Emergency room visits for respiratory conditions in children increased after Guagua Pichincha volcanic eruptions in April 2000 in Quito, Ecuador observational study: time series analysis.

BACKGROUND: This study documented elevated rates of emergency room (ER) visits for acute upper and lower respiratory infections and asthma-related conditions in the children of Quito, Ecuador associated with the eruption of Guagua Pichincha in April of 2000. METHODS: We abstracted 5169 (43% females) ER records with primary respiratory conditions treated from January 1-December 27, 2000 and examined the change in pediatric ER visits for respiratory conditions before, during, and after exposure events of April, 2000. We applied a Poisson regression model adapted to time series of cases for three non-overlapping disease categories: acute upper respiratory infection (AURI), acute lower respiratory infection (ALRI), and asthma-related conditions in boys and girls for three age groups: 0-4, 5-9, and 10-15 years. RESULTS: At the main pediatric medical facility, the Baca Ortiz Pediatric Hospital, the rate of emergency room (ER) visits due to respiratory conditions substantially increased in the three weeks after eruption (RR = 2.22, 95%CI = [1.95, 2.52] and RR = 1.72 95%CI = [1.49, 1.97] for lower and upper respiratory tract infections respectively. The largest impact of eruptions on respiratory distress was observed in children younger than 5 years (RR = 2.21, 95%CI = [1.79, 2.73] and RR = 2.16 95%CI = [1.67, 2.76] in boys and girls respectively). The rate of asthma and asthma-related diagnosis doubled during the period of volcano fumarolic activity (RR = 1.97, 95%CI = [1.19, 3.24]). Overall, 28 days of volcanic activity and ash releases resulted in 345 (95%CI = [241, 460]) additional ER visits due to respiratory conditions. CONCLUSION: The study has demonstrated strong relationship between ash exposure and respiratory effects in children.

Las nubes de ceniza del volcán Tungurahua entre octubre 1999 y septiembre 2001

El seguimiento visual de la actividad eruptiva del volcán Tungurahua permitió conocer con mas exactitud la zona de influencia por caída y dispersión de piroclásticos. Así la ceniza, gases y vapor son predominantes llevados y distribuidos al Oeste. Los materiales expulsados por las explosiones, emisiones y/o fuentes de lava no siempre son detectados por los satélites. En este caso es necesario aplicar parámetros volcanológicos. Las relaciones matemáticas del Desplazamiento Reducido (DR, Aki y Koyagani, 1981) con respecto a la Altura de las Columnas de Ceniza (ACC) y pronóstico de la actividad. Así es posible coordinar acciones en el Departamento de Geofísica, Dirección de Aviación Civil, Instituto de Meteorología e Hidrológia, INAMHI y autoridades. (AU)

El sismo de Santa Rosa del Tejar (5.4 mb), provincia de Imbabura del 8 de octubre de 2000

El 8 de octubre del año 2000, en el sector de Santa Rosa del tejar (sur de Ibarra) se produjo un sismo de magnitud 5.4 (mb-RENSIG, 2000), generando daños en la zona epicentral. Este evento posiblemente esta relacionado a un sistema de fallas, que a partir de datos de campo se estimó tenia una componente de movimiento siniestral. El mecanismo focal obtenido del evento principal indica una falla transcurrente siniestral con una componente inversa. El evento ocurrió en una zona en que no se ha reportado eventos de importancia anteriormente. (AU)

Patrones sísmicos de Bahía en la zona de subducción ecuatoriano

La zona costera centro-norte del Ecuador se ha visto afectada por varios terremotos con magnitudes mayores a 6.9 Ms como consecuencia del fenómeno de subducción de la Placa Nazca bajo Sudamérica. El registro de la actividad sísmica desde 1991 ha permitido identificar zonas con mayor actividad sísmica y patrones que precedieron al Terremoto de Bahía de 1998 (6.8Mw). estos patrones son gaps y semi-donas simples (Magi, 1985) y compuestas que limitaron la zona de ruptura de este terremoto y que a su vez, delimitan otra zona entre Jama y Punta Galera donde no se ha registrado importante actividad sísmica y que podría registrar un sismo de hasta 7.5 grados. (AU)

Evaluation of seismic hazard in Ecuador

An evaluation of the seismic hazard for Ecuador is presented. Recently recognized noetectonic evidence of main continental fault systems was used. Seismic data for all Ecuador were analyzed to evaluate homogeneity using prediction techniques, historic seismicity and 75 focal mechanisms were studied to obtain source geometry (strike, dip, hypocentral depth and maximum magnitude). Ten seismotectonic provinces were defined and 53 seismic sources were identified. Their seismologic parameters, such as minimum magnitude of homogeneity, B value and activity rate were evaluated. By calibrating the attenuation laws with the values recorded in the Geophysical Institute accelerograph network, two laws were prefered, one for subduction processes using Saragoni's relation (obtained from subduction in Perú, Chile and Argentina), and another for continental faulting using Donovan's law (obtained from world averages). Following a Poison process isoacceleration maps for 200 and 475 years return periods were generated. The results show a good correlation with the maximum MSK historic intensities in Ecuador. The highest values are for the central zone of the Interandean Valley with 160 and 191 gals for 200 and 475 years respectively (AU)