The lava delta continues to be fed by the active lava flows, which show some stability in that they are largely confined to within previous lava flows. However, there are also localised breakouts onto previously unaffected land. The lava delta has reached a thickness of 24 m and is now beginning to spread laterally. Surface activity at the main cone continues to show a mixed mechanism with strombolian activity from multiple vents in the main cone, and more effusive Hawaiian activity from a vent at the base of the NW sector on the main cone, with occasional phreatomagmatic pulses too. Throughout the morning of the 30th, an extensive fumarole field developed on the NE flank of the main cone. The continued presence of a thermal inversion is hampering the dispersal of volcanic gases and ash, leading to a decrease in air quality in the Aridane Valley. SO2 concentrations in Tazacorte peaked at ‘very high’ levels (>500 μg/m3) at 8:00 am local time and increases in SO2 concentrations have also been observed in Los Llanos de Aridane, along with reports of a ‘rotten egg’ smell, although these values do not currently represent a health hazard.

The active lava flow continues cascade down the cliffs of Playa de Los Guirres to the sea, where a lava delta (also called by the Canarianism “fajana”) is being created. The contact of the lava and seawater are creating gases of vapour, although currently due to the prevailing winds these have not spread laterally and are concentrated in a small area around the lava delta. Nonetheless, the confinement order remains in place for neighbourhoods in Tazacorte for the moment. The rest of the lava flows remain practically inactive, and new damage estimates 476 hectares have been covered by the lava flows, and 744 buildings have been damaged or destroyed according to the Copernicus Satellite. Regarding surface activity, strombolian activity continues with pulses of increased and decreased intensity, as well as an effusive focus from the vent on the NW sector of the main cone. Ash concentrations are higher than previous days in the Aridane Valley, so the population are reminded to wear FFP2 or better facemasks when outside and take extra caution. Irrigators and evacuated residents outside the exclusion zone have been allowed in to tend to their crops and remove their belongings, and have been accompanied by UME and the Civil Guard who can monitor gas concentrations in real time.

The lava flow began the day approximately 1000 m from the coast, although it advanced quickly throughout the day due to the large volume of fluid lava being emitted from the effusive vent on the northwest sector of the cone. The lava flow crossed to the south of Todoque mountain and reached the sea at 11:00 pm local time after cascading down the cliffs at Playa de Los Guirres. Due to the clouds of vapour being produced by the contact of the lava with the sea, which could contain high concentrations of gases such as hydrogen chloride (HCl), the confinement order in Tazacorte remains in place. Throughout the day, there were also issues with suspended particles in the air, both directly from the volcano and from the burning of plastic and other noxious materials in greenhouses and agricultural buildings by the lava flows. This problem was exacerbated by a low temperature inversion at 600 m preventing the dispersal of these particles in the evening. This led to the exceedance of the PM10 particle air quality threshold level (50 μg/m3) in Los Llanos de Aridane.

The eruption has seen a large variation of activity, with increases and decreases in the intensity of Strombolian activity, as well as pulses of phreatomagmatic activity (characterised by white plumes rich in water vapour) and periods of no strombolian activity from the main cone. The first period of cessation was between 4:10-4:30 am local time, and similar activity with occasional weak ash-rich explosions was seen throughout much of the day. These cessations were accompanied with greatly reduced volcanic tremor values, and have been attributed to a temporary plugging of the conduit. From approximately 6:30 pm local time, continuous strombolian activity returned to the vents in the main cone and increased in intensity throughout the evening, accompanied with a sharp increase in volcanic tremor. The lava flows continue to advance and are located between 800-1000 m from the coast, although the northern lava flow front which reached Todoque mountain on the 26th has greatly slowed. Nonetheless, due to the potential hazards from explosions and noxious clouds of vapour when the lava contacts the sea, preventative confinement measures have been put in place for 300 people in the coastal areas of Tazacorte.

