Trapdoor Fault Activation: A Step Toward Caldera Collapse at Sierra Negra, Galápagos, Ecuador

Abstract

Basaltic volcanoes are the most frequently erupting systems on Earth. Well-documented subaerial basaltic eruptions occur at hotspot calderas (Kılauea,

Quantifying Magma Overpressure Beneath a Submarine Caldera: A Mechanical Modeling Approach to Tsunamigenic Trapdoor Faulting Near Kita‐Ioto Island, Japan

“…First, different segments of the intra‐caldera ring fault may have caused microseismic or aseismic slips prior to the occurrence of M w ∼ 5 trapdoor faulting. In Sierra Negra caldera, high microseismicity was observed along the western segment of the intra‐caldera fault, leading to trapdoor faulting on the southern segment before eruption (Bell et al., 2021; Shreve & Delgado, 2023). Similarly, during the 2018 eruption and summit caldera collapse sequence of Kilauea, large collapse events accompanying M w ∼ 5 earthquakes were located on the southeastern and northwestern sides of the summit caldera, while high microseismicity was found on other segments (Lai et al., 2021; Shelly & Thelen, 2019).…”

“…This hypothesis is mainly from analogy with other better-studied calderas, which accompanied vertical-T CLVD earthquakes causing large caldera deformation and/or tsunamis. The trapdoor faulting accompanying a vertical-T CLVD earthquake of M w ∼ 5 was first reported in a subaerial caldera of Sierra Negra volcano in the Galapagos Islands, where the phenomenon occurred several times and caused the caldera uplift of a few meters by each event (Amelung et al, 2000;Gregg et al, 2018;Jónsson, 2009;Shreve & Delgado, 2023;Zheng et al, 2022). Recently, Sandanbata et al (2022 revealed that trapdoor faulting repeated with M w 5.4-5.8 vertical-T CLVD earthquakes and generated large tsunamis at two submarine calderas: Sumisu caldera in the Izu-Bonin Arc (Sandanbata et al, 2022), and a submerged caldera near Curtis Island, or Curtis caldera, in the Kermadec Arc .…”

“…This hypothesis is mainly from analogy with other better‐studied calderas, which accompanied vertical‐T CLVD earthquakes causing large caldera deformation and/or tsunamis. The trapdoor faulting accompanying a vertical‐T CLVD earthquake of M w ∼ 5 was first reported in a subaerial caldera of Sierra Negra volcano in the Galapagos Islands, where the phenomenon occurred several times and caused the caldera uplift of a few meters by each event (Amelung et al., 2000; Gregg et al., 2018; Jónsson, 2009; Shreve & Delgado, 2023; Zheng et al., 2022). Recently, Sandanbata et al.…”

The utility of TerraSAR-X, TanDEM-X, and PAZ for studying global volcanic activity: Successes, challenges, and future prospects

“…In addition, if deformation produces geometric distortions without significantly affecting the SAR image reflectivity, displacements can be calculated directly from the amplitudes of SAR images acquired over time through pixel-offset tracking [Casu et al 2011;Pinel et al 2014]. This technique measures deformation in the along-and across-track directions using normalized cross correlation of windows of pixels and has a lower sensitivity to deformation than InSAR, but does not suffer from phase aliasing in zones of large strain [Casu et al 2011;Shreve and Delgado 2023].…”

“…The thicknesses of the lava flows erupted on the north flank at Sierra Negra (Galápagos) in 2018 (Figure 12) have been calculated by using both a DEM derived from Pléiades optical images subtracted from the 12 m TanDEM-X WorldDEM [Shreve and Delgado 2023], and by using bistatic TSX/TDX (CoSSC) data subtracted from the same WorldDEM (Table 2)…”