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- The 1991 eruption of Mount Pinatubo in the Philippines' Luzon Volcanic Arc was the second-largest volcanic eruption of the 20th century, behind only the 1912 eruption of Novarupta in Alaska. Eruptive activity began on April 2 as a series of phreatic explosions from a fissure that opened on the north side of Mount Pinatubo. Seismographs were set up and began monitoring the volcano for earthquakes. In late May, the number of seismic events under the volcano fluctuated from day-to-day. Beginning June 6, a swarm of progressively shallower earthquakes accompanied by inflationary tilt on the upper east flank of the mountain, culminated in the extrusion of a small lava dome. On June 12, the volcano’s first spectacular eruption sent an ash column 19 km (12 mi) into the atmosphere. Additional explosions occurred overnight and the morning of June 13. Seismic activity during this period became intense. When even more highly gas-charged magma reached Pinatubo's surface on June 15, the volcano exploded, sending an ash cloud 40 km (25 mi) into the atmosphere. Volcanic ash and pumice blanketed the countryside. Huge pyroclastic flows roared down the flanks of Pinatubo, filling once-deep valleys with fresh volcanic deposits as much as 200 m (660 ft) thick. The eruption removed so much magma and rock from beneath the volcano that the summit collapsed to form a small caldera 2.5 km (1.6 mi) across. Fine ash from the eruption fell as far away as the Indian Ocean and satellites tracked the ash cloud as it traveled several times around the globe. At least 16 commercial jets inadvertently flew through the drifting ash cloud, sustaining about $100 million in damage. With the ashfall came darkness and the sounds of lahars rumbling down nearby river valleys. Several smaller lahars washed through the Clark Air Base, flowing across the base in enormously powerful sheets, slamming into buildings and scattering cars. Nearly every bridge within 30 km (19 mi) of Mount Pinatubo was destroyed. Several lowland towns were flooded or partially buried in mud. More than 840 people were killed from the collapse of roofs under wet heavy ash and several more were injured. Rain continued to create hazards over the next several years, as the volcanic deposits were remobilized into secondary mudflows. Damage to bridges, irrigation-canal systems, roads, cropland, and urban areas occurred in the wake of each significant rainfall. Many more people were affected for much longer by rain-induced lahars than by the eruption itself. (en)
- Letusan Gunung Pinatubo 1991 di Busur Vulkanik Luzon di Filipina adalah letusan gunung berapi terbesar kedua pada abad ke-20, setelah letusan tahun 1912 di Alaska. Aktivitas letusan dimulai pada 2 April sebagai serangkaian letusan freatik dari celah yang terbuka di sisi utara Gunung Pinatubo. Seismograf dipasang dan mulai memantau gunung berapi untuk mendeteksi gempa bumi. Pada akhir Mei, jumlah kejadian seismik di bawah gunung berapi berfluktuasi dari hari ke hari. Mulai 6 Juni, bebarapa gempa bumi yang semakin dangkal disertai dengan kemiringan inflasi di sisi timur atas gunung, berpuncak pada ekstrusi kubah lava kecil. Pada tanggal 12 Juni, letusan spektakuler pertama gunung berapi mengirimkan kolom abu sepanjang 19 km ke atmosfer. Letusan lanjutan terjadi semalam dan pagi hari pada tanggal 13 Juni. Aktivitas seismik selama periode ini menjadi intens. Ketika magma bermuatan gas yang lebih tinggi mencapai permukaan gunung Pinatubo pada tanggal 15 Juni, gunung berapi itu meletus, mengirimkan awan abu sejauh 40 km ke atmosfer. Abu vulkanik dan batu apung menyelimuti pedesaan. Aliran piroklastik besar mengalir di sisi-sisi gunung Pinatubo, mengisi lembah yang dulunya dalam dengan endapan vulkanik setebal 200 m. Letusan tersebut mengeluarkan begitu banyak magma dan batuan dari bawah gunung berapi sehingga puncaknya runtuh membentuk sebuah kaldera kecil berukuran 2,5 km. Abu halus dari letusan jatuh sejauh Samudra Hindia dan satelit melacak awan abu saat melakukan perjalanan beberapa kali di seluruh dunia. Setidaknya 16 jet komersial secara tidak sengaja terbang melalui awan abu yang melayang, menyebabkan kerusakan sekitar $100 juta. Bersamaan dengan hujan abu, kegelapan datang dan suara lahar bergemuruh di lembah sungai terdekat. Beberapa lahar yang lebih kecil menyapu , mengalir melintasi pangkalan dalam lembaran-lembaran yang sangat kuat, menghantam gedung-gedung dan menghamburkan mobil-mobil. Hampir setiap jembatan dalam jarak 30 km dari Gunung Pinatubo hancur. Beberapa kota dataran rendah terendam banjir atau sebagian terkubur lumpur. Lebih dari 840 orang tewas akibat runtuhnya atap di bawah abu tebal yang basah dan beberapa lainnya terluka. Hujan abu terus menimbulkan bahaya selama beberapa tahun berikutnya, karena endapan vulkanik dipindahkan ke aliran lumpur sekunder. Kerusakan jembatan, sistem saluran irigasi, jalan, lahan pertanian, dan daerah perkotaan terjadi setelah setiap curah hujan yang signifikan. Lebih banyak orang terpengaruh lebih lama oleh lahar yang disebabkan oleh hujan daripada oleh letusan itu sendiri. (in)
- L'eruzione del Pinatubo del 1991 è stata un'eruzione vulcanica krakatoiana del vulcano Pinatubo, nelle Filippine. L'evento eruttivo è iniziato il 7 giugno e ha avuto conseguenze catastrofiche sull'ambiente e la popolazione. (it)
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- L'eruzione del Pinatubo del 1991 è stata un'eruzione vulcanica krakatoiana del vulcano Pinatubo, nelle Filippine. L'evento eruttivo è iniziato il 7 giugno e ha avuto conseguenze catastrofiche sull'ambiente e la popolazione. (it)
- The 1991 eruption of Mount Pinatubo in the Philippines' Luzon Volcanic Arc was the second-largest volcanic eruption of the 20th century, behind only the 1912 eruption of Novarupta in Alaska. Eruptive activity began on April 2 as a series of phreatic explosions from a fissure that opened on the north side of Mount Pinatubo. Seismographs were set up and began monitoring the volcano for earthquakes. In late May, the number of seismic events under the volcano fluctuated from day-to-day. Beginning June 6, a swarm of progressively shallower earthquakes accompanied by inflationary tilt on the upper east flank of the mountain, culminated in the extrusion of a small lava dome. (en)
- Letusan Gunung Pinatubo 1991 di Busur Vulkanik Luzon di Filipina adalah letusan gunung berapi terbesar kedua pada abad ke-20, setelah letusan tahun 1912 di Alaska. Aktivitas letusan dimulai pada 2 April sebagai serangkaian letusan freatik dari celah yang terbuka di sisi utara Gunung Pinatubo. Seismograf dipasang dan mulai memantau gunung berapi untuk mendeteksi gempa bumi. Pada akhir Mei, jumlah kejadian seismik di bawah gunung berapi berfluktuasi dari hari ke hari. Mulai 6 Juni, bebarapa gempa bumi yang semakin dangkal disertai dengan kemiringan inflasi di sisi timur atas gunung, berpuncak pada ekstrusi kubah lava kecil. (in)
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