Scientists at the USGS Hawaiian Volcano Observatory (HVO) say that the number of earthquakes near Pahala has gone from about 60 per week to 600 in the last five years. Pahala is a small town between the volcanoes Mauna Loa and Kilauea. It used to be a sugar plantation. Even though only about 1,400 people live there, they often feel earthquakes several times a day.
In a 2015 study, scientists from the USGS found the area where earthquakes are happening and put them into two groups: seismic tremor, which is usually caused by deep magma movement, and volcano-tectonic earthquakes, which are caused by rock breaking under the surface.
The area 12 to 25 miles below the surface is where earthquakes here often come from. Scientists thought the seismic tremor was caused by magma moving from a deep hot spot in Hawaii to a shallower one. Above this magma movement, volcano-tectonic tremors can be felt from where the tremors start all the way down to the centre of Kilauea Volcano. Scientists from the USGS thought that the way the earthquakes were happening showed a path of magma moving underground from the storage area below Pahala to the top of Kilauea.
(CalTech) Seismologists at the California Institute of Technology just came out with a new study that shows what is going on deep below Pahala. Scientists have used a new technique called “machine learning” to find a lot of very small earthquakes happening under the Pahala region that HVO didn’t know about before. Microseismicity is too small to be picked up by the automated systems that are usually used to discover earthquakes.
Many of these events are volcanic-tectonic earthquakes in the area where USGS scientists have found deep Pahala seismicity. This large number of newly discovered volcanic and tectonic events outline what seems to be a sill complex, which is a place where magma is stored in horizontal layers deep beneath Pahala. Long – lasting earthquakes, which show that fluids like magma are moving, can be seen in these sills, which supports this idea. These observations indicate that deep earthquakes under Pahala are consistent with magma moving through and being stored in this sill complex.
Based on the CalTech study, it is thought that the way earthquakes are spread out may show a way for magma to get from the deep Pahala sill complex to Kilauea’s magma reservoir. HVO warns that more studies and evidence are needed to prove or disprove such a hypothesis.
To learn more about the earthquakes and volcanoes in the area, HVO put 86 temporary seismographs all over Pahala to record earthquakes that happened in this area over 3 months. HVO has also suggested putting 1,600 more temporary seismometers on Kilauea’s summit this summer to record seismic signals there for 6 weeks.
In their latest Volcano Watch update, HVO says, “These dense, temporary deployments will record seismic activity in the Kilauea and Pahala regions more accurately than HVO’s permanent network of instruments. Seismologists at HVO will look at these seismic data to determine if the magma stored in Pahala’s active sill complex is linked to Kilauea and if it is a source of magma for Kilauea.
Scientists from HVO keep an eye on the ongoing earthquakes in Hawaii and the current volcanic activity.
The Kilauea Volcano is erupting right now. Its summit eruption in Halema’uma’u crater in Hawaii Volcanoes National Park is still going on, and vents erupting in the centre and east of the crater floor. Over the past week, Summit tilt has shown several deflation trends and inflation. Summit earthquake activity is still low, and tremors are still happening. On January 9, a sulphur dioxide emission rate of 3,500 tonnes per day was measured. These emissions make the air in Aloha State look like smog.
The world’s largest active volcano, Mauna Loa, is not erupting. Webcams show no signs of activity on the volcano, which just finished an eruption last month, according to HVO. Mauna Loa. Seismic activity stays low. The rate at which the ground moves and the rate at which sulphur dioxide (SO2) is released are at background levels.
