New information available about Leilani Estates Mw 6.9 earthquake

New analysis of ground motion (deformation) reveals details of the Mw 6.9 Leilani Estates earthquake. Credit: Smith-Konter, et al., 2018.

On April 30, 2018, along the East Rift Zone of Kilauea Volcano, Pu’u ‘O’o crater began to collapse, followed by increased seismicity and deformation (ground motion) down-rift. Observations of deflationary tilt at the summit began and small ground cracks opened near Leilani Estates on May 1-2.  On May 3,  eruptive surface fissures began inundating the community of Leilani Estates, marking the official onset of eruption by the Hawaiian Volcanoes Observatory. On May 4, 2018, a Mw6.9 earthquake struck the south flank of Kilauea, manifested as slip along a shallow dipping thrust fault with a hypocenter at ~2km depth. Increased seismicity began at the summit and has been followed by continued deflation. Along the rift zone, seismicity and deformation continue, with 18 fissure eruptions as of May 13.

InSAR (Interferometric Synthetic Aperture Radar) maps ground motion (or deformation) using radar images of the Earth’s surface that are collected from orbiting satellites.  When two radar images (taken at different times) are combined, differences may appear if the ground moved over the time that the images were taken.   Ground motion can be horizontal (like to the north or to the east), or it can be vertical (like up or down), or it can be a combination of these.

New InSAR maps created by a team of SOEST geophysicists, show motion along Kilauea as a result of volcanic and earthquake processes.   The InSAR rainbow “fringe” patterns indicate where the most motion occurs.   One complete rainbow is roughly equivalent to 2.8 cm of motion toward or away from the satellite.   Lots of fringes mean lots of motion.

Radar line-of-sight (LOS) maps are also generated to observe crustal motions.

Radar line-of-sight (LOS) maps are also generated to observe crustal motions.   In these maps (representing motion viewed from the satellite), red colors show primarily upward motion and blue show down, but east or west directed motions are also recorded.   The colorbar labels help interpret the horizontal (east or west direction of motion).

View all the new maps here.