Mauna loa when was the last eruption

This extension rate is the highest since immediately after the eruption. GPS measurements have only been made at Mauna Loa since , but in that relatively short time an abrupt change in ground movement has been recorded figure Measurements made during January May show small velocities of ground displacement towards the SW. In contrast, during May-September the direction of ground motion changed from a fairly uniform, southeastward movement to a predominately radial pattern.

In addition, the rate of ground motion increased by 5 to 10 times. Ground tilt away from the caldera occurs when magma accumulates beneath the surface.

Although electronic measurements provide much more precise readings, the dry-tilt method remains in use at HVO after 35 years for several reasons. First, the measurements can be made nearly anywhere at any time.

Second, they are not subject to long-term instrument drift. Lastly, they provide an independent corroboration of measurements made by more sophisticated modern instruments. Dry-tilt measurements revealed the following: inflation between the and eruptions figure 21a , inflation after the eruption, continuing until figure 21b , and deflation from through March probably May figure 21c. After March probably May , the tilt returned to an inflationary pattern figure 21d.

The most recent pattern of inflation is based on only two sets of measurements, and the tilt varies, with some smaller arrows pointing inward, so it is much less certain than the past patterns.

Still, the radial pattern strongly suggests that inflation is occurring. HVO's telemetered seismographic network recorded significant changes in seismicity before the Mauna Loa eruptions in and figure The short-term forecasts of these eruptions were based in large part on precursory activity.

From the eruption until late April , approximately 30 earthquakes were located per year beneath Mauna Loa's summit and upper flanks. Rates of seismicity moderately increased beginning in late April , particularly at depths greater than 15 km figure 22d. As of 29 September , earthquakes were recorded in below the summit and upper flanks of the volcano, 83 of which occurred after mid-April.

This rate is markedly higher than those of previous years, but it is still well below the rates seen prior to the last two eruptions.

Before an eruption becomes imminent, HVO scientists expect that rates of shallow seismicity will elevate to levels much higher than those observed in late September Prodigous submarine landslides on the Hawaiian Ridge. Holocene eruptive history of Mauna Loa volcano. Deep, long-period earthquake swarm and contraction in July and August After a swarm of deep earthquakes centered just S of Mauna Loa's summit caldera in late April , seismicity remained barely elevated until July In other words, seismicity during late April July stood far lower than it did in the months prior to the and eruptions.

Neither the depth nor the magnitude of the earthquakes changed significantly. Through 13 October more than related earthquakes occurred beneath the summit caldera and the adjacent part of the SW rift zone.

The location and magnitude of earthquakes making up the recent swarm seismicity from 24 April October , a 6-month interval are shown in figure Such a concentration of deep LP earthquakes from this part of Mauna Loa was unprecedented in the modern earthquake record dating back to the s. In contrast, more typical seismicity over a 6-month period at Mauna Loa is shown in a figure in a previous issue BGVN By comparison to the interval 24 April October , earthquakes in a typical 6 month interval are relatively sparse.

Inflation continued at the summit through the start of the earthquake swarm. In late August , however, distances across the summit caldera began to contract significantly, apparently caused by the center of inflation shifting slightly to the S, rather than by deflation. This was the first contraction since inflation started in late April or early May Toward the end of September, the contraction ended and the line once again began to lengthen. During , the inflation had been at a fairly steady to slightly increasing rate until the contraction in late August.

When present, the lengthening, uplift, and tilting were taken to indicate swelling of the magma reservoir within the volcano. This compilation of synonyms and subsidiary features may not be comprehensive. Synonyms of features appear indented below the primary name.

In some cases additional feature type, elevation, or location details are provided. 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 km from Mauna Loa; the second of the Alika avalanches was emplaced about , years ago Moore et al. During a year eruptive period beginning about years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano's surface.

The ensuing 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. The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Brigham W T, The volcanoes of Kilauea and Mauna Loa. Mem B P Bishop Museum , 2: Submarine growth and internal structure of ocean island volcanoes based on submarine observations of Mauna Loa volcano, Hawaii.

