TY - JOUR
T1 - The 'tsunami earthquake' of 1932 June 22 in Manzanillo, Mexico
T2 - Seismological study and tsunami simulations
AU - Okal, Emile A.
AU - Borrero, José C.
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2011/12
Y1 - 2011/12
N2 - We conduct a detailed seismological study of the large Colima, Mexico earthquake of 1932 June 3 and of its aftershocks of June 18 and 22. The latter (Event III) generated a tsunami more devastating than that of the main shock despite much smaller seismic magnitudes, thus qualifying as a so-called 'tsunami earthquake'. Relocation based on published arrival times shows that Event III took place up-dip of the main shock. The analysis of the spectral amplitude of mantle surface waves yields low-frequency moments of 24, 5.2 and 4 times 1027 dyn cm, respectively, with Event III featuring a moment growing with period, which expresses the source slowness characteristic of 'tsunami earthquakes'. This is confirmed by a deficient energy-to-moment ratio, as derived from high-frequency P waves recorded at Pasadena. Near-field hydrodynamic simulations show that the effects of the main shock's tsunami are well modelled by a standard seismic source, whereas the stronger tsunami from Event III can be modelled by rupture along a splay fault in a mechanically deficient material. All our results then fit the model for 'tsunami earthquake' aftershocks proposed for the Kuril Islands by Fukao in 1979.
AB - We conduct a detailed seismological study of the large Colima, Mexico earthquake of 1932 June 3 and of its aftershocks of June 18 and 22. The latter (Event III) generated a tsunami more devastating than that of the main shock despite much smaller seismic magnitudes, thus qualifying as a so-called 'tsunami earthquake'. Relocation based on published arrival times shows that Event III took place up-dip of the main shock. The analysis of the spectral amplitude of mantle surface waves yields low-frequency moments of 24, 5.2 and 4 times 1027 dyn cm, respectively, with Event III featuring a moment growing with period, which expresses the source slowness characteristic of 'tsunami earthquakes'. This is confirmed by a deficient energy-to-moment ratio, as derived from high-frequency P waves recorded at Pasadena. Near-field hydrodynamic simulations show that the effects of the main shock's tsunami are well modelled by a standard seismic source, whereas the stronger tsunami from Event III can be modelled by rupture along a splay fault in a mechanically deficient material. All our results then fit the model for 'tsunami earthquake' aftershocks proposed for the Kuril Islands by Fukao in 1979.
KW - Earthquake source observations
KW - Pacific Ocean
KW - Tsunamis
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U2 - 10.1111/j.1365-246X.2011.05199.x
DO - 10.1111/j.1365-246X.2011.05199.x
M3 - Article
AN - SCOPUS:81555219122
VL - 187
SP - 1443
EP - 1459
JO - Geophysical Journal International
JF - Geophysical Journal International
SN - 0956-540X
IS - 3
ER -