catalogo de terremotos para america del sur catalog of earthquakes ...

108
Ecuador: Magnitudes (mb) were provided from the project SISAN. A
description of these magnitudes is included in Ocola (1984). Other magnitudes
with the source code OAE and the scale code K were converted from MSK
intensities using the formula given in equation 9 above.
Peru: The InstLtuto Geofisica del Peru (IGP) has computed magnitudes (mb)
for, many events prior to 1963. These were based on seismograms from the
seismograph stations in Huancayo, Peru, and La Paz, Bolivia, using the
following eo'atin:
mb = log(A/T) + Q (10)
where Q is determined from Q(PZ) charts given by Duda (1970). Additional mb
magnitudes, identified by the code IGH, were calculated from a set of
unpublished data by Daniel Huaco of IGP. For non-instrumental events,
magnitudes were calculated from maximum intensities and labeled with scale
code 'I', using the following formulas:
M = 0.090 10 + 4.147 log (h) + 0.752
for I > 6 and 0 < h < 33 (11)
M = 0.472 10 - 5.361 log (h) + 13.023
for 10> 6 and 3 < h < 100 (12)
M = 0.287 I o + 1.200 log (h) + 1.703
for 2 < 10 < 6 and 0 < h < 33 (13)
M = 0.284 + 4.223 log (h) - 4.147
for 2 < 10 < 6 and 33 < h < 130 (14)
where h is depth, and T ° is the maximum Intensity on the MSK scale. In order
to convert from MSK to MM intensities, all available intensity data were
examined. The Peruvian investigators used not only the maximum observed