San Miguel

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  • Country
  • Subregion Name
  • Primary Volcano Type
  • Last Known Eruption
  • 13.434°N
  • 88.269°W

  • 2130 m
    6986 ft

  • 343100
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

9 April-15 April 2014

According to SNET, the Ministerio de Medio Ambiente y Recursos Naturales (MARN) reported that on 12 April moderate to strong gas plumes from San Miguel rose from the crater and drifted SW. The most robust plume occurred at 1607 and rose 400 m. Images recorded by a webcam showed that the plumes had dark tones, suggesting small amounts of ash.

Source: Servicio Nacional de Estudios Territoriales (SNET)



Index of Monthly Reports

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

04/1970 (CSLP 32-70) Eruption during 30 March-4 April causes ashfall 10 km away

12/1976 (SEAN 01:15) Explosive eruption began on 2 December; ashfall damages crops

03/1977 (BVE 17) New spatter cone in the central crater

12/1980 (SEAN 05:12) Small vapor plume

01/1986 (SEAN 11:01) Ash emission and seismicity

03/1995 (BGVN 20:03) Increased seismicity and minor ashfall near the crater

02/2002 (BGVN 27:02) Minor gas-and-ash emission in January 2002; summary of earlier activity

10/2006 (BGVN 31:10) Restlessness persists during 2005-6; heavy tropical rains trigger lahars

09/2007 (BGVN 32:09) Background seismicity since October 2006; crater visit in July 2007


Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

All times are local (= UTC - 6 hours)

04/1970 (CSLP 32-70) Eruption during 30 March-4 April causes ashfall 10 km away

Card 0902 (03 April 1970) Renewed activity on 30 March

Reports arriving from the city of San Miguel state that Chaparraspique [Chaparrastique] volcano has again become active, at times intensively. It was reported that the first signs that the volcano had become active were noticed at 1300 GMT 30 March and that it continues to be covered by a layer of smoke and mist, which indicates that it may become active again at any moment, forcing the authorities to evacuate the area populated by hundreds of families.

Card 0904 (07 April 1970) Ashfall extends 10 km from the summit; crater visit

"Ash erupted from the crater of San Miguel volcano, El Salvador, on 30 March 1970, at 0230, 0700, and 0800. The first ash eruption, accompanied by a loud noise heard four kilometers away, reached a height of 400 m above the crater floor, according to Sr. Santiago Ventura Arevalo, Secretary of the Finca la Placita, San Miguel, and a report in La Prensa (San Salvador) of 31 March 1970. Ash fell in a fan-shaped area extending at least 10 km NE of the summit. From measurements of ash deposits three and four days after the eruption, the minimum volume of ash is estimated to be 75,000 m3. At the time of the ascent into the crater on 4 April 1970, there was ash in the crater floor to a depth of 15 mm. Infrequent ash eruptions up to 100 m high were observed on 3 and 4 April from the deep chimney in the summit crater. A land-based infrared radiation thermometry survey on 4 April detected no anomalous heat patterns on the NW side of the cone."

Information Contacts:
Card 0902 (03 April 1970) San Salvador Domestic Service, El Salvador.
Card 0904 (07 April 1970) Richard E. Stoiber, Dartmouth College, USA; Ian Lange, Fresno State College; Richard Birnie, USA Cold Reg. Research and Engineering Laboratory.

12/1976 (SEAN 01:15) Explosive eruption began on 2 December; ashfall damages crops

An explosive eruption of San Miguel was reported to have begun during the morning of 2 December. "Smoke", loud noises, and a sulfur smell were reported from the nearby town of San Miguel. By 9 December, the eruption cloud was visible from a considerable distance and ashfalls had caused some crop damage. A few persons were evacuated. Although "fire" was reported by the press, only a white cloud was seen by Richard Stoiber during a 9 December overflight. The last activity at San Miguel was the eruption of more than 75,000 m3 of ash beginning 30 March 1970.

Further Reference. Martinez, M.A., 1977, The eruption of 2 December, 1976 of San Miguel Volcano, Republic of El Salvador, Central America: Centro de Investigaciones Geotécnicas, San Salvador, 4 p.

Information Contacts: AFP; Sercano Radio Network; R. Stoiber, Dartmouth College.

