Volcano Watch — Yes, that was an earthquake? Did You Feel It? Community Internet Intensity Maps

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You've just felt an earthquake!

Yes, that was an earthquake? Did You Feel It? Community Internet In...

USGS Community Internet Intensity Map.
February 16, 2006, 15:22 HST.

(Public domain.)

After checking to see that all around you are safe, you go to the Hawaiian Volcano Observatory (HVO) web page to fill out your felt report. You find the link to fill out your report and click on it.

What's there? You will find a list of recent earthquakes in the Hawai`i region, which includes the preliminary location, date, time, and magnitude. Click on the event that best fits the time of the earthquake you felt. This will take you to a USGS Community Internet Intensity Map (CIIM) that plots the earthquake and assigned intensity for areas where felt reports have already been received. The areas are based on postal zip codes, and intensities are calculated and subsequently color-coded on the map from answers to questions on the report form. You have the opportunity to fill out your own felt report by selecting "Did you feel it?" at the top of the page. If you don't find an earthquake that matches the time of the one you felt, you may click on "New Earthquake.?"

The new form is longer and more comprehensive than HVO's old form. It gives the reporter the opportunity to convey more detailed information of their sensation of the earthquake. Scientists have come to rely on this kind of information for magnitude calculation, intensity maps, and other data products. Each incoming report is accounted for, and, even if your zone is already color-coded, do not hesitate to fill out the form. Your information will be recorded, added to a database, and sent to USGS scientists. As the maps update automatically, you will be able to see online how the earthquake affects different areas according to the reports received.

Why did HVO make the change? We did it to conform to the USGS standard of documenting felt reports and creating the CIIMs and because of the phenomenal growth in Internet use. The zip code zoning works well for many areas. There is a slight drawback, however, for the State of Hawai`i, where a single zip code is sometimes assigned to a large area. On the island of Hawai`i, zip codes can extend over very sparsely populated or unpopulated areas. Some zip codes include several subdivisions where the reports might vary over a range of intensities. We have only begun to explore how to catalog the reports for Hawai`i.

The USGS Fact Sheet, "Did You Feel It? Citizens Contribute to Earthquake Science," describes the importance of CIIMs.

"Since the early 1990s, the magnitude and location of an earthquake have been available within minutes on the Internet. Now, as a result of work by the U.S. Geological Survey and with the cooperation of various regional seismic networks, people who experience an earthquake can go online and share information about its effects to help create a map of shaking intensities and damage. Such 'Community Internet Intensity Maps' (CIIMs) contribute greatly toward the quick assessment of the scope of an earthquake emergency and provide valuable data for earthquake research."

The entire fact sheet is available online. Visit the above sites to see how your contributions could impact earthquake information products.

Please continue to report your felt earthquake observations. We thank you for your past and continued support.


Volcano Activity Update

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater. Lava continues to flow through the PKK lava tube from its source on the flank of Pu`u `O`o to the ocean. Surface flow activity is mainly limited to the margins of the "Campout flow," on the coastal plain. In early August, the Campout flow entered the ocean at East Ka`ili`ili, where the lava bench is now about 550 m (1800 ft) long with an area of about 1.8 ha (4.5 acres). As of August 23, the new ocean entry, which is located 7.8 km (4.7 mi) from the end of Chain of Craters Road, was still active.

Lava is still entering the ocean at East Lae`apuki, also in Hawai`i Volcanoes National Park. The lava bench has refilled the gap left by the partial collapse on July 30 and has a total surface area of about 21 ha (53 acres).

Access to the sea cliff near the ocean entries is closed, due to significant hazards. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

One earthquake beneath Hawai`i Island was reported felt during the week ending August 23. The quake, which occurred at 10:31 a.m. on August 21, 6 km (4 mi) north of Ka`ena Point, had a magnitude of 3.7 and a depth of 9 km (5 mi).

Mauna Loa is not erupting. During the past week, four short-period, intermediate-depth earthquakes were recorded southeast of the summit, and eight long-period, deep earthquakes were recorded southwest of the summit. Extension of distances between locations spanning the summit, indicating inflation, continues at slow rates.