Publication Date:
2020-10-27
Description:
Recent studies on seismological data indicate that earthquake magnitude
scales with either the dominant period or the peak amplitude in the seismogram’s first
few seconds. At first sight, this may indicate that the earthquake’s final size is somehow
related to the way rupture starts. One working hypothesis is that strong radiation
from the initial phase of rupture is indicative of a triggering asperity releasing a consistent
amount of elastic energy, with the potential to drive the fracture to large extents.
We tested this concept with a number of numerical simulations, but within the models
investigated, scaling was found only for ruptures extending up to about four times the
size of the initial asperity; at larger distances the correlation was lost. Alternatively, a
careful kinematic analysis of the earthquake source radiation shows that the initial
signal recorded at any station does not necessarily correspond to the rupture initiation
but may represent an extended portion of the radiating source. Using the concept of
isochrones, we show that the apparent scaling may be explained by a simple kinematic
model respecting causality, up to a given magnitude threshold where the scaling relation
saturates. The saturation level is in agreement with that observed in some, but
not all, of the real seismicity catalogs.
Description:
Published
Description:
1-23
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
early warning
;
earthquake magnitude
;
04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
