This electronic supplement provides a detailed compilation of the macroseismic intensity observations for the 2 October 1847 ~7:30 a.m. local time (LT) Tecomán subduction zone earthquake (Electronic Supplement S1) and the 2 October 1847 ~9:30 a.m. LT Chapala graben crustal earthquake (Electronic Supplement S2). The subduction zone earthquake was devastating in Tecomán. It caused severe damage in the towns of Colima and Zapotlán el Grande (now Ciudad Guzmán), minor damage in Mexico City, and was felt in the epicentral region of the subsequent devastating Chapala graben crustal earthquake as well as in Guadalajara. The intensity data points (IDPs) of the ~9:30 a.m. LT Chapala graben crustal earthquake, which occurred only two hours later, are limited to Guadalajara and the high-intensity region north of Lake Chapala (Fig. 2 in the main article). Previous studies including macroseismic information about these earthquakes (e.g., Figueroa, 1974; García Acosta and Suárez Reynoso, 1996; Núñez Cornú, 2011) did not discriminate between these two sources but assumed a single source.
The locations (9 for the subduction zone earthquake and 14 for the crustal earthquake) are listed in alphabetical order, followed by their coordinates. For each IDP, some key observations (mostly in Spanish) are indicated from primary sources. For each observation, I determined the related intensity (marked in red) based on the modified Mercalli intensity (MMI) scale (version by Brazee, 1979). The summary value for each IDP is marked in green after its coordinates. These are the values on which the macroseismic map (Fig. 2 in the main article) is based.
Most of this macroseismic information was extracted from newspaper reports. An exception are the letters by the Ocotlán and La Barca parish priests, Julián Martín del Campo, and Ramón Castillón, to the Bishop of Guadalajara, Diego Aranda, both dated 4 October 1847, which are preserved at Archivo Histórico de la Arquidiócesis de Guadalajara. Details about the sources are provided in the intensity listings and in Data and Resources of the main article.
Unfortunately, not much specific information is available about the type of constructions in the epicentral region of the crustal earthquake, which would permit more concise intensity assignments. The Capilla de la Purísima Concepción in Ocotlán, a sixteenth-century stone-and-mortar construction, remained standing but was severely fractured, whereas the sixteenth-century San Pedro y San Pablo convent in Poncitlán, also made of masonry (Kubler, 1948, and references therein), was razed. Most residential buildings were likely one-story adobe constructions. The intensity assignments might be somewhat high, given the likely vulnerability of local structures at the time. High intensities are notoriously difficult to determine in cases where all local structures were highly vulnerable (S. Hough, written comm., 2017).
I have not been able to find macroseismic information about the crustal earthquake either for the region between Poncitlán and Guadalajara or the population centers on the north shore of Lake Chapala. Furthermore, no macroseismic observations have been compiled for the region south of the Lerma River (Fig. 2 in the main article), which belongs to the state of Michoacán. I have not searched local Michoacán newspapers or archives. It is therefore likely that the felt area or even the damage area of the crustal earthquake extends somewhat farther south. However, no reports from that region could be found in the consulted American or Mexican national newspapers.
An economic hub in the epicentral region of the crustal earthquake seems to have been Hacienda San Andrés, located somewhat east of Ocotlán, which was owned by the Augustinian convent in Guadalajara and leased to Pedro Castellanos (Lancaster-Jones, 1964), who also owned the tavern at the nearby Santiago River crossing. According to the letter by Ramón Castillón, both the hacienda buildings and the tavern were destroyed by the earthquake (see below). A request by Castellanos to be reimbursed for the repair of the earthquake damage to the hacienda buildings was declined by their owner (Fray Silverio García dice que el Colegio de Guadalajara no esta obligado a indemnizar a Don Pedro Castellanos por los males que sufrió con el temblor del año del 47. Salamanca, 17 de noviembre de 1848; Biblioteca Pública del Estado de Jalisco/Fondo Franciscano/vol. 13/identificador 108/no. 1008). A preserved repair bill (Cuenta de gastos en la reposición casas nuevas, Guadalajara, 4 de 1848; Biblioteca Pública del Estado de Jalisco/Fondo Franciscano/vol. 3/identificador 224/no. 435) amounted to $2123 Pesos, as compared to the annual lease valued at $1800 Pesos (Lancaster-Jones, 1964). However, both documents do not provide specific information about the earthquake damage at Hacienda San Andrés or the construction material of the main hacienda building.
