Report on Sabancaya (Peru) — 9 July-15 July 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 July-15 July 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Sabancaya (Peru). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 July-15 July 2014. Smithsonian Institution and US Geological Survey.
15.787°S, 71.857°W; summit elev. 5960 m
All times are local (unless otherwise noted)
IGP reported that during 12-27 June there were renewed signs of activity from Sabancaya. Fumarolic activity increased and gases were notably more blue and gray. Seismicity also increased, particularly long-period (LP) earthquakes (~100 LP events per day during 18, 19, and 21 June). Since 6 June, hybrid earthquakes were detected; IGP noted that this seismicity can be attributed to rising magma. During 6-10 July, a daily average of 11 hybrid earthquakes was recorded. In the past few weeks, volcano-tectonic (VT) earthquakes migrated closer to the volcano, especially when the locations were compared with those from 2013. Within a week, the concentration of VT earthquakes had moved ~10 km closer to the crater, reaching a distance ~6 km N of the crater. This activity prompted IGP to install a new seismometer to augment their monitoring capabilities, now comprising six seismometers.
From mid-June through 10 July, fumarolic activity continued and white plumes were visible, although with less intensity within the last two weeks. Seismicity increased during this time period, particularly on 30 June and 1 July when a daily average of 87 LP earthquakes was recorded. From 27 June through 6 July, there was a daily average of 44 VT earthquakes. VT earthquakes were also occurring close to the crater. There were three persistent clusters of VT earthquakes near the crater: 6 km N, 16 km NE, and 10 km E.
Geologic Background. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.