The U.S. Geological Survey recorded a moment-magnitude 6.4 quake at 03:34:59 UTC on Nov. 9, centered 30 km west-southwest of Lata in the Solomon Islands at a depth of 17 km. In the Solomons, which keep to UTC plus 11, the ground shook at about 2:35 in the afternoon. The agency’s automated loss-estimation system, PAGER, rated the event green for both casualties and economic losses.
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A smaller shock followed within two hours. The USGS catalog lists an M4.8 event at 05:16:56 UTC, 26 km southwest of Lata and 10 km deep. Between them, those two earthquakes were the only magnitude 4 or larger events logged within 150 km of the mainshock on Nov. 9 when the catalog was queried.
The USGS solution for event us7000tx16
The agency’s event page for us7000tx16 carries the reviewed solution, and the machine-readable catalog record fills in the details: a Mww magnitude of 6.4 (a moment magnitude derived from long-period seismic waves, the standard measure for events this size), coordinates near 10.87 degrees south and 165.56 degrees east, a status of reviewed, and 129 stations contributing to the location. Its significance score is 630 and the estimated peak shaking intensity is about 6.4 on the Modified Mercalli scale.
The record’s tsunami flag was 0, and no felt reports had been entered when the data was pulled. Lata is the provincial capital of Temotu Province, a scattering of islands with small towns and villages rather than large cities, the island group at the far southeastern end of the Solomons chain, so an epicenter offshore to the west-southwest places the strongest shaking close to the town without putting the capital, Honiara, anywhere near it.
Timing helps explain how the sequence unfolded. The M4.8 event came about an hour and 42 minutes after the mainshock, shallower at 10 km, and roughly 4 km closer to the southwest. Aftershocks of that size are routine after a magnitude 6.4 event, and the catalog showed no larger follow-up shock, and a single M4 or larger shock in that interval points to a sequence that had not become energetic at the time the catalog was searched.
A green PAGER rating and roughly 21,000 people in the shaking footprint
According to the PAGER one-pager, the model sees a low likelihood of casualties and damage. It estimates about 4,000 people exposed to light shaking at intensity IV, about 5,000 to moderate shaking at intensity V and about 12,000 to strong shaking at intensity VI, with no estimated exposure at intensity VII or above. Damage at those levels is expected to be light to moderate.
The caution in the one-pager concerns construction. Most residents live in structures classed as vulnerable to shaking, chiefly mud-wall and informal buildings of metal, timber and galvanized iron, and those would fare worse than resistant buildings at the same intensity. USGS also stresses that PAGER output is generated automatically, models only structural damage and carries uncertainty in its inputs and loss models. The system’s design and color scale are described on the PAGER program page.
Earlier earthquakes near Lata in the PAGER record
The one-pager also lists three past events that exposed comparable populations. A 1999 magnitude 6.8 earthquake struck just 7 km from the current epicenter and put about 7,000 people at intensity VIII. A 1989 magnitude 6.9 shock 345 km away produced intensity VIII for about 5,000, and a 1980 magnitude 6.0 event 224 km away produced intensity IV for about 2,000. PAGER lists no deaths for any of the three.
The fastest way to follow the aftermath is the catalog search for magnitude 4 and larger events within 150 km, which showed only the M4.8 aftershock beyond the mainshock itself.
The shaking itself would have been felt as strong near the epicenter. The estimated peak intensity of about 6.4 sits at the boundary between moderate and strong on the Modified Mercalli scale, a level at which shaking is felt by nearly everyone nearby and weakly built structures can be damaged. The PAGER exposure table puts the 12,000 people at intensity VI as the group most likely to have noticed damage to weaker structures.
The 1999 comparison is the one local officials are likely to keep in view. That earthquake was larger at magnitude 6.8 and struck almost under the same stretch of coast, yet the PAGER record lists no deaths from it, which suggests that damage in the Temotu islands tends to fall on houses and community buildings rather than in loss of life. The Nov. 9 event was smaller and, at 30 km offshore, a little farther from the town.
What remains unresolved is the human side. USGS reported no felt reports and modeled no exposure at damaging intensities, but the model cannot see individual houses, and the agency’s own record of 1999, when the shaking reached intensity VIII about 7 km away, is the nearest benchmark for what a closer or deeper rupture would have done.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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