Geology , Green J, Short N M, New York: Springer-Verlag, p. Hitchcock C H, Hawaii and its Volcanoes. Honolulu: Hawaiian Gazette Pub Co, p. Channel overflows of the Pohue Bay flow, Mauna Loa, Hawai'i: examples of the contrast between surface and interior lava. Bull Volcanol , The formation of circular littoral cones from tube-fed pahoehoe, Mauna Loa, Hawai'i.

Lipman P W, Declining growth of Mauna Loa during the last 10, years: rates of lava accumulation vs. Structure, Composition, History, and Hazards. Geophys Monogr, Macdonald G A, Hawaiian Islands. Prodigious submarine landslides on the Hawaiian Ridge. Res , 17,, Newhall C G, Dzurisin D, Historical unrest at large calderas of the world. U S Geol Surv Bull , p, 2 vol. The length of channelized lava flows: Insight from the eruption of Mauna Loa volcano, Hawaii.

Calculated volumes of individual shield volcanoes at the young end of the Hawaiian Ridge. Shield-stage alkalic volcanism on Mauna Loa volcano, Hawaii.

Yokose H, Lipman P W, Emplacement mechanisms of the South Kona slide complex, Hawaii Island: sampling and observations by remotely operated vehicle Kaiko. Emplacement of the Mauna Loa basalt flow as derived from precision topography and satellite imaging. The lava flows discussed in the text are outlined and labeled. The dashed boxes delimit areas covered in Figures 4?

The fringes at the summit of Mauna Loa indicate long-term volcano inflation confirmed by GPS measurements and are not related to the 15 October earthquakes. Poland, M. Bulletin of the Seismological Society of America, 2 , Remarks: InSAR shows inflation of a dike-like magma body in the southwest rift zone between and A Averaged to satellite radar interferogram of the Big Island of Hawaii showing ground velocity in the radar line-of-sight LOS direction. The star denotes the Kaoiki earthquake.

B Vertical and east component of the ground-velocity field obtained by combining averaged interferograms from four different viewing geometries. The black line and circle indicate the dike and magma chamber, respectively, of the model in Fig. Stress control of deep rift intrusion at Mauna Loa volcano, Hawaii. Science , , The maps shown below have been scanned from the GVP map archives and include the volcano on this page. Clicking on the small images will load the full dpi map.

Very small-scale maps such as world maps are not included. The maps database originated over 30 years ago, but was only recently updated and connected to our main database. We welcome users to tell us if they see incorrect information or other problems with the maps; please use the Contact GVP link at the bottom of the page to send us email.

Catalog number links will open a window with more information. Mauna Loa. Figure Radar interferograms of Mauna Loa covering the time intervals of a 11 October November and b 24 March April These interferograms highlight the slowing of inflation during the latter interval. The large number of color bands 'fringes' in a indicates an increased rate of inflation compared to the fewer number of fringes in b. As depicted in the scale bar bottom center , concentric and cyclical sets of fringes indicate a ground movement of 2.

A cartoon representation of the basic principles of radar interferometry. As the satellite makes its first pass over a ground surface 'Initial ground surface' , it collects radar waves reflected off of the ground surface solid wave, 'pass 1'.

During a subsequent orbit often months to years later , when the satellite again passes over the same ground surface, another collection is made from very nearly the same orbital location dashed wave, 'pass 2'.

If the ground surface deformed during the time between data collections e. The phase difference of the waves is then converted into the component of ground motion along the line-of-sight of the satellite either towards or away from the satellite , and is represented by a color as part of a full color cycle.

Since the technique is based on the phase difference of multiple waves, the accuracy is constrained by detectable fractions of the radar wave's wavelength. Image not drawn to scale. Image created by GVP staff.

The black line and circle in a and b indicate the map location of the modeled dike and magma chamber, respectively, also shown in cross-section view in c. The location and span of Mauna Loa's summit caldera is indicated at the top of c. The modeled spherical magma chamber and dike beneath the summit are shown in c , indicating modeled opening rates of the dike shown by the colored squares, with scale at bottom right.

