Abstract
Kukuiho’olua Island is an islet that lies 164 m due north of Laie Point, a peninsula of cemented, coastal, Pleistocene and Holocene sand dunes. Kukuiho’olua Island consists of the same dune deposits as Laie Point and is cut by a sea arch, which, documented here for first time, may have formed during the 1 April 1946 “April Fools’s Day Tsunami.” The tsunami-source of formation is supported by previous modeling by other authors, which indicated that the geometry of overhanging sea cliffs can greatly strengthen and focus the force of tsunami waves. Additional changes occurred to the island and arch during the 2015–2016 El Niño event, which was one of the strongest on record. During the event, anomalous wave heights and reversed wind directions occurred across the Pacific. On the night of 24–25 February 2016, large storm waves, resulting from the unique El Niño conditions washed out a large boulder that had lain within the arch since its initial formation, significantly increasing the open area beneath the arch. Large waves also rose high enough for seawater to flow over the peninsula at Laie Point, causing significant erosion of its upper surface. These changes at Laie Point and Kukuio’olua Island serve as examples of long-term, intermittent change to a coastline—changes that, although infrequent, can occur quickly and dramatically, potentially making them geologic hazards.
Highlights
The documentation of coastal change is important at a time of rising eustatic sea levels [1,2]
This paper documents the evolution and change of a sea arch in a small island off of the northeast coast of the larger Hawaiian Island of Oahu, as well as other changes to the nearby coastal peninsula—changes caused by short-duration, but high energy events related to storms and tsunamis
On 1 April 1946, a large tsunami was generated when a Ms = 7.4 earthquake, and likely subsequent, underwater landslide occurred in the Aleutian Trench south of Alaska [31,32,33,34,35,36,37,38]
Summary
The documentation of coastal change is important at a time of rising eustatic sea levels [1,2]. Understanding the history of coastal change at a given location is important for correctly interpreting future hazards at the location and can serve as a proxy for understanding similar hazards and change at other locations. Such documentation is critical for correctly interpreting the geologic history of islands and coasts [4]. This paper documents the evolution and change of a sea arch in a small island off of the northeast coast of the larger Hawaiian Island of Oahu, as well as other changes to the nearby coastal peninsula—changes caused by short-duration, but high energy events related to storms and tsunamis.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
