USGS busy with new volcanic activity on 6 volcanoes in the United States

Pavlof volcano, seen from the southwest. In the background is the Pavlof Sister. Image: David Fee / Alaska Volcano Observatory / University of Fairbanks, Geophysical Institute

The USGS has issued an ORANGE code and a WATCH alert for three volcanoes and a YELLOW code and ADVISORY alert for three volcanoes they are tracking across the country; The USGS says these 6 volcanoes “show signs of elevated unrest above known background level.” While some are showing more signs of volcanic activity than others, the USGS is paying close attention to those with the ORANGE code at this time: Semisopochnoi, Great Sitkin, and Pavlof in Alaska. The other 3 with the high alert level of YELLOW / NOTICE include the world’s largest active volcano, Mauna Loa and Kilauea, both on the island of Hawaii, Cleveland in Alaska, and Pagan north of Guam.

In the United States, the USGS tracks 169 potentially active volcanoes, most of which are in Alaska. Alaska is however home to many volcanoes; there are over 130 volcanoes and volcanic fields that have been active over the past 2 million geologically young years. 50 have been active since the mid-1700s and AVO is studying them as well. Another place famous for its volcanoes is Hawaii; on the Big Island of Hawaii, Kilauea, Mauna Loa, and Hualalai are considered active and potential threats, but none have erupted to date. Kilauea started a new eruption in December 2020, but this eruption ended just a few weeks ago. Hawaii’s volcanoes are monitored by the Hawaii Volcanoes Observatory (HVO) while Alaskan volcanoes are monitored by the Alaska Volcanoes Observatory (AVO). Yellowstone Volcano Observatory. Each of these additional volcanic observatories within the USGS monitors volcanoes in their respective regions. Right now, none of these other observatories are reporting unusual activity or signs of anything more than background noise at the moment.

According to the US Geological Survey (USGS), there are approximately 1,500 potentially active volcanoes in the world, with approximately 500 of the 1,500 erupting volcanoes in history. Most of the world’s volcanoes are located around the “Ring of Fire” around the Pacific Rim. The Ring of Fire is an area around the edge of the Pacific Ocean where numerous volcanic eruptions and earthquakes occur. Caused by plate tectonics, the lithospheric plates under and around the Pacific Ocean move, collide and / or are destroyed, creating the seismic activity for which the Ring of Fire is famous.

These volcanoes in Alaska are on a code yellow / advisory level today.  They are Great Sitkin, top left, Gareloi, top right, Semisopochnoi, bottom left, and Cleveland, bottom right.  Image: AVO / USGS
Alaksa volcanoes have come to life this year, including observed activity at Great Sitkin volcano, top left, Gareloi, top right, Semisopochnoi, bottom left, and Cleveland bottom right. Image: AVO / USGS

In the United States, the USGS and volcanic observation units are responsible for issuing aviation codes and volcanic activity alert levels. Aviation codes are green, yellow, orange or red. When ground instrumentation is insufficient to establish that a volcano is at a typical background activity level, it is simply “unaffected.” While green signifies typical activity associated with a non-eruptive state, yellow signifies that a volcano is showing signs of elevated unrest above known background levels. When a volcano exhibits increased or increasing unrest with increased eruption potential, it turns orange. Finally, when an eruption is imminent with a significant emission of volcanic ash expected in the atmosphere or an eruption is in progress with a significant emission of volcanic ash in the atmosphere, the code turns red. Volcanic activity alert levels are normal, advisory, monitoring, or warning. As with aviation codes, if there is insufficient data, it is simply labeled as “unassigned”. When the volcano is at typical background activity in a non-eruptive state, it is considered normal. If the volcano shows signs of elevated unrest above background level, an advisory is issued. If a volcano is exhibiting increased or increasing unrest, a watch is issued while a warning is issued when a dangerous eruption is imminent.

The next volcano to erupt in the United States could be the largest in the world at Mauna Loa in Hawaii. In a recent press release, scientists at the USGS Hawaiian Volcano Observatory (HVO) cautioned: “While an eruption of Mauna Loa is not imminent, now is the time to revisit plans. personal rash. Similar to preparing for hurricane season, having a blowout plan in advance helps in an emergency. “

Mauna Loa is considered the largest active volcano on Earth, rising to 13,681 feet above sea level. Mauna Loa rises from the bottom of the Central Pacific Ocean to a depth of approximately 3 miles. Due to the volcano’s large mass, the ocean floor directly below Mauna Loa is depressed an additional 5 miles. According to the USGS, this places the summit of Mauna Loa about 56,000 feet above its base; the huge volcano covers half of the island of Hawaii, also known simply as the “Big Island of Hawaii”.

This map shows the response time people can expect based on Mauna Loa eruptions over the past 200 years.  Different areas around Mauna Loa are colored depending on how quickly lava flows can reach populated areas.  The warmer the color, the faster the flow will flow.  Mauna Loa lava flows over the past 200 years are shown in gray, and numbers along the coastline indicate lava travel times to the ocean after the vents open.  Large, bold numbers record the average effusion rates for different parts of the volcano in millions of cubic meters per day (Mm3 / d).  Image: USGS
This map shows the response time people can expect based on Mauna Loa eruptions over the past 200 years. Different areas around Mauna Loa are colored depending on how quickly lava flows can reach populated areas. The warmer the color, the faster the flow will flow. Mauna Loa lava flows over the past 200 years are shown in gray, and numbers along the coastline indicate lava travel times to the ocean after the vents open. Large, bold numbers record the average effusion rates for different parts of the volcano in millions of cubic meters per day (Mm3 / d). Image: USGS

Mauna Loa eruptions tend to produce large, rapid lava flows that can impact communities on the east and west sides of the Big Island, from Kona to Hilo. Since the 1850s, Hilo, in eastern Hawaii, has been threatened by 7 lava flows from Mauna Loa. On the southern and western sides of the island, lava flows from Mauna Loa reached the coast there 8 times: in 1859, 1868, 1887, 1926, 1919 and three times in 1950.

According to the USGS, while Mauna Loa is not currently erupting, strain and seismicity rates remain high above long-term background levels. GPS measurements continue to show slow, long-term summit inflation consistent with the supply of magma to the volcano’s shallow storage system. A slight increase in the inflation rate that began in January continues.

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