The dike opening rates are based on a uniform excess-magma pressure model of 1. Modified from Amelung and others Information is preliminary and subject to change. Figure 1. Plot of cumulative number of local earthquakes at shallow km and intermediate km depths, and extension in mm on two survey lines across the summit caldera, for left , and right.

Figure 2. Number of earthquakes per day at Mauna Loa, 1 January-5 April. The start of the eruption is indicated by an arrow. Figure 3. Sketch maps of the NE rift zone and summit of Mauna Loa, showing positions of lava flows stippled as of 5 April. Eruption fissures are indicated by hachured lines.

The edge of the suburbs of Hilo is shown by a dotted line on the NE rift zone map. The areas covered are shown by the index map inset. Figure 4. Rates of movement of flows 1, 1A, and 1B in kilometers per day. Small circles represnet observations of flow positions. Courtesy of J. Figure 5. Tilt changes near the summit of Mauna Loa, July March Figure 6.

Plot of summit tilt vs. Figure 7. Change in horizontal distance across the summit of Mauna Loa vs. Figure 8. Rate of propagation of eruption fissures, shown as distance from the cone in the SW part of the summit caldera vs. Figure 9. All values less than 10 milliatmosphere-cm ppm-meters have been supressed.

Each number or letter represents the average SO2 value within an area 50 km across. Courtesy of Arlin Krueger. Courtesy of HVO. Daily number of recorded short-period top and long-period middle summit microearthquakes, and NE rift events bottom at Mauna Loa, January November Dry tilt changes near the summit of Mauna Loa from April to November Courtesy of T.

Kilauea has been in the throes of a fiery, dramatic and sometimes destructive eruptive period for decades now. But over the past week, the Hawaii Volcano Observatory recorded over small magnitude earthquakes below Mauna Loa.

The most recent eruption of Mauna Loa in saw lava reach the outskirts of Hilo on the other side of the island - home to the University of Hawaii - but with several weeks warning. An eruption does not necessarily mean a threat to people or property though, as half of the eruptions recorded from Mauna Loa have remained contained to the remote summit area.

That said, several eruptions have sent lava flowing all the way to the ocean in a matter of mere hours. The ocean floor actually bends under the weight of this mammoth mountain. By itself, the land mass that Mauna Loa encompasses is almost equal twice all of the other Hawaiian islands combined. Eruptions of Mauna Loa have historically been characterized by high volume flows that produce lava capable of travelling long distances, contributing to its shape. Scientists believe that 90 percent of the volcano's surface has been covered with flows that erupted within the past 4, years.

The two rift zones are historically very active, sending out flows toward the city of Hilo in and South Kona in respectively. A series of 33 radial vents also extend to the northwest. Six large vent structures eventually formed in this area around the active vents. Lava channel blockage caused an overflow of the main lava channel leading from the "2,m vents" of the Mauna Loa eruption. Lava spills over the collapsed side levee to feed new flows. By daybreak on March 26, these ventswere feeding lava to a fast-moving flow flow E on map that had advanced 9 km 5.

The prison was put on alert, because the shorter lava flows were as close as 3. These flows, however, stopped advancing within 48 hours and never crossed the Powerline Road. Its rate of advance slowed as it moved downslope, but by March 29 the flow had moved 29 km At this time, the flow front was about 6.

Smoke from burning vegetation, loud explosions caused by methane gas along the advancing flow front, and the intense glow at night all contributed to a growing concern among Hilo's residents. Would the lava reach the city? Early in the morning, a levee along the lava channel broke at the 1, m elevation 5, ft about 13 km 8 mi upslope from the flow front flow E on map. The lava was diverted into a new subparallel flow flow F on map and flow E stagnated, temporarily relieving emergency-response officials and residents of Hilo.

The 13th was the last full day of eruption. Note two geologists for scale in lower right in green flight suits.