LARGEST QUAKES -
This morning -
None 5.0 or higher.
Yesterday -
4/23/11 -
5.0 FIJI REGION
5.0 OFF EAST COAST OF HONSHU, JAPAN
6.0 NEAR EAST COAST OF HONSHU, JAPAN
6.9 SOLOMON ISLANDS
4/22/11 -
5.5 TONGA REGION
5.0 OFF EAST COAST OF HONSHU, JAPAN
5.5 NEAR EAST COAST OF HONSHU, JAPAN
5.0 OFF EAST COAST OF HONSHU, JAPAN
5.2 OFFSHORE BIO-BIO, CHILE
An expedition is getting under way in the South Pacific to investigate one of the most seismically-active fault lines in the world. Researchers are planning to study the Tonga Trench - a deep feature where the Pacific tectonic plate is being forced under the Indo-Australian plate. The island nation of Tonga is regularly hit by tremors - most recently a 6.4 magnitude quake offshore last month. The research expedition will last about one month.
The focus of the study will be an UNUSUAL zone on the seabed where undersea volcanoes are being dragged into the fault. Scientists want a better understanding of how the submarine mountains affect the likelihood of earthquakes. The volcanoes lie on the 4,000km-long Louisville Ridge and either act as a brake on the Pacific plate - or intensify the quakes which follow. The area where they are pulled into the seabed suffers relatively fewer tremors than other stretches of the fault line. "We want to know whether subducted seamounts are holding up earthquakes or whether they cause earthquakes. This is important to find out so that we can learn what controls earthquakes and make better assessments about where they may occur in the future."
Subduction zones like the Tonga Trench can trigger tsunamis - as happened off Japan last month and off Sumatra on Boxing Day 2004. One recent study of an earthquake in Peru in 2001 showed that underwater mountains may have held up the quake for 40 seconds before rupturing. A study of the Nankaido earthquake in Japan in 1946 successfully imaged a seamount that had been dragged 10km deep - and apparently limited the scale of the rupture and the tsunami risk.
Japan quake briefly cut US military computer links - The Air Force says computer links with some US bases in the Pacific were severed by the earthquake and tsunami that hit Japan on March 11, but one of its cyber squadrons restored them within five hours. The Air Force said Thursday that bases in Japan, Korea and Guam were affected. It wasn't immediately clear what the consequences were. The 561st Network Operations Squadron in Hawaii coordinated the repairs. The Air Force says the Hawaii squadron also canceled planned interruptions for maintenance on Pacific computer networks so they would remain open.
VOLCANOES -
Three Philippine volcanoes active - Three volcanoes in the Philippines are currently active, with one showing signs of near eruptionand the rest initial signs of heating up, the Philippine Institute of Volcanology and Seismology and Seismology said. Taal Volcano in Batangas, southern Philippines, had 19 volcanic quakes within 24 hours, Phivolcs said in a Saturday update. The temperature at the main crater's lake increased from 30.5 to 31.5 degrees Celsius, and Taal's magma was nearing the surface. Alert level two remained hoisted on Taal since last week, prompting residents to return to the crater's danger zone.
Meanwhile, four quakes were recorded in Bulusan Volcano and one in Mayon Volcano, both in the Bicol Region in southern Luzon. The Philippines has 22 active volcanoes.
HAWAII - Recent earthquake is a small piece to a much larger puzzle. On April 2, 2011, at 11:11 a.m. HST, a magnitude-3.6 earthquake occurred 9 km (5 mi) southwest of Volcano Village. HVO seismic analysts who reviewed the data from this earthquake verified that the earthquake occurred in a part of Kilauea volcano known as the Koa`e fault system.
