We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hespérides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ≥2.

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<p>Between September and December 2021, a Strombolian fissure eruption with phreatomagmatic pulses occurred in the Westside of the Island of La Palma (Canary Islands, Spain), giving rise to a volcanic edifice called Tajogaite and whose cone reached a height of 1121 m. above sea level (200 m above the pre-eruption topography) with a volume of 34 Mm<sup>3</sup> consisting of the alignment of 6 different craters of 557 meters in length, direction N130ºE.</p><p>In order to analyze the stability of the volcanic edifice and estimate the possible risk of lahars from pyroclastic materials lying on the slopes of the volcano and the surrounding areas, a series of investigations have been carried out consisting on historical series of rainfall data, thickness estimation  of the ashes deposits, laboratory tests on in situ samples, density, friction angle and cohesion of the soils determinations, as well as a geophysical survey using MASW seismic technique geotechnical properties of the slope layers in the first 30 meters of the volcano slopes. Based on these investigations, a stability analysis of the slopes of the volcanic edifice has been carried out considering different rainfall scenarios. Slope stability calculations were carried out using the Slide V6 program, from geotechnical data obtained in laboratory and from limit equilibrium back analysis conditions. Two main scenarios were analyzed including the most probable and the least probable rainfall, corresponding to the return period of  10 years and 50 years respectably.</p><p>Risk of lahars had been indentify as possible for the 50 years return period, as a consequence of both the instability of the cone slopes and the surrounding ash deposits, associated with very intense rains. These data has been incorporated to the land planning of reconstruction development, particularly the adoption of preventive measures in case of intense rainfall, as well as for the design of drainage infrastructures.</p>