03/77 (BVE 17) New spatter cone in the central crater

The following is based on a report in BVE 17. After 6 years of dormancy since the last activity in 1970, San Miguel started erupting at about 0030 on 2 December 1976. The eruption was characterized by lava fountains. On 12 December the eruption stopped, and fumarole activity was seen around a new spatter cone in the bottom of the central crater. Fifty-six days later, the activity started again during the night of 28 February and lasting until 1 March 1977.

Information Contacts: M.A. Martinez, Centro de Investigaciones Geotécnicas, San Salvador, El Salvador.

12/1980 (SEAN 05:12) Small vapor plume

During a flight over El Salvador by Dartmouth geologists, a small, continuous vapor plume rose from the summit crater.

Information Contacts: R. Stoiber, S. Williams, R. Naslund, L. Malinconico, and M. Conrad, Dartmouth College.

01/1986 (SEAN 11:01) Ash emission and seismicity

Weak steam and ash emission accompanied by frequent small earthquakes began in November and were continuing in early February. The eruption deposited a thin layer of ash near the summit. Geologists installed a telemetering seismometer about 1 km from the summit, recording about 200 discrete microseismic events/day from November through much of January. By the end of January, seismic activity had declined somewhat, to 100-120 events/day.

Information Contacts: José González and Salvador Jesus, Dept de Sismología, Centro de Investigaciones Geotécnicas, San Salvador, El Salvador; David Harlow, USGS.

03/1995 (BGVN 20:03) Increased seismicity and minor ashfall near the crater

New fumaroles were found near the central vent in early January, followed by an increase in seismic activity from an average of 20-30 events/day. On 8 February there were 52 recorded earthquakes. Seismicity increased to 73 events on 19 February, 100 on the 20th, and peaked at 267 on the 21st. This activity then declined on 22 February to an average of 76 events/day, a rate which continued through at least 24 March. Minor ashfall was reported on 23 March within ~100 m of the crater.

The Centro de Investigaciones Geotécnicas (CIG) concluded that this activity was no cause for alarm, but they would increase their monitoring efforts. The population at risk from an eruption with significant ashfall is a mix of urban and rural residents. The city of San Miguel (at the foot of the W flank) has a population of ~150,000, and the rural zone that would likely be affected has a population of ~100,000.

Information Contact: Jorge Alberto Rodríguez Deras, Director, Centro de Investigaciones Geotécnicas, San Salvador, El Salvador.

02/2002 (BGVN 27:02) Minor gas-and-ash emission in January 2002; summary of earlier activity

On 16 January 2002 a gas-and-steam plume containing a little ash rose with a mushroom-like profile a few hundred meters above the summit crater of San Miguel. During a visit to the summit on 28-29 January, Demetrio Escobar and a group from Michigan Technological University observed a thin layer of ash inside the summit crater produced by the 16 January event. COSPEC measurements of 100 metric tons/day were recorded at a time that the plume from San Miguel rose about 100 m above the crater rim. Long-period earthquakes, volcanic tremor, and explosion events were recorded at San Miguel in late January and February. This style of increased seismicity and gas emission is within the range of normal activity at San Miguel, and the Servicio Geologico de El Salvador concluded that this activity was no cause for alarm, but planned the installation of more telemetry seismic stations. The population at risk from an eruption with significant ashfall is a mix of urban and rural residents. The city of San Miguel (at the foot of the W flank) has a population of ~150,000, and the rural zone that would likely be affected has a population of ~100,000.

The events at San Miguel received extensive coverage in the local press, which had previously reported ash eruptions on 25 December 2001. However, during field studies around the volcano during 4-6 January by Escobar and Craig Chesner, extensive interviews of local residents revealed that the report of ashfall was incorrect. Vigorous steam plumes from the volcano had been confused with fly ash from the burning of sugar cane fields.

Summary of previous activity. Intermittent periods of vigorous steam-and-gas emission from San Miguel have been commonly reported in recent years. On at least two occasions, in early 1995 and at the end of December 1997, minor gas-and-ash emissions had occurred. Although discussed previously in BGVN 20:03, Escobar provided additional information on the 1995 event. Elevated seismicity and gas emission occurred at San Miguel from 26 December 1994 to 11 January 1995.

On 12 January 1995 Escobar visited the volcano and heard jet-like sounds at the crater, along with probable small explosions. Gas emission formed a plume about 100 m high that was blown to the SW. Escobar found 3-4 mm of ash in the summit crater. He also observed fine ashfall deposits on the SW flank and measured up to 2-3 mm of gray ash on the NW flank at a distance of 3 km from the crater. Residents reported that the ashfall caused damage to coffee plantations.

