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| The day before the M5.0 and 4.6 earthquakes near Pāhala. Hawaiian Volcano Observatory released its Volcano Watch, focusing on preparation and safety during earthquakes and lava flows, as well as info on the Great Shakeout, coming up Oct. 20. See more below. Images from Great Hawai'i Shakeout |
M4.6 AND M5.0 EARTHQUAKES SHOOK KA'Ū FRIDAY, WITHIN SECONDS OF EACH OTHER, making them feel like one long, extended temblor. The epicenter of the 4.6 at 9:07 a.m. was just offshore, south of Pāhala. The 5.0 was on land, about half way between Pāhala and Punalu'u at Highway 11. They were 24 seconds apart.
Both quakes were at shallower depths than most quakes in the ongoing swarm around Pāhala. The 4.6 was 8 miles deep and the 5.0 was 4 miles deep, according to the U.S. Geological Survey.
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| A few items fell off shelves and broke at Aun Tee's at Pāhala Center during 4.6 and 5.0 earthquakes Friday. Staff relocated other items onto the floor during the aftershocks. The coffee and gift shop reopened when electricity came back on. Photo by Julia Neal |
The quakes prompted Kaʻū High & Pāhala Elementary School Principal Sharon Beck to sound off the alarm, evacuating all students into the schoolyard. At the adjacent Robert E. Herkes Kaʻū District Gym, which is also the regional disaster shelter, some ceiling panels fell. Light fixtures fell inside Pāhala Post Office, which shut its front door and announced it would hand out packages out the back door, and continue to service the postal boxes, with no counter service until further notice.
Items fell off shelves at Mizuno Superette and Aun Tee's coffee shop at Pāhala Center. Electricity went off for hours in Pāhala and both Bank of Hawai'i and Long's shut their doors. Mizuno's and Aun Tee's opened with the return of electricity. Kaʻū Hospital remained opened and was largely unscathed with inspectors making a check on structural stability.
Residents talked about mirrors and artwork crashing onto floors along with dishes and other items, leaving a lot of glass to sweep up. Some residents reported leaks in water pipes.
At Punalu'u, SeaMountain condominium guests and residents reported some shaking but no loss of power.
See more earthquake coverage on https://www.hawaiinewsnow.com/2022/10/14/49-magnitude-earthquake-shakes-hawaii-island/.com,
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| Both the ATM and counter service shut down at Bank of Hawai'i in Pāhala. Photo by Julia Neal |
"This sequence of earthquakes appears to be related to readjustments along the southeast flank of Mauna Loa volcano. There has been no immediate effect on the continuing unrest beneath Mauna Loa summit, which remains elevated at levels similar to the past week. On several occasions large earthquakes have
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| Longs Drugs shutdown after the earthquake due to power outage. Photo by Julia Neal |
The Hawaiian Volcano Observatory will continue to closely monitor Mauna Loa for any changes. "
To read comments, add your own, and like this story, see www.facebook.com/kaucalendar. See latest print edition at wwwkaucalendar.com. See upcoming events at https://kaunewsbriefs.blogspot.com/2022/04/upcoming-events-for-kau-and-volcano.html.
THE DAY BEFORE THE 5.0 QUAKE, the weekly Volcano Watch column by USGS Hawaiian Volcano Observatory and scientists focused on preparedness for quakes and lava flows, particularly from Mauna Loa. It was written by geophysicist Jefferson Chang:
Feeling occasional earthquakes is part of the experience of living in the State of Hawai'i. Most of the
Feeling occasional earthquakes is part of the experience of living in the State of Hawai'i. Most of the
earthquakes are small, but the less common large earthquakes can be damaging, so it is important to be prepared.
The U.S. Geological Survey Hawaiian Volcano Observatory records tens of thousands of earthquakes beneath our islands every year. Luckily, most of these are less than magnitude-2, and are not felt. Over the past 30 years, Hawai'i has had four earthquakes of magnitude-6 or larger. Three of them were deep (greater than 12 miles or 20 kilometers) and likely the result of the stresses brought forth by the Hawaiian Islands sitting on top of the Pacific plate. A recent example was the magnitude-6.2 earthquake that struck 17 miles (27 kilometers) south of Nā‘ālehu, a few minutes before midnight on Oct. 10, 2021.
Another was a magnitude-6.9 on May 4, 2018, which is the largest earthquake recorded in Hawai'i in the past 30 years. This event was much shallower (less than 9 miles or 15 kilometers) and was likely related to magma moving through the Kīlauea plumbing system at the start of the 2018 lower East Rift Zone eruption.
It is a bit of a chicken or egg problem, whether these large, shallow earthquakes under volcanoes lead to eruptions, or if it is the magma shifting stresses along faults that trigger earthquakes. These are two end-member hypotheses, and in reality, it is most likely a combination of both. Earthquakes and volcanic eruptions go hand-in-hand.
We see this kind of interplay between magma movement and seismicity with the ongoing swarm of earthquakes under Mauna Loa summit caldera (Moku'āweoweo) and the upper northwest flank. This elevated seismic activity is accompanied by slight ground inflation (or swelling), which suggests that the Mauna Loa magma reservoir is filling.
Does this mean that Mauna Loa will erupt soon? Not necessarily.
Mauna Loa has been in a period of prolonged unrest. The sleeping giant may just be snoring a little louder than it did a few years ago, but it does not necessarily mean that it will wake up soon.
