Everest in the Himalaya mountain range, sit higher relative to sea level. All large land masses such as mountains also push down upon the Earth's crust due to their enormous weight. So, directly beneath Mauna Loa, the sea floor on which it sits is depressed by and additional 26, ft m. Thus, if one wanted to say how thick at its center is the lava pile that makes up Mauna Loa, one would need to add its above sea level height, its sea floor to sea level height, and the thickness of its depression in the Pacific sea floor.
These total 56, ft 17, m. For more details about estimation of the actual thickness of Mauna Loa volcano, see the write up on "How high is Mauna Loa volcano" at the HVO website. Mauna Loa Awakening? The summit of Mauna Loa began inflating slowly between and after a decade of slight deflation, after experiencing a brief swarm of deep long-period earthquakes. Inflation wasn't constant, with slowdowns in winter , Spring , and since sept But, inflation was fairly steady in and the first half of following a more intense swarm of several thousand deep earthquakesin late , all of which suggested that the magma reservoir within the volcano was swelling.
Then inflation slowed again in , ceased in late , and resumed slowly in late , continuing through mid i. Im late Aug , HVO raised the alter level at Mauna Loa because of long-term increased seismicity rates and inflation of the summit as measured by cross-caldera difference. This doesn't mean an eruption is imminent, but signs are consistent with magma entering the shallow part of the magmatic system at the volcano.
Earthquakes activity increased in early July and continued through Fall , but then slowed significantly throughout and remained at a level of about 10 a week. Activity peaked in Sept. That earthquake swarm was the greatest number of such earthquales since the beginning of the modern HVO earthquake catalog in the s.
HVO scientists continue to monitor the volcano closely. Alerts In Effect Dismiss. Dismiss View all alerts. Mauna Loa. Mauna Loa is the largest active volcano on the planet. Meaning "long mountain" in Hawaiian, it is the quintessential shield volcano in its shape— signified by broad, rounded slopes. More impressive, however, it rises an astonishing 30, feet 9, m from the bottom of the sea, a greater height than Mount Everest.
One to 2 years prior to the and eruptions, swarms of small earthquakes increased in intensity. The strongest swarms included hundreds of small earthquakes per day for weeks. Bursts, as they were called, were separated by 3—6 months of relative quiet [ Koyanagi et al.
Recently, swarms on the west flank have increased in number and size, but the durations of the swarms are less than pre and levels. Similarly, swarms of tiny earthquakes beneath the caldera have not occurred at rates seen in the months prior to the and eruptions. Interestingly, during the days to weeks prior to the past two eruptions, the number of small earthquakes fluctuated instead of building up steadily, even reaching relatively low rates for short periods prior to eruption [ Koyanagi, ; Lockwood et al.
However, both eruptions had distinct short-term seismic precursors. The eruption was preceded by less than an hour of strong tremor in the summit caldera area [ Lockwood et al. In , small less than M 0. Harmonic tremor began about 2 hours prior to eruption, with a large increase in tremor amplitude and a swarm of earthquakes 30 minutes prior to eruption.
Seven earthquakes larger than M 3 occurred during a period from 30 minutes before the eruption until just over 1 hour after the onset of the eruption.
Some aspects of the current unrest are similar to unrest prior to eruptions in and Earthquake locations, temporal behavior, and energy release suggest that the volcano may be following a similar pattern. Other aspects, however, differ from the periods prior to the and eruptions.
During the current unrest period, we have not observed the kind of moderate to large flank earthquakes that preceded many historical eruptions [ Walter and Amelung, ], including the and eruptions. Also, as of fall , we have not seen the high rates of small earthquakes observed about 7—14 months prior to the and eruptions, even though our ability to detect them has improved. Thus, if current unrest follows previous patterns of seismicity, we may expect that the volcano is still many months from eruption.
We must also consider that current unrest might not follow previous patterns , and an eruption could occur without months of elevated microseismicity. It is possible that after years of intermittent inflation, shallow magma storage is exerting pressures already near the breaking point of the overlying rock. However, an eruption will likely be immediately preceded by an hours-long, dramatic increase in small earthquakes at least one earthquake per minute , strong tremor, and the occurrence of several M 3 or stronger earthquakes, similar to the lead-up to the and eruptions.
It is also possible that current elevated rates of seismicity and deformation may not culminate in eruption anytime soon; rather, this could be yet another episode of unrest that gradually diminishes. During the year repose between the and eruptions, seismic unrest in , , and did not lead to eruption, although in hindsight, each is considered a long-term precursor to the eruption [ Koyanagi et al.
We can make one forecast with relative certainty: On the basis of nearly years of documented activity, it is highly likely that the next eruption will begin in the summit region and then, within days to years, migrate into one of the two primary rift zones [ Lockwood et al.
Similar patterns of seismicity prior to the and eruptions did not result in sustained activity in the SWRZ. In , the eruption began at the summit and migrated to the upper SWRZ before activity focused along the NERZ, suggesting that a magma body extending into the uppermost SWRZ—similar to that inferred from current data—was also active prior to that eruption.
Improvements in monitoring networks and alarming systems since put the Hawaiian Volcano Observatory in a better position to provide early warning and, once an eruption has commenced, help guide emergency response. In , HVO installed new web cameras and upgraded real-time gas and temperature sensors in the summit caldera. Alarms have been set to alert scientists to significant changes in several data streams, including real-time seismic amplitude a measure of seismic energy release , ground tilt, and satellite- and ground-based thermal imagery.
Revised maps showing potential inundation zones and likely lava flow paths based on topography derived from digital elevation maps have been prepared. As with any precursory volcanic eruption sequence, it will be challenging to choose the correct time to alert authorities and elevate public concern about a possible eruption. Get the ad-free version! Why is there advertising on this site? Support us - Help us upgrade our services! Copyrights: VolcanoDiscovery and other sources as noted. Use of material: Most texts and images, in particular photographs, on this website are protected by copyright.
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