The Koa`e system lies south of Kilauea’s summit caldera, extending southwest-to-northeast between Kilauea’s southwest and east rift zones. It is delineated by a series of cracks and mostly north-facing pali (cliffs). The most striking of these pali is possibly the one that visitors to Hawai`i Volcanoes National Park cross as they drive along Hilina Pali Road. The magnitude-3.6 earthquake was located at a depth of just 200 meters (650 ft) below the Earth’s surface. This is UNUSUALLY SHALLOW for an earthquake occurring outside Kilauea’s summit caldera or rift zones. Given its magnitude and depth, the earthquake would most likely have been felt only by people in very close proximity to the epicenter. Seismic energy released by the earthquake would have been severely dampened in the shallow crust.
Recent results clearly show a signal from the April 2 earthquake. The north side of the Kulanaokuaiki pali (eastern Koa`e fault zone) dropped relative to its south side by 1–2 centimeters (0.4–0.8 in) over a distance of 900 m (0.5 mi) along the pali. This week, HVO scientists resurveyed points along Kulanaokuaiki pali that were originally set up more than 40 years ago and measured repeatedly in the years since. They found that the pali had moved up relative to the north side by nearly 2 cm (0.8 in).
While a magnitude-3.6 earthquake is usually large enough to be felt, it is SOMEWHAT UNUSUAL that it would lead to ground disruption large enough to be visible in an InSAR image. Because of its location amidst Kilauea’s volcanically active summit caldera, rift zones, and mobile south flank, the Koa`e fault system has long been viewed as one of the most complex features of the volcano. For example, some scientists have suggested that the Koa`e fault system overlies a large zone of magma accumulation or that it is a connector between the east and southwest rift zones, which forms the northern limit of Kilauea’s mobile south flank. Others have suggested that the Koa`e faults provide evidence that a larger summit caldera complex may have existed in Kilauea’s earlier history.
TROPICAL STORMS -
No current tropical storms.
SEVERE RAIN STORMS, FLOODING, LANDSLIDES -
BRAZIL - Landslides and floods triggered by torrential rain have killed at least 10 people in southern Brazil. Among the dead were three children whose home was among several buried in the town of Novo Hamburgo in the state of Rio Grande do Sul. Floods and landslides in January killed about 800 people in a mountainous region near Rio de Janeiro. The latest flooding also caused deaths in Igrejinha, Fazenda Vila Nova and Sapucaia do Sul. Rescue workers were searching for two missing people after homes in Igrejinha were engulfed by mudslides. Surrounding areas believed at risk from further landslides are being evacuated. Flooding was also reported near Porto Alegre, state capital of Rio Grande do Sul, and about 100,000 residents there are reported to be without power.
US Experiences Wild Weather - The tornados that struck St. Louis this week are the latest in a RECORD-BREAKING NUMBER OF TWISTERS that have swept across the country this month. That's in addition to historic droughts and fires in Texas, record low temperatures in Seattle, and snow and flooding in the Midwest. What's going on with the weather? (audio article from National Public Radio)
HEALTH THREATS -
A North Carolina vegetable and fruit distributor has recalled cucumbers distributed to nine states, after some of the vegetables distributed to Florida were found contaminated with salmonella. Only one lot of about 1,600 cartons of cucumbers distributed to wholesalers is affected. Because the cucumbers were picked on March 29 and FDA guidelines indicate cucumbers are fresh for 10 to 14 days after being harvested, they are already largely past their shelf life. L&M was not disclosing the wholesale distributors of the cucumbers, because they may have sold the produce to various retailers or restaurants. However, "the company has accounted for the entire lot of recalled product and requested that customers who may still have the recalled product in inventory remove it from commerce and destroy it immediately."
The company recalled the entire lot of cucumbers harvested in south Florida on March 29; the largest number of cucumbers were distributed in Florida and Mississippi, but other than Illinois and Indiana, the bulk cucumbers also were sold to wholesalers in New York, Tennessee, Nebraska, Wyoming and Texas. Because the cucumbers were distributed to wholesalers, they may have been distributed to other states as well. There are no reports of people becoming ill after having eaten the cucumbers, according to the company.