Elevated seismicity continued, and similar conditions were observed during a visit to the crater in February 1995. On 20 March the telemetered seismic station worked only 11 hours, but registered 48 events, including 4 volcanic tremor events and 39 LP events. Three events were felt by residents living near the volcano.

At the time of a 23-24 April 1995 visit, residents reported they had not felt any seismic events, but that ashfall had occurred on 19 April following a rainstorm. Seismicity returned to normal in May of that year.

On 17 June 1996 seismic stations registered a seismic swarm at San Miguel volcano during 1128 to 1333, consisting of 24 volcano-tectonic events with a maximum magnitude of 2.5. No felt events were reported.

Residents living near the volcano reported minor ashfall on 31 December 1997, although no geologists were present to document the ashfall distribution. On 13 January 2000, volcanic tremor was recorded for 15 minutes. On 25 January, 17 minutes of tremor occurred, along with explosion events. During May tremor was recorded for a total of 2.5 hours, and intervals of long-period earthquakes, volcanic tremor and explosion events occurred later in the year.

On 26 August 2000 a lahar from San Miguel damaged houses and a highway N of the volcano, and a similar event on 6 September 2001 affected a highway. Previously lahars had destroyed or damaged houses and highways N of the volcano on 7 May 1985 and 28 September 1992.

Information Contacts: Carlos Pullinger and Demetrio Escobar, Seccion Vulcanologia, Servicio Geológico de El Salvador, c/o Servicio Nacional de Estudios Territoriales, Alameda Roosevelt y 55 Avenida Norte, Edificio Torre El Salvador, Quinta Planta, San Salvador, El Salvador (Email: pulga@salnet.net; cdescoba@mtu.edu); Gustavo Chigna, Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH), Ministero de Communicaciones, Transporto, Obras Públicas y Vivienda, 7a. Av. 14-57, zona 13, Guatemala City 01013, Guatemala (http://www.insivumeh.pagina.de), Bill Rose, Liset Rodríguez, Gustavo Chigna, Otoniel Matías, Janelle Byman, Elly Bunzendahll, Ivonne Branan, and Matt Watson, Michigan Technological University, Houghton, MI 49931 USA (Email: raman@mtu.edu).

10/2006 (BGVN 31:10) Restlessness persists during 2005-6; heavy tropical rains trigger lahars

According to El Salvador's Servicio Nacional de Estudios Territoriales (SNET) activity levels at San Miguel have generally remained similar to those during January 2002 when a minor plume rose above the summit crater (BGVN 27:02). The volcano's vigor continued into at least October 2006 at a level slightly at or above the base line of normal activity.

Recent publications have discussed the volcano and its lahar-hazard potential (Escobar, 2003; Chesner and others, 2003; Major and others, 2001). Figures 1 and 2 are taken from the latter publication.

Figure 1. Index map indicating El Salvador's volcanic front and the location of volcan San Miguel. Major cities are also shown (circles). From Major and others (2001).
Figure 2. The lahar hazard map of San Miguel depicts likely lahar paths, which are shown as colored or shaded areas. The contour interval is 20 m; the urban center ~ 11 km NE of the summit is San Miguel. From Major and others (2001); their plate 1, cropped, highly reduced, and excluding the key.

In January 2005 observers saw new fumaroles as well as small landslides on the N and SW wall of the crater. The accumulation of mass-wasted material in the crater led to a rise in the elevation of the crater floor.

During February 2005, weak fumaroles and small rock landslides persisted in the central crater. Digital sensors installed there recorded fumarolic temperatures in real time. On the outer portions of the cone the terrain is steeply sloping and contains prominent gullies (figure 3).

Figure 3. A photo of San Miguel taken from the N on 22 February 2005 showing the steep sides of the upper slopes and the incised drainages there. Although much of the area on the volcano is rural, hazards could easily affect 40,000 residents living nearby. Courtesy of Servicio Nacional de Estudios Territoriales (SNET).

The SNET reports for March and April 2005 noted that the crater was structurally weak due to the fumarolic activity, ongoing rock alteration, occasional landslides, and fractures on the western plateau. Microseismicity had increased; but it did not exceed typical base-line levels. Workers at the Santa Isabel farm (finca) noted N-flank lahars after heavy rains during March. The N flank contains abundant fine-grained volcanic deposits of the sort easily swept away during times of heavy rain.

