Abstract
Non-volcanic tremor has been observed at the roots of many fault systems
around the Pacific rim, including convergent and transform plate
boundaries. The extent to which deep tremor signals are prevalent along
plate boundaries elsewhere, including the Mediterranean basin, has not
yet been documented in detail. A body of evidence suggests that tremor
triggered during the surface waves of teleseismic events may commonly
occur where ambient tremor during Episodic Tremor and Slip episodes
occur, suggesting triggered tremor provides a useful tool to identify
regions with ambient tremor. We perform a systematic search of triggered
tremor associated with large teleseismic events between 2010 and 2020,
at four major fault systems within the central-eastern Mediterranean
basin namely the Hellenic and Calabrian subduction zones, and the North
Anatolian and Kefalonia transform faults. In addition, we search for
ambient tremor during a ~50-daylong slow slip event in
the eastern Sea of Marmara along a secondary branch of the North
Anatolian Fault, and two ~4-month long slow slip events
beneath western Peloponnese. We find no unambiguous evidence for deep
triggered tremor nor for ambient tremor. The absence of triggered tremor
at the Hellenic and Calabrian subduction zones supports the less
favorable conditions for tremorgenesis in the presence of old and cold
slabs. The absence of tremor along the transform faults may be due to an
absence of the conditions commonly promoting tremorgenesis in such
settings, including high fluid pressures and low differential stresses
between the down-dip limit of the seismogenic layer and the Moho.