On 30 March, HVO reported that the Aviation Color Code and the Volcano Alert Level for Mauna Loa were both lowered to Green and Normal, respectively. Deformation had not been noted since mid-2009 and seismicity was at normal levels.

24 March 2010            Back to Top

On 30 March, HVO reported that the Aviation Color Code and the Volcano Alert Level for Mauna Loa were both lowered to Green and Normal, respectively. Deformation had not been noted since mid-2009 and seismicity was at normal levels.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

17 August 2005            Back to Top

HVO reported on 21 August that extension across Mauna Loa's summit had resumed over the previous few weeks after pausing for much of July. Seismicity remained at low levels at the volcano.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

13 October 2004            Back to Top

According to HVO, since early July 2004 an increased number of earthquakes had been recorded from beneath Mauna Loa. From week to week, the numbers fluctuated but remained well above the norm. During the week ending 13 October, 110 earthquakes were located under the summit, up from 47 for the week ending 6 October. Through 13 October, more than 730 earthquakes related to the ongoing seismic activity have been centered beneath Mauna Loa's summit caldera and the adjacent part of the southwest rift zone.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

6 October 2004            Back to Top

According to HVO, since early July 2004 an increased number of earthquakes had been recorded from beneath Mauna Loa. From week to week, the numbers fluctuated but remained well above the norm. Through September, more than 580 earthquakes were centered beneath Mauna Loa's summit caldera and the adjacent part of the southwest rift zone. Most of these earthquakes were quite deep, from 35 to 50 km below the ground surface and small, less than M 3. They were "long-period" (LP) earthquakes, which means that their signals gradually rise out of the background rather than appearing abruptly. Such a concentrated number of deep LP earthquakes from this part of Mauna Loa is unprecedented, at least in the modern earthquake record dating back to the 1960s. During about 4-11 October, however, only 23 earthquakes were located under the summit.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

22 September 2004            Back to Top

No changes were noted by HVO at Mauna Loa through 27 September. Since early July 2004, an increasing number of earthquakes had been recorded from beneath Mauna Loa. From week to week the numbers fluctuated but remained well above the earlier established norm. Through the third week of September, more than 560 earthquakes were centered beneath Mauna Loa's summit caldera and the adjacent part of the southwest rift zone. Most of these earthquakes were quite deep, 35-50 km below the surface, and less than M 3. Inflation continued at the summit and showed no change during the increased seismic activity.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

15 September 2004            Back to Top

No changes have been noted by HVO at Mauna Loa through 21 September. Since early July 2004, an increasing number of earthquakes has been recorded from beneath Mauna Loa. From week to week the numbers fluctuate but remain well above the earlier established norm. Through the second week of September, more than 500 earthquakes were centered beneath the summit caldera and the adjacent part of the southwest rift zone. Most of these earthquakes were quite deep, 35-50 km below the surface, and less than M 3. Inflation was continuing at the summit and has so far shown no change during the increased seismic activity.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

8 September 2004            Back to Top

HVO reported that beginning in early July 2004 an increasing number of earthquakes had been recorded beneath Mauna Loa. From week to week, the numbers fluctuated but remained well above the norm. Through the first week of September, more than 350 earthquakes were centered beneath Mauna Loa's summit caldera and the adjacent part of the southwest rift zone. Most of these earthquakes were quite deep, from 35 to 50 km below the ground surface. They were "long-period" (LP) earthquakes, which means that their signals gradually rise out of the ambient seismic background. Such a concentrated number of deep LP earthquakes from this part of Mauna Loa is unprecedented, at least in the modern earthquake catalog dating back to the 1960s. Inflation continued at the summit and as of 12 September showed no change during the increased seismic activity.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

14 May 2003            Back to Top

HVO reported on 18 May that inflation may have resumed at Mauna Loa's summit during the week, after slackening off following an increase in mid-February. Seismicity, however, remained low. Inflation was noted where the GPS network first showed definite lengthening of the lines across the summit caldera in late April or May 2002, after nearly 10 years of slight deflation. HVO interpreted the lengthening, uplift, and tilting to indicate resumed swelling of the magma reservoir within the volcano.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

12 March 2003            Back to Top

HVO reported on 16 March 2003 that renewed inflation at Mauna Loa's Moku`aweoweo summit caldera began in late February 2003. The GPS network first showed inflation in late April or May 2002, which tailed off and perhaps stopped in mid-winter. The lengthening, uplift, and tilting were interpreted to indicate resumed swelling of the magma reservoir within Mauna Loa. Seismicity remained at low levels.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

22 January 2003            Back to Top

HVO reported on 27 January that during the previous couple of months the rate of lengthening across Mauna Loa's summit caldera (Moku`aweoweo) slowed significantly. The lengthening started in late April or May, as did uplift measured by GPS and ground tilt measured by several dry-tilt stations. As of the 27th, seismicity remained at low levels.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

30 October 2002            Back to Top

On the afternoon of 1 November volcanic tremor, centered low on Mauna Loa's SE flank, occurred for 30 minutes. HVO stated that this is a common occurrence, taking place several times a year in the same general region. The permanent, continuous GPS network indicated ongoing lengthening across Moku`aweoweo summit caldera, as it has since late April or May 2002.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