Intense rains during May 2005 were associated with tropical storm Adrian (over an unstated interval the meteorological station near the volcano, San Miguel UES, recorded 428 mm of rainfall). As a result of the deluge, fumarolic activity from the crater increased. The crater walls remained intact, but eroded material previously deposited in the central crater that was poorly consolidated had to some degree stabilized. Substantial further compaction, settling, or collapse in the central crater seemed to have ceased by July 2005. During August 2005 the crisis at volcan Santa Ana forestalled visits to San Miguel.

A spike in seismic activity occurred during August 2005, with 7,048 long-period earthquakes, compared to July 2005, with 2,239 long-period earthquakes. SNET reports noted that based on monitoring, San Miguel generally remained within its base-line of normal behavior during the reporting interval. Figure 4 shows a histogram of long-period and volcano-tectonic events from the SNET reports for the interval September 2005-June 2006.

Figure 4. A plot of seismicity at San Miguel during September 2005-June 2006. Courtesy of SNET.

On 14 September 2005 a visiting group (OIKOS- Soliradaridad Internacional) made a trek to the summit and videotaped the scene there. SNET said the video disclosed a lack of significant changes in the crater; however, they saw debris-flow deposits in summit drainages on the volcano's outboard flanks. The visitors described both sounds of degassing and moderately intense odors of H2S. During the course of September the seismic system recorded several minutes of tremor.

The October 2005 SNET report noted that workers at the plantation Santa Isabel noted N-slope lahars associated with rainfall. The lahars were also described as small debris flows; they descended from the high-elevation headwater areas, which are steep sided and narrow. The November report commented about the quantity of debris-flow material accumulating at the base of some N-flank channels. The same report also mentioned that moderate degassing was seen in the crater leaving areas of abundant sulfur, which appeared as yellow zones in one or more fumarolic areas.

The November 2005 report of SNET also discussed substantial landslides inside the crater that were followed by widening of the funnel-shaped area of collapse in the central crater. The landslides had left three distinct perched remnants of the crater floor (small terraces) at various elevations on the crater walls. The crater's western plain (one such terrace of the sort mentioned above) was stable but showed areas of subsidence (figure 5).

Figure 5. (top) A photo of San Miguel taken on 16 November 2005 showing the 'western plain' of San Miguel's crater (a terrace representing a remnant of a former crater floor). A considerable portion of the remaining terrace is in the process of subsidence (slumping). (bottom) A photo of the same area taken on 15 February 2006 (looking S). A zone of local subsidence, a pit along the head scarp, appears in the foreground but the subsidence also includes the region to the left of the large arcuate area extending well beyond the pit and still conspicuous in the upper left edge of the photograph. Courtesy of SNET.

Lahar monitoring during December 2005 disclosed erosion of easily mobilized cinders and scoria material on the N to NW flanks during the previous wet season. December seismicity was elevated, but cracks in the crater changed little compared to previous measurements. A field team visited the summit on 11 January 2006 and again in February and found few substantive changes in the crater. On the ascent route during January, the team saw a small recent "fall of material" reaching 40 cm thick. Some fumaroles discharged yellowish gases. During February the team conducted measurements of cracks on the western plain but found few changes, suggesting the headscarp had moved little if at all. February and March tremor episodes were centered at ~ 5 Hz and lasted 1-3 minutes.

The March 2006 SNET report noted small rockslides on the crater's N and S sides and, with the beginning of the rainy season in March 2006, there was a potential for the development of lahars. During the March visit the team found abundant granular material in the gullies on the NW flank, judged to be the result of debris flows. Monitored cracks remained stable.

With the arrival of the wet season in April, lahars and enhanced fumarolic output became apparent. One debris flow intersected a highway. On 23-24 April, 105 mm of rain was recorded at plantation (finca) Santa Isabel. Figure 6 shows the results of one lahar which left a trail of debris during the rainy interval. Earlier in the month on the 16th, a tremor or multi-phase episode lasted over an hour.

Figure 6. A San Miguel photo showing a part of the freshly scoured upslope channel in the Gato erosional gully. The material deposited in the channel consisted of reworked volcanic rocks and must have descended as a small lahar or debris flow. Several such flows occurred during heavy late-April rains at the start of the rainy season, a few days before this picture was taken. Courtesy of SNET (from their April 2006 report).

