#seism

[manolomun63]

ce clocher d’Avignon est penché depuis le seisme d’une magnitude de 6.2 de Lambesc en 1909.

this bell tower in Avignon is leaning since the seismic of a magnitude of 6.2 of Lambesc in 1909.

este campanario en Avignon está inclinado desde el seismo de una magnitud de 6.2 de Lambesc en 1909.

[imanetalbii]

The latest earthquake that shook Turkey and Syria has once more highlighted the regrettable truth of how people have lost regard for natural catastrophes and the people they touch. The earthquake, which has already resulted in the deaths of over 5,000 people and the destruction of thousands of structures, has brought attention to the difficult circumstances that the survivors are dealing with. Despite the tragedy's magnitude, a lot of individuals have neglected to show the disaster and those it has impacted the respect and compassion they deserve.

People are embracing the news of tragedies and deaths as simply another sort of entertainment as they grow more numb to it. The continual exposure to such news on television and social media has made tragedy and suffering more commonplace. People watch disaster-related news and information with the same attention and detachment as they would a television program. People are less empathetic and more ready to see catastrophe develop as a result of the public's hunger for provocative material.

Social media has added to this mentality of desensitization to human pain. Persons are now so preoccupied with provocative material that they no longer regard the deceased as actual people but rather as anonymous numbers. This has led to a disregard for the emotional toll that tragedies and death may take on the affected parties and their families.

The frigid weather and damaged roads, which have impeded rescue attempts, have made the aftermath of the earthquake in Turkey and Syria even more challenging. Despite these challenging circumstances, it's critical that we remember the humanity of those affected by the tragedy and provide them with the care and assistance they require.

Last but not least, the recent earthquakes in Turkey and Syria have once more brought to light the regrettable truth of how people have grown indifferent to natural catastrophes and the people who are afflicted by them. People have lost sight of the compassion of those who are suffering as a result of the normalization of tragedy and the need for provocative material. Remembering that the victims of a tragedy are not simply abstract statistics but actual individuals with families and loved ones who are grieving their loss is crucial.

[nuadox]

New research detects pre-eruption warning signals at Whakaari White Island and other active volcanoes

- By David Dempsey , Alberto Ardid , Shane Cronin , The Conversation -

Scientifically and emotively, we think every volcano has its own “personality”. However, we’ve discovered that volcanoes share behaviour traits – and this could form the basis for an eruption warning system.

Whakaari White Island (Ed. note: located 48 km from the east coast of the North Island of New Zealand), a picturesque volcanic island in the Bay of Plenty, was a tourist magnet, with its alien landscape and spectacular hydrothermal features. This idyll was shattered on December 9 2019 when high-pressure steam and gas exploded, concentrating in a deadly surge of hot ash down its main access valley. Of the 47 guides and tourists present, 22 died while many others suffered horrific burns.

Since that tragedy, we have been studying past eruptions at Whakaari, and volcanoes like it, to identify the warning signs of an imminent eruption.

Deciphering volcanic language

Every volcano behaves differently: some have crater lakes while others are “dry”, they have diverse magmas and rise to different elevations. Despite these differences, we think volcanoes such as Whakaari, Ruapehu and Tongariro in New Zealand could be driven to eruption by common processes in the shallow sub-surface below their craters.

In our new research, we used machine learning to sift through 40 years of seismic data from the New Zealand volcanoes and three others around the world, listening for particular frequencies that track the depth where gas, magma or water are moving or building up.

We saw one pattern repeatedly in the days before all the known Whakaari eruptions over the past decade, and most Ruapehu and Tongariro ones. This pattern is a slow strengthening of a quantity called Displacement Seismic Amplitude Ratio (DSAR), which peaks a few days before each event.

DSAR is a ratio that compares the “activity” of fluids (gas, hot water, steam) at the volcano’s surface to those several hundred metres deep. When DSAR increases, surface fluids are quiet, but deep ones are still actively moving and circulating vigorously below ground.

This indicates a blockage or seal has formed, preventing gas escape. Like a pressure-cooker, if the gas can’t escape a volcano, it explodes.

What happened at Whakaari

About a month before the December 2019 eruption, deep gas started to rise into Whakaari’s hydrothermal system. This put pressure onto the groundwater, keeping it in a liquid state, even as it became “superheated”.