Based on the evolution of the eruption, the 160 residents evacuated from Tajuya and Tacande on the 24th can return to their homes. According to Maria Jose Blanco, this has been allowed by the lack of the instability seen in the cone on the 24th, as well as the relative stability of eruption parameters such as tremor which was elevated and unstable at the time the evacuation was first ordered. The eruption continues to show both Strombolian activity from 3 or more vents in the main cone, as well as more effusive Hawaiian activity from the vent at the base of the NW sector of the main cone. The lava from this effusive vent continues to feed two active lava flows; a southern flow at travelling at approximately 30 m per hour; and a more fluid flow to the north which has sped up and is travelling at around 100 m per hour and is expected to overrun the front of the older stalled lava flow front to the north according to modelling carried out by the authorities. At 8:15pm, the latter flow reached Todoque mountain, about 1,600 m from the coast.

Given the evolution of the eruptive activity over the last 24 hours, it was decided by PEVOLCA to maintain the latest evacuation order given on the 24th. The two effusive vents that opened on the 24th on the side of the cone showing effusive (Hawaiian) behaviour and emitting lava flows have merged into one vent, exhibiting the same behaviour. The lava flow from this merged vent is fluid but has slowed, from about 80 m per hour in the night of the 24th/25th to 40 m per hour by the afternoon of the 25th. So far, it has travelled approximately 3.6 km on top of previous flows. The older flows are still active, although the front is only advancing incrementally currently. The explosivity of the strombolian activity from the main cone has decreased slightly since the afternoon of the 24th where the highest peak in the eruptive intensity so far was recorded. The activity is concentrated in the main cone through at least three strombolian vents, in addition to a new Hawaiian vent at the base of the NW sector of the main cone. Furthermore, a small rupture in the southern side of the main cone overnight noticeably altered its summit morphology.

Today in Tenerife we finish our month-long GeoIntern programme, an intense summer training camp for Earth Science students. But instead of winding down and heading for the beach, we are anxiously packing up to head to La Palma to cover the ongoing volcanic eruption. We’re...

An increase in explosive activity throughout the day, to the most energetic levels seen since the eruption began, has prompted the evacuation of a further 160 people to the northwest of the volcano, in Tajuya, Tacande de Abajo and those not already evacuated in Tacande de Arriba. The decision was made because of the increased risk of volcanic materials and pressure waves reaching and causing damage in areas outside of the current exclusion zone. In particular, this related to the opening of two new effusive vents as well as a fracture in the NW flank of the main cone, which could destabilise the cone and increase the risk of a sector collapse. The two new effusive vents emit fluid lava flows, that travel faster than previous flows but flow over the top of previous flows. In total, the number of evacuees has now reached 6,000. Latest estimates of damage indicate up to 400 buildings affected by the lava flows.

The two lava flow fronts, one to the north and one to the south, continue to advance slowly. The maximum length of the flow is now 3,800 m, with 2,100 m to go to reach the sea, and the flows now cover 220 hectares in total. The northern front moves at approximately 1 m per hour and is up to 12 m thick, whereas the southern front moves faster, at 4-5 m per hour. Current estimates of damage include about 300 homes already affected by the lava flows. The eruptive activity continues to show a strombolian mechanism, although with a more explosive and ash-rich behaviour. This more energetic activity is mirrored in the plume height, which is measured at around 4,500 m compared to 3,000 m on previous days, and the SO2 emissions, which are estimated at over 12,000 tons per day. Changes in the wind direction and increased height of the plume have led to the dispersal of ash eastwards towards Santa Cruz de La Palma and La Palma airport, causing disruption to its operations for the first time since the eruption began.

Due to cooling and the infilling of topographic lows, the lava flow fronts have slowed significantly, and now advance at around 4 metres per hour. The total area affected by the lava flow stands at 140 hectares, with the flow fronts measuring 600 metres across. The episode of increased explosiveness that began at 7pm local time on the 21st ended at 2am local time and coincided with a small collapse of a portion of the cone. Strombolian activity continues producing both ash and lava flows from multiple vents in the vicinity of a principal cone that has formed around the most active vents. In the current state, up to 9 vents along one fissure have been observed by the authorities, although on average only 4 of these are active at any one time. This activity is emitting over 12,000 tons of SO2 per day up to 3000 m, although the amount of SO2 released per day is thought to be an underestimate according to PEVOLCA, as such ground-based measurements cannot be used to observe the full extent of the plume, unlike satellite observations.