Volcanic hazard assessment for tephra fallout in Martinique

Mount Pelée (Martinique) is one of the most active volcanoes in the Lesser Antilles arc with more than 34 magmatic events in the last 24,000 years, including the deadliest eruption of the 20th century. The current volcanic hazard map used in the civil security plan puts the emphasis on the volcanic hazard close to the volcano. This map is however based on an incomplete eruptive history and does not take into account the variability of the expected source conditions (mass eruption rate, total erupted mass, and grain-size distribution) or the wind effect on ash dispersal. We propose here to refine the volcanic hazard map for tephra fallout by using the 2-D model of ash dispersal HAZMAP. We first simulate the maximum expected eruptive scenario at Mount Pelée (i.e., the P3 eruption) using a seasonal wind profile. Building upon the good agreement with field data, we compute probability maps based on this maximum expected scenario, which show that tephra fallout hazard could threaten not only areas close to the volcano but also the southern part of Martinique. We then use a comprehensive approach based on 16 eruptive scenarios that include new field constraints obtained in the recent years on the past Plinian eruptions of Mount Pelée volcano. Each eruptive scenario considers different values of total erupted mass and mass eruption rate, and is characterized by a given probability of occurrence estimated from the refined eruptive history of the volcano. The 1979-2019 meteorological ERA-5 database is used to further take into account the daily variability of winds. These new probability maps show that the area of probable total destruction is wider when considering the 16 scenarios compared to the maximum expected scenario. The southern part of Martinique, although less threatened than when considering the maximum expected scenario, would still be impacted both by tephra fallout and by its high dependence on the water and electrical network carried from the northern part of the island. Finally, we show that key infrastructures in Martinique (such as the international airport) have a non-negligible probability of being impacted by a future Plinian eruption of the Mount Pelée. These results provide strong arguments for and will support significant and timely reconceiving of the emergency procedures as the local authorities have now placed Mount Pelée volcano on alert level yellow (vigilance) based on increased seismicity and tremor-type signals.

Pemodelan Aliran Awanpanas (Aliran Piroklastik) Sebagai Data Pendukung Peta Kawasan Rawan Bencana Gunungapi (Studi Kasus Gunungapi Sinabung Sumatra Utara) Pyroclastic Flows Modeling As A Supporting Data For Volcanic Hazard Map (Case Study Sinabung Volcano-North Sumatra)

ABSTRAKIndonesia mempunyai 127 gunungapi aktif dan berdasarkan sejarah erupsi 67 di antaranya merupakan gunungapi berbahaya. Erupsi gunungapi memiliki risiko merusak dan mematikan tidak hanya bagi masyarakat yang bermukimdi sekitarnya tapi juga menyebabkan bencana bagi masyarakat luas. Salah satu bahaya primer erupsi gunungapi adalah aliran awanpanas, produk erupsi gunungapi yang sampai saat ini paling banyak menyebabkan jatuhnya korban jiwa, untuk itu diperlukan suatu simulasi/pemodelan untuk mengetahui pola aliran awanpanas guna mendukung penentuan Kawasan Rawan Bencana (KRB) erupsi gunungapi.Simulasi/pemodelan aliran awanpanas ini dibuat berdasarkan data Model Elevasi Digital (DEM) dan memanfaatkan aplikasi Sistem Informasi Geografis (GIS), dengan output berupa representasi dinamis dari kecepatan aliran awanpanas, ketebalan deposit, dan daerah terdampak, dengan studi kasusGunungapi Sinabung Sumatra Utara. Setelah erupsi terakhir 1200 tahun lalu peningkatan aktivitas Gunungapi sinabung ditandai dengan terjadinya letusan freatik pada periode Agustus-September 2010. Setelah 3 tahun beristirahat, aktivitas erupsi kembali terjadi sejak September 2013 hingga saat ini. Aktivitas erupsi berupa pertumbuhan kubah lava dan luncuran awanpanas telah mengakibatkan jatuhnya korban jiwa serta memaksa penduduk mengungsi menjauhi daerah bahaya.Simulasi/pemodelan aliran awanpanas Gunungapi Sinabung karena runtuhnya kubah lava dibuat ke berbagai arah dengan skenario volume kubah lava ; 1, 2 dan 3 juta m3. Hasil overlay antara daerah landaaan awanpanas dengan skenario 3 juta m3 pada Peta KRB menunjukan jangkauan aliran awanpanas pada sektor tenggara, barat dan timurlaut telah sedikit melewati batas KRB III (kawasan sangat berpotensi terlanda awan panas, aliran lava, guguran lava dangas beracun).Kata kunci : awanpanas, Simulasi/model, titan2d, KRBABSTRACTIndonesia has 127 active volcanoes and based on historical eruption, 67 of them are dangerous. Volcano eruption having destructive risk and deadly, not only for the people who lived around, but also caused disaster for large society. One of the primary danger of volcano eruption is the pyroclastic flow, volcano eruption products that until recently was the most caused the loss of life, therefore necessary creating a simulation/modeling to know pyroclastic flow pattern to support of a determination the Volcanic hazard map. Pyroclastic flow Simulation/modeling is made based on the Digital Elevation Model (DEM) data and using Geographical Information System (GIS) application, with output of representation dynamic from the pyroclastic flow velocity, the thickness of deposit, and affected areas, with case Sinabung Volcano in North Sumatra.Since lates eruption about 1.200 years ago, Increased activity Sinabung volcano started by phreatic eruptions during August – September 2010. After three years of rest, eruption activity occurs again on September 2013 until today, with lava dome growth and pyroclastic flow acitvity have caused casualties and forcing residents were being evacuated away from the danger area.The pyroclastic flow simulation/modeling due the lava dome collapse is made into various directions with scenario of lava dome volume ; 1, 2 and 3 million m3. The results of overlay between areas affected by pyroclastic flow model with scenario 3 million m3 and volcanic hazard map showed the range of pyroclastic flow to the southeast, west and northeast sector reached the limit of zone III at volcanic hazard map (Very potentially affected by pyroclastic flow, lava flow, lava avalanche, and toxic volcanic gas ).Keywords : pyroclastic, simulation/modeling Titan2D, volcanic hazard map