As this fluid circulates below the vent, it is registered as noise or “tremor” on seismometers. GNS Science noted this increased tremor and, on November 18, raised Whakaari’s alert level to Volcanic Alert Level (VAL) 2, which is the highest level outside an eruption.

Key changes at Whakaari White Island leading up to the December 9 2019 eruption. Provided by author, CC BY-SA

About a week later, Whakaari began to pulse. Pressure and tremor would build over about 24 hours, before discharging explosively at the bottom of the crater lake. This resulted in geysers and fountains, throwing mud and debris up to the height of a ten-storey building.

Crucially, these gas bursts were safety valves, easing the pressure in the system.

At the beginning of December, the gas bursts stopped and the surface became quiet. Rather than being cause for relief, we think this indicated a new and much more dangerous phase. A seal had formed, trapping the gas. The high DSAR shows that below the seal, the system was as noisy as ever, with pressure continuing to rise.

Between 9pm and midnight on December 8 2019, there was a strong burst of seismic energy. This was likely fresh magmatic fluid arriving to ramp up the pressure on gas and water already trapped in the rock. It also began the process of explosive release, because it caused small cracks to form in the seal.

The growth of cracks began to accelerate, setting Whakaari on the path to a cascading system failure, as has been seen before in eruptions in 2012 and 2013. Once the weakness was widespread, the seal failed, disgorging the massive steam-explosion at 2:11pm on December 9.

Understanding Ruapehu

Mount Ruapehu is a 2800m stratovolcano in New Zealand’s central North Island.

It is also capped by a hydrothermal system and a warm crater lake (Te Wai a Moe). The temperature and level of its lake is known to vary in cycles, responding to changes in gas released into its base, local weather or the occasional formation of a gas seal.

Unfortunately, the lake is so large it hides the surface activity that is useful for diagnosing volcanoes like Whakaari.

This is where DSAR is so powerful. We have spotted the same pattern that reveals gas sealing at Whakaari numerous times at Ruapehu. We monitor DSAR at Ruapehu closely: over the past month it has increased dramatically.

We think this shows a new seal has formed, building pressure. This could end in an eruption similar to the 2006/07 cycle that generated destructive lahars (volcanic mud flows).

GNS Science has reported similar concerns in their decision to raise Ruapehu’s alert level to VAL 2.

This type of analysis is so new we have not had many chances to test how reliable the DSAR and other automated measures are for forecasting. However, the current high DSAR and lake heating have put all scientist on alert. History shows this state does not always lead to an eruption, but we must remain vigilant.

David Dempsey, Senior lecturer, University of Canterbury; Alberto Ardid, Post Doctoral Researcher, University of Canterbury, and Shane Cronin, Professor of Earth Sciences, University of Auckland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Read Also

Unravelling the when, where and how of volcanic eruptions

[freighternity]

MUGU.SEISM. Traffic: 2016 Breaza, RO.

[imx-doomer]

Otro temblor. No lo sentí, pero de cualquier modo le mando un abrazo a mis lectores de México, espero estén bien.

[valiendomother]

Veo las muestras de solidaridad, de apoyo. Los centros de acopio llenos, la gente abarrotando las calles, las miles de manos que son ofrecidas para remover escombro. Las veo y se me hace un nudo en la garganta, porque todxs están dando lo mejor de sí, porque los ciudadanos respondieron sin chistar. 

Pero que no se les olvide, que esto siempre pasa. En dos semanas, cuando pase la euforia, cuando los canales vuelvan a la novela, cuando regreses a la escuela, cuando los rescatados sean menos, cuando se compartan memes nuevos en Facebook, cuando ya donaste una vez... No se les olvide que ahí es cuando más nos necesita nuestro país, México. 

México, tierra surrealista, donde una tragedia supera a la otra, y el olvido está a la vuelta de la esquina, en dos semanas, tres semanas. Que no se nos olvide, muchachxs, que lo aterrador viene en la reconstrucción, y no sólo en la luz de las cámaras de los primeros días.

[convict-240]

Force ! Mexico, cute and dear

[freighternity]

SEISM 2015.

Spotted: 2016 Bacău, Romania.