Scientists at HVO look at many different monitoring streams to document changes in Mauna Loa’s behavior. Some of these changes may alert scientists when an eruption is more likely. Large shallow earthquakes are one of the indicators that move the probability of an eruption of Mauna Loa from “not necessarily” to “highly likely”. For example, a magnitude-6.7 earthquake happened a few months before the last eruption of Mauna Loa in 1984. The 1950 eruption was also preceded by a large earthquake, but only 2 days prior to the onset of the eruption.
However, not all Mauna Loa eruptions are preceded by large earthquakes. And some large earthquakes, such as the 1975 magnitude-7.7 Kalapana earthquake was not accompanied by a major eruption of Kīlauea volcano.
Large shallow earthquakes are not just a potential precursor to volcanic eruptions, but can be a disaster on their own. Damage done by large earthquakes can be mitigated to reduce the hazards and risks associated with violent shaking. Modern building codes make houses much more resistant to damage. Efforts like securing tall heavy objects to the wall so they are less likely to tip over and fall will reduce the likelihood of damage and injury when a large earthquake hits. Earthquake safety drills for “Drop. Cover. Hold On.” should be practiced regularly so that instinct kicks in when the initial shaking is felt.
Join us, and the rest of the world, on Thursday, Oct. 20 at 10:20 a.m. local time for the Great Hawai'i ShakeOut.
Visit shakeout.org to sign-up and learn more about ways to prepare for large damaging earthquakes.
The U.S. Geological Survey Hawaiian Volcano Observatory records tens of thousands of earthquakes beneath our islands every year. Luckily, most of these are less than magnitude-2, and are not felt. Over the past 30 years, Hawai'i has had four earthquakes of magnitude-6 or larger. Three of them were deep (greater than 12 miles or 20 kilometers) and likely the result of the stresses brought forth by the Hawaiian Islands sitting on top of the Pacific plate. A recent example was the magnitude-6.2 earthquake that struck 17 miles (27 kilometers) south of Nā‘ālehu, a few minutes before midnight on Oct. 10, 2021.
Another was a magnitude-6.9 on May 4, 2018, which is the largest earthquake recorded in Hawai'i in the past 30 years. This event was much shallower (less than 9 miles or 15 kilometers) and was likely related to magma moving through the Kīlauea plumbing system at the start of the 2018 lower East Rift Zone eruption.
It is a bit of a chicken or egg problem, whether these large, shallow earthquakes under volcanoes lead to eruptions, or if it is the magma shifting stresses along faults that trigger earthquakes. These are two end-member hypotheses, and in reality, it is most likely a combination of both. Earthquakes and volcanic eruptions go hand-in-hand.
We see this kind of interplay between magma movement and seismicity with the ongoing swarm of earthquakes under Mauna Loa summit caldera (Moku'āweoweo) and the upper northwest flank. This elevated seismic activity is accompanied by slight ground inflation (or swelling), which suggests that the Mauna Loa magma reservoir is filling.
Does this mean that Mauna Loa will erupt soon? Not necessarily.
Mauna Loa has been in a period of prolonged unrest. The sleeping giant may just be snoring a little louder than it did a few years ago, but it does not necessarily mean that it will wake up soon.
Scientists at HVO look at many different monitoring streams to document changes in Mauna Loa’s behavior. Some of these changes may alert scientists when an eruption is more likely. Large shallow earthquakes are one of the indicators that move the probability of an eruption of Mauna Loa from “not necessarily” to “highly likely”. For example, a magnitude-6.7 earthquake happened a few months before the last eruption of Mauna Loa in 1984. The 1950 eruption was also preceded by a large earthquake, but only 2 days prior to the onset of the eruption.
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| See shakeout.org for the Great Hawai'i Shakeout event Oct. 20. |
Large shallow earthquakes are not just a potential precursor to volcanic eruptions, but can be a disaster on their own. Damage done by large earthquakes can be mitigated to reduce the hazards and risks associated with violent shaking. Modern building codes make houses much more resistant to damage. Efforts like securing tall heavy objects to the wall so they are less likely to tip over and fall will reduce the likelihood of damage and injury when a large earthquake hits. Earthquake safety drills for “Drop. Cover. Hold On.” should be practiced regularly so that instinct kicks in when the initial shaking is felt.
Join us, and the rest of the world, on Thursday, Oct. 20 at 10:20 a.m. local time for the Great Hawai'i ShakeOut.
Visit shakeout.org to sign-up and learn more about ways to prepare for large damaging earthquakes.
To read comments, add your own, and like this story, see www.facebook.com/kaucalendar. See latest print edition at wwwkaucalendar.com. See upcoming events at https://kaunewsbriefs.blogspot.com/2022/04/upcoming-events-for-kau-and-volcano.html.
THE ROBERT E. HERKES KAʻŪ DISTRICT GYM WILL HOST GIRLS VOLLEYBALL FINALS for the Big Island Interscholastic Federation this Saturday afternoon. In football, the Trojans will host Kohala at 1:30 p.m.
To read comments, add your own, and like this story, see www.facebook.com/kaucalendar. See latest print edition at wwwkaucalendar.com. See upcoming events at https://kaunewsbriefs.blogspot.com/2022/04/upcoming-events-for-kau-and-volcano.html.
