Some explanations referencing Shishaldin Volcano after M7.0 env(S Sandpoint)

We are observing selective news for Shishaldin Volcano since Jul 12;

Jul12:

The alert for the volcano was raised to Yellow, as elevated surface temperatures were identified in the upper edifice area today.

The Alaska Volcano Observatory (AVO) detected high temperatures in the summit crater. This also confirms a heat radiation image from MIROVA (Middle Infrared Observations of volcanic activity), which measured a high thermal anomaly (100 MW) in the crater area.

From a seismic point of view, intermittent volcanic tremor and low-frequency earthquakes have become more frequent over the past week.

This change represents a variation from the background levels at the volcano, but this doesn't hint an imminent eruption so far.

The AVO continues: "Shishaldin is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. The local monitoring network is partially impaired, therefore AVO is also using nearby geophysical networks, satellite data and regional infrasound and lighting data to detect activity. AVO will continue to closely monitor unrest at Shishaldin Volcano."

Source: Alaska Volcano Observatory volcano activity update 12 July 2023

Jul13:

Highly elevated temperatures continue to be detected in the inner summit crater of the volcano, the AVO reported.
A night-time glow was detected through a surveillance camera last night associated with SO2 emissions.
Periods of amplitude volcanic tremor have increased over the past 24 hours.
These observations might suggest a presence of magma beneath the crater, which led scientists to rise the alert level for the volcano to Orange, immediately after rising the alert to Yellow yesterday.
Source: Alaska Volcano Observatory volcano activity update 13 July 2023

Jul14:

US Coast guard flew over the volcano yesterday and could see a cinder cone that has formed in the summit crater of the snow-clad volcano. Steam plumes from the cone suggest that it was active, most likely, in the form of strombolian explosions from the cone.

Jul14:

Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Anchorage warned about a volcanic ash plume that rose up to estimated 25000 ft (7600 m) altitude or flight level 250 and is moving at 30 kts in S direction.
The full report is as follows:

FVAK21 at 14:46 UTC, 14/07/23 from PAWU
VAAAK1
VA ADVISORY

DTG: 20230714/1445Z

VAAC: ANCHORAGE

VOLCANO: SHISHALDIN 311360

PSN: N5445 W16358

AREA: ALEUTIAN ISLANDS

SUMMIT ELEV: 9374 FT [2857 M]

ADVISORY NR: 2023/001

INFO SOURCE: GOES/AVO

AVIATION COLOR CODE: ORANGE

ERUPTION DETAILS: VA NOTED IN SATELLITE IMAGERY.

OBS VA DTG: 14/1445Z

OBS VA CLD: SFC/FL250 N5443 W16416 - N5110 W16427 - N5050 W16156
- N5358 W16048 - N5443 W16416 MOV S 30KT

FCST VA CLD +6HR: 14/2045Z SFC/FL250 N5440 W16410 - N4902 W16513
- N4853 W16119 - N5337 W16028 - N5440 W16410

FCST VA CLD +12HR: 15/0245Z SFC/FL250 N5436 W16405 - N4745
W16503 - N4730 W15948 - N5304 W15953 - N5436 W16405

FCST VA CLD +18HR: 15/0845Z SFC/FL250 N5445 W16412 - N4645
W16513 - N4644 W15848 - N5304 W15925 - N5445 W16412 - N5445 W16412

RMK: AVO REPORTS LAVA FLOW REACHED CST AND STEAM CARRIED ASH INTO ATMOSPHERE....
RV

NXT ADVISORY: WILL BE ISSUED BY 20230714/2045Z

 

Jul14:

The explosive eruption at the volcano continues.
The newly cinder cone within the summit vent continues to grow by ejecting ash and lappili-to-bomb-sized material around its edifice.
At least two explosions took place from the cone since midnight. A little after 07:00 am this morning, a small amount of ash and gas was observed from the summit.
The Volcanic Ash Advisory Center (VAAC) Anchorage reported ash emissions reaching an altitude of about 25,000 ft (7,600 m).
Source: Alaska Volcano Observatory volcano activity update 14 July 2023

