Report on Santa Maria (Guatemala) — 18 June-24 June 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 June-24 June 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 June-24 June 2014. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
Eruptions continued at Santa María's Santiaguito lava-dome complex during the week of 18-24 June. Incandescence from the E border of the summit observed early on 18 June was accompanied by minor avalanches from a lava flow. On 18 June INSIVUMEH also reported a hot lahar descending the S-flank Nimá I river drainage, carrying blocks 50-150 cm in diameter as well as tree trunks and branches. The lahar was 30 m wide and 1.5 m deep, and had a strong sulfur odor.
Rumbling sounds and an eruption reported at 0630 on 19 June generated an ash plume up to 3,100 m (10,000 ft) a.s.l. Ashfall dispersed SW and was reported in the mountainous areas of Parcelamiento Monte Claro (S of the summit). The lava flow generated several weak avalanches at the leading edges. Degassing plumes from the dome reached 2,900 m (9,500 ft) a.s.l. A white plume was also noted on 20 June, but cloud cover reduced visibility. At 0552 on 21 June an ash plume rose to 3,000 m (9,800 ft) a.s.l. and dispersed SW. Rumbling sounds and strong fumarolic activity were also noted.
On 22 June, three explosions sent gray plumes up to 3,000 m (9,800 ft) a.s.l. Two of these events were accompanied by incandescence. Constant avalanches from the front of the lava flow that were deposited into the Nimá 1 drainage. Degassing continued, generating plumes ~600 m above the crater rim; the sustained plumes were gray. Columns of gas and steam reached 2,200 m (7,200 ft) a.s.l. on 23 June then drifted SW. One weak explosion occurred at 0615, producing a plume to 3,200 m (10,500 ft) a.s.l. plume that drifted SW. A series of weak avalanches were observed from the front of the active lava flow in the direction of Nimá 1 river.
On 23 and 24 June, INSIVUMEH reported that heavy rainfall generated moderate lahars within the Nimá I and San Isidro (on 23 June) rivers. The Nimá 1 contained a hot lahar similar to that on the 18th. One explosion was recorded at 0611 on 24 June; this event generated a white plume.
Geologic Background. Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.