23 October 2002            Back to Top

As of 28 October Mauna Loa continued to inflate, but seismicity remained at low levels. The permanent, continuous GPS network indicated ongoing lengthening across Moku`aweoweo summit caldera, as it has since late April or May 2002.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

9 October 2002            Back to Top

A brief period of low-amplitude tremor occurred at Mauna Loa's summit on 7 October, lasting several minutes. It apparently was triggered by, or at least quickly followed, a small earthquake. The following day, several more small earthquakes took place. By the 10th, seismicity had returned to low levels. During 8-15 October, the permanent continuous global positioning system network indicated that ongoing lengthening occurred across Moku`aweoweo summit caldera as it has since late April or May.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

25 September 2002            Back to Top

HVO reported on 30 September that a pattern of slow deflation occurring at Mauna Loa for the past 9 years abruptly changed in mid-May when the summit area began to slowly swell and stretch. Global Positioning System measurements revealed that distances across the summit caldera (Moku`aweoweo) have been lengthening at a rate of 5-6 cm per year, and the caldera has widened about 2 cm since 12 May. The summit area was slightly higher than before mid-May, consistent with swelling. In addition, the upper part of the SE flank showed outward movement. Seismicity remained low at Mauna Loa, although it may have been slightly higher level than during the pre-inflation interval.

Sources: Associated Press , US Geological Survey Hawaiian Volcano Observatory (HVO)

1 May 2002            Back to Top

A small earthquake cluster event, with magnitudes between 1.1-1.7, occurred at Mauna Loa during 19-26 April. There were no signs indicating that an eruptive event was imminent and no significant deformation was recorded.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)

Below is a summary of eruption dates and Volcanic Explosivity Indices (VEI).

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Brigham W T, 1909. The volcanoes of Kilauea and Mauna Loa. {Mem B P Bishop Museum}, 2: 1-222

Garcia M O, Davis M G, 2001. Submarine growth and internal structure of ocean island volcanoes based on submarine observations of Mauna Loa volcano, Hawaii. {Geology}, 29: 163-166

Green J, Short N M, 1971. {Volcanic Landforms and Surface Features: a Photographic Atlas and Glossary}. New York: Springer-Verlag, 519 p

Hitchcock C H, 1909. {Hawaii and its Volcanoes}. Honolulu: Hawaiian Gazette Pub Co, 306 p

Jurado-Chichay Z, Rowland S K, 1995. Channel overflows of the Pohue Bay flow, Mauna Loa, Hawai'i: examples of the contrast between surface and interior lava. {Bull Volc}, 57: 117-126

Jurado-Chichay Z, Rowland S K, Walker G P L, 1996. The formation of circular littoral cones from tube-fed pahoehoe, Mauna Loa, Hawai'i. {Bull Volc}, 57: 471-482

Lipman P W, 1995. Declining growth of Mauna Loa during the last 10,000 years: rates of lava accumulation vs. gravitational subsidence. {In}: Rhodes J M, Lockwood J P (eds), {Mauna Loa Revealed. Structure, Composition, History, and Hazards}. Geophys Monogr, 92: 45-80

Lockwood J P, Lipman P W, 1987. Holocene eruptive history of Mauna Loa volcano. {U S Geol Surv Prof Pap}, 1350: 509-535

Macdonald G A, 1955. Hawaiian Islands. {Catalog of Active Volcanoes of the World and Solfatara Fields}, Rome: IAVCEI, 3: 1-37

Moore J G, Clague D A, Holcomb R T, Lipman P W, Normark W R, Torresan M E, 1989. Prodigious submarine landslides on the Hawaiian Ridge. {J Geophys Res}, 94: 17,465-17,484

Newhall C G, Dzurisin D, 1988. Historical unrest at large calderas of the world. {U S Geol Surv Bull}, 1855: 1108 p, 2 vol

Riker J M, Cashman K V, Kauahikaua J P, Montierth C M, 2009. The length of channelized lava flows: Insight from the 1859 eruption of Mauna Loa volcano, Hawaii. {J Volc Geotherm Res}, 183: 139-156

Robinson J E, Eakins B W, 2006. Calculated volumes of individual shield volcanoes at the young end of the Hawaiian Ridge. {J Volc Geotherm Res}, 151: 309-317

Wanless V D, Garcia M O, Rhodes J M, Weis D, Norman M D, 2006. Shield-stage alkalic volcanism on Mauna Loa volcano, Hawaii. {J Volc Geotherm Res}, 151: 141-155

Yokose H, Lipman P W, 2004. Emplacement mechanisms of the South Kona slide complex, Hawaii Island: sampling and observations by remotely operated vehicle Kaiko. {Bull Volc}, 66: 569-584

Zimbelman J R, Garry W B, Johnston A K, Williams S H, 2008. Emplacement of the 1907 Mauna Loa basalt flow as derived from precision topography and satellite imaging. {J Volc Geotherm Res}, 177: 837-847

Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world's largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits within an older and larger 6 x 8 km caldera. Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al. 1989). Almost 90% of the surface of the basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano's surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.