List of earthquakes in Ecuador

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This list of earthquakes in Ecuador is a list of notable earthquakes that have affected Ecuador in recorded history. The list is currently incomplete.

Tectonic setting[edit]

The active tectonics of Ecuador is dominated by the effects of the subduction of the Nazca Plate beneath the South American Plate. Ecuador lies within the Northern Volcanic Zone where the subduction zone is moving at a rate of 7 cm/yr to the east-northeast, significantly oblique to the trend of this segment of the Andes. The subduction zone has an overall dip of 25–30°, but varies rapidly along strike due to the effects of subduction of the Carnegie Ridge. The Carnegie Ridge is an oceanic plateau that formed as the Nazca Plate passed over the Galapagos hotspot. The plate interface above the subducted part of the ridge has a shallower dip than the area to both north and south, the boundaries interpreted to consist of two large tears in the downgoing Nazca Plate.[1] The northern part of Ecuador overlies the subducted part of the Carnegie Ridge and is an area where the Nazca Plate is interpreted to be strongly coupled to the South American Plate, causing an unusually large degree of intraplate deformation. The main active fault zones of Ecuador are SSW-NNE trending dextral strike-slip faults running parallel to the main subdivisions of the Andes, two major SW-NE dextral strike-slip zones, the Pallatanga and Chingual faults, and north-south trending reverse faults such as the Quito fault.[2]

Seismicity[edit]

Earthquakes that affect Ecuador can be divided into those that result from movement on the subduction interface along the plate boundary, those that result from deformation within the South American and Nazca Plates and those that are associated with active volcanoes.

Interplate earthquakes[edit]

Megathrust events along the subduction interface generate the largest earthquakes, often triggering destructive tsunamis, such as the 1906 Ecuador-Colombia earthquake.

Intraplate earthquakes[edit]

The most damaging earthquakes to affect Ecuador are those associated with faulting within the South American Plate, such as the 1949 Ambato earthquake.

Earthquakes within the downgoing Nazca Plate, such as the Mw 7.1 event of August 2010, are generally too deep to cause significant damage in Ecuador although they are felt over a wide area.[3]

Volcanic earthquakes[edit]

Swarms of relatively small earthquakes are commonly associated with volcanic activity, such as the Quito swarm in 1998-1999 related to the Guagua Pichincha volcano.[4]

List of notable earthquakes[edit]

Date Time‡ Place Latitude Longitude Fatalities Magnitude Comments Sources
4 February 1797 12:30 Riobamba
see 1797 Riobamba earthquake
-1.6 -78.6 6,000-40,000 8.3 ML [5]
15 August 1868 19:30 Carchi Province
see 1868 Ecuador earthquakes
0.81 -77.72 8.0 Ms [6]
16 August 1868 06:30 Ibarra
see 1868 Ecuador earthquakes
0.31 -78.18 40,000+ 7.7 Ms [6]
31 January 1906 15:36 Esmeraldas
see 1906 Ecuador-Colombia earthquake
1.0 -81.5 ~1,000 8.8 Mw Triggered a large tsunami that caused at least 500 casualties on the coast of Colombia [7]
5 August 1949 19:08 Ambato
see 1949 Ambato earthquake
-1.5 -78.2 5,050 6.8 ML [8]
19 January 1958 09:09 Esmeraldas
see 1958 Ecuador-Colombia earthquake
-1.5 -79.5 11 7.6 Ms [9]
6 March 1987 01:54 & 04:10 Napo Province
see 1987 Ecuador earthquakes
0.09 -77.37 >1,000 6.1 & 6.9 Ms [10]
4 August 1998 13:59 Bahia de Caraquez, Manabi
0.49 -81.76 3 7.2 Mw [11]
12 August 2010 11:54:16 145 km east of Riobamba -1.260 -77.312 7.1 Mw Intermediate focus earthquake (211 km) within the Nazca Plate, a result of normal faulting, causing slight damage over a wide area [3][12]

Magnitudes - Mw Moment magnitude scale, ML Richter magnitude scale, Ms Surface wave magnitude

See also[edit]

References[edit]

  1. ^ Gutscher, M.-A.; Malavieille J., Lallemand S. & Collot J.-Y. (1999). "Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision". Earth and Planetary Science Letters 168: 255–270. Bibcode:1999E&PSL.168..255G. doi:10.1016/S0012-821X(99)00060-6. Retrieved 24 August 2010. 
  2. ^ Eguez, A.; Alvarado A., Yepes H., Machette M.N., Costa C. & Dart R.L. "Database and Map of Quaternary faults and folds of Ecuador and its offshore regions". USGS Open-File Report 03-289. pp. 2–3. Retrieved 22 August 2010. 
  3. ^ a b USGS (20 August 2010). "Magnitude 7.1 - ECUADOR 12 August 2010 11:54:16 UTC". Retrieved 24 August 2010. 
  4. ^ Legrand, D.; Villagómez D., Yepes H. & Calahorrano A. (2004). "Multifractal dimension and b value analysis of the 1998–1999 Quito swarm related to Guagua Pichincha volcano activity, Ecuador". Journal of Geophysical Research 109 (B01307). Bibcode:2004JGRB..10901307L. doi:10.1029/2003JB002572. Retrieved 24 August 2010. 
  5. ^ NGDC. "Comments for the Significant Earthquake". Retrieved 20 August 2010. 
  6. ^ a b Giesecke, A.; Capera A.A.G., Leschiutta I., Migliorini E. & Valverde L.R. (2004). "The CERESIS earthquake catalogue and database of the Andean Region: background, characteristics and examples of use". Annals of Geophysics 47 (2/3): 421–435. Retrieved 22 August 2010. 
  7. ^ Mendoza, C.; Dewey J.W. (1984). "Seismicity associated with the great Colombia-Ecuador earthquakes of 1942, 1958, and 1979: Implications for barrier models of earthquake rupture". Bulletin of the Seismological Society of America 74 (2): 577–593. Retrieved 2010-03-07. 
  8. ^ NGDC. "Comments for the Significant Earthquake". Retrieved 22 August 2010. 
  9. ^ http://www.ngdc.noaa.gov/nndc/struts/results?eq_0=4160&t=101650&s=13&d=22,26,13,12&nd=display
  10. ^ Focal Mechanisms of the March 6, 1987 Ecuador Earthquakes
  11. ^ NGDC. "Comments for the Significant Earthquake". Retrieved 22 February 2011. 
  12. ^ USGS (20 August 2010). "2010 August 12 11:54:16 UTC Earthquake Details". Retrieved 22 August 2010.