Volcano activity of March 26, 2013 - Uncertainty phase because of seismic activity in Hekla volcano, Iceland

This (almost) daily post intends to follow up the activity changes of volcanoes all over the world.
This post is written by geologist Rodger 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. -

March 26, 2013 volcano activity

Official statement from the Iceland Civil Defense

The National Commissioner of the Icelandic Police (NCIP) and the Police commissioner at Hvolsvöllur declare an uncertainty phase (lowest level of warning), because of seismic activity in mount Hekla.

The Icelandic Met Office has informed the Civil Protection and Emergency Management of NCIP about unusual seismic activity in mount Hekla. The Icelandic Met Office has raised the ICAO aviation color code to yellow concerning air traffic, which means that mount Hekla is showing an unusual activity.

Uncertainty phase means that supervision has been raised on that course of events that may threaten public health and safety, or that environment or inhabited area may be threatened. To declare an uncertainty face is a part of work process in the setup of public safety to secure a formal communication between response teams and to secure dissemination of information.

In light of all of this the National Commissioner of the Icelandic Police and the Police commissioner at Hvolsvöllur would warn people from hiking on mount Hekla while this uncertainty phase is in force.

Wikimedia image courtesy Lydur Skulason

Wikimedia image courtesy Lydur Skulason

Something more about Hekla volcano
Hekla is a stratovolcano in the south of Iceland with a height of 1,491 metres (4,892 ft). Hekla is one of Iceland's most active volcanoes; over 20 eruptions have occurred in and around the volcano since 874. During the Middle Ages, Europeans called the volcano the "Gateway to Hell."
Hekla is part of a volcanic ridge, 40 kilometres (25 mi) long. The most active part of this ridge, a fissure about 5.5 km (3.4 mi) long named Heklugjá, is considered to be the volcano Hekla proper. Hekla looks rather like an overturned boat, with its keel being a series of craters, two of which are generally the most active.
The volcano's frequent large eruptions have covered much of Iceland with tephra and these layers can be used to date eruptions of Iceland's other volcanos. 10% of the tephra created in Iceland in the last thousand years has come from Hekla, amounting to 5 km3. The volcano has produced one of the largest volumes of lava of any in the world in the last millennium, around 8 km3.

Webcam of the volcano
Webcam 2
Webcam 3

Hekla eruptions since 1900 : 1947, 1970, 1980, 1981, 1991 and 2000 

Update 18:37 UTC : The seismic unrest cannot be compared with ie El Hierro with hundreds of often strong volcanic earthquakes.
RUV.is did wrote earlier today : Since 10 March 2013, at least seven micro-earthquakes, ranging in size from magnitude 0.4 to 1, have been detected over a small area ~4.5 km to the north-east of the volcano's summit. Sourced mainly at 11 to 12 km depth, these earthquakes have a high-frequency character suggestive of brittle fracturing rather than magma movements. At Hekla, such a clustering of earthquakes in time and space is unusual in between eruptions.
We will keep you posted of course and if needed, a specific page will be build to cover what is going on.

Update 19:01 UTC : Hekla makes people nervous at regular intervals. The video below dates from 1 year ago when also "an emerging eruption" was the discussion of the day 🙂

Normal daily report

Seismicity (including volcanic tremor) and deformation continue at a high level at El Hierro (Canary Islands) (station CHIE).  Event focal depths remain at around 15 km depth.  Maximum event magnitudes reached M3.6 today.

Amplitude of volcanic tremor and earthquakes at Telica volcano (Nicaragua) (station TELN) returned to it's previous high level late yesterday.  Earthquake-Report.com reader Paul Wyse notified me yesterday of an article in the newspaper La Prensa in which INETER scientists describe the current period of unrest at Telica.  According to the report, while seismicity is at an unusually high level at the volcano, no measurable deformation has yet occurred there.


KVERT reports that seismicity at Sheveluch volcano (Kamchatka Peninsula) returned to it's previously moderate level overnight.  Amplitude of volcanic tremor at Tolbachik volcano also rose during that period.  Moderate seismicity continues at Kizimen volcano, while weak seismicity is recorded at Bezymianny volcano.  An equipment outage prevents monitoring of seismicity at Karymsky volcano. Moderate seismicity affects Gorely volcano which has been in a constant state of thermal/seismic unrest for several years.


