Phone call about an earthquake
Phone call about an earthquake was Originally Posted on January 17, 2010 by lavarock
A friend asked me if we just had an earthquake. My answer was “yes”, but I’m not sure my answer was correct for his question. He may not have been following the news and thought that the Haiti quake was out here. We certainly get our share of quakes, in fact, there is usually at least a quake a day; sometimes hundreds a day.
Our current list of quakes is at: http://tux.wr.usgs.gov/Quakes/quakes0.html however, note that this page is automatically updated and by tomorrow, may be different. The current list of quakes (as of 1-17-10) ranges from 1.7 to 3.1 magnitude. The closest quake to my house was about 4 miles away on 1.6 and was a 1.8 magnitude.
Our largest in recent history was a 6.8 on October 15, 2006 and was documented here:
The following is a release by the United States Geological Survey, National Earthquake Information Center: A strong earthquake occurred about 10 miles (15 km) north-northwest of Kailua Kona or 65 miles (100 km) west of Hilo, Hawai`i at 11:07 AM MDT, Oct 15, 2006 (7:07 AM HST in Hawaii). The magnitude and location may be revised when additional data and further analysis results are available.
Numerous people suffered minor injuries, at least 1,173 buildings damaged, roads damaged and landslides blocked roads on Hawai`i. Power outages occurred throughout the Hawaiian Islands. Damage estimated at 73 million dollars. Felt (VII-VIII) in northern and western Hawai`i and (V-VI) in eastern and southern Hawai`i. Also felt (VI) on Maui; (V) on Lana`i, Moloka`i and O`ahu; (IV) on Kaua`i. A tsunami with a wave height of 10 cm was recorded at Kawaihae Harbor.
The Island of Hawaii is the youngest island in a chain of volcanoes that stretches about 3500 miles across the northern Pacific Ocean. The island chain results from a magma source that originates deep beneath the crust. The ocean crust and lithosphere above the magma source, within the Pacific tectonic plate, move to the northwest with respect to the deep magma source. Over millions of years, new island volcanoes are formed and older volcanoes are carried away from the magma source, erode, and eventually subside beneath sea level.
The 15 October earthquake is probably not directly related to future volcanic eruptions. Non-volcanic Hawaiian earthquakes reflect the long-term accumulation and release of lithospheric stresses, rather than short-term processes associated with the motion of magma before or during an eruption. The long-term stresses consist in part of stresses generated in the crust and mantle by the weight of the volcanic rock that composes the islands. In that sense, most Hawaiian earthquakes that are not directly associated with eruptions are nonetheless broadly related to volcanic activity.
Earthquakes on the volcanic Island of Hawaii are not rare. The largest on record was the magnitude 7.9 1868 earthquake near the south coast which triggered a tsunami that drowned 46 people and which spawned numerous landslides that resulted in 31 deaths. A magnitude 6.9 tremor on August 21, 1951, damaged scores of homes on the Kona coast and triggered numerous damaging landslides.
The interesting thing to note was that although we had many building with damage, only a few actually collapsed (I think it was 3), and numerous people experienced minor injuries. The “tsunami” generated was 10 centimeters! We were very lucky that our buildings are to earthquake standards and not very tall.
A video of the quake effecting a pool is on Youtube: http://www.youtube.com/watch?v=31rosvopLb0