In April 2006, an increase in fumarole degassing within the crater and small landslides contributed to the instability of the deposits on the NW flanks of the volcano. Steam emanated from the fumaroles occasionally forming a weak column that reached the edge of the crater. There was a slight increase in seismicity throughout the month. Seismic activity increased in March and April 2006 (figure 4). Rocks in the crater show intense hydrothermal alteration with a yellowish reddish color. Small rock landslides were observed in the N and S zone of the crater.

During June 2006, the temperature of the fumaroles, opening of cracks and the gas discharge by the crater of the volcano, remained stable. There was an increase of small landslides within the crater. The analysis of the seismicity indicates that the volcano is slightly above its base line of normal behavior. New landslides and cracked rock were observed in the walls of the crater (figure 7). Rains have transferred volcanic material down the NW flank. Seismicity gradually increased in both frequency and magnitude beginning on 16 June. 47 VT earthquakes and 7,505 LP earthquakes were recorded, an amount that surpasses those registered in May; but smaller than those registered in March and April (figure 4).

Figure 7. San Miguel's S crater wall exposes zones of altered and fractured rocks. A planar zone of structural weakness appears towards the right. Photo taken on 22 June 2006. Courtesy of SNET.

During July 2006, stability continued with respect to fumarole temperatures, crack openings, and gas emissions around the crater. However, the seismicity increased by ~ 70%. Small and sporadic landslides took place inside the crater off the SE to SW walls. Intense hydrothermal alteration in the NW wall was also observed. SNET did not report any lahars during July 2006; however intense rains have continued to remove volcanic material from the NW flanks. The fumarolic field gave off weak emissions.

In August 2006, the monitored parameters such as fumarole temperature, crack opening, and visual estimates of gas discharge maintained normal levels. The seismicity diminished significantly in relation to July.

During September 2006, San Miguel reached a low level of activity. There were no significant changes in the morphology of the volcano as reported in previous months. At the S wall, there were evidence of small rock slides.

A sudden increase in seismicity occurred on 9 October 2006. Contact was made with other observatories and it was determined there were no landslides or rock falls associated with the event. Seismic increases such as 9 October had previously occurred, particularly on 19 June 2003 and from 2-6 May 2004. The 9 October increases were attributed to gas emission from the crater.

References. Chesner, C. A., Pullinger, C., Escobar, C. D., 2003, Physical and chemical evolution of San Miguel Volcano, El Salvador. GSA Special Paper 375.

Escobar, C.D., 2003, San Miguel Volcano and its Volcanic Hazards; MS thesis, Michigan Technological University, December 2003. 163 p.

Major, J.J.; Schilling, S.P., Pullinger, C.R., Escobar, C.D., Chesner, C.A, and Howell, M.M., 2001, Lahar-Hazard Zonation for San Miguel Volcano, El Salvador: U.S. Geological Survey Open-File Report 01-395. (Available on-line.)

Information Contacts: Carlos Pullinger, Seccion Vulcanologia, Servicio Geológico de El Salvador, c/o Servicio Nacional de Estudios Territoriales, Alameda Roosevelt y 55 Avenida Norte, Edificio Torre El Salvador, Quinta Planta, San Salvador, El Salvador (URL: http://www.snet.gob.sv/Geologia/Vulcanologia/).

09/2007 (BGVN 32:09) Background seismicity since October 2006; crater visit in July 2007

A sudden increase in seismicity occurred on 9 October 2006 but no landslides or rock falls were associated with the event and it was attributed to gas emissions in the crater (BGVN 31:10). This report carries on from 9 October 2006.

During the morning of 10 October 2006, seismic activity declined to a continuous vibration with an amplitude that oscillated between 50 and 75 RSAM (real-time seismic amplitude measurement) units. This condition continued until 0600 on 11 October, when the seismicity increased to 125 continuous RSAM units.

The responsible authorities issued an alert that encompassed an area within 4 km from the center of the crater. Because of the elevated energy level of seismicity relative to the previous activity, the National Service of Territorial Studies elected to monitor the volcano and report developments to the National System of Civil Defense.