Small, shallow,  local earthquakes continue at Iliamna volcano (Alaska Range) (station INE).

A burst of small earthquakes (maximum magnitude M1.7) occurred at Mount Rainier volcano (WA) (station RCS) late yesterday, and continued at lower level through early today.


Small earthquakes continued in the southern Cascade arc (OR) (station ) as well.


Small earthquakes continued around the southern edge of Long Valley caldera (CA) (station MCS).


A high level of surface activity and seismicity continues at Colima volcano (Mexico).  Small pyroclastic flows (the large prolonged signals) now appear to affect the volcano.  Low level volcanic tremor accompanied exhalations of gas (occasionally containing volcanic ash) at Popocatepetl volcano.  The large signals at the bottom of the record are M5.0+ earthquakes occurring along the southern coast of Mexico.


Explosion signals were frequent overnight at Pacaya volcano (Guatemala) (station PCG).  Volcanic tremor and small explosions signals were also recorded at Fuego volcano (station FG3) during that period.  Hybrid earthquakes, rockfall and small pyroclastic flow signals were recorded at Santiaguito Dome Complex (Santa Maria volcano) (station STG3).


Aftershocks of yesterday's M4.3 earthquake continued at San Cristobal volcano (Nicaragua) (station CRIN).  There has been no change in the eruptive behavior of the volcano as a result.  Volcanic seismicity at Concepcion volcano (station CONN) has declined again to almost complete silence (save for some low-magnitude volcanic tremor).  Volcanic tremor increased at Masaya volcano (station MASN) following the arrival of surface waves from the Mexican earthquakes today

Volcanic tremor remains elevated at San Miguel volcano (El Salvador) (station VSM).  Electronic telemetry interference also affects the seismic record.

Volcanic (fluid/gas movement) and volcano-tectonic (magmatic intrusion) earthquake swarms continue at Nevado Del Ruiz volcano (Colombia) (station OLLZ).  Tiny local earthquakes rattle Machin volcano (station CIMA).

Numerous low-magnitude volcanic earthquakes continue at Tungurahua volcano (Ecuador) (station RETU).  Strong volcanic tremor and earthquakes shake Reventador volcano (station CONE), and small earthquakes continue at Cotopaxi volcano (station CO1V).

IGP released a new report on activity at Sabancaya volcano yesterday.  As the accompanying seismogram and graphic shows, volcano-tectonic and volcanic earthquakes continue at a high rate at the volcano.

Hybrid earthquakes continue to punctuate the constant hum of volcanic tremor within White Island volcano (New Zealand).

Recent OMI satellite data show SO2-enriched plumes drifting from Tolbachik, Popocatepetl, Tungurahua, Nyiragongo (DRC), Ambrym (Vanuatu), and Krakatoa (Java) volcanoes.  MODIS satellite thermal sensors detected "hotspots" at Tolbachik and Popocatepetl volcanoes.


  1. Ken Adrian says

    How deep are the quakes in the southern Oregon Cascades - meaning, are they associated with the subducting plate's movements, or are they more shallow than that? How deep is the subducting plate there?

    Thanks for a great web site!

    • Richard Rodger Wilson says

      Hi Ken,

      The earthquakes in the southern Oregon Cascades appear to be shallow (depth = 5-10 km). I say "appear" because seismometer coverage is relatively sparse in that area and that figures into the mix when determining event depths as well as locations. Fortunately, the events have been fairly strong (M2.0-M3.0) so the earthquakes have been well recorded on more distant stations.

      Thanks for your readership!


    • Richard Rodger Wilson says

      Hi again Ken,

      Sorry,...I think I only partially answered your questions! The subducted plate is(was) at about 100-110 km depth beneath that part of the Cascades. I say "was" because several recent tomography-based studies (by UC Berkeley and Japanese scientists) have revealed that the subducted slab beneath much of Oregon has been "removed" (likely 17-20 My ago by the then rising Yellowstone Plume head).

      Thanks again for your support of this site!