Sea level changes can trigger earthquake sequences in a hydrothermal
system near Istanbul
Abstract
Small stress changes such as those from tidal loading can be enough to
trigger earthquakes. If small and large earthquakes initiate similarly,
high resolution catalogs with low detection thresholds are best suited
to illuminate such processes. Below the Sea of Marmara section of the
North Anatolian Fault, a segment of 150 km is late in its seismic cycle.
We generated high-resolution seismicity catalogs for a hydrothermal
region in the eastern Sea of Marmara employing both AI-based and
template matching techniques to investigate a complex long-lasting
sequence including seismicity up to MW 4.5. We document
a strong effect of the Sea of Marmara level changes on the local
seismicity. Both high resolution catalogs show that local seismicity
rates are significantly larger during time periods shortly after local
minima on sea level. Local strainmeters indicate that the associated
strain changes, on the order of 30-300 nstrain, are sufficient to
promote seismicity.