Pemodelan Aliran Awanpanas (Aliran Piroklastik) Sebagai Data Pendukung Peta Kawasan Rawan Bencana Gunungapi (Studi Kasus Gunungapi Sinabung Sumatra Utara)

ABSTRAK Indonesia mempunyai 127 gunungapi aktif dan berdasarkan sejarah erupsi 67 di antaranya merupakan gunungapi berbahaya. Erupsi gunungapi memiliki risiko merusak dan mematikan tidak hanya bagi masyarakat yang bermukim disekitarnya tapi juga menyebabkan bencana bagi masyarakat luas. Salah satu bahaya primer erupsi gunungapi adalah aliran awanpanas, produk erupsi gunungapi yang sampai saat ini paling banyak menyebabkan jatuhnya korban jiwa, untuk itu diperlukan suatu simulasi/pemodelan untuk mengetahui pola aliran awanpanas guna mendukung penentuan Kawasan Rawan Bencana (KRB) erupsi gunungapi. Simulasi/pemodelan aliran awanpanas ini dibuat berdasarkan data Model Elevasi Digital (DEM) dan memanfaatkan aplikasi Sistem Informasi Geografis (GIS), dengan output berupa representasi dinamis dari kecepatan aliran awanpanas, ketebalan deposit, dan daerah terdampak, dengan studi kasus Gunungapi Sinabung Sumatera Utara. Setelah erupsi terakhir 1200 tahun lalu (sutawidjaja, 2013), peningkatan aktivitas Gunungapi sinabung ditandai dengan terjadinya letusan freatik pada periode Agustus-September 2010. Setelah 3 tahun beristirahat, aktivitas erupsi kembali terjadi sejak September 2013 hingga saat ini. Aktivitas erupsi berupa pertumbuhan kubah lava dan luncuran awanpanas telah mengakibatkan jatuhnya korban jiwa serta memaksa penduduk mengungsi menjauhi daerah bahaya. Simulasi/pemodelan aliran awanpanas Gunungapi Sinabung karena runtuhnya kubah lava dibuat ke berbagai arah dengan skenario volume kubah lava ; 1, 2 dan 3 juta m3 . Hasil overlay antara daerah landaan awanpanas dengan skenario 3 juta m3 pada Peta KRB menunjukan jangkauan aliran awanpanas pada sektor tenggara, barat dan timurlaut telah sedikit melewati batas KRB III (kawasan sangat berpotensi terlanda awan panas, aliran lava, guguran lava dan gas beracun). Kata kunci : awanpanas, Simulasi/model, titan2d, KRB ABSTRACT Indonesia has 127 active volcanoes and based on historical eruption, 67 of them are dangerous. Volcano eruption having destructive risk and deadly, not only for the people who lived around, but also caused disaster for large society One of the primary danger of volcano eruption is the pyroclastic flow, volcano eruption products that until recently was the most caused the loss of life, therefore necessary creating a simulation/modeling to know pyroclastic flow pattern to support of a determination the Volcanic hazard map. Pyroclastic flow Simulation/modeling is made based on the Digital Elevation Model (DEM) data and using Geographical Information System (GIS) application, with output of representation dynamic from the pyroclastic flow velocity, the thickness of deposit, and affected areas, with case Sinabung Volcano in North Sumatra. Since lates eruption about 1.200 years ago, Increased activity Sinabung volcano started by phreatic eruptions during August – September 2010. After three years of rest, eruption activity occurs again on September 2013 until today, with lava dome growth and pyroclastic flow acitvity have caused casualties and forcing residents were being evacuated away from the danger area. The pyroclastic flow simulation/modeling due the lava dome collapse is made into various directions with scenario of lava dome volume ; 1, 2 and 3 million m3 . The results of overlay between areas affected by pyroclastic flow model with scenario 3 million m3 and volcanic hazard map showed the range of pyroclastic flow to the southeast, west and northeast sector reached the limit of zone III at volcanic hazard map (Very potentially affected by pyroclastic flow, lava flow, lava avalanche, and toxic volcanic gas ). Keywords : pyroclastic, simulation/modeling Titan2D, volcanic hazard map