Intensity observations in Mexico City of the 2 October 1847 Tecomán earthquake were widely published in the United States newspapers because the earthquake happened during the United States invasion of Mexico, and the capital was occupied at that time by American troops. On the other hand, a mix-up occurred in several United States newspapers between the 2 October 1847 Ocotlán, Jalisco, earthquake and the 19 October 1847 battle of Atlixco, Puebla, resulting in a spurious devastating 23 October 1847 Atlixco, Puebla, earthquake, which was included in the catalog of Mexican earthquakes by Perrey (1847, p. 21) and the worldwide catalog of destructive earthquakes by Milne (1912, p. 61). For example, in The Caledonian (St. Johnsbury, Vermont) (issue of 4 December 1847, p. 3), the fictitious earthquake was reported as follows:
Terrible earthquake at Atlixco−…letters had come from the city of Mexico, announcing that on the 23d of October, the city of Atlixco was totally destroyed by an earthquake. Not a house was left standing, and a large portion of the inhabitants were buried under the ruins. Much damage was also done to the surrounding country and in the neighboring villages and monasteries many of which were overthrown. Only three days previous to the destruction of Atlixco by an earthquake, that city had experienced, to some extent the horrors of a bombardment….
The mix-up was corrected in the Vermont Phoenix (issue of 3 December 1847, p. 3):
There was a mistake in the name of the Mexican city which was lately destroyed by an earthquake. Instead of being Atlixco, it was a place in the State of Jalisco, called Ocotlán. The effects of the disaster are briefly described as having been most terrible and wide-spread. The telegraph is responsible for the error concerning the name.
Electronic Supplement S1 [Adobe PDF; ~23 KB]. Macroseismic intensities for the 2 October 1847 ~7:30 a.m. LT Tecomán earthquake.
Electronic Supplement S2 [Adobe PDF; ~87 KB]. Macroseismic intensities for the 2 October 1847 ~9:30 a.m. LT Chapala graben earthquake.
Brazee, R. J. (1979). Reevaluation of modified Mercalli intensity scale for earthquakes using distance as determinant, Bull. Seismol. Soc. Am. 69, 911–924.
Dávila Garibi, J. I. (1967). Apuntes para la historia de la iglesia en Guadalajara, Vol. 4, parte 2, Editorial Cultura, Ciudad de México, Mexico, 1477 pp. (in Spanish).
Figueroa, J. (1974). Sismicidad en Colima. Macrosismo del 30 de enero de 1973, Report No. 332, Universidad Nacional Autónoma de México, Instituto de Ingeniería, Mexico City, Mexico, 49 pp. (in Spanish).
García Acosta, V., and G. Suárez Reynoso (1996). Los sismos en la historia de México, Universidad Nacional Autónoma de México, Centro de Investigaciones y Estudios Superiores en Antropología Social, and Fondo de Cultura Económica, México City, Mexico, 718 pp. (in Spanish).
Gerhard, P. (1996). La Frontera norte de la Nueva España, Universidad Nacional Autónoma de México, Mexico City, Mexico, 554 pp. (in Spanish).
Kubler, G. (1948). Mexican Architecture of the Sixteenth Century, Vol. 2, Yale University Press, New Haven, Connecticut, 574 pp.
Lancaster-Jones, R. (1964). Bienes del convento Agustino de Guadalajara, Hist. Mex. 13, no. 52, 578–592 (in Spanish).
Milne, J. (1912). A Catalogue of Destructive Earthquakes A.D. 7 to A.D. 1899, British Association for Advancement of Science, Seismological Committee, London, United Kingdom, 92 pp.
Núñez Cornú, F. J. (2011). Peligro sísmico en el bloque de Jalisco, México, Física de la Tierra 23, 199–229 (in Spanish).
Perrey, A. (1847). Documents sur les tremblements de terre au Mexique et dans l'Amérique Central, Ann. Soc. Émul. Vosges 6, no. 2, 1–37 (in French).
Romero, J. G. (1862). Noticia de los terremotos que se han sentido en la República Mexicana, desde la conquista hasta nuestros días, Bol. Soc. Mex. Geogr. Estad. 8, no. 10, 468–470 (in Spanish).
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