Sept. 1 - Oct. 9: Spasmodic Tremor Weakens

Spasmodic tremor on Jan. 23, 2019.

There were only 4 spasmodic tremor events from Sept. 1 through Oct. 9, 2019. This is far less than the preceding months and could signal a weakening in the spasmodic tremor sequence we have been witnessing since Jan. 23, 2019. However, deep seismic activity seems to be increasing as the spasmodic tremor decreases. Could the tremor be in the process of being replaced by normal earthquakes? Only time will tell. Please click the title of this post or "read more" to see spasmodic tremor for the time period stated above...

Mauna Loa is currently experiencing heightened volcanic unrest, including increasing seismicity and uplift. Therefore, the alert level has been raised to ADVISORY and the aviation color code has been raised to YELLOW. Please CLICK HERE to keep up to date with recent alert postings by USGS/HVO for Mauna Loa’s potential eruptive activity.

Kilauea's Halema'uma'u "Crater Lake" on October 7, 2019.

Also, as seen in the picture above, a pond of water has been constantly growing at the bottom of Halema’uma’u crater inside of Kilauea Caldera. It was originally thought to be rainwater, but USGS/HVO now believes it is highly likely this is groundwater. This could spell trouble for Kilauea in the near future. To keep an eye on this growing pond, keep checking the Volcano Watch articles put out by HVO which can be found HERE. Also, you can keep an eye on it yourself if you monitor the webcam at Kilauea which can be found HERE.

Hawaii station locations

usgs eq map for hawaii from sept. 1 through oct. 9, 2019

First off, if you wish to understand what volcanic spasmodic tremor is, and how it relates to ongoing volcanic unrest in Hawaii, please CLICK HERE.

From Sept. 1 through October 9, 2019, there were over 605 earthquakes under the Big Island of Hawaii. Swelling of the ground continues, from an influx of magma from depth, at the Mauna Loa summit, the Kilauea summit, and the Kilauea East Rift Zone.

Spasmodic tremor was almost eerily silent during this time period with only 4 spasmodic tremor events. That is extremely low and all were very weak. It seems deep seismicity is now replacing deep spasmodic tremor. October 4, 2019 saw only one spasmodic tremor but it was the strongest of the past month or two.

Below I will show the usual seismogram and spectrogram plots of the 4 spasmodic tremor events from Sept. 1 through October 9, 2019. They will be shown from 3 stations: PPLD, TRAD, and HUAD. Seismic audio will be included after each event. Seismic audio was obtained from station PPLD through the IRIS Time Series webservice. Speed of the audio has been increased greatly to hear the seismic events in question.

Event 1

Event 1 occurred on Sept. 3, 2019 at 22:33UTC and lasted approximately 36 minutes. This spasmodic tremor was extremely strange looking. Two earthquakes struck somewhere on the island during this time frame, as can be seen below.

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Event 2

Event 2 occurred on Sept. 26, 2019 at 17:12UTC. It lasted around 21 minutes.

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Event 3

Event 3 occurred on Sept. 26, 2019 at 23:15UTC. It lasted around 27 minutes and was so weak it was almost unnoticeable.

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Event 4

Event 4 occurred on October 4, 2019 at 18:34UTC. It lasted approximately 15 minutes, though it was hard too tell since it diminished slowly. This was by far the strongest spasmodic tremor since Sept. 1, 2019.