Jul16:

Explosive activity continues. Volcanic Ash Advisory Center (VAAC) Anchorage warned about a volcanic ash plume that rose up to estimated 12000 ft (3700 m) altitude or flight level 120 and is moving at 20 kts in SSE direction.
The full report is as follows:


FVAK21 at 05:46 UTC, 16/07/23 from PAWU
VAAAK1
VA ADVISORY

DTG: 20230716/0538Z

VAAC: ANCHORAGE

VOLCANO: SHISHALDIN 311360

PSN: N5445 W16358

AREA: ALEUTIAN ISLANDS

SUMMIT ELEV: 9374 FT [2857 M]

ADVISORY NR: 2023/002

INFO SOURCE: HIMAWARI/GOES/POES/AVO

AVIATION COLOR CODE: ORANGE

ERUPTION DETAILS: LOW LEVEL VA ERUPTION DETECTED BY AVO AND WEATHER SAT

OBS VA DTG: 16/0538Z

OBS VA CLD: SFC/FL120 N5502 W16338 - N5431 W16305 - N5413 W16405
- N5445 W16435 - N5502 W16338 MOV SSE 20KT

FCST VA CLD +6HR: 16/1138Z SFC/FL120 N5503 W16337 - N5411 W16147
- N5328 W16318 - N5443 W16442 - N5503 W16337 - N5503 W16337

FCST VA CLD +12HR: 16/1738Z NO VA EXP

FCST VA CLD +18HR: 16/2338Z NO VA EXP

RMK: NONE

NXT ADVISORY: WILL BE ISSUED BY 20230716/1138Z

Jul19:

Update:

The activity at the volcano has been intensifying over the past hours and is still continuing at the time of this update.
The effusive eruption has been picking up within the summit crater at around 01:00 local time tonight caused by an increased surge of magma in the conduit and resulting in a lava flow from the cinder cone. No significant ash emissions have been observed that time. The activity was detected on regional infrasound arrays, increasing seismic tremor, and elevated surface temperatures in satellite data. Overnight webcam images confirmed glowing from the summit with only minor ash emission.
The situation has changed to a relatively dramatic activity as it was getting worsened at 07:00 local time this morning by an increasingly expanding ash plume spreading in the S-Se direction. According to the Volcanic Ash Advisory Center (VAAC) Anchorage, the ash plume rose to an altitude of 30,000 ft (9,100 m).
Therefore, the alert status for the volcano was raised to "Red".
Source: Alaska Volcano Observatory volcano activity update 18 July 2023

Update 8/15:

A seismic unrest has increased at the volcano a couple of hours ago.
The Alaska Volcano Observatory reported that volcanic tremor started to rise over the past five hours, indicating rapid magma flux towards the surface. The activity is being intensified at the time of this update likely.
The volcano observatory identified elevated surface temperatures at the summit vent accompanied by emissions of lava, as detected in the latest satellite images.
Based on previous eruption episodes over the past month at the volcano, strong eruptive phase is likely to appear within the next few hours. This could be a beginning of another, 7th such paroxysm activity in a row. Recent paroxysm series were characterized by continuous ash-rich emissions, lava fountains and lava flows.
Source: Alaska Volcano Observatory volcano activity update 15 August 2023

Update 8/16

The eruptive phase at the volcano has continued throughout yesterday.
Given the previous paroxysm series characterized by tall and dense ash columns, emissions have been reaching only a low-level altitude of about 16,000 ft (5 km) moving northeast. The National Weather Service has issued a SIGMET for this ash cloud.
The 7th such episode from the volcano's summit vent took place within the past month.
Source: Alaska Volcano Observatory volcano activity update 16 August 2023

Update Aug 26:

The volcano entered another 8th strong eruptive episode a few hours ago and is still in progress at the time of this update.
Volcanic tremor started to rise quickly at about 03:00 AM early morning today and has been intensifying until 04:30 PM when it reached its spike. The tremor dropped, but remains elevated.
In the beginning, the eruptive phase consisted of seven explosive events spewing ash emissions up to 40,000 ft (12 km) elevation. Fresh ash deposits (tephra) have covered a considerable part of the edifice. Gradually, but slightly lowering of the continuing dense ash column has been reported by reaching its altitude to 30,000 ft (9 km), later 28,000 ft (8,5 km) extending about 450 km to the northeast of the volcano.
During the eruption, strongly elevated surface temperatures were identified in satellite data associated with emissions generated by fountaining and lava flows atop the summit.
The AVO observatory therefore raised the alert level for the volcano to "RED"
The volcano's tendency to produce such events in series at irregular intervals may continue further in the coming days or weeks.
Source: Alaska Volcano Observatory volcano activity update 26 August 2023

Update Aug 27:

The Alaska Volcano Observatory (AVO) reported that the recent 8th eruptive episode ended at midnight today.
Signs of the weakening seismic activity were monitored at 05:30 PM yesterday and currently remain low.
Hence, the AVO observatory dropped the alert status for the volcano back to Orange.
Phases of strong eruptive periods have continued at the volcano since early July characterized by continuous ash-rich emissions, lava fountains and lava flows.
Source: Alaska Volcano Observatory volcano activity update 26 August 2023

Update Sep6:

After ten days since the latest paroxysm at the volcano, the 9th episode of vigorous lava fountaining and strong ash emissions appeared yesterday.

A typical precursor of the pre-eruptive stage manifested in a several-hour increase in seismic activity. The eruption commenced at about 08:30 AM local time by generating an increasingly rising black dense ash emissions and impressive lava fountains from the summit vent. From the available webcam image, glowing fire fountains seem to reached some lava jets a height of several hundreds of meters above the crater.

The spewing tall ash-rich column reached a maximum elevation of 32,000 ft (9,7 km) that extended about 125 km to the east of the volcano. A spectacular attached Sentinel-3 OLCI satellite image displays traveling fine ash particles ejected by Shishaldin yesterday. Moreover, the grey-to-black lapilli-to-ash-covered edifice from the paroxysm proves the intensity of the eruptive episode.
Based on the intense eruptive activity, the AVO observatory therefore raised the alert level for the volcano to Red.

About 07:00 PM local time, signs of a decreasing activity found in rapidly declining periods of high amplitude tremor. Ash emissions started to decrease to an altitude of 15,000 (4,5 km) and by 01:30 PM local time another day, the spectacular ash plume ended. The seismic activity declined around 12:30 PM and remains low.
Hence, the AVO observatory dropped the alert status for the volcano back to Orange.
Source: Alaska Volcano Observatory volcano activity update 6 September 2023

Update Sep17:

A new, 11th intense paroxysmal eruptive period in a row took place at the volcano yesterday.

The activity followed a usual several-hours lasting strong seismic tremor, a typical precursor of rapid magma flux towards the summit. At 17:10 local time yesterday, it culminated in constant dense ash emissions spewing tephra up to 40,000 ft (12 km) elevation to the east of the volcano. The National Weather Service reported that the ash column was accompanied by volcanic lightning, suggesting ash-rich fine emissions in the plume. So-called dirty thunderstorms form when ash that is to be erupted begins as electrostatically neutral rock fragments. Heat and motion of fragmented material within volcano edifice is among the first source of particle charging, then another fundamental phenomenon to being charged is friction. In order to create volcanic lightning, neutrally charged ash particles must come in contact with another object of differently charged qualities.