As of 15 October 2006, the level of activity at San Miguel was considered to be moderate, implying the possibility of an eruption sometime in the next several months. The civil defense authorities established a Yellow alert level (phase 3) for the area within 4 km of the crater center but later reduced it to Green. Around 15 October the RSAM continued to vary from 8 units to 45 units. During the preceding 24 hours, 55 earthquakes were registered; however, none were noticed by the local population. Sulfur dioxide (SO2) fluxes reached 150-250 metric tons per day, which was considered a low level. On 16 October, tremor fluctuated between 45 and 50 units, and 25 earthquakes were recorded but not felt by residents.

The period from the October 2006 activity through July 2007 was essentially devoid of any abnormal variations in seismicity, volcanism, or elevated gas emissions.

On 4 July 2007, volcanologists from Servicio Nacional de Estudios Territoriales (SNET) and Michigan Technological University climbed San Miguel to make observations and take fumarole temperatures. The volcano remained at a low level of activity. The crater morphology and the intensity and location of fumaroles within the crater remained similar to that observed in recent visits (e.g., October 2006 BGVN 31:10). The main fumarolic area was near the bottom of the crater on the S wall (figure 8). Other sparse fumaroles were present, with most clustered near the crater bottom and on the crater's W wall.

Figure 8. View of the crater at San Miguel, looking S on 4 July 2007. The whitish area in the bottom right of the photo reflects steaming from the main fumarole field. Courtesy of Servicio Nacional de Estudios Territoriales (SNET) and Michigan Technological University.

Fumarole measurements: Temperatures were measured at two fumarolic areas on the upper W crater wall (figure 9). These are visited by SNET on a regular basis and comprise the only fumaroles safely accessible from the rim. Temperatures at fumaroles 1 and 2 were 67°C and 57°C, respectively. The gas lacked any sulfurous smell, suggesting water vapor only. These fumarole temperatures are similar to those measured in recent visits.

Figure 9. View of the W side of San Miguel's crater, taken from the N rim. Fumaroles 1 (F1) and 2 (F2) are in the right central portion of the image. Courtesy of Servicio Nacional de Estudios Territoriales (SNET) and Michigan Tech University.

References. Chesner, C.A., Pullinger, C., Escobar, C.D., 2003, Physical and chemical evolution of San Miguel Volcano, El Salvador. GSA Special Paper 375.

Escobar, C.D., 2003, San Miguel Volcano and its Volcanic Hazards: MS thesis, Michigan Technological University, December 2003, 163 p.

Major, J.J., Schilling, S.P., Pullinger, C.R., Escobar, C.D., Chesner, C.A, and Howell, M.M., 2001, Lahar-Hazard Zonation for San Miguel Volcano, El Salvador: U.S. Geological Survey Open-File Report 01-395 (Available on-line).

Information Contacts: Eduardo Gutierrez, Demetrio Escobar, and Francisco Montalvo, Servicio Nacional de Estudios Territoriales (SNET), Km. 5 ½ carretera a Santa Tecla y Calle las Mercedes, contiguo a Parque de Pelota, Edificio SNET, Apartado Postal #27, Centro de Gobierno, El Salvador (URL: http://www.snet.gob.sv/, Email: egutierrez@snet.gob.sv, descobar@snet.gob.sv, fmontalvo@snet.gob.sv); Matthew Patrick and Anna Colvin, Dept. of Geological and Mining Engineering and Sciences, Michigan Tech University, 1400 Townsend Drive, Houghton, MI 49931, USA (Email: mpatrick@mtu.edu; ascolvin@mtu.edu).

Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2002 Jan 16 2002 Jan 16 Confirmed 1 Historical Observations
1997 Dec 31 Unknown Confirmed 1 Historical Observations
1995 Jan 12 1995 Apr 19 Confirmed 1 Historical Observations
1985 Nov 1986 Feb (in or after) Confirmed 1 Historical Observations
1976 Dec 2 1977 Mar 1 Confirmed 1 Historical Observations
1970 Mar 30 1970 Apr 5 Confirmed 1 Historical Observations
1967 Jan 5 Unknown Confirmed 2 Historical Observations
1966 Jul Unknown Confirmed 2 Historical Observations
1966 Feb 22 Unknown Confirmed 2 Historical Observations
1964 Oct 23 1964 Nov Confirmed 2 Historical Observations
1954 Oct 21 1954 Oct 21 Confirmed 2 Historical Observations
1939 May 1939 Jul Confirmed 2 Historical Observations
[ 1936 (?) ] [ Unknown ] Uncertain 2  
1931 Mar 1931 Jun Confirmed 2 Historical Observations
1930 Jan 26 ± 5 days Unknown Confirmed 2 Historical Observations
1929 Aug Unknown Confirmed 2 Historical Observations
1920 Aug 14 1925 Confirmed 2 Historical Observations
1919 Dec 10 1920 Jan Confirmed 2 Historical Observations
1890 1891 Confirmed 2 Historical Observations
1884 Jan 25 1884 Jan 28 ± 1 days Confirmed 2 Historical Observations NE side of main crater
1882 Dec 5 ± 4 days Unknown Confirmed 2 Historical Observations
1867 Dec 14 1868 Feb 16 (in or after) Confirmed 2 Historical Observations WSW flank (1000 m)
1862 Jan Unknown Confirmed 2 Historical Observations
1857 Nov Unknown Confirmed 2 Historical Observations
1855 Dec Unknown Confirmed 2 Historical Observations SSE flank (800 m)
[ 1854 ] [ Unknown ] Uncertain 2  
1844 Jul 25 1848 Confirmed 2 Historical Observations NNW (1120 m) and upper east flanks
1819 Jul 18 Unknown Confirmed 2 Historical Observations SSE flank (400 m; near Los Perolitos)
[ 1811 ] [ Unknown ] Uncertain 2  
[ 1798 (?) ] [ Unknown ] Uncertain 2  
1787 Sep 21 1787 Sep 23 Confirmed 2 Historical Observations Summit, north and SE flanks
1769 Unknown Confirmed 2 Historical Observations East flank ?
1762 Unknown Confirmed 2 Historical Observations NE flank (400 m)
1699 Unknown Confirmed 2 Historical Observations SE flank (400 m)
1510 ± 5 years Unknown Confirmed   Historical Observations

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Carr M J, 1984. Symmetrical and segmented variation of physical and geochemical characterisitics of the Central American volcanic front. J Volc Geotherm Res, 20: 231-252.

Chesner C A, Pullinger C R, Escobar C D, 2004. Physical and chemical evolution of San Miguel volcano, El Salvador. In: Rose W I, Bommer J J, Lopez D L, Carr M J, Major J J (eds), Natural Hazards in El Salvador, {Geol Soc Amer Spec Pap}, 375: 213-226.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Major J J, Schilling S P, Pullinger C R, Escobar C D, 2004. Debris-flow hazards at San Salvador, San Vicente, and San Miguel volcanoes, El Salvador. In: Rose W I, Bommer J J, Lopez D L, Carr M J, Major J J (eds), Natural Hazards in El Salvador, {Geol Soc Amer Spec Pap}, 375: 89-108.

Major J J, Schilling S P, Pullinger C R, Escobar C D, Chesner C A, Howell M M, 2001. Lahar-hazard zonation for San Miguel volcano, El Salvador. U S Geol Surv Open-File Rpt, 01-395: 1-14.

Mooser F, Meyer-Abich H, McBirney A R, 1958. Central America. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 6: 1-146.

Rodriquez L A, Watson M W, Rose W I, Branan Y K, Bluth G J S, Chigna G, Matias O, Escobar D, Carn S A, Fischer T P, 2004. SO2 emissions to the atmosphere from active volcanoes in Guatemala and El Salvador, 1999-2002. J Volc Geotherm Res, 138: 325-344.

Sapper K, 1925. The Volcanoes of Central America. Halle: Verlag Max Niemeyer, 144 p.

Weber H S, Wiesemann G, 1978. Mapa Geologico de la Republica de El Salvador/America Central. Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover, Germany, 1:100,000 scale geologic map in 6 sheets.

Williams H, Meyer-Abich H, 1955. Volcanism in the southern part of El Salvador with particular reference to the collapse basins of Lakes Coatepeque and Ilopango. Univ Calif Pub Geol Sci, 32: 1-64.

The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. The unvegetated summit of the 2130-m-high volcano rises above slopes draped with coffee plantations. A broad, deep crater complex that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit of the towering volcano, which is also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic-andesitic volcano have fed a series of historical lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the north, NE, and SE sides. The SE-flank lava flows are the largest and form broad, sparsely vegetated lava fields crossed by highways and a railroad skirting the base of the volcano. The location of flank vents has migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.