This (almost) daily post intends to follow up the activity changes of volcanoes all over the world.
This post is written by geologist Richard Wilson who specializes in Volcano seismicity and Armand Vervaeck. Please feel free to tell us about new or changed activity if we haven’t written about it. -
November 17, 2012 volcano activity
Today’s report contains alot of low-level volcanic tremor (and a few local earthquakes) which, at most of the volcanoes we report on constitutes “normal” background activity. The tremor may appear more “impressive” on some records depending on the amplification of the seismic signal. Volcano observatories usually have to factor-in local cultural noise, weather, glaciers, etc to their particular amplification setting choice which results in some volcanoes appearing more or less “noisy” than they actually are.
No tremor at Little Sitkin volcano (Aleutians), just the diminution of yesterday’s strong earthquake swarm. (station LSSA)
No tremor at Long Valley Caldera (CA) either, but small earthquakes continue beneath the South Moat of the caldera today. (station MMX1)
Surface activity is down at Popocatepetl volcano (Mexico), with emissions of gas and ash now occurring at a rate of about 2 per hour. Local seismicity appears to be elevated, though reading the Popo seismogram is again hampered by a persisting software issue. The computer “glitch” produces the repeating pattern in the seismic record.
As mentioned above, mostly background tremor today at Guatemalan volcanoes Pacaya (station PCG), Fuego (station FG3), and Santa Maria (station STG6), though low-level tremor at Pacaya has become more persistent in recent weeks.
Seismic records from San Cristobal (station CRIN), Masaya (station MASN) and Concepcion (station CONN) show similar background levels of tremor and a few small volcanic earthquakes. Tremor at San Cristobal has become more rhythmic during the past week, periodically strengthening and then ebbing over a twenty-four hour time span, while tremor has strengthened somewhat at Masaya volcano during the past week.
Seismicity at San Miguel volcano (El Salvador) while high (station VSM), is also within what is considered “normal” limits. This volcano exhibits longer term (weeks to months) cyclic volcano-seismicity where activity builds to a crescendo over that time period and then slowly diminishes over a similar time period with little in the way of surface activity the result.
Activity at Ruapehu volcano also includes low-level volcanic tremor today, while at nearby Tongariro a tremor-like signal on seismic records may be wind noise. That’s not wind noise at White Island volcano, just some classic banded volcanic tremor.
Recent satellite imagery depicts an SO2-rich plume extending southwest from Popocateptl volcano and a possible eruption in progress at Manam volcano (New Guinea). Lesser plumes of SO2 drift from Costa Rican volcanoes Turrialba and Poas.
Question,( and thanks this a great site for us pensioners! can you explain how wind can have an effect on a seismograph. My instinct would tell me that a seismograph would be an instrument sensitive to only earth movement not atmospheric ones. I realize that the conditions for installing any instruments on any volcano is a tough job even on a good day but, if wind can have an effect on a seismograph how do you separate the two sets of information from each other ? Thanks I am a little new new to the site is there a “blog” or dialog connection?
Storm oand strong winds are giving quit a lot of vibrations – some seismographs are not fixed too well vs other ones
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