The local alert level for the volcano was raised to RED.
The local people from False Pass informed about fresh ash deposits between 18:00 and 20:30 local time.
In a couple hours later, at about 18:30 local time, the seismic activity started to wane rapidly, but remained elevated until 21:00 local time. The ash plume has been lowering its altitude to approx. 22,500 ft (6,8 km), however the volcanic lightning continued during the decreased period until 20:48 local time.
The seismic instrument detected recordings related to pre-eruptive levels, resulting in lowering the alert level back to ORANGE.
Source: Alaska Volcano Observatory volcano activity update 16 September 2023

Sep24:

The volcano entered another 12th eruptive period, commencing yesterday and is still continuing at the time of this update.
A seismic tremor started to accelerate over the past 36 hours. Given the geophysical data and regional infrasound sensors, a low-level minor eruptive activity has been occurring at the summit crater. However, no strong elevated surface temperatures, indicating the presence of new lava at the summit, have been monitored yet. Visibility has been limited due to dense clouds at altitude between 2,000 ft and 15,000 ft.
Whether the activity sharply increases or not is not clear yet, but based on previous eruptive sequences, the activity may culminate in a strong fountaining period (so-called paroxysm) and ash-rich emissions.
The alert level for the volcano remains at Orange so far.
Source: Alaska Volcano Observatory volcano activity update 24 September 2023

Sep 25:

The activity of the volcano has intensified over the past hour.
The increasing trend is shown in a steep rise of seismic tremor detected by the AVO volcano observatory.
Continuous highly elevated surface temperatures may signal a strong paroxysm and lava emissions, another typical sign of an impending eruption. No serious ash emissions have been observed yet.
Based on previous eruptive cycles, abundant ash emissions will likely to occur in the upcoming several hours.
The volcano entered another 12th eruptive period, commencing yesterday and is still continuing at the time of this update.
The alert level for the volcano remains at Orange.
Source: Alaska Volcano Observatory volcano activity update 25 September 2023

Update Sep26:

The 12th eruptive episode, beginning two days ago, culminated in another vigorous paroxysm episode today.
An initial precursor of the eruption onset was characterized by increasing-decreasing tremor phases over the past 48 hours.
Prior to the event, a volcanic-seismic tremor continued to evolve and starting at 05:42 local time today, an increasingly ash-rich plume was monitored in satellite data, initially rising above 20,000 ft (6 km,) associated with volcanic lightning detections, later on, peaked an altitude of 45,000 ft (14 km).


Following the ash height spike, it started lowering its elevation. Lava-fountain jets (paroxysm) have been pulsating above the summit crater terrace overnight. Continuous, highly elevated surface temperatures confirmed the presence of lava flows emerging from the vent onto the north flank of the volcano.
Visibility of the new eruptive phase was very limited due to dense clouds reaching up to 20,000 ft (6 km).


Thus, the Alaska Volcano Observatory (AVO) raised the alert level for the volcano to Red. The National Weather Service has issued a SIGMET for this ash cloud, an Ash Advisory has been issued for False Pass, and a Special Weather Statement has been issued for possible trace ash on Cold Bay, King Cove, and Sand Point.
The current eruptive cycle has been among the longest-lasting events during the 2023 activity.
Source: Alaska Volcano Observatory volcano activity update 25 September 2023

Update Oct4:

The intense eruptive period sustains at the volcano.

The 13th lava-fountaining sequence (paroxysm) followed a usual several-hours lasting strong seismic tremor, a typical precursor of rapid magma flux towards the summit. At 17:20 local time today, it culminated in constant dense ash emissions spewing tephra up to 40,000 ft (12 km) elevation to the east of the volcano. The Alaska Volcano Observatory (AVO) reported that the ash column was accompanied by volcanic lightning, suggesting ash-rich fine emissions in the plume. So-called dirty thunderstorms form when ash that is to be erupted begins as electrostatically neutral rock fragments. Heat and motion of fragmented material within volcano edifice is among the first source of particle charging, then another fundamental phenomenon to being charged is friction. In order to create volcanic lightning, neutrally charged ash particles must come in contact with another object of differently charged qualities.
The local alert level for the volcano was raised to RED.
Source: Alaska Volcano Observatory volcano activity update 3 October 2023

Thursday Oct5:

13th paroxysm episode ended