Review of Historical Earthquakes in the Lower Middle Ages: Earthquakes of the XIV and XV Centuries in Catalonia (NE Spain) - Historical Seismology: Interdisciplinary Studies of Past and Recent Earthquakes - page 152

Fig. 5 Intensity decay data
points for the earthquake of 3
March 1373. The solid line
represents the fit to the
Sponheuer attenuation law

presented in Section 2. These estimates are presented in Table 3. For a same earth-
quake the values of magnitude obtained by different methods show a quite large
dispersion; this is due to several factors:

- the different magnitude scales used (Ms, Mw, Macroseismic magnitude, ),

- the uncertainties associated to each empirical relation for the various magnitude
intervals and for the various regions considered,
- and last but not least, the number of intensity data points available for each earth-
quake and the quality on their intensity assessment.

...

As the documentary review has been finalized and the full set of intensity data points
are available (Olivera et al. 2006), a more detailed study will be undertaken to obtain
a specific relation between isoseismal areas and Mo for the study region.

Fig. 6 Intensity decay data
points for the earthquake of 2
February 1428. The solid line
represents the fit to the
Sponheuer attenuation law