A Long‐Term Earthquake Catalog for the Endeavour Segment: Constraints on the Extensional Cycle and Evidence for Hydrothermal Venting Supported by Propagating Rifts

Abstract

To study the global mid-ocean ridge (MOR) system is to study the creation of Earth's oceanic lithosphere. Extension from seafloor spreading is accommodated in two ways: during episodic diking events, magma is injected into and cools within ridge-parallel dikes that sometimes feed eruptions (Delaney et al., 1998), and both during and between discrete spreading events, extension is also accommodated by faulting (e.g., Buck et al., 2005). The relative contributions from volcanic and tectonic processes at MORs vary widely both spatially (e.g., Karson et al., 1987) and temporally (e.g., Kappel & Ryan, 1986), depending on spreading rate, magma supply, and the effects of hydrothermal cooling on rheology (Behn & Ito, 2008;Chen & Morgan, 1990). The periodicity of diking events means that MOR activity is intrinsically cyclical. Detailed observations not only of discrete

Seismic Constraints on Hydrothermal Circulation and Magmato‐Tectonic Interactions Beneath Lucky Strike Volcano, Mid‐Atlantic Ridge

“…We compared the observed seismicity rate beneath the Lucky Strike hydrothermal field (∼5.4 events/week, Mc = −0.5; Figure 3c) with normalized seismicity rates for other MOR hydrothermal fields, calculated by scaling their corresponding Mc values to same as the Lucky Strike summit region (Table S3 in Supporting Information ). The observed seismicity rate at Lucky Strike is significantly lower than the rates at other hydrothermal fields at fast/intermediate spreading segments (9°50′N EPR hydrothermal field; Tolstoy et al., 2008 and main Endeavour field; Krauss et al., 2023) and at detachment‐dominated slow/ultraslow spreading segment ends (TAG hydrothermal field; de Martin et al., 2007; Rainbow hydrothermal field; Horning et al., 2018; Southwest Indian Ridge's 64°30′E nearly amagmatic ridge region; Chen et al., 2023). The higher rates at fast/intermediate spreading segments could reflect the higher melt influx and faster spreading rates in those areas, enhancing both thermal cooling and tectonic cracking.…”

Seismology in the cloud: guidance for the individual researcher

“…In contrast to the 11,000 located earthquakes in the Krauss et al (2023b) catalog, the TM and EQT workflows find 3,543 and 924 earthquakes, respectively (Figure 5a). Notably, TM and EQT find comparable numbers of picks that are common to the Krauss et al (2023b) catalog (Figure 5b), even though TM decisively finds more earthquakes overall (Figure 5a). The picks found by the TM method are mostly "new" picks: only 2% of the TM picks were also in the Krauss et al (2023b) catalog.…”

“…For the TM detection, we use a set of 53 templates that were chosen as representative of the most frequentlyoccurring families of earthquakes with high waveform similarity during 2017 following . This is far fewer than the total number of earthquakes (> 11,000) in the Krauss et al (2023b) catalog for 2017 (Figure 5a), such that we do not expect the TM de-tection to be able to fully reconstruct the entire catalog. We present the TM detections that have a summed absolute cross correlation across the eight template channels greater than 3.2 (Figure 5), equivalent to a median absolute deviation threshold near 8.…”

“…Notably, TM and EQT find comparable numbers of picks that are common to the Krauss et al (2023b) catalog (Figure 5b), even though TM decisively finds more earthquakes overall (Figure 5a). The picks found by the TM method are mostly "new" picks: only 2% of the TM picks were also in the Krauss et al (2023b) catalog. This suggests that the picks found by TM are almost entirely just smaller or noisier examples of the template events that went undetected by traditional methods.…”

“…Most recorded earthquakes are located within 40 km of the network. For ground truth comparison of the results of TM and EQT detection, we use the catalog of Krauss et al (2023b), which was created using traditional STA/LTA methods and has a magnitude of completeness of Mw ~0.5 for earthquakes within the network.…”