Insights into tectonic hazards since the 2004 Indian Ocean earthquake and tsunami
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The 11-month precursory fault activation of the 2019 ML 5.6 earthquake in the Weiyuan shale gas field, China
Anthropogenic activities such as hydraulic fracturing (HF) can trigger destructive earthquakes, the triggering mechanisms of which are still in debate. We utilize near-fault seismic recordings to study the preparatory phase of the 2019 ML 5.6 earthquake in the Weiyuan shale gas field (WSGF), Sichuan Basin, China, which struck 3 months after stimulation completion. This is one of the largest HF-triggered earthquakes worldwide. We observed an 11-month-long precursory fault activation, during which continuous seismicity illuminated the fault plane and provided warnings for a potential destructive earthquake. The fault activation is a consequence of injections in multiple HF well pads, with a variety of mechanisms at play. Numerical simulation reveals that the occurrence of the mainshock involves stress perturbation from post-injection aseismic slip. This work promotes our understanding of HF-induced earthquakes and suggests incorporating long-term near-fault observations and taking post-injection aseismic slip into account for effective hazard management.
The 2023 Türkiye-Syria earthquake disaster was exacerbated by an atmospheric river
Strong earthquakes in mountain landscapes can trigger widespread slope failures, initiating chains of multiple hydro-geomorphic hazards. These impacts disrupting ongoing response operations may be amplified by extreme post-seismic precipitation delivered by atmospheric rivers (ARs). However, to our knowledge, cases of ARs following major earthquakes have not been previously documented. Here, we document the combined effects of seismic and precipitation extremes that perturbed the area struck by the February 6, 2023, Türkiye-Syrian earthquakes. Strong ground shaking triggered thousands of landslides, and 36 days later, an exceptionally strong AR delivered up to 183 mm of precipitation in just 20 hours. This extreme precipitation induced additional landslides, debris flows, and flooding, disrupting recovery efforts, affecting temporary settlement areas, and claiming more lives. This cascade of hazards highlights the need to integrate seismic and weather extremes into rapid hazard assessment protocols to enhance disaster preparedness and response.
Feature of cascading rupture frequently observed in Northern California
Understanding if earthquakes of different sizes start in the same way and whether the growth process of the rupture of large earthquakes is predictable are fundamental questions in earthquake physics. Recent studies indicate the onsets of seismic waves from small and large earthquakes exhibit similar characteristics, suggesting that an earthquake’s onset does not dictate its final size. However, the factors controlling this process remain unclear. A systematic comparison of 24 years of high-sensitivity seismograph records using cross-correlation for ~75,000 events reveals 125 extremely similar and 1939 similar pairs of co-located large and small earthquakes. An extremely high similarity is observed for pairs of earthquakes occurring on simple faults (44 of 55 large events), whereas large earthquakes occurring on complex faults have a low probability of cascading rupture. Estimating the probability of cascading rupture based primarily on fault geometry can improve the predictability of future earthquakes with a more quantitative size estimation.
Climate change alters the Indian Ocean Dipole and weakens its North Atlantic teleconnection
An important source of long range forecast skill for the North Atlantic Oscillation (NAO) comes from predictability of tropical rainfall. While the El Niño Southern Oscillation (ENSO) is a better-known driver of the NAO, the Indian Ocean Dipole (IOD) also has an influence, particularly when ENSO is inactive. Given future projected changes to ENSO and the IOD, it is important to understand how the IOD–NAO teleconnection may evolve. Here we use climate model simulations to investigate the IOD and its NAO teleconnection. We find that the IOD itself changes considerably under climate change, with a weakening of the present-day anticorrelation between the dipole nodes and a westward shift in the IOD pattern. While historical model simulations reproduce the IOD–NAO teleconnection pathway seen in observational analyses, the teleconnection is projected to weaken in future, with the weakening linked to the westward IOD shift.
Active ice sheet conservation cannot stop the retreat of Sermeq Kujalleq glacier, Greenland
Active conservation of an ice sheet seeks to reduce ice sheet mass loss and sea level rise. Here we explore the response of Sermeq Kujalleq in Greenland to limiting warm water inflow to the fjord it terminates by raising the sill by an artificial barrier at its mouth. We asynchronously couple an ice sheet model with a fjord model, and simulate glacier evolution with varying climate scenarios from the year 2020 to 2100. The tallest barrier cools the fjord water and reduces melt at the ice front. But this has minor impacts on glacier retreat under SSP5-8.5 and SSP2-4.5. Cooling the atmospheric forcing to 1990s levels reduces glacier retreat, but even reducing water temperatures with a barrier cannot stabilize the glacier. The glacier seems to be in an unstoppable phase of marine ice sheet instability on a rapidly deepening retrograde sloping bed and in water much deeper than in 2000s.
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