lipman Peter 1995 Declining growth of Mauna Loa during the last 100,000 years: Rates of lava accumulation vs. gravitational subsidence https://www.researchgate.net/publication/260936600 Geophysical Monograph Series 92 45–80 10.1029/GM092p0045 1995GMS....92...45L 0-87590-049-6 ResearchGate Wyss M. 1986-06-01 Seismic quiescence precursor to the 1983 Kaoiki (MS = 6.6), Hawaii, earthquake https://pubs.geoscienceworld.org/ssa/bssa/article-abstract/76/3/785/118865/Seismic-quiescence-precursor-to-the-1983-Kaoiki-MS March 4, 2023 Bulletin of the Seismological Society of America 76 3 785–800 ISC 2022 ISC-GEM Global Instrument Earthquake Catalogue (1900-2009) http://www.isc.ac.uk/cgi-bin/web-db-run?event_id=565031&out_format=ISF2&request=COMPREHENSIVE www.isc.ac.uk Koyanagi R. Y. Endo E. T. Tanigawa W. R. Nakata J. S. Tomori A. H. Tamura P. N. 1984 Kaoiki, Hawaii earthquake of November 16, 1983; a preliminary compilation of seismographic data at the Hawaiian Volcano Observatory https://pubs.er.usgs.gov/publication/ofr84798 Open-file Report 10.3133/ofr84798 free Buchanan-Banks Jane M. 1987 Structural Damage and Ground Failures from the November 16, 1983 Kaoiki Earthquake, Island of Hawaii U.S. Geological Survey Professional Paper 1350 44 1187–1220 United States Geological Survey External links 565031 Category:1983 earthquakes Category:1983 in Hawaii Category:1983 natural disasters in the United States Category:November 1983 in the United States Category:Earthquakes in Hawaii