Chaitén update, 24 July 2008

[N.B. There has been a gap in The Volcanism Blog's coverage of Chaitén because of our holiday closure. There's a brief catch-up post below, but if you want to check the detail of what has been happening between early July and now, Alan Sullivan's Fresh Bilge blog and Werner Luis's Erupción del volcán Chaitén pages are the places to go.]

SERNAGEOMIN issued a ‘special additional report’ on Chaitén on 22 July 2008; it has been e-mailed to interested parties including this blog (thanks, Javier) but has not yet been published on the SERNAGEOMIN website or elsewhere.

The main news therein is an increase in the number and magnitude of earthquakes around the volcano: ‘The seismic activity recorded by STAB and PUMA telemetry stations indicated about 320 VT-type earthquakes in the last 24 hours, 55 of which were notable for their greater magnitude of more than 2.6M’. These quakes were situated south and south-east of the volcano, but the records of seismic monitoring stations at Calbuco volcano and Lago Ranco (170km and 270km north of Chaitén volcano, respectively) reveal similar higher magnitude earthquakes taking place north of Chaitén as well. The most recent Chaiten bulletin to be made available by SERNAGEOMIN, dated 21 July 2008, also noted the high level of seismic activity (Alan Sullivan’s summary is here). In that earlier bulletin SERNAGEOMIN predicted a prolongation of eruptive activity, and the same point is made in this latest report: ‘As noted in previous reports, both the large number of VT-type earthquakes and the magnitude of a significant number of them can be attributed to a possible new injection of magma, which may prolong the eruption (perhaps for months) and further intensify the eruption column and, perhaps, the growth of the new dome’.

How stable is that very large new dome at Chaitén? We just don’t know, but a period of intensified growth of the dome will increase the possibility of a potentially very violent dome collapse. In any case, Chaitén shows no sign of relapsing into quiescence and continues to make its presence felt across a wide area: at the beginning of the week flights into Puerto Montt were suspended (again) because of the vigour of the volcano’s ash-laden eruption plume.

Meanwhile, the resumption of transport links between Puerto Montt and Aysén means that the evacuated residents of Chaitén town can now ‘return more frequently to visit their homes’, reports 123 Chile today. The ever-optimistic alcalde of Chaitén, José Miguel Fritis,* calls this ‘the beginning of the return’, but Paula Narváez, appointed by President Bachelet to oversee the Chaitén emergency, is quoted as saying that conditions ‘do not permit us to begin, to strengthen or to enhance the site or the settlement of people in the commune of Chaitén’.

Chaiteninos have now been living in limbo for nearly three months. The encouragement by local politicians of the hopes of Chaitén residents that they can ever return to their town is cruelly irresponsible, but the failure of national politicians to state clearly that the town must be abandoned and a new settlement created elsewhere is equally reprehensible: only last week the Minister of Housing was talking about evacuees ‘returning to a rebuilt Chaitén, on the same site known today or another area further north’ as if ‘the same site’ was a realistic possibility. The people of Chaitén need their future back, but before they can have that they need some clarity and honesty from their politicians.

For all our Chaitén coverage: Chaitén « The Volcanism Blog

News
LAN suspende vuelos a Puerto Montt por cenizas de volcán Chaiten – El Mostrador, 20 July 2008 (Spanish)
Evacuados de Chaitén podrán volver con más frecuencia – 123 Chile, 24 July 2008 (Spanish)
Más medidas para damnificados de Chaitén: Ministra de Vivienda anuncia aumento de monto de subsidio – El Vacanudo, 17 July 2008 (Spanish)

Information
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
ONEMI, Oficina Nacional de Emergencia – Chilean government emergencies office (Spanish)
SERNAGEOMIN – Servicio Nacional de Geología y Minería (Spanish)