Stormquakes

Abstract

Seismic signals from ocean‐solid Earth interactions are ubiquitously recorded on our planet. However, these wavefields are typically incoherent in the time domain limiting their utilization for understanding ocean dynamics or solid Earth properties. In contrast, we find that during large storms such as hurricanes and Nor'easters the interaction of long‐period ocean waves with shallow seafloor features located near the edge of continental shelves, known as ocean banks, excites coherent transcontinental Rayleigh wave packets in the 20‐ to 50‐s period band. These “stormquakes” migrate coincident with the storms but are effectively spatiotemporally focused seismic point sources with equivalent earthquake magnitudes that can be greater than 3.5. Stormquakes thus provide new coherent sources to investigate Earth structure in locations that typically lack both seismic instrumentation and earthquakes. Moreover, they provide a new geophysical observable with high spatial and temporal resolution with which to investigate ocean wave dynamics during large storms.

Abundant Spontaneous and Dynamically Triggered Submarine Landslides in the Gulf of Mexico

“…Details are discussed in the Supporting Information. Rayleigh waves have been used successfully for detecting and locating unconventional seismic sources, including glacial quakes, landslides, and stormquakes (Ekström et al, 2003;Fan et al, 2019;Tsai & Ekström, 2007). These events commonly have long durations, are depleted in high-frequencies, lack clear seismic arrivals, and have low signal-to-noise ratios (SNR) (Ekström et al, 2003;Shearer et al, 2011;Tsai & Ekström, 2007).…”

“…These challenges make unconventional seismic sources difficult to detect, and they are commonly missed in standard earthquake catalogs (Ekström, 2006;Shearer, 1994). Our method, which is designed to detect and locate any source of seismic radiation, applies to continuous data and does not require seismic The method divides continental-scale seismic arrays into nonoverlapping triangular subarrays (triads) to measure local surface-wave coherence, and then inverts for a source location using the resolved surface-wave propagation directions and arrival times from the triads (e.g., Figure 2) (Fan et al, 2018(Fan et al, , 2019. To assure the robustness of the detected submarine landslides, only sources seen by more than 150 triads and having location uncertainty less than 5 • are considered in this study (Supporting Information).…”

On the Eigen‐Mode Excitation of Linear Oscillators and the Earth's Polar Motion

“…It has been established that short‐period oceanic waves can induce vibrations in the solid Earth ranging from low‐frequency tremor [ 21 ] to detectable real earthquakes. [ 22 ] These waves are certainly capable of exciting the Chandler Wobble. Practically, however, those short‐period localized waves are most likely averaged out in global integrations unless they are sizable storms.…”

L’espace littoral des territoires ultra-marins français de l’Océanie face aux défis des changements globaux

“…Ils sont également concernés par les dépressions extratropicales et d'origine polaire circulant au sud du Tropique du Capricorne pendant la saison fraîche (hiver austral). On exclut volontairement dans cette présentation sur les aléas naturels de la zone littorale océanienne les tsunamis qui ne sont pas directement associés aux changements globaux si l'on n'intègre pas dans le raisonnement l'hypothèse des « stormquakes » ou secousses de tempêtes récemment formulée par WENYUAN et al, (2019). L'étude portant sur plus de 10 000 séismes survenus entre 2006 et 2019 sur la côte ouest américaine met en évidence, en effet, une relation entre les séismes se produisant pendant la saison cyclonique et le passage des cyclones.…”